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package co.easimart;

import android.content.Context;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;

import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

import bolts.Capture;
import bolts.Task;

/**
 * LocationNotifier is a wrapper around fetching the current device's location. It looks for the GPS
 * and Network LocationProviders by default (printStackTrace()'ing if, for example, the app doesn't
 * have the correct permissions in its AndroidManifest.xml). This class is intended to be used for a
 * single location update.
 * 
 * When testing, if a fakeLocation is provided (via setFakeLocation()), we don't wait for the
 * LocationManager to fire or for the timer to run out; instead, we build a local LocationListener,
 * then call the onLocationChanged() method manually.
 */
/** package */ class LocationNotifier {
  private static Location fakeLocation = null;

  /**
   * Asynchronously gets the current location of the device.
   *
   * This will request location updates from the best provider that match the given criteria
   * and return the first location received.
   *
   * You can customize the criteria to meet your specific needs.
   * * For higher accuracy, you can set {@link Criteria#setAccuracy(int)}, however result in longer
   *   times for a fix.
   * * For better battery efficiency and faster location fixes, you can set
   *   {@link Criteria#setPowerRequirement(int)}, however, this will result in lower accuracy.
   *
   * @param context
   *          The context used to request location updates.
   * @param timeout
   *          The number of milliseconds to allow before timing out.
   * @param criteria
   *          The application criteria for selecting a location provider.
   *
   * @see android.location.LocationManager#getBestProvider(android.location.Criteria, boolean)
   * @see android.location.LocationManager#requestLocationUpdates(String, long, float, android.location.LocationListener)
   */
  /* package */ static Task getCurrentLocationAsync(Context context,
      long timeout, Criteria criteria) {
    final Task.TaskCompletionSource tcs = Task.create();
    final Capture> timeoutFuture = new Capture>();
    final LocationManager manager =
        (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
    final LocationListener listener = new LocationListener() {
      @Override
      public void onLocationChanged(Location location) {
        if (location == null) {
          return;
        }

        timeoutFuture.get().cancel(true);

        tcs.trySetResult(location);
        manager.removeUpdates(this);
      }

      @Override
      public void onProviderDisabled(String provider) {
      }

      @Override
      public void onProviderEnabled(String provider) {
      }

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

    timeoutFuture.set(EasimartExecutors.scheduled().schedule(new Runnable() {
      @Override
      public void run() {
        tcs.trySetError(new EasimartException(EasimartException.TIMEOUT, "Location fetch timed out."));
        manager.removeUpdates(listener);
      }
    }, timeout, TimeUnit.MILLISECONDS));

    String provider = manager.getBestProvider(criteria, true);
    if (provider != null) {
      manager.requestLocationUpdates(provider, /* minTime */ 0, /* minDistance */ 0.0f, listener);
    }

    if (fakeLocation != null) {
      listener.onLocationChanged(fakeLocation);
    }

    return tcs.getTask();
  }

  /**
   * Helper method for testing.
   */
  /* package */ static void setFakeLocation(Location location) {
    fakeLocation = location;
  }
}