package org.purplei2p.i2pd;

import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.Timer;
import java.util.TimerTask;

import android.Manifest;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.ActivityNotFoundException;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.content.SharedPreferences;
import android.content.res.AssetManager;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Bundle;
import android.os.Build;
import android.os.Environment;
import android.os.IBinder;
import android.os.PowerManager;
import android.preference.PreferenceManager;
import android.provider.Settings;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
import android.widget.Toast;


import androidx.annotation.NonNull;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

// For future package update checking

import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;


import static android.provider.Settings.ACTION_IGNORE_BATTERY_OPTIMIZATION_SETTINGS;

public class I2PDActivity extends Activity {
    private WebView webView;

    private static final String TAG = "i2pdActvt";
    private static final int MY_PERMISSION_REQUEST_WRITE_EXTERNAL_STORAGE = 1;
    public static final int GRACEFUL_DELAY_MILLIS = 10 * 60 * 1000;
    public static final String PACKAGE_URI_SCHEME = "package:";

    private TextView textView;
    private boolean assetsCopied;
    private String i2pdpath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/i2pd/";
    //private ConfigParser parser = new ConfigParser(i2pdpath); // TODO:

    private static final DaemonSingleton daemon = DaemonSingleton.getInstance();

    private final DaemonSingleton.StateUpdateListener daemonStateUpdatedListener = new DaemonSingleton.StateUpdateListener() {
        @Override
        public void daemonStateUpdate() {
            processAssets();
            runOnUiThread(() -> {
                try {
                    if (textView == null)
                        return;
                    Throwable tr = daemon.getLastThrowable();
                    if (tr != null) {
                        textView.setText(throwableToString(tr));
                        return;
                    }
                    DaemonSingleton.State state = daemon.getState();
                    String startResultStr = DaemonSingleton.State.startFailed.equals(state) ? String.format(": %s", daemon.getDaemonStartResult()) : "";
                    String graceStr = DaemonSingleton.State.gracefulShutdownInProgress.equals(state) ? String.format(": %s %s", formatGraceTimeRemaining(), getText(R.string.remaining)) : "";
                    textView.setText(String.format("%s%s%s", getText(state.getStatusStringResourceId()), startResultStr, graceStr));
                } catch (Throwable tr) {
                    Log.e(TAG, "error ignored", tr);
                }
            });
        }
    };
    private static volatile long graceStartedMillis;
    private static final Object graceStartedMillis_LOCK = new Object();
    private Menu optionsMenu;

    private static String formatGraceTimeRemaining() {
        long remainingSeconds;
        synchronized (graceStartedMillis_LOCK) {
            remainingSeconds = Math.round(Math.max(0, graceStartedMillis + GRACEFUL_DELAY_MILLIS - System.currentTimeMillis()) / 1000.0D);
        }
        long remainingMinutes = (long) Math.floor(remainingSeconds / 60.0D);
        long remSec = remainingSeconds - remainingMinutes * 60;
        return remainingMinutes + ":" + (remSec / 10) + remSec % 10;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        Log.i(TAG, "onCreate");
        super.onCreate(savedInstanceState);

        textView = new TextView(this);
        setContentView(textView);
        daemon.addStateChangeListener(daemonStateUpdatedListener);
        daemonStateUpdatedListener.daemonStateUpdate();

        // request permissions
        if (Build.VERSION.SDK_INT >= 23) {
            if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                ActivityCompat.requestPermissions(this,
                        new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                        MY_PERMISSION_REQUEST_WRITE_EXTERNAL_STORAGE);
            }
        }

        // set the app be foreground
        doBindService();

        final Timer gracefulQuitTimer = getGracefulQuitTimer();
        if (gracefulQuitTimer != null) {
            long gracefulStopAtMillis;
            synchronized (graceStartedMillis_LOCK) {
                gracefulStopAtMillis = graceStartedMillis + GRACEFUL_DELAY_MILLIS;
            }
            rescheduleGraceStop(gracefulQuitTimer, gracefulStopAtMillis);
        }

        openBatteryOptimizationDialogIfNeeded();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        textView = null;
        daemon.removeStateChangeListener(daemonStateUpdatedListener);
        //cancelGracefulStop0();
        try {
            doUnbindService();
        } catch (Throwable tr) {
            Log.e(TAG, "", tr);
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        if (requestCode == MY_PERMISSION_REQUEST_WRITE_EXTERNAL_STORAGE) {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED)
                Log.e(TAG, "WR_EXT_STORAGE perm granted");
            else {
                Log.e(TAG, "WR_EXT_STORAGE perm declined, stopping i2pd");
                i2pdStop();
                //TODO must work w/o this perm, ask orignal
            }
        }
    }

    private void cancelGracefulStop0() {
        Timer gracefulQuitTimer = getGracefulQuitTimer();
        if (gracefulQuitTimer != null) {
            gracefulQuitTimer.cancel();
            setGracefulQuitTimer(null);
        }
    }

    private CharSequence throwableToString(Throwable tr) {
        StringWriter sw = new StringWriter(8192);
        PrintWriter pw = new PrintWriter(sw);
        tr.printStackTrace(pw);
        pw.close();
        return sw.toString();
    }

    // private LocalService mBoundService;

    private ServiceConnection mConnection = new ServiceConnection() {
        public void onServiceConnected(ComponentName className, IBinder service) {
            // This is called when the connection with the service has been
            // established, giving us the service object we can use to
            // interact with the service.  Because we have bound to a explicit
            // service that we know is running in our own process, we can
            // cast its IBinder to a concrete class and directly access it.
            //		mBoundService = ((LocalService.LocalBinder)service).getService();

            // Tell the user about this for our demo.
            //		Toast.makeText(Binding.this, R.string.local_service_connected,
            //		Toast.LENGTH_SHORT).show();
        }

        public void onServiceDisconnected(ComponentName className) {
            // This is called when the connection with the service has been
            // unexpectedly disconnected -- that is, its process crashed.
            // Because it is running in our same process, we should never
            // see this happen.
            //		mBoundService = null;
            //		Toast.makeText(Binding.this, R.string.local_service_disconnected,
            //		Toast.LENGTH_SHORT).show();
        }
    };

    private static volatile boolean mIsBound;

    private void doBindService() {
        synchronized (I2PDActivity.class) {
            if (mIsBound)
                return;
            // Establish a connection with the service.  We use an explicit
            // class name because we want a specific service implementation that
            // we know will be running in our own process (and thus won't be
            // supporting component replacement by other applications).
            bindService(new Intent(this, ForegroundService.class), mConnection, Context.BIND_AUTO_CREATE);
            mIsBound = true;
        }
    }

    private void doUnbindService() {
        synchronized (I2PDActivity.class) {
            if (mIsBound) {
                // Detach our existing connection.
                unbindService(mConnection);
                mIsBound = false;
            }
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.options_main, menu);
        menu.findItem(R.id.action_battery_otimizations).setVisible(isBatteryOptimizationsOpenOsDialogApiAvailable());
        this.optionsMenu = menu;
        return true;
    }

    private boolean isBatteryOptimizationsOpenOsDialogApiAvailable() {
        return android.os.Build.VERSION.SDK_INT >= 23;
    }

    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        switch (id) {
            case R.id.action_stop:
                i2pdStop();
                return true;

            case R.id.action_graceful_stop:
                synchronized (graceStartedMillis_LOCK) {
                    if (getGracefulQuitTimer() != null)
                        cancelGracefulStop();
                    else
                        i2pdGracefulStop();
                }
                return true;

            case R.id.action_battery_otimizations:
                onActionBatteryOptimizations();
                return true;

            case R.id.action_reload_tunnels_config:
                onReloadTunnelsConfig();
                return true;

            case R.id.action_start_webview:
                setContentView(R.layout.webview);
                this.webView = (WebView) findViewById(R.id.webview1);
                this.webView.setWebViewClient(new WebViewClient());

                WebSettings webSettings = this.webView.getSettings();
                webSettings.setBuiltInZoomControls(true);
                webSettings.setJavaScriptEnabled(false);
                this.webView.loadUrl("http://127.0.0.1:7070"); // TODO: instead 7070 I2Pd....HttpPort
                break;
        }

        return super.onOptionsItemSelected(item);
    }

    private void onActionBatteryOptimizations() {
        if (isBatteryOptimizationsOpenOsDialogApiAvailable()) {
            try {
                startActivity(new Intent(ACTION_IGNORE_BATTERY_OPTIMIZATION_SETTINGS));
            } catch (ActivityNotFoundException e) {
                Log.e(TAG, "BATT_OPTIM_DIALOG_ActvtNotFound", e);
                Toast.makeText(this, R.string.os_version_does_not_support_battery_optimizations_show_os_dialog_api, Toast.LENGTH_SHORT).show();
            }
        }
    }

    private void onReloadTunnelsConfig() {
        Log.d(TAG, "reloading tunnels");
        daemon.reloadTunnelsConfigs();
        Toast.makeText(this, R.string.tunnels_reloading, Toast.LENGTH_SHORT).show();
    }

    private void i2pdStop() {
        cancelGracefulStop0();
        new Thread(() -> {
            Log.d(TAG, "stopping");
            try {
                daemon.stopDaemon();
            } catch (Throwable tr) {
                Log.e(TAG, "", tr);
            }
            quit(); //TODO make menu items for starting i2pd. On my Android, I need to reboot the OS to restart i2pd.
        }, "stop").start();
    }

    private static volatile Timer gracefulQuitTimer;

    private void i2pdGracefulStop() {
        if (daemon.getState() == DaemonSingleton.State.stopped) {
            Toast.makeText(this, R.string.already_stopped, Toast.LENGTH_SHORT).show();
            return;
        }
        if (getGracefulQuitTimer() != null) {
            Toast.makeText(this, R.string.graceful_stop_is_already_in_progress, Toast.LENGTH_SHORT).show();
            return;
        }
        Toast.makeText(this, R.string.graceful_stop_is_in_progress, Toast.LENGTH_SHORT).show();
        new Thread(() -> {
            try {
                Log.d(TAG, "graceful stopping");
                if (daemon.isStartedOkay()) {
                    daemon.stopAcceptingTunnels();
                    long gracefulStopAtMillis;
                    synchronized (graceStartedMillis_LOCK) {
                        graceStartedMillis = System.currentTimeMillis();
                        gracefulStopAtMillis = graceStartedMillis + GRACEFUL_DELAY_MILLIS;
                    }
                    rescheduleGraceStop(null, gracefulStopAtMillis);
                } else
                    i2pdStop();
            } catch (Throwable tr) {
                Log.e(TAG, "", tr);
            }
        }, "gracInit").start();
    }

    private void cancelGracefulStop() {
        cancelGracefulStop0();
        new Thread(() -> {
            try {
                Log.d(TAG, "canceling graceful stop");
                if (daemon.isStartedOkay()) {
                    daemon.startAcceptingTunnels();
                    runOnUiThread(() -> Toast.makeText(this, R.string.shutdown_canceled, Toast.LENGTH_SHORT).show());
                } else
                    i2pdStop();
            } catch (Throwable tr) {
                Log.e(TAG, "", tr);
            }
        }, "gracCancel").start();
    }

    private void rescheduleGraceStop(Timer gracefulQuitTimerOld, long gracefulStopAtMillis) {
        if (gracefulQuitTimerOld != null)
            gracefulQuitTimerOld.cancel();

        if (daemon.GetTransitTunnelsCount() <= 0) { // no tunnels left
            Log.d(TAG, "no transit tunnels left, stopping");
            i2pdStop();
        }

        final Timer gracefulQuitTimer = new Timer(true);
        setGracefulQuitTimer(gracefulQuitTimer);
        gracefulQuitTimer.schedule(new TimerTask() {

            @Override
            public void run() {
                i2pdStop();
            }

        }, Math.max(0, gracefulStopAtMillis - System.currentTimeMillis()));
        final TimerTask tickerTask = new TimerTask() {
            @Override
            public void run() {
                daemonStateUpdatedListener.daemonStateUpdate();
            }
        };
        gracefulQuitTimer.scheduleAtFixedRate(tickerTask, 0/*start delay*/, 1000/*millis period*/);
    }

    private static Timer getGracefulQuitTimer() {
        return gracefulQuitTimer;
    }

    private void setGracefulQuitTimer(Timer gracefulQuitTimer) {
        I2PDActivity.gracefulQuitTimer = gracefulQuitTimer;
        runOnUiThread(() -> {
            Menu menu = optionsMenu;
            if (menu != null) {
                MenuItem item = menu.findItem(R.id.action_graceful_stop);
                if (item != null) {
                    synchronized (graceStartedMillis_LOCK) {
                        item.setTitle(getGracefulQuitTimer() != null ? R.string.action_cancel_graceful_stop : R.string.action_graceful_stop);
                    }
                }
            }
        });
    }

    /**
     * Copy the asset at the specified path to this app's data directory. If the
     * asset is a directory, its contents are also copied.
     *
     * @param path Path to asset, relative to app's assets directory.
     */
    private void copyAsset(String path) {
        AssetManager manager = getAssets();

        // If we have a directory, we make it and recurse. If a file, we copy its
        // contents.
        try {
            String[] contents = manager.list(path);

            // The documentation suggests that list throws an IOException, but doesn't
            // say under what conditions. It'd be nice if it did so when the path was
            // to a file. That doesn't appear to be the case. If the returned array is
            // null or has 0 length, we assume the path is to a file. This means empty
            // directories will get turned into files.
            if (contents == null || contents.length == 0) {
                copyFileAsset(path);
                return;
            }

            // Make the directory.
            File dir = new File(i2pdpath, path);
            boolean result = dir.mkdirs();
            Log.d(TAG, "dir.mkdirs() returned " + result);

            // Recurse on the contents.
            for (String entry : contents) {
                copyAsset(path + '/' + entry);
            }
        } catch (IOException e) {
            Log.e(TAG, "ex ignored for path='" + path + "'", e);
        }
    }

    /**
     * Copy the asset file specified by path to app's data directory. Assumes
     * parent directories have already been created.
     *
     * @param path Path to asset, relative to app's assets directory.
     */
    private void copyFileAsset(String path) {
        File file = new File(i2pdpath, path);
        if (!file.exists()) {
            try {
                try (InputStream in = getAssets().open(path)) {
                    try (OutputStream out = new FileOutputStream(file)) {
                        byte[] buffer = new byte[1024];
                        int read = in.read(buffer);
                        while (read != -1) {
                            out.write(buffer, 0, read);
                            read = in.read(buffer);
                        }
                    }
                }
            } catch (IOException e) {
                Log.e(TAG, "", e);
            }
        }
    }

    private void deleteRecursive(File fileOrDirectory) {
        if (fileOrDirectory.isDirectory()) {
            File[] files = fileOrDirectory.listFiles();
            if (files != null) {
                for (File child : files) {
                    deleteRecursive(child);
                }
            }
        }
        boolean deleteResult = fileOrDirectory.delete();
        if (!deleteResult)
            Log.e(TAG, "fileOrDirectory.delete() returned " + deleteResult + ", absolute path='" + fileOrDirectory.getAbsolutePath() + "'");
    }

    private void processAssets() {
        if (!assetsCopied) {
            try {
                assetsCopied = true; // prevent from running on every state update

                File holderFile = new File(i2pdpath, "assets.ready");
                String versionName = BuildConfig.VERSION_NAME; // here will be app version, like 2.XX.XX
                StringBuilder text = new StringBuilder();

                if (holderFile.exists()) {
                    try { // if holder file exists, read assets version string
                        FileReader fileReader = new FileReader(holderFile);

                        try {
                            BufferedReader br = new BufferedReader(fileReader);

                            try {
                                String line;

                                while ((line = br.readLine()) != null) {
                                    text.append(line);
                                }
                            } finally {
                                try {
                                    br.close();
                                } catch (IOException e) {
                                    Log.e(TAG, "", e);
                                }
                            }
                        } finally {
                            try {
                                fileReader.close();
                            } catch (IOException e) {
                                Log.e(TAG, "", e);
                            }
                        }
                    } catch (IOException e) {
                        Log.e(TAG, "", e);
                    }
                }

                // if version differs from current app version or null, try to delete certificates folder
                if (!text.toString().contains(versionName))
                    try {
                        boolean deleteResult = holderFile.delete();
                        if (!deleteResult)
                            Log.e(TAG, "holderFile.delete() returned " + deleteResult + ", absolute path='" + holderFile.getAbsolutePath() + "'");
                        File certPath = new File(i2pdpath, "certificates");
                        deleteRecursive(certPath);
                    } catch (Throwable tr) {
                        Log.e(TAG, "", tr);
                    }

                // copy assets. If processed file exists, it won't be overwritten
                copyAsset("addressbook");
                copyAsset("certificates");
                copyAsset("tunnels.d");
                copyAsset("i2pd.conf");
                copyAsset("subscriptions.txt");
                copyAsset("tunnels.conf");

                // update holder file about successful copying
                FileWriter writer = new FileWriter(holderFile);
                try {
                    writer.append(versionName);
                } finally {
                    try {
                        writer.close();
                    } catch (IOException e) {
                        Log.e(TAG, "on writer close", e);
                    }
                }
            } catch (Throwable tr) {
                Log.e(TAG, "on assets copying", tr);
            }
        }
    }

    @SuppressLint("BatteryLife")
    private void openBatteryOptimizationDialogIfNeeded() {
        boolean questionEnabled = getPreferences().getBoolean(getBatteryOptimizationPreferenceKey(), true);
        Log.i(TAG, "BATT_OPTIM_questionEnabled==" + questionEnabled);
        if (!isKnownIgnoringBatteryOptimizations()
                && android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M
                && questionEnabled) {
            AlertDialog.Builder builder = new AlertDialog.Builder(this);
            builder.setTitle(R.string.battery_optimizations_enabled);
            builder.setMessage(R.string.battery_optimizations_enabled_dialog);
            builder.setPositiveButton(R.string.continue_str, (dialog, which) -> {
                try {
                    startActivity(new Intent(Settings.ACTION_REQUEST_IGNORE_BATTERY_OPTIMIZATIONS, Uri.parse(PACKAGE_URI_SCHEME + getPackageName())));
                } catch (ActivityNotFoundException e) {
                    Log.e(TAG, "BATT_OPTIM_ActvtNotFound", e);
                    Toast.makeText(this, R.string.device_does_not_support_disabling_battery_optimizations, Toast.LENGTH_SHORT).show();
                }
            });
            builder.setOnDismissListener(dialog -> setNeverAskForBatteryOptimizationsAgain());
            final AlertDialog dialog = builder.create();
            dialog.setCanceledOnTouchOutside(false);
            dialog.show();
        }
    }

    private void setNeverAskForBatteryOptimizationsAgain() {
        getPreferences().edit().putBoolean(getBatteryOptimizationPreferenceKey(), false).apply();
    }

    protected boolean isKnownIgnoringBatteryOptimizations() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            final PowerManager pm = (PowerManager) getSystemService(POWER_SERVICE);
            if (pm == null) {
                Log.i(TAG, "BATT_OPTIM: POWER_SERVICE==null");
                return false;
            }
            boolean ignoring = pm.isIgnoringBatteryOptimizations(getPackageName());
            Log.i(TAG, "BATT_OPTIM: ignoring==" + ignoring);
            return ignoring;
        } else {
            Log.i(TAG, "BATT_OPTIM: old sdk version==" + Build.VERSION.SDK_INT);
            return false;
        }
    }

    protected SharedPreferences getPreferences() {
        return PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
    }

    private String getBatteryOptimizationPreferenceKey() {
        @SuppressLint("HardwareIds") String device = Settings.Secure.getString(getContentResolver(), Settings.Secure.ANDROID_ID);
        return "show_battery_optimization" + (device == null ? "" : device);
    }

    private void quit() {
        try {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                finishAndRemoveTask();
            } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                finishAffinity();
            } else {
                //moveTaskToBack(true);
                finish();
            }
        } catch (Throwable tr) {
            Log.e(TAG, "", tr);
        }
        try {
            daemon.stopDaemon();
        } catch (Throwable tr) {
            Log.e(TAG, "", tr);
        }
        System.exit(0);
    }
}