package org.purplei2p.i2pd;

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.pm.PackageManager;
import android.net.ConnectivityManager;
import android.net.Uri;
import android.os.Bundle;
import android.os.Build;
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.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

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

import static android.provider.Settings.ACTION_IGNORE_BATTERY_OPTIMIZATION_SETTINGS;
import static org.purplei2p.i2pd.DaemonWrapper.State.startedOkay;
import static org.purplei2p.i2pd.DaemonWrapper.State.starting;
import static org.purplei2p.i2pd.DaemonWrapper.State.stopped;

public class I2PDActivity extends Activity {
    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 Button enableButton;
    private Button disableButton;

    private TextView textView;

    private static volatile DaemonWrapper daemon;

    private final DaemonWrapper.StateUpdateListener daemonStateUpdatedListener = new DaemonWrapper.StateUpdateListener() {
        @Override
        public void daemonStateUpdate(DaemonWrapper.State oldValue, DaemonWrapper.State newValue) {
            updateStatusText();
        }
    };

    private void updateStatusText() {
        runOnUiThread(() -> {
            try {
                if (textView == null)
                    return;
                Throwable tr = daemon.getLastThrowable();
                if (tr != null) {
                    textView.setText(throwableToString(tr));
                    return;
                }
                DaemonWrapper.State state = daemon.getState();
                if(state == startedOkay){
                    disableButton.setVisibility(View.VISIBLE);
                }
                String startResultStr = DaemonWrapper.State.startFailed.equals(state) ? String.format(": %s", daemon.getDaemonStartResult()) : "";
                String graceStr = DaemonWrapper.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);
        setContentView(R.layout.activity_main);
        enableButton = findViewById(R.id.enableButton);
        disableButton = findViewById(R.id.disableButton);
        textView = (TextView) findViewById(R.id.appStatusText);
        if (daemon == null) {
            ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
            daemon = new DaemonWrapper(getAssets(), connectivityManager);
        }
        ForegroundService.init(daemon);

        daemon.addStateChangeListener(daemonStateUpdatedListener);
        daemonStateUpdatedListener.daemonStateUpdate(DaemonWrapper.State.uninitialized, daemon.getState());
        enableButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if( daemon.getState() != startedOkay && daemon.getState() != starting ){
                    daemon.stopDaemon();
                    daemon.startDaemon();
                    disableButton.setVisibility(View.VISIBLE);
                }
            }
        });
        disableButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if( daemon.getState() != stopped ){
                    daemon.stopDaemon();
                    disableButton.setVisibility(View.INVISIBLE);
                }
            }
        });
        // request permissions
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            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);
            }
        }

        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;
        ForegroundService.deinit();
        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 Build.VERSION.SDK_INT >= Build.VERSION_CODES.M;
    }

    @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:
                if( daemon.getState() == startedOkay)
                    startActivity(new Intent(getApplicationContext(), WebConsoleActivity.class));
                else
                    Toast.makeText(this,"I2Pd not was started!", Toast.LENGTH_SHORT).show();
                return true;
            case R.id.action_settings:
                startActivity(new Intent(getApplicationContext(), SettingsActivity.class));
                return true;
        }

        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() == DaemonWrapper.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();
            return;
        }

        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() {
                updateStatusText();
            }
        };
        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);
                    }
                }
            }
        });
    }

    @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);
    }
}