Add editing functionality to the bookmarks database view. https://redmine.stoutner...

[PrivacyBrowserAndroid.git] / app / src / main / java / com / stoutner / privacybrowser / activities / MainWebViewActivity.java

/*
 * Copyright © 2015-2017 Soren Stoutner <soren@stoutner.com>.
 *
 * Download cookie code contributed 2017 Hendrik Knackstedt.  Copyright assigned to Soren Stoutner <soren@stoutner.com>.
 *
 * This file is part of Privacy Browser <https://www.stoutner.com/privacy-browser>.
 *
 * Privacy Browser is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Privacy Browser is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Privacy Browser.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.stoutner.privacybrowser.activities;

import android.annotation.SuppressLint;
import android.app.DialogFragment;
import android.app.DownloadManager;
import android.content.BroadcastReceiver;
import android.content.ClipData;
import android.content.ClipboardManager;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.SharedPreferences;
import android.content.res.Configuration;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Typeface;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.net.Uri;
import android.net.http.SslCertificate;
import android.net.http.SslError;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.preference.PreferenceManager;
import android.print.PrintDocumentAdapter;
import android.print.PrintManager;
import android.support.annotation.NonNull;
import android.support.design.widget.CoordinatorLayout;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.NavigationView;
import android.support.design.widget.Snackbar;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.app.AppCompatDialogFragment;
import android.support.v7.widget.Toolbar;
import android.text.Editable;
import android.text.Spanned;
import android.text.TextWatcher;
import android.text.style.ForegroundColorSpan;
import android.util.Patterns;
import android.view.ContextMenu;
import android.view.GestureDetector;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.view.inputmethod.InputMethodManager;
import android.webkit.CookieManager;
import android.webkit.HttpAuthHandler;
import android.webkit.SslErrorHandler;
import android.webkit.WebBackForwardList;
import android.webkit.WebChromeClient;
import android.webkit.WebResourceResponse;
import android.webkit.WebStorage;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.webkit.WebViewDatabase;
import android.widget.CursorAdapter;
import android.widget.EditText;
import android.widget.FrameLayout;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.RadioButton;
import android.widget.RelativeLayout;
import android.widget.TextView;

import com.stoutner.privacybrowser.BannerAd;
import com.stoutner.privacybrowser.BuildConfig;
import com.stoutner.privacybrowser.R;
import com.stoutner.privacybrowser.dialogs.CreateBookmarkDialog;
import com.stoutner.privacybrowser.dialogs.CreateBookmarkFolderDialog;
import com.stoutner.privacybrowser.dialogs.CreateHomeScreenShortcutDialog;
import com.stoutner.privacybrowser.dialogs.DownloadImageDialog;
import com.stoutner.privacybrowser.dialogs.EditBookmarkDialog;
import com.stoutner.privacybrowser.dialogs.EditBookmarkFolderDialog;
import com.stoutner.privacybrowser.dialogs.HttpAuthenticationDialog;
import com.stoutner.privacybrowser.dialogs.PinnedSslCertificateMismatchDialog;
import com.stoutner.privacybrowser.dialogs.UrlHistoryDialog;
import com.stoutner.privacybrowser.dialogs.ViewSslCertificateDialog;
import com.stoutner.privacybrowser.helpers.BookmarksDatabaseHelper;
import com.stoutner.privacybrowser.helpers.DomainsDatabaseHelper;
import com.stoutner.privacybrowser.helpers.OrbotProxyHelper;
import com.stoutner.privacybrowser.dialogs.DownloadFileDialog;
import com.stoutner.privacybrowser.dialogs.SslCertificateErrorDialog;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

// We need to use AppCompatActivity from android.support.v7.app.AppCompatActivity to have access to the SupportActionBar until the minimum API is >= 21.
public class MainWebViewActivity extends AppCompatActivity implements CreateBookmarkDialog.CreateBookmarkListener, CreateBookmarkFolderDialog.CreateBookmarkFolderListener, CreateHomeScreenShortcutDialog.CreateHomeScreenSchortcutListener,
        DownloadFileDialog.DownloadFileListener, DownloadImageDialog.DownloadImageListener, EditBookmarkDialog.EditBookmarkListener, EditBookmarkFolderDialog.EditBookmarkFolderListener, HttpAuthenticationDialog.HttpAuthenticationListener,
        NavigationView.OnNavigationItemSelectedListener, PinnedSslCertificateMismatchDialog.PinnedSslCertificateMismatchListener, SslCertificateErrorDialog.SslCertificateErrorListener, UrlHistoryDialog.UrlHistoryListener {

    // `darkTheme` is public static so it can be accessed from `AboutActivity`, `GuideActivity`, `AddDomainDialog`, `SettingsActivity`, `DomainsActivity`, `DomainsListFragment`, `BookmarksActivity`, `BookmarksDatabaseViewActivity`,
    // `CreateBookmarkDialog`, `CreateBookmarkFolderDialog`, `DownloadFileDialog`, `DownloadImageDialog`, `EditBookmarkDialog`, `EditBookmarkFolderDialog`, `EditBookmarkDatabaseViewDialog`, `HttpAuthenticationDialog`, `MoveToFolderDialog`,
    // `SslCertificateErrorDialog`, `UrlHistoryDialog`, `ViewSslCertificateDialog`, `CreateHomeScreenShortcutDialog`, and `OrbotProxyHelper`. It is also used in `onCreate()`, `applyAppSettings()`, `applyDomainSettings()`, and `updatePrivacyIcons()`.
    public static boolean darkTheme;

    // `favoriteIconBitmap` is public static so it can be accessed from `CreateHomeScreenShortcutDialog`, `BookmarksActivity`, `BookmarksDatabaseViewActivity`, `CreateBookmarkDialog`, `CreateBookmarkFolderDialog`, `EditBookmarkDialog`,
    // `EditBookmarkFolderDialog`, `EditBookmarkDatabaseViewDialog`, and `ViewSslCertificateDialog`.  It is also used in `onCreate()`, `onCreateBookmark()`, `onCreateBookmarkFolder()`, `onCreateHomeScreenShortcutCreate()`, `onSaveEditBookmark()`,
    // `onSaveEditBookmarkFolder()`, and `applyDomainSettings()`.
    public static Bitmap favoriteIconBitmap;

    // `formattedUrlString` is public static so it can be accessed from `BookmarksActivity`, `CreateBookmarkDialog`, and `AddDomainDialog`.
    // It is also used in `onCreate()`, `onOptionsItemSelected()`, `onNavigationItemSelected()`, `onCreateHomeScreenShortcutCreate()`, and `loadUrlFromTextBox()`.
    public static String formattedUrlString;

    // `sslCertificate` is public static so it can be accessed from `DomainsActivity`, `DomainsListFragment`, `DomainSettingsFragment`, `PinnedSslCertificateMismatchDialog`, and `ViewSslCertificateDialog`.  It is also used in `onCreate()`.
    public static SslCertificate sslCertificate;

    // `orbotStatus` is public static so it can be accessed from `OrbotProxyHelper`.  It is also used in `onCreate()`.
    public static String orbotStatus;

    // `webViewTitle` is public static so it can be accessed from `CreateBookmarkDialog` and `CreateHomeScreenShortcutDialog`.  It is also used in `onCreate()`.
    public static String webViewTitle;

    // `displayWebpageImagesBoolean` is public static so it can be accessed from `DomainSettingsFragment`.  It is also used in `applyAppSettings()` and `applyDomainSettings()`.
    public static boolean displayWebpageImagesBoolean;

    // `reloadOnRestart` is public static so it can be accessed from `SettingsFragment`.  It is also used in `onRestart()`
    public static boolean reloadOnRestart;

    // `reloadUrlOnRestart` is public static so it can be accessed from `SettingsFragment`.  It is also used in `onRestart()`.
    public static boolean loadUrlOnRestart;

    // `restartFromBookmarksActivity` is public static so it can be accessed from `BookmarksActivity`.  It is also used in `onRestart()`.
    public static boolean restartFromBookmarksActivity;

    // `currentBookmarksFolder` is public static so it can be accessed from `BookmarksActivity`.  It is also used in `onCreate()`, `onBackPressed()`, `onCreateBookmark()`, `onCreateBookmarkFolder()`, `onSaveEditBookmark()`, `onSaveEditBookmarkFolder()`, and
    // `loadBookmarksFolder()`.
    public static String currentBookmarksFolder;

    // The pinned domain SSL Certificate variables are public static so they can be accessed from `PinnedSslCertificateMismatchDialog`.  They are also used in `onCreate()` and `applyDomainSettings()`.
    public static int domainSettingsDatabaseId;
    public static String pinnedDomainSslIssuedToCNameString;
    public static String pinnedDomainSslIssuedToONameString;
    public static String pinnedDomainSslIssuedToUNameString;
    public static String pinnedDomainSslIssuedByCNameString;
    public static String pinnedDomainSslIssuedByONameString;
    public static String pinnedDomainSslIssuedByUNameString;
    public static Date pinnedDomainSslStartDate;
    public static Date pinnedDomainSslEndDate;


    // `appBar` is used in `onCreate()`, `onOptionsItemSelected()`, `closeFindOnPage()`, and `applyAppSettings()`.
    private ActionBar appBar;

    // `navigatingHistory` is used in `onCreate()`, `onNavigationItemSelected()`, `onSslMismatchBack()`, and `applyDomainSettings()`.
    private boolean navigatingHistory;

    // `favoriteIconDefaultBitmap` is used in `onCreate()` and `applyDomainSettings`.
    private Bitmap favoriteIconDefaultBitmap;

    // `drawerLayout` is used in `onCreate()`, `onNewIntent()`, `onBackPressed()`, and `onRestart()`.
    private DrawerLayout drawerLayout;

    // `rootCoordinatorLayout` is used in `onCreate()` and `applyAppSettings()`.
    private CoordinatorLayout rootCoordinatorLayout;

    // `mainWebView` is used in `onCreate()`, `onPrepareOptionsMenu()`, `onOptionsItemSelected()`, `onNavigationItemSelected()`, `onRestart()`, `onCreateContextMenu()`, `findPreviousOnPage()`, `findNextOnPage()`, `closeFindOnPage()`, `loadUrlFromTextBox()`
    // `onSslMismatchBack()`, and `setDisplayWebpageImages()`.
    private WebView mainWebView;

    // `fullScreenVideoFrameLayout` is used in `onCreate()` and `onConfigurationChanged()`.
    private FrameLayout fullScreenVideoFrameLayout;

    // `swipeRefreshLayout` is used in `onCreate()`, `onPrepareOptionsMenu`, and `onRestart()`.
    private SwipeRefreshLayout swipeRefreshLayout;

    // `urlAppBarRelativeLayout` is used in `onCreate()` and `applyDomainSettings()`.
    private RelativeLayout urlAppBarRelativeLayout;

    // `favoriteIconImageView` is used in `onCreate()` and `applyDomainSettings()`
    private ImageView favoriteIconImageView;

    // `cookieManager` is used in `onCreate()`, `onOptionsItemSelected()`, and `onNavigationItemSelected()`, `loadUrlFromTextBox()`, `onDownloadImage()`, `onDownloadFile()`, and `onRestart()`.
    private CookieManager cookieManager;

    // `customHeader` is used in `onCreate()`, `onOptionsItemSelected()`, `onCreateContextMenu()`, and `loadUrl()`.
    private final Map<String, String> customHeaders = new HashMap<>();

    // `javaScriptEnabled` is also used in `onCreate()`, `onPrepareOptionsMenu()`, `onOptionsItemSelected()`, `applyDomainSettings()`, and `updatePrivacyIcons()`.
    private boolean javaScriptEnabled;

    // `firstPartyCookiesEnabled` is used in `onCreate()`, `onPrepareOptionsMenu()`, `onOptionsItemSelected()`, `onDownloadImage()`, `onDownloadFile()`, and `applyDomainSettings()`.
    private boolean firstPartyCookiesEnabled;

    // `thirdPartyCookiesEnabled` used in `onCreate()`, `onPrepareOptionsMenu()`, `onPrepareOptionsMenu()`, `onOptionsItemSelected()`, and `applyDomainSettings()`.
    private boolean thirdPartyCookiesEnabled;

    // `domStorageEnabled` is used in `onCreate()`, `onPrepareOptionsMenu()`, `onOptionsItemSelected()`, and `applyDomainSettings()`.
    private boolean domStorageEnabled;

    // `saveFormDataEnabled` is used in `onCreate()`, `onPrepareOptionsMenu()`, `onOptionsItemSelected()`, and `applyDomainSettings()`.
    private boolean saveFormDataEnabled;

    // `nightMode` is used in `onCreate()` and  `applyDomainSettings()`.
    private boolean nightMode;

    // `swipeToRefreshEnabled` is used in `onPrepareOptionsMenu()` and `applyAppSettings()`.
    private boolean swipeToRefreshEnabled;

    // 'homepage' is used in `onCreate()`, `onNavigationItemSelected()`, and `applyAppSettings()`.
    private String homepage;

    // `searchURL` is used in `loadURLFromTextBox()` and `applyAppSettings()`.
    private String searchURL;

    // `adBlockerEnabled` is used in `onCreate()` and `applyAppSettings()`.
    private boolean adBlockerEnabled;

    // `privacyBrowserRuntime` is used in `onCreate()`, `onOptionsItemSelected()`, and `applyAppSettings()`.
    private Runtime privacyBrowserRuntime;

    // `incognitoModeEnabled` is used in `onCreate()` and `applyAppSettings()`.
    private boolean incognitoModeEnabled;

    // `fullScreenBrowsingModeEnabled` is used in `onCreate()` and `applyAppSettings()`.
    private boolean fullScreenBrowsingModeEnabled;

    // `inFullScreenBrowsingMode` is used in `onCreate()`, `onConfigurationChanged()`, and `applyAppSettings()`.
    private boolean inFullScreenBrowsingMode;

    // `hideSystemBarsOnFullscreen` is used in `onCreate()` and `applyAppSettings()`.
    private boolean hideSystemBarsOnFullscreen;

    // `translucentNavigationBarOnFullscreen` is used in `onCreate()` and `applyAppSettings()`.
    private boolean translucentNavigationBarOnFullscreen;

    // `currentDomainName` is used in `onCreate()`, `onNavigationItemSelected()`, `onSslMismatchProceed()`, and `applyDomainSettings()`.
    private String currentDomainName;

    // `ignorePinnedSslCertificateForDomain` is used in `onCreate()`, `onSslMismatchProceed()`, and `applyDomainSettings()`.
    private boolean ignorePinnedSslCertificate;

    // `waitingForOrbot` is used in `onCreate()` and `applyAppSettings()`.
    private boolean waitingForOrbot;

    // `domainSettingsApplied` is used in `applyDomainSettings()` and `setDisplayWebpageImages()`.
    private boolean domainSettingsApplied;

    // `displayWebpageImagesInt` is used in `applyDomainSettings()` and `setDisplayWebpageImages()`.
    private int displayWebpageImagesInt;

    // `onTheFlyDisplayImagesSet` is used in `applyDomainSettings()` and `setDisplayWebpageImages()`.
    private boolean onTheFlyDisplayImagesSet;

    // `waitingForOrbotData` is used in `onCreate()` and `applyAppSettings()`.
    private String waitingForOrbotHTMLString;

    // `privateDataDirectoryString` is used in `onCreate()`, `onOptionsItemSelected()`, and `onNavigationItemSelected()`.
    private String privateDataDirectoryString;

    // `findOnPageLinearLayout` is used in `onCreate()`, `onOptionsItemSelected()`, and `closeFindOnPage()`.
    private LinearLayout findOnPageLinearLayout;

    // `findOnPageEditText` is used in `onCreate()`, `onOptionsItemSelected()`, and `closeFindOnPage()`.
    private EditText findOnPageEditText;

    // `mainMenu` is used in `onCreateOptionsMenu()` and `updatePrivacyIcons()`.
    private Menu mainMenu;

    // `drawerToggle` is used in `onCreate()`, `onPostCreate()`, `onConfigurationChanged()`, `onNewIntent()`, and `onNavigationItemSelected()`.
    private ActionBarDrawerToggle drawerToggle;

    // `supportAppBar` is used in `onCreate()`, `onOptionsItemSelected()`, and `closeFindOnPage()`.
    private Toolbar supportAppBar;

    // `urlTextBox` is used in `onCreate()`, `onOptionsItemSelected()`, `loadUrlFromTextBox()`, `loadUrl()`, and `highlightUrlText()`.
    private EditText urlTextBox;

    // `redColorSpan` is used in `onCreate()` and `highlightUrlText()`.
    private ForegroundColorSpan redColorSpan;

    // `initialGrayColorSpan` is sued in `onCreate()` and `highlightUrlText()`.
    private ForegroundColorSpan initialGrayColorSpan;

    // `finalGrayColorSpam` is used in `onCreate()` and `highlightUrlText()`.
    private ForegroundColorSpan finalGrayColorSpan;

    // `adView` is used in `onCreate()` and `onConfigurationChanged()`.
    private View adView;

    // `sslErrorHandler` is used in `onCreate()`, `onSslErrorCancel()`, and `onSslErrorProceed`.
    private SslErrorHandler sslErrorHandler;

    // `httpAuthHandler` is used in `onCreate()`, `onHttpAuthenticationCancel()`, and `onHttpAuthenticationProceed()`.
    private static HttpAuthHandler httpAuthHandler;

    // `inputMethodManager` is used in `onOptionsItemSelected()`, `loadUrlFromTextBox()`, and `closeFindOnPage()`.
    private InputMethodManager inputMethodManager;

    // `mainWebViewRelativeLayout` is used in `onCreate()` and `onNavigationItemSelected()`.
    private RelativeLayout mainWebViewRelativeLayout;

    // `urlIsLoading` is used in `onCreate()`, `loadUrl()`, and `applyDomainSettings()`.
    private boolean urlIsLoading;

    // `pinnedDomainSslCertificate` is used in `onCreate()` and `applyDomainSettings()`.
    private boolean pinnedDomainSslCertificate;

    // `bookmarksDatabaseHelper` is used in `onCreate()`, `onCreateBookmark()`, `onCreateBookmarkFolder()`, `onSaveEditBookmark()`, `onSaveEditBookmarkFolder()`, and `loadBookmarksFolder()`.
    private BookmarksDatabaseHelper bookmarksDatabaseHelper;

    // `bookmarksListView` is used in `onCreate()`, `onCreateBookmark()`, `onCreateBookmarkFolder()`, and `loadBookmarksFolder()`.
    private ListView bookmarksListView;

    // `bookmarksTitleTextView` is used in `onCreate()` and `loadBookmarksFolder()`.
    private TextView bookmarksTitleTextView;

    // `bookmarksCursor` is used in `onCreateBookmark()`, `onCreateBookmarkFolder()`, `onSaveEditBookmark()`, `onSaveEditBookmarkFolder()`, and `loadBookmarksFolder()`.
    private Cursor bookmarksCursor;

    // `bookmarksCursorAdapter` is used in `onCreateBookmark()`, `onCreateBookmarkFolder()` `onSaveEditBookmark()`, `onSaveEditBookmarkFolder()`, and `loadBookmarksFolder()`.
    private CursorAdapter bookmarksCursorAdapter;

    // `oldFolderNameString` is used in `onCreate()` and `onSaveEditBookmarkFolder()`.
    private String oldFolderNameString;

    @Override
    // Remove Android Studio's warning about the dangers of using SetJavaScriptEnabled.  The whole premise of Privacy Browser is built around an understanding of these dangers.
    @SuppressLint({"SetJavaScriptEnabled"})
    // Remove Android Studio's warning about deprecations.  We have to use the deprecated `getColor()` until API >= 23.
    @SuppressWarnings("deprecation")
    protected void onCreate(Bundle savedInstanceState) {
        // Get a handle for `sharedPreferences`.  `this` references the current context.
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);

        // Get the theme preference.
        darkTheme = sharedPreferences.getBoolean("dark_theme", false);

        // Set the activity theme.
        if (darkTheme) {
            setTheme(R.style.PrivacyBrowserDark);
        } else {
            setTheme(R.style.PrivacyBrowserLight);
        }

        // Run the default commands.
        super.onCreate(savedInstanceState);

        // Set the content view.
        setContentView(R.layout.main_drawerlayout);

        // Get a handle for `inputMethodManager`.
        inputMethodManager = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);

        // `SupportActionBar` from `android.support.v7.app.ActionBar` must be used until the minimum API is >= 21.
        supportAppBar = findViewById(R.id.app_bar);
        setSupportActionBar(supportAppBar);
        appBar = getSupportActionBar();

        // This is needed to get rid of the Android Studio warning that `appBar` might be null.
        assert appBar != null;

        // Add the custom `url_app_bar` layout, which shows the favorite icon and the URL text bar.
        appBar.setCustomView(R.layout.url_app_bar);
        appBar.setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);

        // Initialize the `ForegroundColorSpans` and `StyleSpan` for highlighting `urlTextBox`.  We have to use the deprecated `getColor()` until API >= 23.
        redColorSpan = new ForegroundColorSpan(getResources().getColor(R.color.red_a700));
        initialGrayColorSpan = new ForegroundColorSpan(getResources().getColor(R.color.gray_500));
        finalGrayColorSpan = new ForegroundColorSpan(getResources().getColor(R.color.gray_500));

        // Get a handle for `urlTextBox`.
        urlTextBox = appBar.getCustomView().findViewById(R.id.url_edittext);

        // Remove the formatting from `urlTextBar` when the user is editing the text.
        urlTextBox.setOnFocusChangeListener((v, hasFocus) -> {
            if (hasFocus) {  // The user is editing `urlTextBox`.
                // Remove the highlighting.
                urlTextBox.getText().removeSpan(redColorSpan);
                urlTextBox.getText().removeSpan(initialGrayColorSpan);
                urlTextBox.getText().removeSpan(finalGrayColorSpan);
            } else {  // The user has stopped editing `urlTextBox`.
                // Reapply the highlighting.
                highlightUrlText();
            }
        });

        // Set the `Go` button on the keyboard to load the URL in `urlTextBox`.
        urlTextBox.setOnKeyListener((v, keyCode, event) -> {
            // If the event is a key-down event on the `enter` button, load the URL.
            if ((event.getAction() == KeyEvent.ACTION_DOWN) && (keyCode == KeyEvent.KEYCODE_ENTER)) {
                // Load the URL into the mainWebView and consume the event.
                try {
                    loadUrlFromTextBox();
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
                // If the enter key was pressed, consume the event.
                return true;
            } else {
                // If any other key was pressed, do not consume the event.
                return false;
            }
        });

        // Set `waitingForOrbotHTMLString`.
        waitingForOrbotHTMLString = "<html><body><br/><center><h1>" + getString(R.string.waiting_for_orbot) + "</h1></center></body></html>";

        // Initialize `currentDomainName`, `orbotStatus`, and `waitingForOrbot`.
        currentDomainName = "";
        orbotStatus = "unknown";
        waitingForOrbot = false;

        // Create an Orbot status `BroadcastReceiver`.
        BroadcastReceiver orbotStatusBroadcastReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                // Store the content of the status message in `orbotStatus`.
                orbotStatus = intent.getStringExtra("org.torproject.android.intent.extra.STATUS");

                // If we are waiting on Orbot, load the website now that Orbot is connected.
                if (orbotStatus.equals("ON") && waitingForOrbot) {
                    // Reset `waitingForOrbot`.
                    waitingForOrbot = false;

                    // Load `formattedUrlString
                    loadUrl(formattedUrlString);
                }
            }
        };

        // Register `orbotStatusBroadcastReceiver` on `this` context.
        this.registerReceiver(orbotStatusBroadcastReceiver, new IntentFilter("org.torproject.android.intent.action.STATUS"));

        // Get handles for views that need to be accessed.
        drawerLayout = findViewById(R.id.drawerlayout);
        rootCoordinatorLayout = findViewById(R.id.root_coordinatorlayout);
        bookmarksListView = findViewById(R.id.bookmarks_drawer_listview);
        bookmarksTitleTextView = findViewById(R.id.bookmarks_title_textview);
        FloatingActionButton launchBookmarksActivityFab = findViewById(R.id.launch_bookmarks_activity_fab);
        FloatingActionButton createBookmarkFolderFab = findViewById(R.id.create_bookmark_folder_fab);
        FloatingActionButton createBookmarkFab = findViewById(R.id.create_bookmark_fab);
        mainWebViewRelativeLayout = findViewById(R.id.main_webview_relativelayout);
        mainWebView = findViewById(R.id.main_webview);
        findOnPageLinearLayout = findViewById(R.id.find_on_page_linearlayout);
        findOnPageEditText = findViewById(R.id.find_on_page_edittext);
        fullScreenVideoFrameLayout = findViewById(R.id.full_screen_video_framelayout);
        urlAppBarRelativeLayout = findViewById(R.id.url_app_bar_relativelayout);
        favoriteIconImageView = findViewById(R.id.favorite_icon);

        // Set the bookmarks drawer resources according to the theme.  This can't be done in the layout due to compatibility issues with the `DrawerLayout` support widget.
        if (darkTheme) {
            launchBookmarksActivityFab.setImageDrawable(getResources().getDrawable(R.drawable.bookmarks_dark));
            createBookmarkFolderFab.setImageDrawable(getResources().getDrawable(R.drawable.create_folder_dark));
            createBookmarkFab.setImageDrawable(getResources().getDrawable(R.drawable.create_bookmark_dark));
            bookmarksListView.setBackgroundColor(getResources().getColor(R.color.gray_850));
        } else {
            launchBookmarksActivityFab.setImageDrawable(getResources().getDrawable(R.drawable.bookmarks_light));
            createBookmarkFolderFab.setImageDrawable(getResources().getDrawable(R.drawable.create_folder_light));
            createBookmarkFab.setImageDrawable(getResources().getDrawable(R.drawable.create_bookmark_light));
            bookmarksListView.setBackgroundColor(getResources().getColor(R.color.white));
        }

        // Set the launch bookmarks activity FAB to launch the bookmarks activity.
        launchBookmarksActivityFab.setOnClickListener(v -> {
            // Create an intent to launch the bookmarks activity.
            Intent bookmarksIntent = new Intent(getApplicationContext(), BookmarksActivity.class);

            // Include the current folder with the `Intent`.
            bookmarksIntent.putExtra("Current Folder", currentBookmarksFolder);

            // Make it so.
            startActivity(bookmarksIntent);
        });

        // Set the create new bookmark folder FAB to display the `AlertDialog`.
        createBookmarkFolderFab.setOnClickListener(v -> {
            // Show the `CreateBookmarkFolderDialog` `AlertDialog` and name the instance `@string/create_folder`.
            AppCompatDialogFragment createBookmarkFolderDialog = new CreateBookmarkFolderDialog();
            createBookmarkFolderDialog.show(getSupportFragmentManager(), getResources().getString(R.string.create_folder));
        });

        // Set the create new bookmark FAB to display the `AlertDialog`.
        createBookmarkFab.setOnClickListener(view -> {
            // Show the `CreateBookmarkDialog` `AlertDialog` and name the instance `@string/create_bookmark`.
            AppCompatDialogFragment createBookmarkDialog = new CreateBookmarkDialog();
            createBookmarkDialog.show(getSupportFragmentManager(), getResources().getString(R.string.create_bookmark));
        });

        // Create a double-tap listener to toggle full-screen mode.
        final GestureDetector gestureDetector = new GestureDetector(this, new GestureDetector.SimpleOnGestureListener() {
            // Override `onDoubleTap()`.  All other events are handled using the default settings.
            @Override
            public boolean onDoubleTap(MotionEvent event) {
                if (fullScreenBrowsingModeEnabled) {  // Only process the double-tap if full screen browsing mode is enabled.
                    // Toggle `inFullScreenBrowsingMode`.
                    inFullScreenBrowsingMode = !inFullScreenBrowsingMode;

                    if (inFullScreenBrowsingMode) {  // Switch to full screen mode.
                        // Hide the `appBar`.
                        appBar.hide();

                        // Hide the `BannerAd` in the free flavor.
                        if (BuildConfig.FLAVOR.contentEquals("free")) {
                            BannerAd.hideAd(adView);
                        }

                        // Modify the system bars.
                        if (hideSystemBarsOnFullscreen) {  // Hide everything.
                            // Remove the translucent overlays.
                            getWindow().clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);

                            // Remove the translucent status bar overlay on the `Drawer Layout`, which is special and needs its own command.
                            drawerLayout.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);

                            /* SYSTEM_UI_FLAG_FULLSCREEN hides the status bar at the top of the screen.
                             * SYSTEM_UI_FLAG_HIDE_NAVIGATION hides the navigation bar on the bottom or right of the screen.
                             * SYSTEM_UI_FLAG_IMMERSIVE_STICKY makes the status and navigation bars translucent and automatically rehides them after they are shown.
                             */
                            rootCoordinatorLayout.setSystemUiVisibility(View.SYSTEM_UI_FLAG_FULLSCREEN | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY);

                            // Set `rootCoordinatorLayout` to fill the whole screen.
                            rootCoordinatorLayout.setFitsSystemWindows(false);
                        } else {  // Hide everything except the status and navigation bars.
                            // Set `rootCoordinatorLayout` to fit under the status and navigation bars.
                            rootCoordinatorLayout.setFitsSystemWindows(false);

                            if (translucentNavigationBarOnFullscreen) {  // There is an Android Support Library bug that causes a scrim to print on the right side of the `Drawer Layout` when the navigation bar is displayed on the right of the screen.
                                // Set the navigation bar to be translucent.
                                getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);
                            }
                        }
                    } else {  // Switch to normal viewing mode.
                        // Show the `appBar`.
                        appBar.show();

                        // Show the `BannerAd` in the free flavor.
                        if (BuildConfig.FLAVOR.contentEquals("free")) {
                            // Reload the ad.  Because the screen may have rotated, we need to use `reloadAfterRotate`.
                            BannerAd.reloadAfterRotate(adView, getApplicationContext(), getString(R.string.ad_id));

                            // Reinitialize the `adView` variable, as the `View` will have been removed and re-added by `BannerAd.reloadAfterRotate()`.
                            adView = findViewById(R.id.adview);
                        }

                        // Remove the translucent navigation bar flag if it is set.
                        getWindow().clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);

                        // Add the translucent status flag if it is unset.  This also resets `drawerLayout's` `View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN`.
                        getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);

                        // Remove any `SYSTEM_UI` flags from `rootCoordinatorLayout`.
                        rootCoordinatorLayout.setSystemUiVisibility(0);

                        // Constrain `rootCoordinatorLayout` inside the status and navigation bars.
                        rootCoordinatorLayout.setFitsSystemWindows(true);
                    }

                    // Consume the double-tap.
                    return true;
                } else { // Do not consume the double-tap because full screen browsing mode is disabled.
                    return false;
                }
            }
        });

        // Pass all touch events on `mainWebView` through `gestureDetector` to check for double-taps.
        mainWebView.setOnTouchListener((View v, MotionEvent event) -> {
            // Call `performClick()` on the view, which is required for accessibility.
            v.performClick();

            // Send the `event` to `gestureDetector`.
            return gestureDetector.onTouchEvent(event);
        });

        // Update `findOnPageCountTextView`.
        mainWebView.setFindListener(new WebView.FindListener() {
            // Get a handle for `findOnPageCountTextView`.
            final TextView findOnPageCountTextView = (TextView) findViewById(R.id.find_on_page_count_textview);

            @Override
            public void onFindResultReceived(int activeMatchOrdinal, int numberOfMatches, boolean isDoneCounting) {
                if ((isDoneCounting) && (numberOfMatches == 0)) {  // There are no matches.
                    // Set `findOnPageCountTextView` to `0/0`.
                    findOnPageCountTextView.setText(R.string.zero_of_zero);
                } else if (isDoneCounting) {  // There are matches.
                    // `activeMatchOrdinal` is zero-based.
                    int activeMatch = activeMatchOrdinal + 1;

                    // Build the match string.
                    String matchString = activeMatch + "/" + numberOfMatches;

                    // Set `findOnPageCountTextView`.
                    findOnPageCountTextView.setText(matchString);
                }
            }
        });

        // Search for the string on the page whenever a character changes in the `findOnPageEditText`.
        findOnPageEditText.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
                // Do nothing.
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                // Do nothing.
            }

            @Override
            public void afterTextChanged(Editable s) {
                // Search for the text in `mainWebView`.
                mainWebView.findAllAsync(findOnPageEditText.getText().toString());
            }
        });

        // Set the `check mark` button for the `findOnPageEditText` keyboard to close the soft keyboard.
        findOnPageEditText.setOnKeyListener((v, keyCode, event) -> {
            if ((event.getAction() == KeyEvent.ACTION_DOWN) && (keyCode == KeyEvent.KEYCODE_ENTER)) {  // The `enter` key was pressed.
                // Hide the soft keyboard.  `0` indicates no additional flags.
                inputMethodManager.hideSoftInputFromWindow(mainWebView.getWindowToken(), 0);

                // Consume the event.
                return true;
            } else {  // A different key was pressed.
                // Do not consume the event.
                return false;
            }
        });

        // Implement swipe to refresh
        swipeRefreshLayout = findViewById(R.id.swipe_refreshlayout);
        swipeRefreshLayout.setColorSchemeResources(R.color.blue_700);
        swipeRefreshLayout.setOnRefreshListener(() -> mainWebView.reload());

        // `DrawerTitle` identifies the `DrawerLayouts` in accessibility mode.
        drawerLayout.setDrawerTitle(GravityCompat.START, getString(R.string.navigation_drawer));
        drawerLayout.setDrawerTitle(GravityCompat.END, getString(R.string.bookmarks));

        // Listen for touches on the navigation menu.
        final NavigationView navigationView = findViewById(R.id.navigationview);
        navigationView.setNavigationItemSelectedListener(this);

        // Get handles for `navigationMenu` and the back and forward menu items.  The menu is zero-based, so items 1, 2, and 3 are the second, third, and fourth entries in the menu.
        final Menu navigationMenu = navigationView.getMenu();
        final MenuItem navigationBackMenuItem = navigationMenu.getItem(1);
        final MenuItem navigationForwardMenuItem = navigationMenu.getItem(2);
        final MenuItem navigationHistoryMenuItem = navigationMenu.getItem(3);

        // Initialize the bookmarks database helper.  `this` specifies the context.  The two `nulls` do not specify the database name or a `CursorFactory`.
        // The `0` specifies a database version, but that is ignored and set instead using a constant in `BookmarksDatabaseHelper`.
        bookmarksDatabaseHelper = new BookmarksDatabaseHelper(this, null, null, 0);

        // Initialize `currentBookmarksFolder`.  `""` is the home folder in the database.
        currentBookmarksFolder = "";

        // Load the home folder, which is `""` in the database.
        loadBookmarksFolder();

        bookmarksListView.setOnItemClickListener((parent, view, position, id) -> {
            // Convert the id from long to int to match the format of the bookmarks database.
            int databaseID = (int) id;

            // Get the bookmark `Cursor` for this ID and move it to the first row.
            Cursor bookmarkCursor = bookmarksDatabaseHelper.getBookmarkCursor(databaseID);
            bookmarkCursor.moveToFirst();

            // Act upon the bookmark according to the type.
            if (bookmarkCursor.getInt(bookmarkCursor.getColumnIndex(BookmarksDatabaseHelper.IS_FOLDER)) == 1) {  // The selected bookmark is a folder.
                // Store the new folder name in `currentBookmarksFolder`.
                currentBookmarksFolder = bookmarkCursor.getString(bookmarkCursor.getColumnIndex(BookmarksDatabaseHelper.BOOKMARK_NAME));

                // Load the new folder.
                loadBookmarksFolder();
            } else {  // The selected bookmark is not a folder.
                // Load the bookmark URL.
                loadUrl(bookmarkCursor.getString(bookmarkCursor.getColumnIndex(BookmarksDatabaseHelper.BOOKMARK_URL)));

                // Close the bookmarks drawer.
                drawerLayout.closeDrawer(GravityCompat.END);
            }

            // Close the `Cursor`.
            bookmarkCursor.close();
        });

        bookmarksListView.setOnItemLongClickListener((parent, view, position, id) -> {
            // Convert the database ID from `long` to `int`.
            int databaseId = (int) id;

            // Find out if the selected bookmark is a folder.
            boolean isFolder = bookmarksDatabaseHelper.isFolder(databaseId);

            if (isFolder) {
                // Save the current folder name, which is used in `onSaveEditBookmarkFolder()`.
                oldFolderNameString = bookmarksCursor.getString(bookmarksCursor.getColumnIndex(BookmarksDatabaseHelper.BOOKMARK_NAME));

                // Show the edit bookmark folder `AlertDialog` and name the instance `@string/edit_folder`.
                AppCompatDialogFragment editFolderDialog = EditBookmarkFolderDialog.folderDatabaseId(databaseId);
                editFolderDialog.show(getSupportFragmentManager(), getResources().getString(R.string.edit_folder));
            } else {
                // Show the edit bookmark `AlertDialog` and name the instance `@string/edit_bookmark`.
                AppCompatDialogFragment editBookmarkDialog = EditBookmarkDialog.bookmarkDatabaseId(databaseId);
                editBookmarkDialog.show(getSupportFragmentManager(), getResources().getString(R.string.edit_bookmark));
            }

            // Consume the event.
            return true;
        });

        // The `DrawerListener` allows us to update the Navigation Menu.
        drawerLayout.addDrawerListener(new DrawerLayout.DrawerListener() {
            @Override
            public void onDrawerSlide(View drawerView, float slideOffset) {
            }

            @Override
            public void onDrawerOpened(View drawerView) {
            }

            @Override
            public void onDrawerClosed(View drawerView) {
            }

            @Override
            public void onDrawerStateChanged(int newState) {
                if ((newState == DrawerLayout.STATE_SETTLING) || (newState == DrawerLayout.STATE_DRAGGING)) {  // The drawer is opening or closing.
                    // Update the `Back`, `Forward`, and `History` menu items.
                    navigationBackMenuItem.setEnabled(mainWebView.canGoBack());
                    navigationForwardMenuItem.setEnabled(mainWebView.canGoForward());
                    navigationHistoryMenuItem.setEnabled((mainWebView.canGoBack() || mainWebView.canGoForward()));

                    // Hide the keyboard (if displayed) so we can see the navigation menu.  `0` indicates no additional flags.
                    inputMethodManager.hideSoftInputFromWindow(mainWebView.getWindowToken(), 0);

                    // Clear the focus from `urlTextBox` if it has it.
                    urlTextBox.clearFocus();
                }
            }
        });

        // drawerToggle creates the hamburger icon at the start of the AppBar.
        drawerToggle = new ActionBarDrawerToggle(this, drawerLayout, supportAppBar, R.string.open_navigation_drawer, R.string.close_navigation_drawer);

        // Initialize `adServerSet`.
        final Set<String> adServersSet = new HashSet<>();

        // Load the list of ad servers into memory.
        try {
            // Load `pgl.yoyo.org_adservers.txt` into a `BufferedReader`.
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(getAssets().open("pgl.yoyo.org_adservers.txt")));

            // Create a string for storing each ad server.
            String adServer;

            // Populate `adServersSet`.
            while ((adServer = bufferedReader.readLine()) != null) {
                adServersSet.add(adServer);
            }

            // Close `bufferedReader`.
            bufferedReader.close();
        } catch (IOException ioException) {
            // We're pretty sure the asset exists, so we don't need to worry about the `IOException` ever being thrown.
        }

        mainWebView.setWebViewClient(new WebViewClient() {
            // `shouldOverrideUrlLoading` makes this `WebView` the default handler for URLs inside the app, so that links are not kicked out to other apps.
            // We have to use the deprecated `shouldOverrideUrlLoading` until API >= 24.
            @SuppressWarnings("deprecation")
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                if (url.startsWith("mailto:")) {  // Load the URL in an external email program because it begins with `mailto:`.
                    // We use `ACTION_SENDTO` instead of `ACTION_SEND` so that only email programs are launched.
                    Intent emailIntent = new Intent(Intent.ACTION_SENDTO);

                    // Parse the url and set it as the data for the `Intent`.
                    emailIntent.setData(Uri.parse(url));

                    // `FLAG_ACTIVITY_NEW_TASK` opens the email program in a new task instead as part of Privacy Browser.
                    emailIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

                    // Make it so.
                    startActivity(emailIntent);

                    // Returning `true` indicates the application is handling the URL.
                    return true;
                } else {  // Load the URL in Privacy Browser.
                    // Apply the domain settings for the new URL.
                    applyDomainSettings(url);

                    // Returning `false` causes the current `WebView` to handle the URL and prevents it from adding redirects to the history list.
                    return false;
                }
            }

            // Block ads.  We have to use the deprecated `shouldInterceptRequest` until minimum API >= 21.
            @SuppressWarnings("deprecation")
            @Override
            public WebResourceResponse shouldInterceptRequest(WebView view, String url){
                if (adBlockerEnabled) {  // Block ads.
                    // Extract the host from `url`.
                    Uri requestUri = Uri.parse(url);
                    String requestHost = requestUri.getHost();

                    // Initialize a variable to track if this is an ad server.
                    boolean requestHostIsAdServer = false;

                    // Check all the subdomains of `requestHost` if it is not `null` against the ad server database.
                    if (requestHost != null) {
                        while (requestHost.contains(".") && !requestHostIsAdServer) {  // Stop checking if we run out of `.` or if we already know that `requestHostIsAdServer` is `true`.
                            if (adServersSet.contains(requestHost)) {
                                requestHostIsAdServer = true;
                            }

                            // Strip out the lowest subdomain of `requestHost`.
                            requestHost = requestHost.substring(requestHost.indexOf(".") + 1);
                        }
                    }

                    if (requestHostIsAdServer) {  // It is an ad server.
                        // Return an empty `WebResourceResponse`.
                        return new WebResourceResponse("text/plain", "utf8", new ByteArrayInputStream("".getBytes()));
                    } else {  // It is not an ad server.
                        // `return null` loads the requested resource.
                        return null;
                    }
                } else {  // Ad blocking is disabled.
                    // `return null` loads the requested resource.
                    return null;
                }
            }

            // Handle HTTP authentication requests.
            @Override
            public void onReceivedHttpAuthRequest(WebView view, HttpAuthHandler handler, String host, String realm) {
                // Store `handler` so it can be accessed from `onHttpAuthenticationCancel()` and `onHttpAuthenticationProceed()`.
                httpAuthHandler = handler;

                // Display the HTTP authentication dialog.
                AppCompatDialogFragment httpAuthenticationDialogFragment = HttpAuthenticationDialog.displayDialog(host, realm);
                httpAuthenticationDialogFragment.show(getSupportFragmentManager(), getString(R.string.http_authentication));
            }

            // Update the URL in urlTextBox when the page starts to load.
            @Override
            public void onPageStarted(WebView view, String url, Bitmap favicon) {
                // If night mode is enabled, hide `mainWebView` until after the night mode CSS is applied.
                if (nightMode) {
                    mainWebView.setVisibility(View.INVISIBLE);
                }

                // Hide the keyboard.  `0` indicates no additional flags.
                inputMethodManager.hideSoftInputFromWindow(mainWebView.getWindowToken(), 0);

                // Check to see if we are waiting on Orbot.
                if (!waitingForOrbot) {  // We are not waiting on Orbot, so we need to process the URL.
                    // We need to update `formattedUrlString` at the beginning of the load, so that if the user toggles JavaScript during the load the new website is reloaded.
                    formattedUrlString = url;

                    // Display the formatted URL text.
                    urlTextBox.setText(formattedUrlString);

                    // Apply text highlighting to `urlTextBox`.
                    highlightUrlText();

                    // Apply any custom domain settings if the URL was loaded by navigating history.
                    if (navigatingHistory) {
                        applyDomainSettings(url);
                    }

                    // Set `urlIsLoading` to `true`, so that redirects while loading do not trigger changes in the user agent, which forces another reload of the existing page.
                    urlIsLoading = true;
                }
            }

            // It is necessary to update `formattedUrlString` and `urlTextBox` after the page finishes loading because the final URL can change during load.
            @Override
            public void onPageFinished(WebView view, String url) {
                // Reset `urlIsLoading`, which is used to prevent reloads on redirect if the user agent changes.
                urlIsLoading = false;

                // Clear the cache and history if Incognito Mode is enabled.
                if (incognitoModeEnabled) {
                    // Clear the cache.  `true` includes disk files.
                    mainWebView.clearCache(true);

                    // Clear the back/forward history.
                    mainWebView.clearHistory();

                    // Manually delete cache folders.
                    try {
                        // Delete the main `cache` folder.
                        privacyBrowserRuntime.exec("rm -rf " + privateDataDirectoryString + "/cache");

                        // Delete the `app_webview` folder, which contains an additional `WebView` cache.  See `https://code.google.com/p/android/issues/detail?id=233826&thanks=233826&ts=1486670530`.
                        privacyBrowserRuntime.exec("rm -rf " + privateDataDirectoryString + "/app_webview");
                    } catch (IOException e) {
                        // Do nothing if an error is thrown.
                    }
                }

                // Update `urlTextBox` and apply domain settings if not waiting on Orbot.
                if (!waitingForOrbot) {
                    // Check to see if `WebView` has set `url` to be `about:blank`.
                    if (url.equals("about:blank")) {  // `WebView` is blank, so `formattedUrlString` should be `""` and `urlTextBox` should display a hint.
                        // Set `formattedUrlString` to `""`.
                        formattedUrlString = "";

                        urlTextBox.setText(formattedUrlString);

                        // Request focus for `urlTextBox`.
                        urlTextBox.requestFocus();

                        // Display the keyboard.
                        inputMethodManager.showSoftInput(urlTextBox, 0);

                        // Apply the domain settings.  This clears any settings from the previous domain.
                        applyDomainSettings(formattedUrlString);
                    } else {  // `WebView` has loaded a webpage.
                        // Set `formattedUrlString`.
                        formattedUrlString = url;

                        // Only update `urlTextBox` if the user is not typing in it.
                        if (!urlTextBox.hasFocus()) {
                            // Display the formatted URL text.
                            urlTextBox.setText(formattedUrlString);

                            // Apply text highlighting to `urlTextBox`.
                            highlightUrlText();
                        }
                    }

                    // Store the SSL certificate so it can be accessed from `ViewSslCertificateDialog` and `PinnedSslCertificateMismatchDialog`.
                    sslCertificate = mainWebView.getCertificate();

                    // Check the current website SSL certificate against the pinned SSL certificate if there is a pinned SSL certificate the user has not chosen to ignore it for this session.
                    if (pinnedDomainSslCertificate && !ignorePinnedSslCertificate) {
                        // Initialize the current SSL certificate variables.
                        String currentWebsiteIssuedToCName = "";
                        String currentWebsiteIssuedToOName = "";
                        String currentWebsiteIssuedToUName = "";
                        String currentWebsiteIssuedByCName = "";
                        String currentWebsiteIssuedByOName = "";
                        String currentWebsiteIssuedByUName = "";
                        Date currentWebsiteSslStartDate = null;
                        Date currentWebsiteSslEndDate = null;


                        // Extract the individual pieces of information from the current website SSL certificate if it is not null.
                        if (sslCertificate != null) {
                            currentWebsiteIssuedToCName = sslCertificate.getIssuedTo().getCName();
                            currentWebsiteIssuedToOName = sslCertificate.getIssuedTo().getOName();
                            currentWebsiteIssuedToUName = sslCertificate.getIssuedTo().getUName();
                            currentWebsiteIssuedByCName = sslCertificate.getIssuedBy().getCName();
                            currentWebsiteIssuedByOName = sslCertificate.getIssuedBy().getOName();
                            currentWebsiteIssuedByUName = sslCertificate.getIssuedBy().getUName();
                            currentWebsiteSslStartDate = sslCertificate.getValidNotBeforeDate();
                            currentWebsiteSslEndDate = sslCertificate.getValidNotAfterDate();
                        }

                        // Initialize `String` variables to store the SSL certificate dates.  `Strings` are needed to compare the values below, which doesn't work with `Dates` if they are `null`.
                        String currentWebsiteSslStartDateString = "";
                        String currentWebsiteSslEndDateString = "";
                        String pinnedDomainSslStartDateString = "";
                        String pinnedDomainSslEndDateString = "";

                        // Convert the `Dates` to `Strings` if they are not `null`.
                        if (currentWebsiteSslStartDate != null) {
                            currentWebsiteSslStartDateString = currentWebsiteSslStartDate.toString();
                        }

                        if (currentWebsiteSslEndDate != null) {
                            currentWebsiteSslEndDateString = currentWebsiteSslEndDate.toString();
                        }

                        if (pinnedDomainSslStartDate != null) {
                            pinnedDomainSslStartDateString = pinnedDomainSslStartDate.toString();
                        }

                        if (pinnedDomainSslEndDate != null) {
                            pinnedDomainSslEndDateString = pinnedDomainSslEndDate.toString();
                        }

                        // Check to see if the pinned SSL certificate matches the current website certificate.
                        if (!currentWebsiteIssuedToCName.equals(pinnedDomainSslIssuedToCNameString) || !currentWebsiteIssuedToOName.equals(pinnedDomainSslIssuedToONameString) || !currentWebsiteIssuedToUName.equals(pinnedDomainSslIssuedToUNameString) ||
                                !currentWebsiteIssuedByCName.equals(pinnedDomainSslIssuedByCNameString) || !currentWebsiteIssuedByOName.equals(pinnedDomainSslIssuedByONameString) || !currentWebsiteIssuedByUName.equals(pinnedDomainSslIssuedByUNameString) ||
                                !currentWebsiteSslStartDateString.equals(pinnedDomainSslStartDateString) || !currentWebsiteSslEndDateString.equals(pinnedDomainSslEndDateString)) {  // The pinned SSL certificate doesn't match the current domain certificate.
                            //Display the pinned SSL certificate mismatch `AlertDialog`.
                            AppCompatDialogFragment pinnedSslCertificateMismatchDialogFragment = new PinnedSslCertificateMismatchDialog();
                            pinnedSslCertificateMismatchDialogFragment.show(getSupportFragmentManager(), getString(R.string.ssl_certificate_mismatch));
                        }
                    }
                }
            }

            // Handle SSL Certificate errors.
            @Override
            public void onReceivedSslError(WebView view, SslErrorHandler handler, SslError error) {
                // Get the current website SSL certificate.
                SslCertificate currentWebsiteSslCertificate = error.getCertificate();

                // Extract the individual pieces of information from the current website SSL certificate.
                String currentWebsiteIssuedToCName = currentWebsiteSslCertificate.getIssuedTo().getCName();
                String currentWebsiteIssuedToOName = currentWebsiteSslCertificate.getIssuedTo().getOName();
                String currentWebsiteIssuedToUName = currentWebsiteSslCertificate.getIssuedTo().getUName();
                String currentWebsiteIssuedByCName = currentWebsiteSslCertificate.getIssuedBy().getCName();
                String currentWebsiteIssuedByOName = currentWebsiteSslCertificate.getIssuedBy().getOName();
                String currentWebsiteIssuedByUName = currentWebsiteSslCertificate.getIssuedBy().getUName();
                Date currentWebsiteSslStartDate = currentWebsiteSslCertificate.getValidNotBeforeDate();
                Date currentWebsiteSslEndDate = currentWebsiteSslCertificate.getValidNotAfterDate();

                // Proceed to the website if the current SSL website certificate matches the pinned domain certificate.
                if (pinnedDomainSslCertificate &&
                        currentWebsiteIssuedToCName.equals(pinnedDomainSslIssuedToCNameString) && currentWebsiteIssuedToOName.equals(pinnedDomainSslIssuedToONameString) && currentWebsiteIssuedToUName.equals(pinnedDomainSslIssuedToUNameString) &&
                        currentWebsiteIssuedByCName.equals(pinnedDomainSslIssuedByCNameString) && currentWebsiteIssuedByOName.equals(pinnedDomainSslIssuedByONameString) && currentWebsiteIssuedByUName.equals(pinnedDomainSslIssuedByUNameString) &&
                        currentWebsiteSslStartDate.equals(pinnedDomainSslStartDate) && currentWebsiteSslEndDate.equals(pinnedDomainSslEndDate)) {  // An SSL certificate is pinned and matches the current domain certificate.
                    // Proceed to the website without displaying an error.
                    handler.proceed();
                } else {  // Either there isn't a pinned SSL certificate or it doesn't match the current website certificate.
                    // Store `handler` so it can be accesses from `onSslErrorCancel()` and `onSslErrorProceed()`.
                    sslErrorHandler = handler;

                    // Display the SSL error `AlertDialog`.
                    AppCompatDialogFragment sslCertificateErrorDialogFragment = SslCertificateErrorDialog.displayDialog(error);
                    sslCertificateErrorDialogFragment.show(getSupportFragmentManager(), getString(R.string.ssl_certificate_error));
                }
            }
        });

        // Get a handle for the progress bar.
        final ProgressBar progressBar = findViewById(R.id.progress_bar);

        mainWebView.setWebChromeClient(new WebChromeClient() {
            // Update the progress bar when a page is loading.
            @Override
            public void onProgressChanged(WebView view, int progress) {
                // Inject the night mode CSS if night mode is enabled.
                if (nightMode) {
                    // `background-color: #212121` sets the background to be dark gray.  `color: #BDBDBD` sets the text color to be light gray.  `box-shadow: none` removes a lower underline on links used by WordPress.
                    // `text-decoration: none` removes all text underlines.  `text-shadow: none` removes text shadows, which usually have a hard coded color.  `border: none` removes all borders, which can also be used to underline text.
                    // `a {color: #1565C0}` sets links to be a dark blue.  `!important` takes precedent over any existing sub-settings.
                    mainWebView.evaluateJavascript("(function() {var parent = document.getElementsByTagName('head').item(0); var style = document.createElement('style'); style.type = 'text/css'; style.innerHTML = '" +
                            "* {background-color: #212121 !important; color: #BDBDBD !important; box-shadow: none !important; text-decoration: none !important; text-shadow: none !important; border: none !important;}" +
                            "a {color: #1565C0 !important;}" +
                            "'; parent.appendChild(style)})()", value -> {
                                // Initialize a `Handler` to display `mainWebView`.
                                Handler displayWebViewHandler = new Handler();

                                // Setup a `Runnable` to display `mainWebView` after a delay to allow the CSS to be applied.
                                Runnable displayWebViewRunnable = () -> {
                                    // Only display `mainWebView` if the progress bar is one.  This prevents the display of the `WebView` while it is still loading.
                                    if (progressBar.getVisibility() == View.GONE) {
                                        mainWebView.setVisibility(View.VISIBLE);
                                    }
                                };

                                // Use `displayWebViewHandler` to delay the displaying of `mainWebView` for 500 milliseconds.
                                displayWebViewHandler.postDelayed(displayWebViewRunnable, 500);
                            });
                }

                progressBar.setProgress(progress);
                if (progress < 100) {
                    // Show the progress bar.
                    progressBar.setVisibility(View.VISIBLE);
                } else {
                    // Hide the progress bar.
                    progressBar.setVisibility(View.GONE);

                    // Display `mainWebView` if night mode is disabled.
                    // Because of a race condition between `applyDomainSettings` and `onPageStarted`, when night mode is set by domain settings the `WebView` may be hidden even if night mode is not currently enabled.
                    if (!nightMode) {
                        mainWebView.setVisibility(View.VISIBLE);
                    }

                    //Stop the `SwipeToRefresh` indicator if it is running
                    swipeRefreshLayout.setRefreshing(false);
                }
            }

            // Set the favorite icon when it changes.
            @Override
            public void onReceivedIcon(WebView view, Bitmap icon) {
                // Only update the favorite icon if the website has finished loading.
                if (progressBar.getVisibility() == View.GONE) {
                    // Save a copy of the favorite icon.
                    favoriteIconBitmap = icon;

                    // Place the favorite icon in the appBar.
                    favoriteIconImageView.setImageBitmap(Bitmap.createScaledBitmap(icon, 64, 64, true));
                }
            }

            // Save a copy of the title when it changes.
            @Override
            public void onReceivedTitle(WebView view, String title) {
                // Save a copy of the title.
                webViewTitle = title;
            }

            // Enter full screen video
            @Override
            public void onShowCustomView(View view, CustomViewCallback callback) {
                // Pause the ad if this is the free flavor.
                if (BuildConfig.FLAVOR.contentEquals("free")) {
                    BannerAd.pauseAd(adView);
                }

                // Remove the translucent overlays.
                getWindow().clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);

                // Remove the translucent status bar overlay on the `Drawer Layout`, which is special and needs its own command.
                drawerLayout.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);

                /* SYSTEM_UI_FLAG_FULLSCREEN hides the status bar at the top of the screen.
                 * SYSTEM_UI_FLAG_HIDE_NAVIGATION hides the navigation bar on the bottom or right of the screen.
                 * SYSTEM_UI_FLAG_IMMERSIVE_STICKY makes the status and navigation bars translucent and automatically rehides them after they are shown.
                 */
                rootCoordinatorLayout.setSystemUiVisibility(View.SYSTEM_UI_FLAG_FULLSCREEN | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY);

                // Set `rootCoordinatorLayout` to fill the entire screen.
                rootCoordinatorLayout.setFitsSystemWindows(false);

                // Add `view` to `fullScreenVideoFrameLayout` and display it on the screen.
                fullScreenVideoFrameLayout.addView(view);
                fullScreenVideoFrameLayout.setVisibility(View.VISIBLE);
            }

            // Exit full screen video
            public void onHideCustomView() {
                // Hide `fullScreenVideoFrameLayout`.
                fullScreenVideoFrameLayout.removeAllViews();
                fullScreenVideoFrameLayout.setVisibility(View.GONE);

                // Add the translucent status flag.  This also resets `drawerLayout's` `View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN`.
                getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);

                // Set `rootCoordinatorLayout` to fit inside the status and navigation bars.  This also clears the `SYSTEM_UI` flags.
                rootCoordinatorLayout.setFitsSystemWindows(true);

                // Show the ad if this is the free flavor.
                if (BuildConfig.FLAVOR.contentEquals("free")) {
                    // Reload the ad.  Because the screen may have rotated, we need to use `reloadAfterRotate`.
                    BannerAd.reloadAfterRotate(adView, getApplicationContext(), getString(R.string.ad_id));

                    // Reinitialize the `adView` variable, as the `View` will have been removed and re-added by `BannerAd.reloadAfterRotate()`.
                    adView = findViewById(R.id.adview);
                }
            }
        });

        // Register `mainWebView` for a context menu.  This is used to see link targets and download images.
        registerForContextMenu(mainWebView);

        // Allow the downloading of files.
        mainWebView.setDownloadListener((url, userAgent, contentDisposition, mimetype, contentLength) -> {
            // Show the `DownloadFileDialog` `AlertDialog` and name this instance `@string/download`.
            AppCompatDialogFragment downloadFileDialogFragment = DownloadFileDialog.fromUrl(url, contentDisposition, contentLength);
            downloadFileDialogFragment.show(getSupportFragmentManager(), getString(R.string.download));
        });

        // Allow pinch to zoom.
        mainWebView.getSettings().setBuiltInZoomControls(true);

        // Hide zoom controls.
        mainWebView.getSettings().setDisplayZoomControls(false);

        // Set `mainWebView` to use a wide viewport.  Otherwise, some web pages will be scrunched and some content will render outside the screen.
        mainWebView.getSettings().setUseWideViewPort(true);

        // Set `mainWebView` to load in overview mode (zoomed out to the maximum width).
        mainWebView.getSettings().setLoadWithOverviewMode(true);

        // Explicitly disable geolocation.
        mainWebView.getSettings().setGeolocationEnabled(false);

        // Initialize cookieManager.
        cookieManager = CookieManager.getInstance();

        // Replace the header that `WebView` creates for `X-Requested-With` with a null value.  The default value is the application ID (com.stoutner.privacybrowser.standard).
        customHeaders.put("X-Requested-With", "");

        // Initialize the default preference values the first time the program is run.  `this` is the context.  `false` keeps this command from resetting any current preferences back to default.
        PreferenceManager.setDefaultValues(this, R.xml.preferences, false);

        // Get the intent that started the app.
        final Intent launchingIntent = getIntent();

        // Extract the launching intent data as `launchingIntentUriData`.
        final Uri launchingIntentUriData = launchingIntent.getData();

        // Convert the launching intent URI data (if it exists) to a string and store it in `formattedUrlString`.
        if (launchingIntentUriData != null) {
            formattedUrlString = launchingIntentUriData.toString();
        }

        // Get a handle for the `Runtime`.
        privacyBrowserRuntime = Runtime.getRuntime();

        // Store the application's private data directory.
        privateDataDirectoryString = getApplicationInfo().dataDir;  // `dataDir` will vary, but will be something like `/data/user/0/com.stoutner.privacybrowser.standard`, which links to `/data/data/com.stoutner.privacybrowser.standard`.

        // Initialize `inFullScreenBrowsingMode`, which is always false at this point because Privacy Browser never starts in full screen browsing mode.
        inFullScreenBrowsingMode = false;

        // Initialize AdView for the free flavor.
        adView = findViewById(R.id.adview);

        // Initialize the privacy settings variables.
        javaScriptEnabled = false;
        firstPartyCookiesEnabled = false;
        thirdPartyCookiesEnabled = false;
        domStorageEnabled = false;
        saveFormDataEnabled = false;
        nightMode = false;

        // Initialize `webViewTitle`.
        webViewTitle = getString(R.string.no_title);

        // Initialize `favoriteIconBitmap`.  We have to use `ContextCompat` until API >= 21.
        Drawable favoriteIconDrawable = ContextCompat.getDrawable(getApplicationContext(), R.drawable.world);
        BitmapDrawable favoriteIconBitmapDrawable = (BitmapDrawable) favoriteIconDrawable;
        favoriteIconDefaultBitmap = favoriteIconBitmapDrawable.getBitmap();

        // If the favorite icon is null, load the default.
        if (favoriteIconBitmap == null) {
            favoriteIconBitmap = favoriteIconDefaultBitmap;
        }

        // Apply the app settings from the shared preferences.
        applyAppSettings();

        // Load `formattedUrlString` if we are not waiting for Orbot to connect.
        if (!waitingForOrbot) {
            loadUrl(formattedUrlString);
        }
    }

    @Override
    protected void onNewIntent(Intent intent) {
        // Sets the new intent as the activity intent, so that any future `getIntent()`s pick up this one instead of creating a new activity.
        setIntent(intent);

        if (intent.getData() != null) {
            // Get the intent data and convert it to a string.
            final Uri intentUriData = intent.getData();
            formattedUrlString = intentUriData.toString();
        }

        // Close the navigation drawer if it is open.
        if (drawerLayout.isDrawerVisible(GravityCompat.START)) {
            drawerLayout.closeDrawer(GravityCompat.START);
        }

        // Load the website.
        loadUrl(formattedUrlString);

        // Clear the keyboard if displayed and remove the focus on the urlTextBar if it has it.
        mainWebView.requestFocus();
    }

    @Override
    public void onRestart() {
        super.onRestart();

        // Apply the app settings, which may have been changed in `SettingsActivity`.
        applyAppSettings();

        // Update the privacy icon.  `true` runs `invalidateOptionsMenu` as the last step.
        updatePrivacyIcons(true);

        // Set the display webpage images mode.
        setDisplayWebpageImages();

        // Reload the webpage if displaying of images has been disabled in `SettingsFragment`.
        if (reloadOnRestart) {
            // Reload `mainWebView`.
            mainWebView.reload();

            // Reset `reloadOnRestartBoolean`.
            reloadOnRestart = false;
        }

        // Load the URL on restart to apply changes to night mode.
        if (loadUrlOnRestart) {
            // Load the current `formattedUrlString`.
            loadUrl(formattedUrlString);

            // Reset `loadUrlOnRestart.
            loadUrlOnRestart = false;
        }

        //
        if (restartFromBookmarksActivity) {
            // Close the bookmarks drawer.
            drawerLayout.closeDrawer(GravityCompat.END);

            // Reload the bookmarks drawer.
            loadBookmarksFolder();

            // Reset `restartFromBookmarksActivity`.
            restartFromBookmarksActivity = false;
        }
    }

    // `onResume()` runs after `onStart()`, which runs after `onCreate()` and `onRestart()`.
    @Override
    public void onResume() {
        super.onResume();

        // Resume JavaScript (if enabled).
        mainWebView.resumeTimers();

        // Resume `mainWebView`.
        mainWebView.onResume();

        // Resume the adView for the free flavor.
        if (BuildConfig.FLAVOR.contentEquals("free")) {
            BannerAd.resumeAd(adView);
        }
    }

    @Override
    public void onPause() {
        // Pause `mainWebView`.
        mainWebView.onPause();

        // Stop all JavaScript.
        mainWebView.pauseTimers();

        // Pause the adView or it will continue to consume resources in the background on the free flavor.
        if (BuildConfig.FLAVOR.contentEquals("free")) {
            BannerAd.pauseAd(adView);
        }

        super.onPause();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.webview_options_menu, menu);

        // Set mainMenu so it can be used by `onOptionsItemSelected()` and `updatePrivacyIcons`.
        mainMenu = menu;

        // Set the initial status of the privacy icons.  `false` does not call `invalidateOptionsMenu` as the last step.
        updatePrivacyIcons(false);

        // Get handles for the menu items.
        MenuItem toggleFirstPartyCookiesMenuItem = menu.findItem(R.id.toggle_first_party_cookies);
        MenuItem toggleThirdPartyCookiesMenuItem = menu.findItem(R.id.toggle_third_party_cookies);
        MenuItem toggleDomStorageMenuItem = menu.findItem(R.id.toggle_dom_storage);
        MenuItem toggleSaveFormDataMenuItem = menu.findItem(R.id.toggle_save_form_data);

        // Only display third-party cookies if SDK >= 21
        toggleThirdPartyCookiesMenuItem.setVisible(Build.VERSION.SDK_INT >= 21);

        // Get the shared preference values.  `this` references the current context.
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);

        // Set the status of the additional app bar icons.  The default is `false`.
        if (sharedPreferences.getBoolean("display_additional_app_bar_icons", false)) {
            toggleFirstPartyCookiesMenuItem.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM);
            toggleDomStorageMenuItem.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM);
            toggleSaveFormDataMenuItem.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM);
        } else { //Do not display the additional icons.
            toggleFirstPartyCookiesMenuItem.setShowAsAction(MenuItem.SHOW_AS_ACTION_NEVER);
            toggleDomStorageMenuItem.setShowAsAction(MenuItem.SHOW_AS_ACTION_NEVER);
            toggleSaveFormDataMenuItem.setShowAsAction(MenuItem.SHOW_AS_ACTION_NEVER);
        }

        return true;
    }

    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        // Get handles for the menu items.
        MenuItem toggleFirstPartyCookiesMenuItem = menu.findItem(R.id.toggle_first_party_cookies);
        MenuItem toggleThirdPartyCookiesMenuItem = menu.findItem(R.id.toggle_third_party_cookies);
        MenuItem toggleDomStorageMenuItem = menu.findItem(R.id.toggle_dom_storage);
        MenuItem toggleSaveFormDataMenuItem = menu.findItem(R.id.toggle_save_form_data);
        MenuItem clearCookiesMenuItem = menu.findItem(R.id.clear_cookies);
        MenuItem clearDOMStorageMenuItem = menu.findItem(R.id.clear_dom_storage);
        MenuItem clearFormDataMenuItem = menu.findItem(R.id.clear_form_data);
        MenuItem fontSizeMenuItem = menu.findItem(R.id.font_size);
        MenuItem displayImagesMenuItem = menu.findItem(R.id.display_images);
        MenuItem refreshMenuItem = menu.findItem(R.id.refresh);

        // Set the status of the menu item checkboxes.
        toggleFirstPartyCookiesMenuItem.setChecked(firstPartyCookiesEnabled);
        toggleThirdPartyCookiesMenuItem.setChecked(thirdPartyCookiesEnabled);
        toggleDomStorageMenuItem.setChecked(domStorageEnabled);
        toggleSaveFormDataMenuItem.setChecked(saveFormDataEnabled);
        displayImagesMenuItem.setChecked(mainWebView.getSettings().getLoadsImagesAutomatically());

        // Enable third-party cookies if first-party cookies are enabled.
        toggleThirdPartyCookiesMenuItem.setEnabled(firstPartyCookiesEnabled);

        // Enable `DOM Storage` if JavaScript is enabled.
        toggleDomStorageMenuItem.setEnabled(javaScriptEnabled);

        // Enable `Clear Cookies` if there are any.
        clearCookiesMenuItem.setEnabled(cookieManager.hasCookies());

        // Get a count of the number of files in the `Local Storage` directory.
        File localStorageDirectory = new File (privateDataDirectoryString + "/app_webview/Local Storage/");
        int localStorageDirectoryNumberOfFiles = 0;
        if (localStorageDirectory.exists()) {
            localStorageDirectoryNumberOfFiles = localStorageDirectory.list().length;
        }

        // Get a count of the number of files in the `IndexedDB` directory.
        File indexedDBDirectory = new File (privateDataDirectoryString + "/app_webview/IndexedDB");
        int indexedDBDirectoryNumberOfFiles = 0;
        if (indexedDBDirectory.exists()) {
            indexedDBDirectoryNumberOfFiles = indexedDBDirectory.list().length;
        }

        // Enable `Clear DOM Storage` if there is any.
        clearDOMStorageMenuItem.setEnabled(localStorageDirectoryNumberOfFiles > 0 || indexedDBDirectoryNumberOfFiles > 0);

        // Enable `Clear Form Data` is there is any.
        WebViewDatabase mainWebViewDatabase = WebViewDatabase.getInstance(this);
        clearFormDataMenuItem.setEnabled(mainWebViewDatabase.hasFormData());

        // Initialize font size variables.
        int fontSize = mainWebView.getSettings().getTextZoom();
        String fontSizeTitle;
        MenuItem selectedFontSizeMenuItem;

        // Prepare the font size title and current size menu item.
        switch (fontSize) {
            case 25:
                fontSizeTitle = getString(R.string.font_size) + " - " + getString(R.string.twenty_five_percent);
                selectedFontSizeMenuItem = menu.findItem(R.id.font_size_twenty_five_percent);
                break;

            case 50:
                fontSizeTitle = getString(R.string.font_size) + " - " + getString(R.string.fifty_percent);
                selectedFontSizeMenuItem = menu.findItem(R.id.font_size_fifty_percent);
                break;

            case 75:
                fontSizeTitle = getString(R.string.font_size) + " - " + getString(R.string.seventy_five_percent);
                selectedFontSizeMenuItem = menu.findItem(R.id.font_size_seventy_five_percent);
                break;

            case 100:
                fontSizeTitle = getString(R.string.font_size) + " - " + getString(R.string.one_hundred_percent);
                selectedFontSizeMenuItem = menu.findItem(R.id.font_size_one_hundred_percent);
                break;

            case 125:
                fontSizeTitle = getString(R.string.font_size) + " - " + getString(R.string.one_hundred_twenty_five_percent);
                selectedFontSizeMenuItem = menu.findItem(R.id.font_size_one_hundred_twenty_five_percent);
                break;

            case 150:
                fontSizeTitle = getString(R.string.font_size) + " - " + getString(R.string.one_hundred_fifty_percent);
                selectedFontSizeMenuItem = menu.findItem(R.id.font_size_one_hundred_fifty_percent);
                break;

            case 175:
                fontSizeTitle = getString(R.string.font_size) + " - " + getString(R.string.one_hundred_seventy_five_percent);
                selectedFontSizeMenuItem = menu.findItem(R.id.font_size_one_hundred_seventy_five_percent);
                break;

            case 200:
                fontSizeTitle = getString(R.string.font_size) + " - " + getString(R.string.two_hundred_percent);
                selectedFontSizeMenuItem = menu.findItem(R.id.font_size_two_hundred_percent);
                break;

            default:
                fontSizeTitle = getString(R.string.font_size) + " - " + getString(R.string.one_hundred_percent);
                selectedFontSizeMenuItem = menu.findItem(R.id.font_size_one_hundred_percent);
                break;
        }

        // Set the font size title and select the current size menu item.
        fontSizeMenuItem.setTitle(fontSizeTitle);
        selectedFontSizeMenuItem.setChecked(true);

        // Only show `Refresh` if `swipeToRefresh` is disabled.
        refreshMenuItem.setVisible(!swipeToRefreshEnabled);

        // Run all the other default commands.
        super.onPrepareOptionsMenu(menu);

        // `return true` displays the menu.
        return true;
    }

    @Override
    // Remove Android Studio's warning about the dangers of using SetJavaScriptEnabled.
    @SuppressLint("SetJavaScriptEnabled")
    // removeAllCookies is deprecated, but it is required for API < 21.
    @SuppressWarnings("deprecation")
    public boolean onOptionsItemSelected(MenuItem menuItem) {
        int menuItemId = menuItem.getItemId();

        // Set the commands that relate to the menu entries.
        switch (menuItemId) {
            case R.id.toggle_javascript:
                // Switch the status of javaScriptEnabled.
                javaScriptEnabled = !javaScriptEnabled;

                // Apply the new JavaScript status.
                mainWebView.getSettings().setJavaScriptEnabled(javaScriptEnabled);

                // Update the privacy icon.  `true` runs `invalidateOptionsMenu` as the last step.
                updatePrivacyIcons(true);

                // Display a `Snackbar`.
                if (javaScriptEnabled) {  // JavaScrip is enabled.
                    Snackbar.make(findViewById(R.id.main_webview), R.string.javascript_enabled, Snackbar.LENGTH_SHORT).show();
                } else if (firstPartyCookiesEnabled) {  // JavaScript is disabled, but first-party cookies are enabled.
                    Snackbar.make(findViewById(R.id.main_webview), R.string.javascript_disabled, Snackbar.LENGTH_SHORT).show();
                } else {  // Privacy mode.
                    Snackbar.make(findViewById(R.id.main_webview), R.string.privacy_mode, Snackbar.LENGTH_SHORT).show();
                }

                // Reload the WebView.
                mainWebView.reload();
                return true;

            case R.id.toggle_first_party_cookies:
                // Switch the status of firstPartyCookiesEnabled.
                firstPartyCookiesEnabled = !firstPartyCookiesEnabled;

                // Update the menu checkbox.
                menuItem.setChecked(firstPartyCookiesEnabled);

                // Apply the new cookie status.
                cookieManager.setAcceptCookie(firstPartyCookiesEnabled);

                // Update the privacy icon.  `true` runs `invalidateOptionsMenu` as the last step.
                updatePrivacyIcons(true);

                // Display a `Snackbar`.
                if (firstPartyCookiesEnabled) {  // First-party cookies are enabled.
                    Snackbar.make(findViewById(R.id.main_webview), R.string.first_party_cookies_enabled, Snackbar.LENGTH_SHORT).show();
                } else if (javaScriptEnabled){  // JavaScript is still enabled.
                    Snackbar.make(findViewById(R.id.main_webview), R.string.first_party_cookies_disabled, Snackbar.LENGTH_SHORT).show();
                } else {  // Privacy mode.
                    Snackbar.make(findViewById(R.id.main_webview), R.string.privacy_mode, Snackbar.LENGTH_SHORT).show();
                }

                // Reload the WebView.
                mainWebView.reload();
                return true;

            case R.id.toggle_third_party_cookies:
                if (Build.VERSION.SDK_INT >= 21) {
                    // Switch the status of thirdPartyCookiesEnabled.
                    thirdPartyCookiesEnabled = !thirdPartyCookiesEnabled;

                    // Update the menu checkbox.
                    menuItem.setChecked(thirdPartyCookiesEnabled);

                    // Apply the new cookie status.
                    cookieManager.setAcceptThirdPartyCookies(mainWebView, thirdPartyCookiesEnabled);

                    // Display a `Snackbar`.
                    if (thirdPartyCookiesEnabled) {
                        Snackbar.make(findViewById(R.id.main_webview), R.string.third_party_cookies_enabled, Snackbar.LENGTH_SHORT).show();
                    } else {
                        Snackbar.make(findViewById(R.id.main_webview), R.string.third_party_cookies_disabled, Snackbar.LENGTH_SHORT).show();
                    }

                    // Reload the WebView.
                    mainWebView.reload();
                } // Else do nothing because SDK < 21.
                return true;

            case R.id.toggle_dom_storage:
                // Switch the status of domStorageEnabled.
                domStorageEnabled = !domStorageEnabled;

                // Update the menu checkbox.
                menuItem.setChecked(domStorageEnabled);

                // Apply the new DOM Storage status.
                mainWebView.getSettings().setDomStorageEnabled(domStorageEnabled);

                // Update the privacy icon.  `true` runs `invalidateOptionsMenu` as the last step.
                updatePrivacyIcons(true);

                // Display a `Snackbar`.
                if (domStorageEnabled) {
                    Snackbar.make(findViewById(R.id.main_webview), R.string.dom_storage_enabled, Snackbar.LENGTH_SHORT).show();
                } else {
                    Snackbar.make(findViewById(R.id.main_webview), R.string.dom_storage_disabled, Snackbar.LENGTH_SHORT).show();
                }

                // Reload the WebView.
                mainWebView.reload();
                return true;

            case R.id.toggle_save_form_data:
                // Switch the status of saveFormDataEnabled.
                saveFormDataEnabled = !saveFormDataEnabled;

                // Update the menu checkbox.
                menuItem.setChecked(saveFormDataEnabled);

                // Apply the new form data status.
                mainWebView.getSettings().setSaveFormData(saveFormDataEnabled);

                // Display a `Snackbar`.
                if (saveFormDataEnabled) {
                    Snackbar.make(findViewById(R.id.main_webview), R.string.form_data_enabled, Snackbar.LENGTH_SHORT).show();
                } else {
                    Snackbar.make(findViewById(R.id.main_webview), R.string.form_data_disabled, Snackbar.LENGTH_SHORT).show();
                }

                // Update the privacy icon.  `true` runs `invalidateOptionsMenu` as the last step.
                updatePrivacyIcons(true);

                // Reload the WebView.
                mainWebView.reload();
                return true;

            case R.id.clear_cookies:
                Snackbar.make(findViewById(R.id.main_webview), R.string.cookies_deleted, Snackbar.LENGTH_LONG)
                        .setAction(R.string.undo, v -> {
                            // Do nothing because everything will be handled by `onDismissed()` below.
                        })
                        .addCallback(new Snackbar.Callback() {
                            @Override
                            public void onDismissed(Snackbar snackbar, int event) {
                                switch (event) {
                                    // The user pushed the `Undo` button.
                                    case Snackbar.Callback.DISMISS_EVENT_ACTION:
                                        // Do nothing.
                                        break;

                                    // The `Snackbar` was dismissed without the `Undo` button being pushed.
                                    default:
                                        // `cookieManager.removeAllCookie()` varies by SDK.
                                        if (Build.VERSION.SDK_INT < 21) {
                                            cookieManager.removeAllCookie();
                                        } else {
                                            // `null` indicates no callback.
                                            cookieManager.removeAllCookies(null);
                                        }
                                }
                            }
                        })
                        .show();
                return true;

            case R.id.clear_dom_storage:
                Snackbar.make(findViewById(R.id.main_webview), R.string.dom_storage_deleted, Snackbar.LENGTH_LONG)
                        .setAction(R.string.undo, v -> {
                            // Do nothing because everything will be handled by `onDismissed()` below.
                        })
                        .addCallback(new Snackbar.Callback() {
                            @Override
                            public void onDismissed(Snackbar snackbar, int event) {
                                switch (event) {
                                    // The user pushed the `Undo` button.
                                    case Snackbar.Callback.DISMISS_EVENT_ACTION:
                                        // Do nothing.
                                        break;

                                    // The `Snackbar` was dismissed without the `Undo` button being pushed.
                                    default:
                                        // Delete the DOM Storage.
                                        WebStorage webStorage = WebStorage.getInstance();
                                        webStorage.deleteAllData();

                                        // Manually remove `IndexedDB` if it exists.
                                        try {
                                            privacyBrowserRuntime.exec("rm -rf " + privateDataDirectoryString + "/app_webview/IndexedDB");
                                        } catch (IOException e) {
                                            // Do nothing if an error is thrown.
                                        }
                                }
                            }
                        })
                        .show();
                return true;

            case R.id.clear_form_data:
                Snackbar.make(findViewById(R.id.main_webview), R.string.form_data_deleted, Snackbar.LENGTH_LONG)
                        .setAction(R.string.undo, v -> {
                            // Do nothing because everything will be handled by `onDismissed()` below.
                        })
                        .addCallback(new Snackbar.Callback() {
                            @Override
                            public void onDismissed(Snackbar snackbar, int event) {
                                switch (event) {
                                    // The user pushed the `Undo` button.
                                    case Snackbar.Callback.DISMISS_EVENT_ACTION:
                                        // Do nothing.
                                        break;

                                    // The `Snackbar` was dismissed without the `Undo` button being pushed.
                                    default:
                                        // Delete the form data.
                                        WebViewDatabase mainWebViewDatabase = WebViewDatabase.getInstance(getApplicationContext());
                                        mainWebViewDatabase.clearFormData();
                                }
                            }
                        })
                        .show();
                return true;

            case R.id.font_size_twenty_five_percent:
                mainWebView.getSettings().setTextZoom(25);
                return true;

            case R.id.font_size_fifty_percent:
                mainWebView.getSettings().setTextZoom(50);
                return true;

            case R.id.font_size_seventy_five_percent:
                mainWebView.getSettings().setTextZoom(75);
                return true;

            case R.id.font_size_one_hundred_percent:
                mainWebView.getSettings().setTextZoom(100);
                return true;

            case R.id.font_size_one_hundred_twenty_five_percent:
                mainWebView.getSettings().setTextZoom(125);
                return true;

            case R.id.font_size_one_hundred_fifty_percent:
                mainWebView.getSettings().setTextZoom(150);
                return true;

            case R.id.font_size_one_hundred_seventy_five_percent:
                mainWebView.getSettings().setTextZoom(175);
                return true;

            case R.id.font_size_two_hundred_percent:
                mainWebView.getSettings().setTextZoom(200);
                return true;

            case R.id.display_images:
                if (mainWebView.getSettings().getLoadsImagesAutomatically()) {  // Images are currently loaded automatically.
                    mainWebView.getSettings().setLoadsImagesAutomatically(false);
                    mainWebView.reload();
                } else {  // Images are not currently loaded automatically.
                    mainWebView.getSettings().setLoadsImagesAutomatically(true);
                }

                // Set `onTheFlyDisplayImagesSet`.
                onTheFlyDisplayImagesSet = true;
                return true;

            case R.id.share:
                // Setup the share string.
                String shareString = webViewTitle + " – " + urlTextBox.getText().toString();

                // Create the share intent.
                Intent shareIntent = new Intent();
                shareIntent.setAction(Intent.ACTION_SEND);
                shareIntent.putExtra(Intent.EXTRA_TEXT, shareString);
                shareIntent.setType("text/plain");

                // Make it so.
                startActivity(Intent.createChooser(shareIntent, "Share URL"));
                return true;

            case R.id.find_on_page:
                // Hide the URL app bar.
                supportAppBar.setVisibility(View.GONE);

                // Show the Find on Page `RelativeLayout`.
                findOnPageLinearLayout.setVisibility(View.VISIBLE);

                // Display the keyboard.  We have to wait 200 ms before running the command to work around a bug in Android.  http://stackoverflow.com/questions/5520085/android-show-softkeyboard-with-showsoftinput-is-not-working
                findOnPageEditText.postDelayed(() -> {
                    // Set the focus on `findOnPageEditText`.
                    findOnPageEditText.requestFocus();

                    // Display the keyboard.  `0` sets no input flags.
                    inputMethodManager.showSoftInput(findOnPageEditText, 0);
                }, 200);
                return true;

            case R.id.print:
                // Get a `PrintManager` instance.
                PrintManager printManager = (PrintManager) getSystemService(Context.PRINT_SERVICE);

                // Convert `mainWebView` to `printDocumentAdapter`.
                PrintDocumentAdapter printDocumentAdapter = mainWebView.createPrintDocumentAdapter();

                // Remove the lint error below that `printManager` might be `null`.
                assert printManager != null;

                // Print the document.  The print attributes are `null`.
                printManager.print(getString(R.string.privacy_browser_web_page), printDocumentAdapter, null);
                return true;

            case R.id.add_to_homescreen:
                // Show the `CreateHomeScreenShortcutDialog` `AlertDialog` and name this instance `R.string.create_shortcut`.
                AppCompatDialogFragment createHomeScreenShortcutDialogFragment = new CreateHomeScreenShortcutDialog();
                createHomeScreenShortcutDialogFragment.show(getSupportFragmentManager(), getString(R.string.create_shortcut));

                //Everything else will be handled by `CreateHomeScreenShortcutDialog` and the associated listener below.
                return true;

            case R.id.refresh:
                mainWebView.reload();
                return true;

            default:
                // Don't consume the event.
                return super.onOptionsItemSelected(menuItem);
        }
    }

    // removeAllCookies is deprecated, but it is required for API < 21.
    @SuppressWarnings("deprecation")
    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
        int menuItemId = menuItem.getItemId();

        switch (menuItemId) {
            case R.id.home:
                loadUrl(homepage);
                break;

            case R.id.back:
                if (mainWebView.canGoBack()) {
                    // Set `navigatingHistory` so that the domain settings are applied when the new URL is loaded.
                    navigatingHistory = true;

                    // Load the previous website in the history.
                    mainWebView.goBack();
                }
                break;

            case R.id.forward:
                if (mainWebView.canGoForward()) {
                    // Set `navigatingHistory` so that the domain settings are applied when the new URL is loaded.
                    navigatingHistory = true;

                    // Load the next website in the history.
                    mainWebView.goForward();
                }
                break;

            case R.id.history:
                // Get the `WebBackForwardList`.
                WebBackForwardList webBackForwardList = mainWebView.copyBackForwardList();

                // Show the `UrlHistoryDialog` `AlertDialog` and name this instance `R.string.history`.  `this` is the `Context`.
                AppCompatDialogFragment urlHistoryDialogFragment = UrlHistoryDialog.loadBackForwardList(this, webBackForwardList);
                urlHistoryDialogFragment.show(getSupportFragmentManager(), getString(R.string.history));
                break;

            case R.id.downloads:
                // Launch the system Download Manager.
                Intent downloadManagerIntent = new Intent(DownloadManager.ACTION_VIEW_DOWNLOADS);

                // Launch as a new task so that Download Manager and Privacy Browser show as separate windows in the recent tasks list.
                downloadManagerIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

                startActivity(downloadManagerIntent);
                break;

            case R.id.domains:
                // Reset `currentDomainName` so that domain settings are reapplied after returning to `MainWebViewActivity`.
                currentDomainName = "";

                // Launch `DomainsActivity`.
                Intent domainsIntent = new Intent(this, DomainsActivity.class);
                startActivity(domainsIntent);
                break;

            case R.id.settings:
                // Reset `currentDomainName` so that domain settings are reapplied after returning to `MainWebViewActivity`.
                currentDomainName = "";

                // Launch `SettingsActivity`.
                Intent settingsIntent = new Intent(this, SettingsActivity.class);
                startActivity(settingsIntent);
                break;

            case R.id.guide:
                // Launch `GuideActivity`.
                Intent guideIntent = new Intent(this, GuideActivity.class);
                startActivity(guideIntent);
                break;

            case R.id.about:
                // Launch `AboutActivity`.
                Intent aboutIntent = new Intent(this, AboutActivity.class);
                startActivity(aboutIntent);
                break;

            case R.id.clearAndExit:
                // Get a handle for `sharedPreferences`.  `this` references the current context.
                SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);

                boolean clearEverything = sharedPreferences.getBoolean("clear_everything", true);

                // Clear cookies.
                if (clearEverything || sharedPreferences.getBoolean("clear_cookies", true)) {
                    // The command to remove cookies changed slightly in API 21.
                    if (Build.VERSION.SDK_INT >= 21) {
                        cookieManager.removeAllCookies(null);
                    } else {
                        cookieManager.removeAllCookie();
                    }

                    // Manually delete the cookies database, as `CookieManager` sometimes will not flush its changes to disk before `System.exit(0)` is run.
                    try {
                        // We have to use two commands because `Runtime.exec()` does not like `*`.
                        privacyBrowserRuntime.exec("rm -f " + privateDataDirectoryString + "/app_webview/Cookies");
                        privacyBrowserRuntime.exec("rm -f " + privateDataDirectoryString + "/app_webview/Cookies-journal");
                    } catch (IOException e) {
                        // Do nothing if an error is thrown.
                    }
                }

                // Clear DOM storage.
                if (clearEverything || sharedPreferences.getBoolean("clear_dom_storage", true)) {
                    // Ask `WebStorage` to clear the DOM storage.
                    WebStorage webStorage = WebStorage.getInstance();
                    webStorage.deleteAllData();

                    // Manually delete the DOM storage files and directories, as `WebStorage` sometimes will not flush its changes to disk before `System.exit(0)` is run.
                    try {
                        // We have to use a `String[]` because the directory contains a space and `Runtime.exec` will not escape the string correctly otherwise.
                        privacyBrowserRuntime.exec(new String[] {"rm", "-rf", privateDataDirectoryString + "/app_webview/Local Storage/"});

                        // We have to use multiple commands because `Runtime.exec()` does not like `*`.
                        privacyBrowserRuntime.exec("rm -rf " + privateDataDirectoryString + "/app_webview/IndexedDB");
                        privacyBrowserRuntime.exec("rm -f " + privateDataDirectoryString + "/app_webview/QuotaManager");
                        privacyBrowserRuntime.exec("rm -f " + privateDataDirectoryString + "/app_webview/QuotaManager-journal");
                        privacyBrowserRuntime.exec("rm -rf " + privateDataDirectoryString + "/app_webview/databases");
                    } catch (IOException e) {
                        // Do nothing if an error is thrown.
                    }
                }

                // Clear form data.
                if (clearEverything || sharedPreferences.getBoolean("clear_form_data", true)) {
                    WebViewDatabase webViewDatabase = WebViewDatabase.getInstance(this);
                    webViewDatabase.clearFormData();

                    // Manually delete the form data database, as `WebViewDatabase` sometimes will not flush its changes to disk before `System.exit(0)` is run.
                    try {
                        // We have to use a `String[]` because the database contains a space and `Runtime.exec` will not escape the string correctly otherwise.
                        privacyBrowserRuntime.exec(new String[] {"rm", "-f", privateDataDirectoryString + "/app_webview/Web Data"});
                        privacyBrowserRuntime.exec(new String[] {"rm", "-f", privateDataDirectoryString + "/app_webview/Web Data-journal"});
                    } catch (IOException e) {
                        // Do nothing if an error is thrown.
                    }
                }

                // Clear the cache.
                if (clearEverything || sharedPreferences.getBoolean("clear_cache", true)) {
                    // `true` includes disk files.
                    mainWebView.clearCache(true);

                    // Manually delete the cache directories.
                    try {
                        // Delete the main cache directory.
                        privacyBrowserRuntime.exec("rm -rf " + privateDataDirectoryString + "/cache");

                        // Delete the secondary `Service Worker` cache directory.  We have to use a `String[]` because the directory contains a space and `Runtime.exec` will not escape the string correctly otherwise.
                        privacyBrowserRuntime.exec(new String[] {"rm", "-rf", privateDataDirectoryString + "/app_webview/Service Worker/"});
                    } catch (IOException e) {
                        // Do nothing if an error is thrown.
                    }
                }

                // Clear SSL certificate preferences.
                mainWebView.clearSslPreferences();

                // Clear the back/forward history.
                mainWebView.clearHistory();

                // Clear `formattedUrlString`.
                formattedUrlString = null;

                // Clear `customHeaders`.
                customHeaders.clear();

                // Detach all views from `mainWebViewRelativeLayout`.
                mainWebViewRelativeLayout.removeAllViews();

                // Destroy the internal state of `mainWebView`.
                mainWebView.destroy();

                // Manually delete the `app_webview` folder, which contains the cookies, DOM storage, form data, and `Service Worker` cache.
                // See `https://code.google.com/p/android/issues/detail?id=233826&thanks=233826&ts=1486670530`.
                if (clearEverything) {
                    try {
                        privacyBrowserRuntime.exec("rm -rf " + privateDataDirectoryString + "/app_webview");
                    } catch (IOException e) {
                        // Do nothing if an error is thrown.
                    }
                }

                // Close Privacy Browser.  `finishAndRemoveTask` also removes Privacy Browser from the recent app list.
                if (Build.VERSION.SDK_INT >= 21) {
                    finishAndRemoveTask();
                } else {
                    finish();
                }

                // Remove the terminated program from RAM.  The status code is `0`.
                System.exit(0);
                break;
        }

        // Close the navigation drawer.
        drawerLayout.closeDrawer(GravityCompat.START);
        return true;
    }

    @Override
    public void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);

        // Sync the state of the DrawerToggle after onRestoreInstanceState has finished.
        drawerToggle.syncState();
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);

        // Reload the ad for the free flavor if we are not in full screen mode.
        if (BuildConfig.FLAVOR.contentEquals("free") && !inFullScreenBrowsingMode) {
            // Reload the ad.
            BannerAd.reloadAfterRotate(adView, getApplicationContext(), getString(R.string.ad_id));

            // Reinitialize the `adView` variable, as the `View` will have been removed and re-added by `BannerAd.reloadAfterRotate()`.
            adView = findViewById(R.id.adview);
        }

        // `invalidateOptionsMenu` should recalculate the number of action buttons from the menu to display on the app bar, but it doesn't because of the this bug:  https://code.google.com/p/android/issues/detail?id=20493#c8
        // ActivityCompat.invalidateOptionsMenu(this);
    }

    @Override
    public void onCreateContextMenu(ContextMenu menu, View view, ContextMenu.ContextMenuInfo menuInfo) {
        // Store the `HitTestResult`.
        final WebView.HitTestResult hitTestResult = mainWebView.getHitTestResult();

        // Create strings.
        final String imageUrl;
        final String linkUrl;

        // Get a handle for the `ClipboardManager`.
        final ClipboardManager clipboardManager = (ClipboardManager) getSystemService(CLIPBOARD_SERVICE);

        // Remove the lint errors below that `clipboardManager` might be `null`.
        assert clipboardManager != null;

        switch (hitTestResult.getType()) {
            // `SRC_ANCHOR_TYPE` is a link.
            case WebView.HitTestResult.SRC_ANCHOR_TYPE:
                // Get the target URL.
                linkUrl = hitTestResult.getExtra();

                // Set the target URL as the title of the `ContextMenu`.
                menu.setHeaderTitle(linkUrl);

                // Add a `Load URL` entry.
                menu.add(R.string.load_url).setOnMenuItemClickListener(item -> {
                    loadUrl(linkUrl);
                    return false;
                });

                // Add a `Copy URL` entry.
                menu.add(R.string.copy_url).setOnMenuItemClickListener(item -> {
                    // Save the link URL in a `ClipData`.
                    ClipData srcAnchorTypeClipData = ClipData.newPlainText(getString(R.string.url), linkUrl);

                    // Set the `ClipData` as the clipboard's primary clip.
                    clipboardManager.setPrimaryClip(srcAnchorTypeClipData);
                    return false;
                });

                // Add a `Cancel` entry, which by default closes the `ContextMenu`.
                menu.add(R.string.cancel);
                break;

            case WebView.HitTestResult.EMAIL_TYPE:
                // Get the target URL.
                linkUrl = hitTestResult.getExtra();

                // Set the target URL as the title of the `ContextMenu`.
                menu.setHeaderTitle(linkUrl);

                // Add a `Write Email` entry.
                menu.add(R.string.write_email).setOnMenuItemClickListener(item -> {
                    // We use `ACTION_SENDTO` instead of `ACTION_SEND` so that only email programs are launched.
                    Intent emailIntent = new Intent(Intent.ACTION_SENDTO);

                    // Parse the url and set it as the data for the `Intent`.
                    emailIntent.setData(Uri.parse("mailto:" + linkUrl));

                    // `FLAG_ACTIVITY_NEW_TASK` opens the email program in a new task instead as part of Privacy Browser.
                    emailIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

                    // Make it so.
                    startActivity(emailIntent);
                    return false;
                });

                // Add a `Copy Email Address` entry.
                menu.add(R.string.copy_email_address).setOnMenuItemClickListener(item -> {
                    // Save the email address in a `ClipData`.
                    ClipData srcEmailTypeClipData = ClipData.newPlainText(getString(R.string.email_address), linkUrl);

                    // Set the `ClipData` as the clipboard's primary clip.
                    clipboardManager.setPrimaryClip(srcEmailTypeClipData);
                    return false;
                });

                // Add a `Cancel` entry, which by default closes the `ContextMenu`.
                menu.add(R.string.cancel);
                break;

            // `IMAGE_TYPE` is an image.
            case WebView.HitTestResult.IMAGE_TYPE:
                // Get the image URL.
                imageUrl = hitTestResult.getExtra();

                // Set the image URL as the title of the `ContextMenu`.
                menu.setHeaderTitle(imageUrl);

                // Add a `View Image` entry.
                menu.add(R.string.view_image).setOnMenuItemClickListener(item -> {
                    loadUrl(imageUrl);
                    return false;
                });

                // Add a `Download Image` entry.
                menu.add(R.string.download_image).setOnMenuItemClickListener(item -> {
                    // Show the `DownloadImageDialog` `AlertDialog` and name this instance `@string/download`.
                    AppCompatDialogFragment downloadImageDialogFragment = DownloadImageDialog.imageUrl(imageUrl);
                    downloadImageDialogFragment.show(getSupportFragmentManager(), getString(R.string.download));
                    return false;
                });

                // Add a `Copy URL` entry.
                menu.add(R.string.copy_url).setOnMenuItemClickListener(item -> {
                    // Save the image URL in a `ClipData`.
                    ClipData srcImageTypeClipData = ClipData.newPlainText(getString(R.string.url), imageUrl);

                    // Set the `ClipData` as the clipboard's primary clip.
                    clipboardManager.setPrimaryClip(srcImageTypeClipData);
                    return false;
                });

                // Add a `Cancel` entry, which by default closes the `ContextMenu`.
                menu.add(R.string.cancel);
                break;


            // `SRC_IMAGE_ANCHOR_TYPE` is an image that is also a link.
            case WebView.HitTestResult.SRC_IMAGE_ANCHOR_TYPE:
                // Get the image URL.
                imageUrl = hitTestResult.getExtra();

                // Set the image URL as the title of the `ContextMenu`.
                menu.setHeaderTitle(imageUrl);

                // Add a `View Image` entry.
                menu.add(R.string.view_image).setOnMenuItemClickListener(item -> {
                    loadUrl(imageUrl);
                    return false;
                });

                // Add a `Download Image` entry.
                menu.add(R.string.download_image).setOnMenuItemClickListener(item -> {
                    // Show the `DownloadImageDialog` `AlertDialog` and name this instance `@string/download`.
                    AppCompatDialogFragment downloadImageDialogFragment = DownloadImageDialog.imageUrl(imageUrl);
                    downloadImageDialogFragment.show(getSupportFragmentManager(), getString(R.string.download));
                    return false;
                });

                // Add a `Copy URL` entry.
                menu.add(R.string.copy_url).setOnMenuItemClickListener(item -> {
                    // Save the image URL in a `ClipData`.
                    ClipData srcImageAnchorTypeClipData = ClipData.newPlainText(getString(R.string.url), imageUrl);

                    // Set the `ClipData` as the clipboard's primary clip.
                    clipboardManager.setPrimaryClip(srcImageAnchorTypeClipData);
                    return false;
                });

                // Add a `Cancel` entry, which by default closes the `ContextMenu`.
                menu.add(R.string.cancel);
                break;
        }
    }

    @Override
    public void onCreateBookmark(AppCompatDialogFragment dialogFragment) {
        // Get the `EditTexts` from the `dialogFragment`.
        EditText createBookmarkNameEditText = dialogFragment.getDialog().findViewById(R.id.create_bookmark_name_edittext);
        EditText createBookmarkUrlEditText = dialogFragment.getDialog().findViewById(R.id.create_bookmark_url_edittext);

        // Extract the strings from the `EditTexts`.
        String bookmarkNameString = createBookmarkNameEditText.getText().toString();
        String bookmarkUrlString = createBookmarkUrlEditText.getText().toString();

        // Convert the favoriteIcon Bitmap to a byte array.  `0` is for lossless compression (the only option for a PNG).
        ByteArrayOutputStream favoriteIconByteArrayOutputStream = new ByteArrayOutputStream();
        favoriteIconBitmap.compress(Bitmap.CompressFormat.PNG, 0, favoriteIconByteArrayOutputStream);
        byte[] favoriteIconByteArray = favoriteIconByteArrayOutputStream.toByteArray();

        // Display the new bookmark below the current items in the (0 indexed) list.
        int newBookmarkDisplayOrder = bookmarksListView.getCount();

        // Create the bookmark.
        bookmarksDatabaseHelper.createBookmark(bookmarkNameString, bookmarkUrlString, currentBookmarksFolder, newBookmarkDisplayOrder, favoriteIconByteArray);

        // Update `bookmarksCursor` with the current contents of this folder.
        bookmarksCursor = bookmarksDatabaseHelper.getAllBookmarksCursorByDisplayOrder(currentBookmarksFolder);

        // Update the `ListView`.
        bookmarksCursorAdapter.changeCursor(bookmarksCursor);

        // Scroll to the new bookmark.
        bookmarksListView.setSelection(newBookmarkDisplayOrder);
    }

    @Override
    public void onCreateBookmarkFolder(AppCompatDialogFragment dialogFragment) {
        // Get handles for the views in `dialogFragment`.
        EditText createFolderNameEditText = dialogFragment.getDialog().findViewById(R.id.create_folder_name_edittext);
        RadioButton defaultFolderIconRadioButton = dialogFragment.getDialog().findViewById(R.id.create_folder_default_icon_radiobutton);
        ImageView folderIconImageView = dialogFragment.getDialog().findViewById(R.id.create_folder_default_icon);

        // Get new folder name string.
        String folderNameString = createFolderNameEditText.getText().toString();

        // Get the new folder icon `Bitmap`.
        Bitmap folderIconBitmap;
        if (defaultFolderIconRadioButton.isChecked()) {  // Use the default folder icon.
            // Get the default folder icon and convert it to a `Bitmap`.
            Drawable folderIconDrawable = folderIconImageView.getDrawable();
            BitmapDrawable folderIconBitmapDrawable = (BitmapDrawable) folderIconDrawable;
            folderIconBitmap = folderIconBitmapDrawable.getBitmap();
        } else {  // Use the `WebView` favorite icon.
            folderIconBitmap = favoriteIconBitmap;
        }

        // Convert `folderIconBitmap` to a byte array.  `0` is for lossless compression (the only option for a PNG).
        ByteArrayOutputStream folderIconByteArrayOutputStream = new ByteArrayOutputStream();
        folderIconBitmap.compress(Bitmap.CompressFormat.PNG, 0, folderIconByteArrayOutputStream);
        byte[] folderIconByteArray = folderIconByteArrayOutputStream.toByteArray();

        // Move all the bookmarks down one in the display order.
        for (int i = 0; i < bookmarksListView.getCount(); i++) {
            int databaseId = (int) bookmarksListView.getItemIdAtPosition(i);
            bookmarksDatabaseHelper.updateDisplayOrder(databaseId, i + 1);
        }

        // Create the folder, which will be placed at the top of the `ListView`.
        bookmarksDatabaseHelper.createFolder(folderNameString, currentBookmarksFolder, folderIconByteArray);

        // Update `bookmarksCursor` with the current contents of this folder.
        bookmarksCursor = bookmarksDatabaseHelper.getAllBookmarksCursorByDisplayOrder(currentBookmarksFolder);

        // Update the `ListView`.
        bookmarksCursorAdapter.changeCursor(bookmarksCursor);

        // Scroll to the new folder.
        bookmarksListView.setSelection(0);
    }

    @Override
    public void onCreateHomeScreenShortcut(AppCompatDialogFragment dialogFragment) {
        // Get shortcutNameEditText from the alert dialog.
        EditText shortcutNameEditText = dialogFragment.getDialog().findViewById(R.id.shortcut_name_edittext);

        // Create the bookmark shortcut based on formattedUrlString.
        Intent bookmarkShortcut = new Intent();
        bookmarkShortcut.setAction(Intent.ACTION_VIEW);
        bookmarkShortcut.setData(Uri.parse(formattedUrlString));

        // Place the bookmark shortcut on the home screen.
        Intent placeBookmarkShortcut = new Intent();
        placeBookmarkShortcut.putExtra("android.intent.extra.shortcut.INTENT", bookmarkShortcut);
        placeBookmarkShortcut.putExtra("android.intent.extra.shortcut.NAME", shortcutNameEditText.getText().toString());
        placeBookmarkShortcut.putExtra("android.intent.extra.shortcut.ICON", favoriteIconBitmap);
        placeBookmarkShortcut.setAction("com.android.launcher.action.INSTALL_SHORTCUT");
        sendBroadcast(placeBookmarkShortcut);
    }

    @Override
    public void onDownloadImage(AppCompatDialogFragment dialogFragment, String imageUrl) {
        // Download the image if it has an HTTP or HTTPS URI.
        if (imageUrl.startsWith("http")) {
            // Get a handle for the system `DOWNLOAD_SERVICE`.
            DownloadManager downloadManager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);

            // Parse `imageUrl`.
            DownloadManager.Request downloadRequest = new DownloadManager.Request(Uri.parse(imageUrl));

            // Pass cookies to download manager if cookies are enabled.  This is required to download images from websites that require a login.
            // Code contributed 2017 Hendrik Knackstedt.  Copyright assigned to Soren Stoutner <soren@stoutner.com>.
            if (firstPartyCookiesEnabled) {
                // Get the cookies for `imageUrl`.
                String cookies = cookieManager.getCookie(imageUrl);

                // Add the cookies to `downloadRequest`.  In the HTTP request header, cookies are named `Cookie`.
                downloadRequest.addRequestHeader("Cookie", cookies);
            }

            // Get the file name from `dialogFragment`.
            EditText downloadImageNameEditText = dialogFragment.getDialog().findViewById(R.id.download_image_name);
            String imageName = downloadImageNameEditText.getText().toString();

            // Once we have `WRITE_EXTERNAL_STORAGE` permissions we can use `setDestinationInExternalPublicDir`.
            if (Build.VERSION.SDK_INT >= 23) { // If API >= 23, set the download save in the the `DIRECTORY_DOWNLOADS` using `imageName`.
                downloadRequest.setDestinationInExternalFilesDir(this, "/", imageName);
            } else { // Only set the title using `imageName`.
                downloadRequest.setTitle(imageName);
            }

            // Allow `MediaScanner` to index the download if it is a media file.
            downloadRequest.allowScanningByMediaScanner();

            // Add the URL as the description for the download.
            downloadRequest.setDescription(imageUrl);

            // Show the download notification after the download is completed.
            downloadRequest.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);

            // Remove the lint warning below that `downloadManager` might be `null`.
            assert downloadManager != null;

            // Initiate the download.
            downloadManager.enqueue(downloadRequest);
        } else {  // The image is not an HTTP or HTTPS URI.
            Snackbar.make(mainWebView, R.string.cannot_download_image, Snackbar.LENGTH_INDEFINITE).show();
        }
    }

    @Override
    public void onDownloadFile(AppCompatDialogFragment dialogFragment, String downloadUrl) {
        // Download the file if it has an HTTP or HTTPS URI.
        if (downloadUrl.startsWith("http")) {

            // Get a handle for the system `DOWNLOAD_SERVICE`.
            DownloadManager downloadManager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);

            // Parse `downloadUrl`.
            DownloadManager.Request downloadRequest = new DownloadManager.Request(Uri.parse(downloadUrl));

            // Pass cookies to download manager if cookies are enabled.  This is required to download files from websites that require a login.
            // Code contributed 2017 Hendrik Knackstedt.  Copyright assigned to Soren Stoutner <soren@stoutner.com>.
            if (firstPartyCookiesEnabled) {
                // Get the cookies for `downloadUrl`.
                String cookies = cookieManager.getCookie(downloadUrl);

                // Add the cookies to `downloadRequest`.  In the HTTP request header, cookies are named `Cookie`.
                downloadRequest.addRequestHeader("Cookie", cookies);
            }

            // Get the file name from `dialogFragment`.
            EditText downloadFileNameEditText = dialogFragment.getDialog().findViewById(R.id.download_file_name);
            String fileName = downloadFileNameEditText.getText().toString();

            // Once we have `WRITE_EXTERNAL_STORAGE` permissions we can use `setDestinationInExternalPublicDir`.
            if (Build.VERSION.SDK_INT >= 23) { // If API >= 23, set the download location to `/sdcard/Android/data/com.stoutner.privacybrowser.standard/files` named `fileName`.
                downloadRequest.setDestinationInExternalFilesDir(this, "/", fileName);
            } else { // Only set the title using `fileName`.
                downloadRequest.setTitle(fileName);
            }

            // Allow `MediaScanner` to index the download if it is a media file.
            downloadRequest.allowScanningByMediaScanner();

            // Add the URL as the description for the download.
            downloadRequest.setDescription(downloadUrl);

            // Show the download notification after the download is completed.
            downloadRequest.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);

            // Remove the lint warning below that `downloadManager` might be `null`.
            assert downloadManager != null;

            // Initiate the download.
            downloadManager.enqueue(downloadRequest);
        } else {  // The download is not an HTTP or HTTPS URI.
            Snackbar.make(mainWebView, R.string.cannot_download_file, Snackbar.LENGTH_INDEFINITE).show();
        }
    }

    @Override
    public void onSaveBookmark(AppCompatDialogFragment dialogFragment, int selectedBookmarkDatabaseId) {
        // Get handles for the views from `dialogFragment`.
        EditText editBookmarkNameEditText = dialogFragment.getDialog().findViewById(R.id.edit_bookmark_name_edittext);
        EditText editBookmarkUrlEditText = dialogFragment.getDialog().findViewById(R.id.edit_bookmark_url_edittext);
        RadioButton currentBookmarkIconRadioButton = dialogFragment.getDialog().findViewById(R.id.edit_bookmark_current_icon_radiobutton);

        // Store the bookmark strings.
        String bookmarkNameString = editBookmarkNameEditText.getText().toString();
        String bookmarkUrlString = editBookmarkUrlEditText.getText().toString();

        // Update the bookmark.
        if (currentBookmarkIconRadioButton.isChecked()) {  // Update the bookmark without changing the favorite icon.
            bookmarksDatabaseHelper.updateBookmark(selectedBookmarkDatabaseId, bookmarkNameString, bookmarkUrlString);
        } else {  // Update the bookmark using the `WebView` favorite icon.
            // Convert the favorite icon to a byte array.  `0` is for lossless compression (the only option for a PNG).
            ByteArrayOutputStream newFavoriteIconByteArrayOutputStream = new ByteArrayOutputStream();
            favoriteIconBitmap.compress(Bitmap.CompressFormat.PNG, 0, newFavoriteIconByteArrayOutputStream);
            byte[] newFavoriteIconByteArray = newFavoriteIconByteArrayOutputStream.toByteArray();

            //  Update the bookmark and the favorite icon.
            bookmarksDatabaseHelper.updateBookmark(selectedBookmarkDatabaseId, bookmarkNameString, bookmarkUrlString, newFavoriteIconByteArray);
        }

        // Update `bookmarksCursor` with the current contents of this folder.
        bookmarksCursor = bookmarksDatabaseHelper.getAllBookmarksCursorByDisplayOrder(currentBookmarksFolder);

        // Update the `ListView`.
        bookmarksCursorAdapter.changeCursor(bookmarksCursor);
    }

    @Override
    public void onSaveBookmarkFolder(AppCompatDialogFragment dialogFragment, int selectedFolderDatabaseId) {
        // Get handles for the views from `dialogFragment`.
        EditText editFolderNameEditText = dialogFragment.getDialog().findViewById(R.id.edit_folder_name_edittext);
        RadioButton currentFolderIconRadioButton = dialogFragment.getDialog().findViewById(R.id.edit_folder_current_icon_radiobutton);
        RadioButton defaultFolderIconRadioButton = dialogFragment.getDialog().findViewById(R.id.edit_folder_default_icon_radiobutton);
        ImageView folderIconImageView = dialogFragment.getDialog().findViewById(R.id.edit_folder_default_icon_imageview);

        // Get the new folder name.
        String newFolderNameString = editFolderNameEditText.getText().toString();

        // Check if the favorite icon has changed.
        if (currentFolderIconRadioButton.isChecked()) {  // Only the name has changed.
            // Update the name in the database.
            bookmarksDatabaseHelper.updateFolder(selectedFolderDatabaseId, oldFolderNameString, newFolderNameString);
        } else if (!currentFolderIconRadioButton.isChecked() && newFolderNameString.equals(oldFolderNameString)) {  // Only the icon has changed.
            // Get the new folder icon `Bitmap`.
            Bitmap folderIconBitmap;
            if (defaultFolderIconRadioButton.isChecked()) {
                // Get the default folder icon and convert it to a `Bitmap`.
                Drawable folderIconDrawable = folderIconImageView.getDrawable();
                BitmapDrawable folderIconBitmapDrawable = (BitmapDrawable) folderIconDrawable;
                folderIconBitmap = folderIconBitmapDrawable.getBitmap();
            } else {  // Use the `WebView` favorite icon.
                folderIconBitmap = favoriteIconBitmap;
            }

            // Convert the folder `Bitmap` to a byte array.  `0` is for lossless compression (the only option for a PNG).
            ByteArrayOutputStream folderIconByteArrayOutputStream = new ByteArrayOutputStream();
            folderIconBitmap.compress(Bitmap.CompressFormat.PNG, 0, folderIconByteArrayOutputStream);
            byte[] folderIconByteArray = folderIconByteArrayOutputStream.toByteArray();

            // Update the folder icon in the database.
            bookmarksDatabaseHelper.updateFolder(selectedFolderDatabaseId, folderIconByteArray);
        } else {  // The folder icon and the name have changed.
            // Get the new folder icon `Bitmap`.
            Bitmap folderIconBitmap;
            if (defaultFolderIconRadioButton.isChecked()) {
                // Get the default folder icon and convert it to a `Bitmap`.
                Drawable folderIconDrawable = folderIconImageView.getDrawable();
                BitmapDrawable folderIconBitmapDrawable = (BitmapDrawable) folderIconDrawable;
                folderIconBitmap = folderIconBitmapDrawable.getBitmap();
            } else {  // Use the `WebView` favorite icon.
                folderIconBitmap = MainWebViewActivity.favoriteIconBitmap;
            }

            // Convert the folder `Bitmap` to a byte array.  `0` is for lossless compression (the only option for a PNG).
            ByteArrayOutputStream folderIconByteArrayOutputStream = new ByteArrayOutputStream();
            folderIconBitmap.compress(Bitmap.CompressFormat.PNG, 0, folderIconByteArrayOutputStream);
            byte[] folderIconByteArray = folderIconByteArrayOutputStream.toByteArray();

            // Update the folder name and icon in the database.
            bookmarksDatabaseHelper.updateFolder(selectedFolderDatabaseId, oldFolderNameString, newFolderNameString, folderIconByteArray);
        }

        // Update `bookmarksCursor` with the current contents of this folder.
        bookmarksCursor = bookmarksDatabaseHelper.getAllBookmarksCursorByDisplayOrder(currentBookmarksFolder);

        // Update the `ListView`.
        bookmarksCursorAdapter.changeCursor(bookmarksCursor);
    }

    @Override
    public void onHttpAuthenticationCancel() {
        // Cancel the `HttpAuthHandler`.
        httpAuthHandler.cancel();
    }

    @Override
    public void onHttpAuthenticationProceed(AppCompatDialogFragment dialogFragment) {
        // Get handles for the `EditTexts`.
        EditText usernameEditText = dialogFragment.getDialog().findViewById(R.id.http_authentication_username);
        EditText passwordEditText = dialogFragment.getDialog().findViewById(R.id.http_authentication_password);

        // Proceed with the HTTP authentication.
        httpAuthHandler.proceed(usernameEditText.getText().toString(), passwordEditText.getText().toString());
    }

    public void viewSslCertificate(View view) {
        // Show the `ViewSslCertificateDialog` `AlertDialog` and name this instance `@string/view_ssl_certificate`.
        DialogFragment viewSslCertificateDialogFragment = new ViewSslCertificateDialog();
        viewSslCertificateDialogFragment.show(getFragmentManager(), getString(R.string.view_ssl_certificate));
    }

    @Override
    public void onSslErrorCancel() {
        sslErrorHandler.cancel();
    }

    @Override
    public void onSslErrorProceed() {
        sslErrorHandler.proceed();
    }

    @Override
    public void onSslMismatchBack() {
        if (mainWebView.canGoBack()) {  // There is a back page in the history.
            // Set `navigatingHistory` so that the domain settings are applied when the new URL is loaded.
            navigatingHistory = true;

            // Go back.
            mainWebView.goBack();
        } else {  // There are no pages to go back to.
            // Load a blank page
            loadUrl("");
        }
    }

    @Override
    public void onSslMismatchProceed() {
        // Do not check the pinned SSL certificate for this domain again until the domain changes.
        ignorePinnedSslCertificate = true;
    }

    @Override
    public void onUrlHistoryEntrySelected(int moveBackOrForwardSteps) {
        // Set `navigatingHistory` so that the domain settings are applied when the new URL is loaded.
        navigatingHistory = true;

        // Load the history entry.
        mainWebView.goBackOrForward(moveBackOrForwardSteps);
    }

    @Override
    public void onClearHistory() {
        // Clear the history.
        mainWebView.clearHistory();
    }

    // Override `onBackPressed` to handle the navigation drawer and `mainWebView`.
    @Override
    public void onBackPressed() {
        if (drawerLayout.isDrawerVisible(GravityCompat.START)) {  // The navigation drawer is open.
            // Close the navigation drawer.
            drawerLayout.closeDrawer(GravityCompat.START);
        } else if (drawerLayout.isDrawerVisible(GravityCompat.END)){  // The bookmarks drawer is open.
            if (currentBookmarksFolder.isEmpty()) {  // The home folder is displayed.
                // close the bookmarks drawer.
                drawerLayout.closeDrawer(GravityCompat.END);
            } else {  // A subfolder is displayed.
                // Place the former parent folder in `currentFolder`.
                currentBookmarksFolder = bookmarksDatabaseHelper.getParentFolder(currentBookmarksFolder);

                // Load the new folder.
                loadBookmarksFolder();
            }

        } else if (mainWebView.canGoBack()) {  // There is at least one item in the `WebView` history.
            // Set `navigatingHistory` so that the domain settings are applied when the new URL is loaded.
            navigatingHistory = true;

            // Go back.
            mainWebView.goBack();
        } else {  // There isn't anything to do in Privacy Browser.
            // Pass `onBackPressed()` to the system.
            super.onBackPressed();
        }
    }

    private void loadUrlFromTextBox() throws UnsupportedEncodingException {
        // Get the text from urlTextBox and convert it to a string.  trim() removes white spaces from the beginning and end of the string.
        String unformattedUrlString = urlTextBox.getText().toString().trim();

        // Check to see if `unformattedUrlString` is a valid URL.  Otherwise, convert it into a search.
        if ((Patterns.WEB_URL.matcher(unformattedUrlString).matches()) || (unformattedUrlString.startsWith("http://")) || (unformattedUrlString.startsWith("https://"))) {
            // Add `http://` at the beginning if it is missing.  Otherwise the app will segfault.
            if (!unformattedUrlString.startsWith("http")) {
                unformattedUrlString = "http://" + unformattedUrlString;
            }

            // Initialize `unformattedUrl`.
            URL unformattedUrl = null;

            // Convert `unformattedUrlString` to a `URL`, then to a `URI`, and then back to a `String`, which sanitizes the input and adds in any missing components.
            try {
                unformattedUrl = new URL(unformattedUrlString);
            } catch (MalformedURLException e) {
                e.printStackTrace();
            }

            // The ternary operator (? :) makes sure that a null pointer exception is not thrown, which would happen if `.get` was called on a `null` value.
            final String scheme = unformattedUrl != null ? unformattedUrl.getProtocol() : null;
            final String authority = unformattedUrl != null ? unformattedUrl.getAuthority() : null;
            final String path = unformattedUrl != null ? unformattedUrl.getPath() : null;
            final String query = unformattedUrl != null ? unformattedUrl.getQuery() : null;
            final String fragment = unformattedUrl != null ? unformattedUrl.getRef() : null;

            // Build the URI.
            Uri.Builder formattedUri = new Uri.Builder();
            formattedUri.scheme(scheme).authority(authority).path(path).query(query).fragment(fragment);

            // Decode `formattedUri` as a `String` in `UTF-8`.
            formattedUrlString = URLDecoder.decode(formattedUri.build().toString(), "UTF-8");
        } else {
            // Sanitize the search input and convert it to a search.
            final String encodedUrlString = URLEncoder.encode(unformattedUrlString, "UTF-8");

            // Add the base search URL.
            formattedUrlString = searchURL + encodedUrlString;
        }

        loadUrl(formattedUrlString);
    }


    private void loadUrl(String url) {
        // Apply any custom domain settings.
        applyDomainSettings(url);

        // Load the URL.
        mainWebView.loadUrl(url, customHeaders);

        // Set `urlIsLoading` to prevent changes in the user agent on websites with redirects from reloading the current website.
        urlIsLoading = true;
    }

    public void findPreviousOnPage(View view) {
        // Go to the previous highlighted phrase on the page.  `false` goes backwards instead of forwards.
        mainWebView.findNext(false);
    }

    public void findNextOnPage(View view) {
        // Go to the next highlighted phrase on the page. `true` goes forwards instead of backwards.
        mainWebView.findNext(true);
    }

    public void closeFindOnPage(View view) {
        // Delete the contents of `find_on_page_edittext`.
        findOnPageEditText.setText(null);

        // Clear the highlighted phrases.
        mainWebView.clearMatches();

        // Hide the Find on Page `RelativeLayout`.
        findOnPageLinearLayout.setVisibility(View.GONE);

        // Show the URL app bar.
        supportAppBar.setVisibility(View.VISIBLE);

        // Hide the keyboard so we can see the webpage.  `0` indicates no additional flags.
        inputMethodManager.hideSoftInputFromWindow(mainWebView.getWindowToken(), 0);
    }

    private void applyAppSettings() {
        // Get a handle for `sharedPreferences`.  `this` references the current context.
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);

        // Store the values from `sharedPreferences` in variables.
        String homepageString = sharedPreferences.getString("homepage", "https://start.duckduckgo.com");
        String torHomepageString = sharedPreferences.getString("tor_homepage", "https://3g2upl4pq6kufc4m.onion");
        String torSearchString = sharedPreferences.getString("tor_search", "https://3g2upl4pq6kufc4m.onion/html/?q=");
        String torSearchCustomURLString = sharedPreferences.getString("tor_search_custom_url", "");
        String searchString = sharedPreferences.getString("search", "https://duckduckgo.com/html/?q=");
        String searchCustomURLString = sharedPreferences.getString("search_custom_url", "");
        adBlockerEnabled = sharedPreferences.getBoolean("block_ads", true);
        incognitoModeEnabled = sharedPreferences.getBoolean("incognito_mode", false);
        boolean doNotTrackEnabled = sharedPreferences.getBoolean("do_not_track", false);
        boolean proxyThroughOrbot = sharedPreferences.getBoolean("proxy_through_orbot", false);
        fullScreenBrowsingModeEnabled = sharedPreferences.getBoolean("full_screen_browsing_mode", false);
        hideSystemBarsOnFullscreen = sharedPreferences.getBoolean("hide_system_bars", false);
        translucentNavigationBarOnFullscreen = sharedPreferences.getBoolean("translucent_navigation_bar", true);
        swipeToRefreshEnabled = sharedPreferences.getBoolean("swipe_to_refresh", false);
        displayWebpageImagesBoolean = sharedPreferences.getBoolean("display_webpage_images", true);

        // Set the homepage, search, and proxy options.
        if (proxyThroughOrbot) {  // Set the Tor options.
            // Set `torHomepageString` as `homepage`.
            homepage = torHomepageString;

            // If formattedUrlString is null assign the homepage to it.
            if (formattedUrlString == null) {
                formattedUrlString = homepage;
            }

            // Set the search URL.
            if (torSearchString.equals("Custom URL")) {  // Get the custom URL string.
                searchURL = torSearchCustomURLString;
            } else {  // Use the string from the pre-built list.
                searchURL = torSearchString;
            }

            // Set the proxy.  `this` refers to the current activity where an `AlertDialog` might be displayed.
            OrbotProxyHelper.setProxy(getApplicationContext(), this, "localhost", "8118");

            // Set the `appBar` background to indicate proxying through Orbot is enabled.  `this` refers to the context.
            if (darkTheme) {
                appBar.setBackgroundDrawable(ContextCompat.getDrawable(this, R.color.dark_blue_30));
            } else {
                appBar.setBackgroundDrawable(ContextCompat.getDrawable(this, R.color.blue_50));
            }

            // Display a message to the user if we are waiting on Orbot.
            if (!orbotStatus.equals("ON")) {
                // Set `waitingForOrbot`.
                waitingForOrbot = true;

                // Load a waiting page.  `null` specifies no encoding, which defaults to ASCII.
                mainWebView.loadData(waitingForOrbotHTMLString, "text/html", null);
            }
        } else {  // Set the non-Tor options.
            // Set `homepageString` as `homepage`.
            homepage = homepageString;

            // If formattedUrlString is null assign the homepage to it.
            if (formattedUrlString == null) {
                formattedUrlString = homepage;
            }

            // Set the search URL.
            if (searchString.equals("Custom URL")) {  // Get the custom URL string.
                searchURL = searchCustomURLString;
            } else {  // Use the string from the pre-built list.
                searchURL = searchString;
            }

            // Reset the proxy to default.  The host is `""` and the port is `"0"`.
            OrbotProxyHelper.setProxy(getApplicationContext(), this, "", "0");

            // Set the default `appBar` background.  `this` refers to the context.
            if (darkTheme) {
                appBar.setBackgroundDrawable(ContextCompat.getDrawable(this, R.color.gray_900));
            } else {
                appBar.setBackgroundDrawable(ContextCompat.getDrawable(this, R.color.gray_100));
            }

            // Reset `waitingForOrbot.
            waitingForOrbot = false;
        }

        // Set swipe to refresh.
        swipeRefreshLayout.setEnabled(swipeToRefreshEnabled);

        // Set Do Not Track status.
        if (doNotTrackEnabled) {
            customHeaders.put("DNT", "1");
        } else {
            customHeaders.remove("DNT");
        }

        // Apply the appropriate full screen mode the `SYSTEM_UI` flags.
        if (fullScreenBrowsingModeEnabled && inFullScreenBrowsingMode) {
            if (hideSystemBarsOnFullscreen) {  // Hide everything.
                // Remove the translucent navigation setting if it is currently flagged.
                getWindow().clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);

                // Remove the translucent status bar overlay.
                getWindow().clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);

                // Remove the translucent status bar overlay on the `Drawer Layout`, which is special and needs its own command.
                drawerLayout.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);

                /* SYSTEM_UI_FLAG_FULLSCREEN hides the status bar at the top of the screen.
                 * SYSTEM_UI_FLAG_HIDE_NAVIGATION hides the navigation bar on the bottom or right of the screen.
                 * SYSTEM_UI_FLAG_IMMERSIVE_STICKY makes the status and navigation bars translucent and automatically rehides them after they are shown.
                 */
                rootCoordinatorLayout.setSystemUiVisibility(View.SYSTEM_UI_FLAG_FULLSCREEN | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY);
            } else {  // Hide everything except the status and navigation bars.
                // Add the translucent status flag if it is unset.
                getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);

                if (translucentNavigationBarOnFullscreen) {
                    // Set the navigation bar to be translucent.
                    getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);
                } else {
                    // Set the navigation bar to be black.
                    getWindow().clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);
                }
            }
        } else {  // Switch to normal viewing mode.
            // Reset `inFullScreenBrowsingMode` to `false`.
            inFullScreenBrowsingMode = false;

            // Show the `appBar` if `findOnPageLinearLayout` is not visible.
            if (findOnPageLinearLayout.getVisibility() == View.GONE) {
                appBar.show();
            }

            // Show the `BannerAd` in the free flavor.
            if (BuildConfig.FLAVOR.contentEquals("free")) {
                // Reload the ad.  Because the screen may have rotated, we need to use `reloadAfterRotate`.
                BannerAd.reloadAfterRotate(adView, getApplicationContext(), getString(R.string.ad_id));

                // Reinitialize the `adView` variable, as the `View` will have been removed and re-added by `BannerAd.reloadAfterRotate()`.
                adView = findViewById(R.id.adview);
            }

            // Remove the translucent navigation bar flag if it is set.
            getWindow().clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);

            // Add the translucent status flag if it is unset.  This also resets `drawerLayout's` `View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN`.
            getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);

            // Remove any `SYSTEM_UI` flags from `rootCoordinatorLayout`.
            rootCoordinatorLayout.setSystemUiVisibility(0);

            // Constrain `rootCoordinatorLayout` inside the status and navigation bars.
            rootCoordinatorLayout.setFitsSystemWindows(true);
        }
    }

    // We have to use the deprecated `.getDrawable()` until the minimum API >= 21.
    @SuppressWarnings("deprecation")
    private void applyDomainSettings(String url) {
        // Reset `navigatingHistory`.
        navigatingHistory = false;

        // Parse the URL into a URI.
        Uri uri = Uri.parse(url);

        // Extract the domain from `uri`.
        String hostName = uri.getHost();

        // Initialize `loadingNewDomainName`.
        boolean loadingNewDomainName;

        // If either `hostName` or `currentDomainName` are `null`, run the options for loading a new domain name.
        // The lint suggestion to simplify the `if` statement is incorrect, because `hostName.equals(currentDomainName)` can produce a `null object reference.`
        //noinspection SimplifiableIfStatement
        if ((hostName == null) || (currentDomainName == null)) {
            loadingNewDomainName = true;
        } else {  // Determine if `hostName` equals `currentDomainName`.
            loadingNewDomainName = !hostName.equals(currentDomainName);
        }

        // Only apply the domain settings if we are loading a new domain.  This allows the user to set temporary settings for JavaScript, cookies, DOM storage, etc.
        if (loadingNewDomainName) {
            // Set the new `hostname` as the `currentDomainName`.
            currentDomainName = hostName;

            // Reset `ignorePinnedSslCertificate`.
            ignorePinnedSslCertificate = false;

            // Reset `favoriteIconBitmap` and display it in the `appbar`.
            favoriteIconBitmap = favoriteIconDefaultBitmap;
            favoriteIconImageView.setImageBitmap(Bitmap.createScaledBitmap(favoriteIconBitmap, 64, 64, true));

            // Initialize the database handler.  `this` specifies the context.  The two `nulls` do not specify the database name or a `CursorFactory`.
            // The `0` specifies the database version, but that is ignored and set instead using a constant in `DomainsDatabaseHelper`.
            DomainsDatabaseHelper domainsDatabaseHelper = new DomainsDatabaseHelper(this, null, null, 0);

            // Get a full cursor from `domainsDatabaseHelper`.
            Cursor domainNameCursor = domainsDatabaseHelper.getDomainNameCursorOrderedByDomain();

            // Initialize `domainSettingsSet`.
            Set<String> domainSettingsSet = new HashSet<>();

            // Get the domain name column index.
            int domainNameColumnIndex = domainNameCursor.getColumnIndex(DomainsDatabaseHelper.DOMAIN_NAME);

            // Populate `domainSettingsSet`.
            for (int i = 0; i < domainNameCursor.getCount(); i++) {
                // Move `domainsCursor` to the current row.
                domainNameCursor.moveToPosition(i);

                // Store the domain name in `domainSettingsSet`.
                domainSettingsSet.add(domainNameCursor.getString(domainNameColumnIndex));
            }

            // Close `domainNameCursor.
            domainNameCursor.close();

            // Initialize variables to track if domain settings will be applied and, if so, under which name.
            domainSettingsApplied = false;
            String domainNameInDatabase = null;

            // Check the hostname.
            if (domainSettingsSet.contains(hostName)) {
                domainSettingsApplied = true;
                domainNameInDatabase = hostName;
            }

            // If `hostName` is not `null`, check all the subdomains of `hostName` against wildcard domains in `domainCursor`.
            if (hostName != null) {
                while (hostName.contains(".") && !domainSettingsApplied) {  // Stop checking if we run out of  `.` or if we already know that `domainSettingsApplied` is `true`.
                    if (domainSettingsSet.contains("*." + hostName)) {  // Check the host name prepended by `*.`.
                        domainSettingsApplied = true;
                        domainNameInDatabase = "*." + hostName;
                    }

                    // Strip out the lowest subdomain of `host`.
                    hostName = hostName.substring(hostName.indexOf(".") + 1);
                }
            }

            // Get a handle for the shared preference.  `this` references the current context.
            SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);

            // Store the general preference information.
            String defaultFontSizeString = sharedPreferences.getString("default_font_size", "100");
            String defaultUserAgentString = sharedPreferences.getString("user_agent", "PrivacyBrowser/1.0");
            String defaultCustomUserAgentString = sharedPreferences.getString("custom_user_agent", "PrivacyBrowser/1.0");
            nightMode = sharedPreferences.getBoolean("night_mode", false);

            if (domainSettingsApplied) {  // The url we are loading has custom domain settings.
                // Get a cursor for the current host and move it to the first position.
                Cursor currentHostDomainSettingsCursor = domainsDatabaseHelper.getCursorForDomainName(domainNameInDatabase);
                currentHostDomainSettingsCursor.moveToFirst();

                // Get the settings from the cursor.
                domainSettingsDatabaseId = (currentHostDomainSettingsCursor.getInt(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper._ID)));
                javaScriptEnabled = (currentHostDomainSettingsCursor.getInt(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.ENABLE_JAVASCRIPT)) == 1);
                firstPartyCookiesEnabled = (currentHostDomainSettingsCursor.getInt(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.ENABLE_FIRST_PARTY_COOKIES)) == 1);
                thirdPartyCookiesEnabled = (currentHostDomainSettingsCursor.getInt(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.ENABLE_THIRD_PARTY_COOKIES)) == 1);
                domStorageEnabled = (currentHostDomainSettingsCursor.getInt(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.ENABLE_DOM_STORAGE)) == 1);
                saveFormDataEnabled = (currentHostDomainSettingsCursor.getInt(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.ENABLE_FORM_DATA)) == 1);
                String userAgentString = currentHostDomainSettingsCursor.getString(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.USER_AGENT));
                int fontSize = currentHostDomainSettingsCursor.getInt(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.FONT_SIZE));
                displayWebpageImagesInt = currentHostDomainSettingsCursor.getInt(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.DISPLAY_IMAGES));
                int nightModeInt = currentHostDomainSettingsCursor.getInt(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.NIGHT_MODE));
                pinnedDomainSslCertificate = (currentHostDomainSettingsCursor.getInt(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.PINNED_SSL_CERTIFICATE)) == 1);
                pinnedDomainSslIssuedToCNameString = currentHostDomainSettingsCursor.getString(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.SSL_ISSUED_TO_COMMON_NAME));
                pinnedDomainSslIssuedToONameString = currentHostDomainSettingsCursor.getString(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.SSL_ISSUED_TO_ORGANIZATION));
                pinnedDomainSslIssuedToUNameString = currentHostDomainSettingsCursor.getString(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.SSL_ISSUED_TO_ORGANIZATIONAL_UNIT));
                pinnedDomainSslIssuedByCNameString = currentHostDomainSettingsCursor.getString(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.SSL_ISSUED_BY_COMMON_NAME));
                pinnedDomainSslIssuedByONameString = currentHostDomainSettingsCursor.getString(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.SSL_ISSUED_BY_ORGANIZATION));
                pinnedDomainSslIssuedByUNameString = currentHostDomainSettingsCursor.getString(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.SSL_ISSUED_BY_ORGANIZATIONAL_UNIT));

                // Set `nightMode` according to `nightModeInt`.  If `nightModeInt` is `DomainsDatabaseHelper.NIGHT_MODE_SYSTEM_DEFAULT` the current setting from `sharedPreferences` will be used.
                switch (nightModeInt) {
                    case DomainsDatabaseHelper.NIGHT_MODE_ENABLED:
                        nightMode = true;
                        break;

                    case DomainsDatabaseHelper.NIGHT_MODE_DISABLED:
                        nightMode = false;
                        break;
                }

                // Set `javaScriptEnabled` to be `true` if `night_mode` is `true`.
                if (nightMode) {
                    javaScriptEnabled = true;
                }

                // Set the pinned SSL certificate start date to `null` if the saved date `long` is 0.
                if (currentHostDomainSettingsCursor.getLong(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.SSL_START_DATE)) == 0) {
                    pinnedDomainSslStartDate = null;
                } else {
                    pinnedDomainSslStartDate = new Date(currentHostDomainSettingsCursor.getLong(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.SSL_START_DATE)));
                }

                // Set the pinned SSL certificate end date to `null` if the saved date `long` is 0.
                if (currentHostDomainSettingsCursor.getLong(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.SSL_END_DATE)) == 0) {
                    pinnedDomainSslEndDate = null;
                } else {
                    pinnedDomainSslEndDate = new Date(currentHostDomainSettingsCursor.getLong(currentHostDomainSettingsCursor.getColumnIndex(DomainsDatabaseHelper.SSL_END_DATE)));
                }

                // Close `currentHostDomainSettingsCursor`.
                currentHostDomainSettingsCursor.close();

                // Apply the domain settings.
                mainWebView.getSettings().setJavaScriptEnabled(javaScriptEnabled);
                cookieManager.setAcceptCookie(firstPartyCookiesEnabled);
                mainWebView.getSettings().setDomStorageEnabled(domStorageEnabled);
                mainWebView.getSettings().setSaveFormData(saveFormDataEnabled);

                // Apply the font size.
                if (fontSize == 0) {  // Apply the default font size.
                    mainWebView.getSettings().setTextZoom(Integer.valueOf(defaultFontSizeString));
                } else {  // Apply the specified font size.
                    mainWebView.getSettings().setTextZoom(fontSize);
                }

                // Set third-party cookies status if API >= 21.
                if (Build.VERSION.SDK_INT >= 21) {
                    cookieManager.setAcceptThirdPartyCookies(mainWebView, thirdPartyCookiesEnabled);
                }

                // Only set the user agent if the webpage is not currently loading.  Otherwise, changing the user agent on redirects can cause the original website to reload.  <https://redmine.stoutner.com/issues/160>
                if (!urlIsLoading) {
                    switch (userAgentString) {
                        case "System default user agent":
                            // Set the user agent according to the system default.
                            switch (defaultUserAgentString) {
                                case "WebView default user agent":
                                    // Set the user agent to `""`, which uses the default value.
                                    mainWebView.getSettings().setUserAgentString("");
                                    break;

                                case "Custom user agent":
                                    // Set the custom user agent.
                                    mainWebView.getSettings().setUserAgentString(defaultCustomUserAgentString);
                                    break;

                                default:
                                    // Use the selected user agent.
                                    mainWebView.getSettings().setUserAgentString(defaultUserAgentString);
                            }
                            break;

                        case "WebView default user agent":
                            // Set the user agent to `""`, which uses the default value.
                            mainWebView.getSettings().setUserAgentString("");
                            break;

                        default:
                            // Use the selected user agent.
                            mainWebView.getSettings().setUserAgentString(userAgentString);
                    }
                }

                // Set a green background on `urlTextBox` to indicate that custom domain settings are being used.  We have to use the deprecated `.getDrawable()` until the minimum API >= 21.
                if (darkTheme) {
                    urlAppBarRelativeLayout.setBackground(getResources().getDrawable(R.drawable.url_bar_background_dark_blue));
                } else {
                    urlAppBarRelativeLayout.setBackground(getResources().getDrawable(R.drawable.url_bar_background_light_green));
                }
            } else {  // The URL we are loading does not have custom domain settings.  Load the defaults.
                // Store the values from `sharedPreferences` in variables.
                javaScriptEnabled = sharedPreferences.getBoolean("javascript_enabled", false);
                firstPartyCookiesEnabled = sharedPreferences.getBoolean("first_party_cookies_enabled", false);
                thirdPartyCookiesEnabled = sharedPreferences.getBoolean("third_party_cookies_enabled", false);
                domStorageEnabled = sharedPreferences.getBoolean("dom_storage_enabled", false);
                saveFormDataEnabled = sharedPreferences.getBoolean("save_form_data_enabled", false);

                // Set `javaScriptEnabled` to be `true` if `night_mode` is `true`.
                if (nightMode) {
                    javaScriptEnabled = true;
                }

                // Apply the default settings.
                mainWebView.getSettings().setJavaScriptEnabled(javaScriptEnabled);
                cookieManager.setAcceptCookie(firstPartyCookiesEnabled);
                mainWebView.getSettings().setDomStorageEnabled(domStorageEnabled);
                mainWebView.getSettings().setSaveFormData(saveFormDataEnabled);
                mainWebView.getSettings().setTextZoom(Integer.valueOf(defaultFontSizeString));

                // Reset the pinned SSL certificate information.
                domainSettingsDatabaseId = -1;
                pinnedDomainSslCertificate = false;
                pinnedDomainSslIssuedToCNameString = "";
                pinnedDomainSslIssuedToONameString = "";
                pinnedDomainSslIssuedToUNameString = "";
                pinnedDomainSslIssuedByCNameString = "";
                pinnedDomainSslIssuedByONameString = "";
                pinnedDomainSslIssuedByUNameString = "";
                pinnedDomainSslStartDate = null;
                pinnedDomainSslEndDate = null;

                // Set third-party cookies status if API >= 21.
                if (Build.VERSION.SDK_INT >= 21) {
                    cookieManager.setAcceptThirdPartyCookies(mainWebView, thirdPartyCookiesEnabled);
                }

                // Only set the user agent if the webpage is not currently loading.  Otherwise, changing the user agent on redirects can cause the original website to reload.  <https://redmine.stoutner.com/issues/160>
                if (!urlIsLoading) {
                    switch (defaultUserAgentString) {
                        case "WebView default user agent":
                            // Set the user agent to `""`, which uses the default value.
                            mainWebView.getSettings().setUserAgentString("");
                            break;

                        case "Custom user agent":
                            // Set the custom user agent.
                            mainWebView.getSettings().setUserAgentString(defaultCustomUserAgentString);
                            break;

                        default:
                            // Use the selected user agent.
                            mainWebView.getSettings().setUserAgentString(defaultUserAgentString);
                    }
                }

                // Set a transparent background on `urlTextBox`.  We have to use the deprecated `.getDrawable()` until the minimum API >= 21.
                urlAppBarRelativeLayout.setBackgroundDrawable(getResources().getDrawable(R.color.transparent));
            }

            // Close `domainsDatabaseHelper`.
            domainsDatabaseHelper.close();

            // Remove the `onTheFlyDisplayImagesSet` flag and set the display webpage images mode.  `true` indicates that custom domain settings are applied.
            onTheFlyDisplayImagesSet = false;
            setDisplayWebpageImages();

            // Update the privacy icons, but only if `mainMenu` has already been populated.
            if (mainMenu != null) {
                updatePrivacyIcons(true);
            }
        }
    }

    private void setDisplayWebpageImages() {
        if (!onTheFlyDisplayImagesSet) {
            if (domainSettingsApplied) {  // Custom domain settings are applied.
                switch (displayWebpageImagesInt) {
                    case DomainsDatabaseHelper.DISPLAY_WEBPAGE_IMAGES_SYSTEM_DEFAULT:
                        mainWebView.getSettings().setLoadsImagesAutomatically(displayWebpageImagesBoolean);
                        break;

                    case DomainsDatabaseHelper.DISPLAY_WEBPAGE_IMAGES_ENABLED:
                        mainWebView.getSettings().setLoadsImagesAutomatically(true);
                        break;

                    case DomainsDatabaseHelper.DISPLAY_WEBPAGE_IMAGES_DISABLED:
                        mainWebView.getSettings().setLoadsImagesAutomatically(false);
                        break;
                }
            } else {  // Default settings are applied.
                mainWebView.getSettings().setLoadsImagesAutomatically(displayWebpageImagesBoolean);
            }
        }
    }

    private void updatePrivacyIcons(boolean runInvalidateOptionsMenu) {
        // Get handles for the icons.
        MenuItem privacyIconMenuItem = mainMenu.findItem(R.id.toggle_javascript);
        MenuItem firstPartyCookiesIconMenuItem = mainMenu.findItem(R.id.toggle_first_party_cookies);
        MenuItem domStorageIconMenuItem = mainMenu.findItem(R.id.toggle_dom_storage);
        MenuItem formDataIconMenuItem = mainMenu.findItem(R.id.toggle_save_form_data);

        // Update `privacyIcon`.
        if (javaScriptEnabled) {  // JavaScript is enabled.
            privacyIconMenuItem.setIcon(R.drawable.javascript_enabled);
        } else if (firstPartyCookiesEnabled) {  // JavaScript is disabled but cookies are enabled.
            privacyIconMenuItem.setIcon(R.drawable.warning);
        } else {  // All the dangerous features are disabled.
            privacyIconMenuItem.setIcon(R.drawable.privacy_mode);
        }

        // Update `firstPartyCookiesIcon`.
        if (firstPartyCookiesEnabled) {  // First-party cookies are enabled.
            firstPartyCookiesIconMenuItem.setIcon(R.drawable.cookies_enabled);
        } else {  // First-party cookies are disabled.
            if (darkTheme) {
                firstPartyCookiesIconMenuItem.setIcon(R.drawable.cookies_disabled_dark);
            } else {
                firstPartyCookiesIconMenuItem.setIcon(R.drawable.cookies_disabled_light);
            }
        }

        // Update `domStorageIcon`.
        if (javaScriptEnabled && domStorageEnabled) {  // Both JavaScript and DOM storage are enabled.
            domStorageIconMenuItem.setIcon(R.drawable.dom_storage_enabled);
        } else if (javaScriptEnabled) {  // JavaScript is enabled but DOM storage is disabled.
            if (darkTheme) {
                domStorageIconMenuItem.setIcon(R.drawable.dom_storage_disabled_dark);
            } else {
                domStorageIconMenuItem.setIcon(R.drawable.dom_storage_disabled_light);
            }
        } else {  // JavaScript is disabled, so DOM storage is ghosted.
            if (darkTheme) {
                domStorageIconMenuItem.setIcon(R.drawable.dom_storage_ghosted_dark);
            } else {
                domStorageIconMenuItem.setIcon(R.drawable.dom_storage_ghosted_light);
            }
        }

        // Update `formDataIcon`.
        if (saveFormDataEnabled) {  // Form data is enabled.
            formDataIconMenuItem.setIcon(R.drawable.form_data_enabled);
        } else {  // Form data is disabled.
            if (darkTheme) {
                formDataIconMenuItem.setIcon(R.drawable.form_data_disabled_dark);
            } else {
                formDataIconMenuItem.setIcon(R.drawable.form_data_disabled_light);
            }
        }

        // `invalidateOptionsMenu` calls `onPrepareOptionsMenu()` and redraws the icons in the `AppBar`.  `this` references the current activity.
        if (runInvalidateOptionsMenu) {
            ActivityCompat.invalidateOptionsMenu(this);
        }
    }

    private void highlightUrlText() {
        String urlString = urlTextBox.getText().toString();

        if (urlString.startsWith("http://")) {  // Highlight connections that are not encrypted.
            urlTextBox.getText().setSpan(redColorSpan, 0, 7, Spanned.SPAN_INCLUSIVE_INCLUSIVE);
        } else if (urlString.startsWith("https://")) {  // Highlight connections that are encrypted.
            urlTextBox.getText().setSpan(initialGrayColorSpan, 0, 8, Spanned.SPAN_INCLUSIVE_INCLUSIVE);
        }

        // Get the index of the `/` immediately after the domain name.
        int endOfDomainName = urlString.indexOf("/", (urlString.indexOf("//") + 2));

        // De-emphasize the text after the domain name.
        if (endOfDomainName > 0) {
            urlTextBox.getText().setSpan(finalGrayColorSpan, endOfDomainName, urlString.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
        }
    }

    private void loadBookmarksFolder() {
        // Update `bookmarksCursor` with the contents of the bookmarks database for the current folder.
        bookmarksCursor = bookmarksDatabaseHelper.getAllBookmarksCursorByDisplayOrder(currentBookmarksFolder);

        // Populate the bookmarks cursor adapter.  `this` specifies the `Context`.  `false` disables `autoRequery`.
        bookmarksCursorAdapter = new CursorAdapter(this, bookmarksCursor, false) {
            @Override
            public View newView(Context context, Cursor cursor, ViewGroup parent) {
                // Inflate the individual item layout.  `false` does not attach it to the root.
                return getLayoutInflater().inflate(R.layout.bookmarks_drawer_item_linearlayout, parent, false);
            }

            @Override
            public void bindView(View view, Context context, Cursor cursor) {
                // Get handles for the views.
                ImageView bookmarkFavoriteIcon = view.findViewById(R.id.bookmark_favorite_icon);
                TextView bookmarkNameTextView = view.findViewById(R.id.bookmark_name);

                // Get the favorite icon byte array from the `Cursor`.
                byte[] favoriteIconByteArray = cursor.getBlob(cursor.getColumnIndex(BookmarksDatabaseHelper.FAVORITE_ICON));

                // Convert the byte array to a `Bitmap` beginning at the first byte and ending at the last.
                Bitmap favoriteIconBitmap = BitmapFactory.decodeByteArray(favoriteIconByteArray, 0, favoriteIconByteArray.length);

                // Display the bitmap in `bookmarkFavoriteIcon`.
                bookmarkFavoriteIcon.setImageBitmap(favoriteIconBitmap);

                // Get the bookmark name from the cursor and display it in `bookmarkNameTextView`.
                String bookmarkNameString = cursor.getString(cursor.getColumnIndex(BookmarksDatabaseHelper.BOOKMARK_NAME));
                bookmarkNameTextView.setText(bookmarkNameString);

                // Make the font bold for folders.
                if (cursor.getInt(cursor.getColumnIndex(BookmarksDatabaseHelper.IS_FOLDER)) == 1) {
                    bookmarkNameTextView.setTypeface(Typeface.DEFAULT_BOLD);
                } else {  // Reset the font to default for normal bookmarks.
                    bookmarkNameTextView.setTypeface(Typeface.DEFAULT);
                }
            }
        };

        // Populate the `ListView` with the adapter.
        bookmarksListView.setAdapter(bookmarksCursorAdapter);

        // Set the bookmarks drawer title.
        if (currentBookmarksFolder.isEmpty()) {
            bookmarksTitleTextView.setText(R.string.bookmarks);
        } else {
            bookmarksTitleTextView.setText(currentBookmarksFolder);
        }
    }
}