/*
 * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0
 */
package com.wireguard.android

import android.content.Context
import android.content.Intent
import android.content.SharedPreferences
import android.content.SharedPreferences.OnSharedPreferenceChangeListener
import android.os.Build
import android.os.StrictMode
import android.os.StrictMode.ThreadPolicy
import android.os.StrictMode.VmPolicy
import android.util.Log
import androidx.appcompat.app.AppCompatDelegate
import androidx.preference.PreferenceManager
import com.wireguard.android.backend.Backend
import com.wireguard.android.backend.GoBackend
import com.wireguard.android.backend.WgQuickBackend
import com.wireguard.android.configStore.FileConfigStore
import com.wireguard.android.model.TunnelManager
import com.wireguard.android.util.ModuleLoader
import com.wireguard.android.util.RootShell
import com.wireguard.android.util.ToolsInstaller
import kotlinx.coroutines.CompletableDeferred
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.Job
import kotlinx.coroutines.cancel
import kotlinx.coroutines.launch
import java.lang.ref.WeakReference
import java.util.Locale

class Application : android.app.Application(), OnSharedPreferenceChangeListener {
    private val futureBackend = CompletableDeferred<Backend>()
    private val coroutineScope = CoroutineScope(Job() + Dispatchers.Main.immediate)
    private var backend: Backend? = null
    private lateinit var moduleLoader: ModuleLoader
    private lateinit var rootShell: RootShell
    private lateinit var sharedPreferences: SharedPreferences
    private lateinit var toolsInstaller: ToolsInstaller
    private lateinit var tunnelManager: TunnelManager

    override fun attachBaseContext(context: Context) {
        super.attachBaseContext(context)
        if (BuildConfig.MIN_SDK_VERSION > Build.VERSION.SDK_INT) {
            val intent = Intent(Intent.ACTION_MAIN)
            intent.addCategory(Intent.CATEGORY_HOME)
            intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK)
            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
            startActivity(intent)
            System.exit(0)
        }
        if (BuildConfig.DEBUG) {
            StrictMode.setVmPolicy(VmPolicy.Builder().detectAll().penaltyLog().build())
            StrictMode.setThreadPolicy(ThreadPolicy.Builder().detectAll().penaltyLog().build())
        }
    }

    private fun determineBackend(): Backend {
        var backend: Backend? = null
        var didStartRootShell = false
        if (!ModuleLoader.isModuleLoaded() && moduleLoader.moduleMightExist()) {
            try {
                rootShell.start()
                didStartRootShell = true
                moduleLoader.loadModule()
            } catch (ignored: Exception) {
            }
        }
        if (!sharedPreferences.getBoolean("disable_kernel_module", false) && ModuleLoader.isModuleLoaded()) {
            try {
                if (!didStartRootShell)
                    rootShell.start()
                val wgQuickBackend = WgQuickBackend(applicationContext, rootShell, toolsInstaller)
                wgQuickBackend.setMultipleTunnels(sharedPreferences.getBoolean("multiple_tunnels", false))
                backend = wgQuickBackend
            } catch (ignored: Exception) {
            }
        }
        if (backend == null) {
            backend = GoBackend(applicationContext)
            GoBackend.setAlwaysOnCallback { get().tunnelManager.restoreState(true) }
        }
        return backend
    }

    override fun onCreate() {
        Log.i(TAG, USER_AGENT)
        super.onCreate()
        rootShell = RootShell(applicationContext)
        toolsInstaller = ToolsInstaller(applicationContext, rootShell)
        moduleLoader = ModuleLoader(applicationContext, rootShell, USER_AGENT)
        sharedPreferences = PreferenceManager.getDefaultSharedPreferences(applicationContext)
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q) {
            AppCompatDelegate.setDefaultNightMode(
                    if (sharedPreferences.getBoolean("dark_theme", false)) AppCompatDelegate.MODE_NIGHT_YES else AppCompatDelegate.MODE_NIGHT_NO)
        } else {
            AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM)
        }
        tunnelManager = TunnelManager(FileConfigStore(applicationContext))
        tunnelManager.onCreate()
        coroutineScope.launch(Dispatchers.IO) {
            try {
                backend = determineBackend()
                futureBackend.complete(backend!!)
            } catch (e: Throwable) {
                Log.e(TAG, Log.getStackTraceString(e))
            }
        }
        sharedPreferences.registerOnSharedPreferenceChangeListener(this)
    }

    override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences, key: String) {
        if ("multiple_tunnels" == key && backend != null && backend is WgQuickBackend)
            (backend as WgQuickBackend).setMultipleTunnels(sharedPreferences.getBoolean(key, false))
    }

    override fun onTerminate() {
        sharedPreferences.unregisterOnSharedPreferenceChangeListener(this)
        coroutineScope.cancel()
        super.onTerminate()
    }

    companion object {
        val USER_AGENT = String.format(Locale.ENGLISH, "WireGuard/%s (Android %d; %s; %s; %s %s; %s)", BuildConfig.VERSION_NAME, Build.VERSION.SDK_INT, if (Build.SUPPORTED_ABIS.isNotEmpty()) Build.SUPPORTED_ABIS[0] else "unknown ABI", Build.BOARD, Build.MANUFACTURER, Build.MODEL, Build.FINGERPRINT)
        private const val TAG = "WireGuard/Application"
        private lateinit var weakSelf: WeakReference<Application>

        @JvmStatic
        fun get(): Application {
            return weakSelf.get()!!
        }

        @JvmStatic
        suspend fun getBackend() = get().futureBackend.await()

        @JvmStatic
        fun getModuleLoader() = get().moduleLoader

        @JvmStatic
        fun getRootShell() = get().rootShell

        @JvmStatic
        fun getSharedPreferences() = get().sharedPreferences

        @JvmStatic
        fun getToolsInstaller() = get().toolsInstaller

        @JvmStatic
        fun getTunnelManager() = get().tunnelManager

        @JvmStatic
        fun getCoroutineScope() = get().coroutineScope
    }

    init {
        weakSelf = WeakReference(this)
    }
}