package de.dennisguse.opentracks.services.handlers;

import android.content.Context;
import android.content.SharedPreferences;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.util.Log;

import androidx.annotation.NonNull;

import java.time.Duration;

import de.dennisguse.opentracks.R;
import de.dennisguse.opentracks.content.data.Distance;
import de.dennisguse.opentracks.content.data.TrackPoint;
import de.dennisguse.opentracks.util.LocationUtils;
import de.dennisguse.opentracks.util.PreferencesUtils;

class LocationHandler implements LocationListener, GpsStatus.GpsStatusListener {

    private final String TAG = LocationHandler.class.getSimpleName();

    private LocationManager locationManager;
    private final HandlerServer handlerServer;
    private GpsStatus gpsStatus;
    private LocationListenerPolicy locationListenerPolicy;
    private Duration currentRecordingInterval;
    private Distance thresholdHorizontalAccuracy;
    private TrackPoint lastTrackPoint;

    public LocationHandler(HandlerServer handlerServer) {
        this.handlerServer = handlerServer;
    }

    public void onStart(@NonNull Context context, SharedPreferences sharedPreferences) {
        onSharedPreferenceChanged(context, sharedPreferences, null);
        gpsStatus = new GpsStatus(context, this);
        locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
        registerLocationListener();
        gpsStatus.start();
    }

    public void onStop() {
        if (locationManager != null) {
            locationManager.removeUpdates(this);
            locationManager = null;
        }

        if (gpsStatus != null) {
            gpsStatus.stop();
            gpsStatus = null;
        }
    }

    public void onSharedPreferenceChanged(@NonNull Context context, @NonNull SharedPreferences sharedPreferences, String key) {
        if (PreferencesUtils.isKey(context, R.string.min_recording_interval_key, key)) {
            int minRecordingInterval = PreferencesUtils.getMinRecordingInterval(sharedPreferences, context);
            if (minRecordingInterval == PreferencesUtils.getMinRecordingIntervalAdaptBatteryLife(context)) {
                // Choose battery life over moving time accuracy.
                locationListenerPolicy = new AdaptiveLocationListenerPolicy(Duration.ofSeconds(30), Duration.ofSeconds(5), 5);
            } else if (minRecordingInterval == PreferencesUtils.getMinRecordingIntervalAdaptAccuracy(context)) {
                // Get all the updates.
                locationListenerPolicy = new AdaptiveLocationListenerPolicy(Duration.ofSeconds(1), Duration.ofSeconds(30), 0);
            } else {
                locationListenerPolicy = new AbsoluteLocationListenerPolicy(Duration.ofSeconds(minRecordingInterval));
            }

            registerLocationListener();
        }
        if (PreferencesUtils.isKey(context, R.string.recording_gps_accuracy_key, key)) {
            thresholdHorizontalAccuracy = PreferencesUtils.getThresholdHorizontalAccuracy(sharedPreferences, context);
        }
        if (PreferencesUtils.isKey(context, R.string.min_recording_interval_key, key)) {
            if (gpsStatus != null) {
                gpsStatus.onMinRecordingIntervalChanged(PreferencesUtils.getMinRecordingInterval(sharedPreferences, context));
            }
        }
        if (PreferencesUtils.isKey(context, R.string.recording_distance_interval_key, key)) {
            if (gpsStatus != null) {
                gpsStatus.onRecordingDistanceChanged(PreferencesUtils.getRecordingDistanceInterval(sharedPreferences, context));
            }
        }
    }

    /**
     * Checks if location is valid and builds a track point that will be send through HandlerServer.
     *
     * @param location {@link Location} object.
     */
    @Override
    public void onLocationChanged(@NonNull Location location) {
        TrackPoint trackPoint = new TrackPoint(location, handlerServer.createNow());
        boolean isAccurate = trackPoint.fulfillsAccuracy(thresholdHorizontalAccuracy);
        boolean isValid = LocationUtils.isValidLocation(location);

        if (gpsStatus != null) {
            gpsStatus.onLocationChanged(trackPoint);
        }

        if (!isValid) {
            Log.w(TAG, "Ignore newTrackPoint. location is invalid.");
            return;
        }

        if (!isAccurate) {
            Log.d(TAG, "Ignore newTrackPoint. Poor accuracy.");
            return;
        }

        Duration idleTime = Duration.ofSeconds(0);
        if (lastTrackPoint != null && trackPoint.getTime().isAfter(lastTrackPoint.getTime())) {
            idleTime = Duration.between(lastTrackPoint.getTime(), trackPoint.getTime());
        }

        locationListenerPolicy.updateIdleTime(idleTime);
        if (currentRecordingInterval != locationListenerPolicy.getDesiredPollingInterval()) {
            registerLocationListener();
        }

        lastTrackPoint = trackPoint;
        handlerServer.onNewTrackPoint(trackPoint, thresholdHorizontalAccuracy);
    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
    }

    @Override
    public void onProviderEnabled(@NonNull String provider) {
        if (gpsStatus != null) {
            gpsStatus.onGpsEnabled();
        }
    }

    @Override
    public void onProviderDisabled(@NonNull String provider) {
        if (gpsStatus != null) {
            gpsStatus.onGpsDisabled();
        }
    }

    private void registerLocationListener() {
        if (locationManager == null) {
            Log.e(TAG, "locationManager is null.");
            return;
        }
        try {
            Duration interval = locationListenerPolicy.getDesiredPollingInterval();
            currentRecordingInterval = interval;
            locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, interval.toMillis(), locationListenerPolicy.getMinDistance_m(), this);
        } catch (SecurityException e) {
            Log.e(TAG, "Could not register location listener; permissions not granted.", e);
        }
    }

    TrackPoint getLastTrackPoint() {
        return lastTrackPoint;
    }

    /**
     * Called from {@link GpsStatus} to inform that GPS status has changed from prevStatus to currentStatus.
     *
     * @param prevStatus    previous {@link GpsStatusValue}.
     * @param currentStatus current {@link GpsStatusValue}.
     */
    @Override
    public void onGpsStatusChanged(GpsStatusValue prevStatus, GpsStatusValue currentStatus) {
        handlerServer.sendGpsStatus(currentStatus);
    }
}