/*
 * Copyright © 2016-2021 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.fragments

import android.content.Intent
import android.content.res.Configuration
import android.net.Uri
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.webkit.WebResourceResponse
import android.webkit.WebView
import android.webkit.WebViewClient

import androidx.fragment.app.Fragment
import androidx.webkit.WebSettingsCompat
import androidx.webkit.WebViewAssetLoader
import androidx.webkit.WebViewAssetLoader.AssetsPathHandler
import androidx.webkit.WebViewFeature

import com.stoutner.privacybrowser.R

// Define the class constants.
private const val TAB_NUMBER = "tab_number"
private const val SCROLL_X = "scroll_x"
private const val SCROLL_Y = "scroll_y"

class AboutWebViewFragment : Fragment() {
    // Define the class variables.
    private var tabNumber = 0

    // Declare the class views.
    private lateinit var webViewLayout: View

    companion object {
        fun createTab(tabNumber: Int): AboutWebViewFragment {
            // Create an arguments bundle.
            val argumentsBundle = Bundle()

            // Store the arguments in the bundle.
            argumentsBundle.putInt(TAB_NUMBER, tabNumber)

            // Create a new instance of the tab fragment.
            val aboutWebViewFragment = AboutWebViewFragment()

            // Add the arguments bundle to the fragment.
            aboutWebViewFragment.arguments = argumentsBundle

            // Return the new fragment.
            return aboutWebViewFragment
        }
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        // Run the default commands.
        super.onCreate(savedInstanceState)

        // Store the tab number in a class variable.
        tabNumber = requireArguments().getInt(TAB_NUMBER)
    }

    override fun onCreateView(layoutInflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
        // Inflate the layout.  False does not attach the inflated layout as a child of container.  The fragment will take care of attaching the root automatically.
        webViewLayout = layoutInflater.inflate(R.layout.bare_webview, container, false)

        // Get a handle for tab WebView.
        val tabWebView = webViewLayout as WebView

        // Create a WebView asset loader.
        val webViewAssetLoader = WebViewAssetLoader.Builder().addPathHandler("/assets/", AssetsPathHandler(requireContext())).build()

        // Set a WebView client.
        tabWebView.webViewClient = object : WebViewClient() {
            // `shouldOverrideUrlLoading` allows the sending of external links back to the main Privacy Browser WebView.  The deprecated `shouldOverrideUrlLoading` must be used until API >= 24.
            override fun shouldOverrideUrlLoading(view: WebView, url: String): Boolean {
                // Create an intent to view the URL.
                val urlIntent = Intent(Intent.ACTION_VIEW)

                // Add the URL to the intent.
                urlIntent.data = Uri.parse(url)

                // Make it so.
                startActivity(urlIntent)
                return true
            }

            override fun shouldInterceptRequest(webView: WebView, url: String): WebResourceResponse? {
                // Have the WebView asset loader process the request.  This allows the loading of SVG files, which otherwise is prevented by the CORS policy.
                return webViewAssetLoader.shouldInterceptRequest(Uri.parse(url))
            }
        }

        // Get the current theme status.
        val currentThemeStatus = resources.configuration.uiMode and Configuration.UI_MODE_NIGHT_MASK

        // Check to see if the app is in night mode.
        if (currentThemeStatus == Configuration.UI_MODE_NIGHT_YES && WebViewFeature.isFeatureSupported(WebViewFeature.FORCE_DARK)) {  // The app is in night mode.
            // Apply the dark WebView theme.
            WebSettingsCompat.setForceDark(tabWebView.settings, WebSettingsCompat.FORCE_DARK_ON)
        }

        // Load the indicated tab.  The tab numbers start at 0, with the WebView tabs starting at 1.
        when (tabNumber) {
            1 -> tabWebView.loadUrl("https://appassets.androidplatform.net/assets/" + getString(R.string.android_asset_path) + "/about_permissions.html")
            2 -> tabWebView.loadUrl("https://appassets.androidplatform.net/assets/" + getString(R.string.android_asset_path) + "/about_privacy_policy.html")
            3 -> tabWebView.loadUrl("https://appassets.androidplatform.net/assets/" + getString(R.string.android_asset_path) + "/about_changelog.html")
            4 -> tabWebView.loadUrl("https://appassets.androidplatform.net/assets/" + getString(R.string.android_asset_path) + "/about_licenses.html")
            5 -> tabWebView.loadUrl("https://appassets.androidplatform.net/assets/" + getString(R.string.android_asset_path) + "/about_contributors.html")
            6 -> tabWebView.loadUrl("https://appassets.androidplatform.net/assets/" + getString(R.string.android_asset_path) + "/about_links.html")
        }

        // Scroll the tab if the saved instance state is not null.
        if (savedInstanceState != null) {
            tabWebView.post {
                tabWebView.scrollX = savedInstanceState.getInt(SCROLL_X)
                tabWebView.scrollY = savedInstanceState.getInt(SCROLL_Y)
            }
        }

        // Return the formatted WebView layout.
        return webViewLayout
    }

    override fun onSaveInstanceState(savedInstanceState: Bundle) {
        // Run the default commands.
        super.onSaveInstanceState(savedInstanceState)

        // Get a handle for the tab WebView.  A class variable cannot be used because it gets out of sync when restarting.
        val tabWebView = webViewLayout as WebView?

        // Save the scroll positions if the layout is not null, which can happen if a tab is not currently selected.
        if (tabWebView != null) {
            savedInstanceState.putInt(SCROLL_X, tabWebView.scrollX)
            savedInstanceState.putInt(SCROLL_Y, tabWebView.scrollY)
        }
    }
}