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package cgeo.geocaching.sensors;
import cgeo.geocaching.utils.Log;
import cgeo.geocaching.utils.RxUtils.ConnectableLooperCallbacks;
import rx.Observable;
import rx.Observable.OnSubscribe;
import rx.Subscriber;
import rx.observables.ConnectableObservable;
import rx.subjects.BehaviorSubject;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import java.util.concurrent.TimeUnit;
public class GeoDataProvider implements OnSubscribe<IGeoData> {
private final LocationManager geoManager;
private final LocationData gpsLocation = new LocationData();
private final LocationData netLocation = new LocationData();
private final BehaviorSubject<IGeoData> subject;
private static class LocationData {
public Location location;
public long timestamp = 0;
public void update(final Location location) {
this.location = location;
timestamp = System.currentTimeMillis();
}
public boolean isRecent() {
return isValid() && System.currentTimeMillis() < timestamp + 30000;
}
public boolean isValid() {
return location != null;
}
}
/**
* Build a new geo data provider object.
* <p/>
* There is no need to instantiate more than one such object in an application, as observers can be added
* at will.
*
* @param context the context used to retrieve the system services
*/
protected GeoDataProvider(final Context context) {
geoManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
subject = BehaviorSubject.create(findInitialLocation());
}
public static Observable<IGeoData> create(final Context context) {
final GeoDataProvider provider = new GeoDataProvider(context);
return provider.worker.refCount();
}
@Override
public void call(final Subscriber<? super IGeoData> subscriber) {
subject.subscribe(subscriber);
}
final ConnectableObservable<IGeoData> worker = new ConnectableLooperCallbacks<IGeoData>(this, 2500, TimeUnit.MILLISECONDS) {
private final Listener networkListener = new Listener(LocationManager.NETWORK_PROVIDER, netLocation);
private final Listener gpsListener = new Listener(LocationManager.GPS_PROVIDER, gpsLocation);
@Override
protected void onStart() {
Log.d("GeoDataProvider: starting the GPS and network listeners");
for (final Listener listener : new Listener[]{networkListener, gpsListener}) {
try {
geoManager.requestLocationUpdates(listener.locationProvider, 0, 0, listener);
} catch (final Exception e) {
Log.w("There is no location provider " + listener.locationProvider);
}
}
}
@Override
protected void onStop() {
Log.d("GeoDataProvider: stopping the GPS and network listeners");
geoManager.removeUpdates(networkListener);
geoManager.removeUpdates(gpsListener);
}
};
private IGeoData findInitialLocation() {
final Location initialLocation = new Location("initial");
try {
// Try to find a sensible initial location from the last locations known to Android.
final Location lastGpsLocation = geoManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
final Location lastNetworkLocation = geoManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
// If both providers are non-null, take the most recent one
if (lastGpsLocation != null && lastNetworkLocation != null) {
if (lastGpsLocation.getTime() >= lastNetworkLocation.getTime()) {
copyCoords(initialLocation, lastGpsLocation);
} else {
copyCoords(initialLocation, lastNetworkLocation);
}
} else if (lastGpsLocation != null) {
copyCoords(initialLocation, lastGpsLocation);
} else if (lastNetworkLocation != null) {
copyCoords(initialLocation, lastNetworkLocation);
} else {
Log.i("GeoDataProvider: no last known location available");
}
} catch (final Exception e) {
// This error is non-fatal as its only consequence is that we will start with a dummy location
// instead of a previously known one.
Log.e("GeoDataProvider: error when retrieving last known location", e);
}
// Start with an historical GeoData just in case someone queries it before we get
// a chance to get any information.
return new GeoData(initialLocation);
}
private static void copyCoords(final Location target, final Location source) {
target.setLatitude(source.getLatitude());
target.setLongitude(source.getLongitude());
}
private class Listener implements LocationListener {
private final String locationProvider;
private final LocationData locationData;
Listener(final String locationProvider, final LocationData locationData) {
this.locationProvider = locationProvider;
this.locationData = locationData;
}
@Override
public void onStatusChanged(final String provider, final int status, final Bundle extras) {
// nothing
}
@Override
public void onProviderDisabled(final String provider) {
// nothing
}
@Override
public void onProviderEnabled(final String provider) {
// nothing
}
@Override
public void onLocationChanged(final Location location) {
locationData.update(location);
selectBest();
}
}
private LocationData best() {
if (gpsLocation.isRecent() || !netLocation.isValid()) {
return gpsLocation.isValid() ? gpsLocation : null;
}
if (!gpsLocation.isValid()) {
return netLocation;
}
return gpsLocation.timestamp > netLocation.timestamp ? gpsLocation : netLocation;
}
private void selectBest() {
assign(best());
}
private void assign(final LocationData locationData) {
if (locationData == null) {
return;
}
// We do not necessarily get signalled when satellites go to 0/0.
final IGeoData current = new GeoData(locationData.location);
subject.onNext(current);
}
}
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