// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package com.tailscale.ipn;

import android.app.Application;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentTransaction;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.SharedPreferences;
import android.content.BroadcastReceiver;
import android.provider.Settings;
import android.net.ConnectivityManager;
import android.view.View;
import android.os.Build;

import java.io.IOException;
import java.io.File;
import java.io.FileOutputStream;

import java.security.GeneralSecurityException;

import androidx.security.crypto.EncryptedSharedPreferences;
import androidx.security.crypto.MasterKey;

import com.google.android.gms.auth.api.signin.GoogleSignIn;
import com.google.android.gms.auth.api.signin.GoogleSignInAccount;
import com.google.android.gms.auth.api.signin.GoogleSignInClient;
import com.google.android.gms.auth.api.signin.GoogleSignInOptions;

import org.gioui.Gio;

public class App extends Application {
	@Override public void onCreate() {
		super.onCreate();
		// Load and initialize the Go library.
		Gio.init(this);
		registerNetworkCallback();
	}

	private void registerNetworkCallback() {
		BroadcastReceiver connectivityChanged = new BroadcastReceiver() {
			@Override public void onReceive(Context ctx, Intent intent) {
				boolean noconn = intent.getBooleanExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY, false);
				onConnectivityChanged(!noconn);
			}
		};
		registerReceiver(connectivityChanged, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
	}

	public void startVPN() {
		Intent intent = new Intent(this, IPNService.class);
		intent.setAction(IPNService.ACTION_CONNECT);
		startService(intent);
	}

	public void stopVPN() {
		Intent intent = new Intent(this, IPNService.class);
		intent.setAction(IPNService.ACTION_DISCONNECT);
		startService(intent);
	}

	// encryptToPref a byte array of data using the Jetpack Security
	// library and writes it to a global encrypted preference store.
	public void encryptToPref(String prefKey, String plaintext) throws IOException, GeneralSecurityException {
		getEncryptedPrefs().edit().putString(prefKey, plaintext).commit();
	}

	// decryptFromPref decrypts a encrypted preference using the Jetpack Security
	// library and returns the plaintext.
	public String decryptFromPref(String prefKey) throws IOException, GeneralSecurityException {
		return getEncryptedPrefs().getString(prefKey, null);
	}

	private SharedPreferences getEncryptedPrefs() throws IOException, GeneralSecurityException {
		MasterKey key = new MasterKey.Builder(this)
			.setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
			.build();

		return EncryptedSharedPreferences.create(
				this,
				"secret_shared_prefs",
				key,
				EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
				EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
		);
	}

	void googleSignOut() {
		GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
			.build();
		GoogleSignInClient client = GoogleSignIn.getClient(this, gso);
		client.signOut();
	}

	void setTileStatus(boolean wantRunning) {
		if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N) {
			return;
		}
		QuickToggleService.setStatus(this, wantRunning);
	}

	String getHostname() {
		String userConfiguredDeviceName = getUserConfiguredDeviceName();
		if (!isEmpty(userConfiguredDeviceName)) return userConfiguredDeviceName;

		return getModelName();
	}

	String getModelName() {
		String manu = Build.MANUFACTURER;
		String model = Build.MODEL;
		// Strip manufacturer from model.
		int idx = model.toLowerCase().indexOf(manu.toLowerCase());
		if (idx != -1) {
			model = model.substring(idx + manu.length());
			model = model.trim();
		}
		return manu + " " + model;
	}

	String getOSVersion() {
		return Build.VERSION.RELEASE;
	}

	// get user defined nickname from Settings
	// returns null if not available
	private String getUserConfiguredDeviceName() {
		String nameFromSystemBluetooth = Settings.System.getString(getContentResolver(), "bluetooth_name");
		String nameFromSecureBluetooth = Settings.Secure.getString(getContentResolver(), "bluetooth_name");
		String nameFromSystemDevice = Settings.Secure.getString(getContentResolver(), "device_name");

		if (!isEmpty(nameFromSystemBluetooth)) return nameFromSystemBluetooth;
		if (!isEmpty(nameFromSecureBluetooth)) return nameFromSecureBluetooth;
		if (!isEmpty(nameFromSystemDevice)) return nameFromSystemDevice;
		return null;
	}

	private static boolean isEmpty(String str) {
		return str == null || str.length() == 0;
	}

	// Tracklifecycle adds a Peer fragment for tracking the Activity
	// lifecycle.
	static void trackLifecycle(View view) {
		Activity act = (Activity)view.getContext();
		FragmentTransaction ft = act.getFragmentManager().beginTransaction();
		ft.add(new Peer(), "Peer");
		ft.commit();
		act.getFragmentManager().executePendingTransactions();
	}

	boolean isChromeOS() {
		return getPackageManager().hasSystemFeature("android.hardware.type.pc");
	}

	private static native void onConnectivityChanged(boolean connected);
}