/*** Location Monitor ***
 *** monitors location and provides updates
 * 
 * Copyright (c) 2014
 * Randroid Solutions (http://www.randroidsolutions.com/)
 * All Rights Reserved.
 *
 * The right to use, copy, modify, merge, publish, distribute, sublicense, 
 * and/or sell copies of this software, and/or to permit persons to whom the 
 * software is furnished to do so is NOT PERMITTED without the written consent
 * of Randroid Solutions [dev@randroidsolutions.com].
 *
 */


package com.randroid.library.gps.objects;

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

import com.randroid.library.gps.GlobalPosition;
import com.randroid.library.gps.R;

public abstract class LocationMonitor {
	protected boolean gps_enabled = false;
	protected boolean net_enabled = false;
	protected LocationResult mResult;
	private Context mContext;
	private LocationManager mManager;
	private Location gpsLocation = null;
	private Location netLocation = null;
	
	public interface LocationResult {
		public void update(final Location location);
		public void failure(final String error);
		public void unavailable();
	}
	
	public LocationMonitor(final Context context, final LocationResult result) {
		mContext = context;
		mResult = result;

		if (mManager == null) {
			mManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
		}

		//determine which location services are available
		try {
			gps_enabled = mManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
		} catch (final Exception e) {}
		
		try {
			net_enabled = mManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
		} catch (final Exception e) {}
		
		if (!gps_enabled && !net_enabled){
			mResult.unavailable();
		}
		else { //request updates from the enabled location services
			if (gps_enabled) {
				mManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 0, gpsListener);					
			}
			if (net_enabled) {
				mManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 1000, 0, netListener);					
			}
		}
	}
    
	public void cancelUpdates() {
		mManager.removeUpdates(gpsListener);
		mManager.removeUpdates(netListener);
	}

	protected abstract void locationChanged(final Location location);

	protected LocationListener gpsListener = new LocationListener() {
		//handle gps location updates
		public void onLocationChanged(final Location location) {
			locationChanged(location);
			gpsLocation = location;
		}
		public void onProviderDisabled(final String provider) {
			gps_enabled = false;
			if (!net_enabled) {
				cancelUpdates();
				mResult.unavailable();
			}
		}
		public void onProviderEnabled(final String provider) {}
		public void onStatusChanged(final String provider, int status, final Bundle extras) {}
	};

	protected LocationListener netListener = new LocationListener() {
		//handle network location updates
		public void onLocationChanged(final Location location) {
			locationChanged(location);
			netLocation = location;
		}
		public void onProviderDisabled(final String provider) {
			net_enabled = false;
			if (!gps_enabled) {
				cancelUpdates();
				mResult.unavailable();
			}
		}
		public void onProviderEnabled(final String provider) {}
		public void onStatusChanged(final String provider, int status, final Bundle extras) {}
	};

	protected Location getBestLocation() throws LocationException {
		Location result = null;
    	
		//allow a location monitor that halts prematurely, such as a timeout,
		//to return the most accurate or last known location

		if ((gpsLocation != null) && (netLocation != null)) {			
			if (gpsLocation.getAccuracy() < netLocation.getAccuracy()) {
				result = gpsLocation;
			}
			else {
				result = netLocation;
			}
		}
		else if (gpsLocation != null) {
			result = gpsLocation;
		}
		else if (netLocation != null) {
			result = netLocation;
		}

		if (result == null) {
			result = GlobalPosition.getLastLocation(mContext);
		}

		if (result == null) {
			throw new LocationException(mContext.getString(R.string.error_unavailable_location));
		}
		else {
			return result;
		}
	}
	
	public class LocationException extends Exception {
		private static final long serialVersionUID = -6617766248520865577L;
		
		public LocationException(final String message) {
			super(message);
		}
	}
}