services/java/com/android/server/TwilightService.java - platform/frameworks/base - Git at Google

 /*
  * Copyright (C) 2012 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package com.android.server;

 import android.app.AlarmManager;
 import android.app.PendingIntent;
 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.location.Criteria;
 import android.location.Location;
 import android.location.LocationListener;
 import android.location.LocationManager;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
 import android.os.SystemClock;
 import android.text.format.DateUtils;
 import android.text.format.Time;
 import android.util.Slog;

 import java.text.DateFormat;
 import java.util.ArrayList;
 import java.util.Date;
 import java.util.Iterator;

 import libcore.util.Objects;

 /**
  * Figures out whether it's twilight time based on the user's location.
  *
  * Used by the UI mode manager and other components to adjust night mode
  * effects based on sunrise and sunset.
  */
 public final class TwilightService {
     private static final String TAG = "TwilightService";

     private static final boolean DEBUG = false;

     private static final String ACTION_UPDATE_TWILIGHT_STATE =
             "com.android.server.action.UPDATE_TWILIGHT_STATE";

     private final Context mContext;
     private final AlarmManager mAlarmManager;
     private final LocationManager mLocationManager;
     private final LocationHandler mLocationHandler;

     private final Object mLock = new Object();

     private final ArrayList<TwilightListenerRecord> mListeners =
             new ArrayList<TwilightListenerRecord>();

     private boolean mSystemReady;

     private TwilightState mTwilightState;

     public TwilightService(Context context) {
         mContext = context;

         mAlarmManager = (AlarmManager)mContext.getSystemService(Context.ALARM_SERVICE);
         mLocationManager = (LocationManager)mContext.getSystemService(Context.LOCATION_SERVICE);
         mLocationHandler = new LocationHandler();
     }

     void systemReady() {
         synchronized (mLock) {
             mSystemReady = true;

             IntentFilter filter = new IntentFilter(Intent.ACTION_AIRPLANE_MODE_CHANGED);
             filter.addAction(Intent.ACTION_TIME_CHANGED);
             filter.addAction(Intent.ACTION_TIMEZONE_CHANGED);
             filter.addAction(ACTION_UPDATE_TWILIGHT_STATE);
             mContext.registerReceiver(mUpdateLocationReceiver, filter);

             if (!mListeners.isEmpty()) {
                 mLocationHandler.enableLocationUpdates();
             }
         }
     }

     /**
      * Gets the current twilight state.
      *
      * @return The current twilight state, or null if no information is available.
      */
     public TwilightState getCurrentState() {
         synchronized (mLock) {
             return mTwilightState;
         }
     }

     /**
      * Listens for twilight time.
      *
      * @param listener The listener.
      * @param handler The handler on which to post calls into the listener.
      */
     public void registerListener(TwilightListener listener, Handler handler) {
         synchronized (mLock) {
             mListeners.add(new TwilightListenerRecord(listener, handler));

             if (mSystemReady && mListeners.size() == 1) {
                 mLocationHandler.enableLocationUpdates();
             }
         }
     }

     private void setTwilightState(TwilightState state) {
         synchronized (mLock) {
             if (!Objects.equal(mTwilightState, state)) {
                 if (DEBUG) {
                     Slog.d(TAG, "Twilight state changed: " + state);
                 }

                 mTwilightState = state;
                 int count = mListeners.size();
                 for (int i = 0; i < count; i++) {
                     mListeners.get(i).post();
                 }
             }
         }
     }

     // The user has moved if the accuracy circles of the two locations don't overlap.
     private static boolean hasMoved(Location from, Location to) {
         if (to == null) {
             return false;
         }

         if (from == null) {
             return true;
         }

         // if new location is older than the current one, the device hasn't moved.
         if (to.getElapsedRealtimeNanos() < from.getElapsedRealtimeNanos()) {
             return false;
         }

         // Get the distance between the two points.
         float distance = from.distanceTo(to);

         // Get the total accuracy radius for both locations.
         float totalAccuracy = from.getAccuracy() + to.getAccuracy();

         // If the distance is greater than the combined accuracy of the two
         // points then they can't overlap and hence the user has moved.
         return distance >= totalAccuracy;
     }

     /**
      * Describes whether it is day or night.
      * This object is immutable.
      */
     public static final class TwilightState {
         private final boolean mIsNight;
         private final long mYesterdaySunset;
         private final long mTodaySunrise;
         private final long mTodaySunset;
         private final long mTomorrowSunrise;

         TwilightState(boolean isNight,
                 long yesterdaySunset,
                 long todaySunrise, long todaySunset,
                 long tomorrowSunrise) {
             mIsNight = isNight;
             mYesterdaySunset = yesterdaySunset;
             mTodaySunrise = todaySunrise;
             mTodaySunset = todaySunset;
             mTomorrowSunrise = tomorrowSunrise;
         }

         /**
          * Returns true if it is currently night time.
          */
         public boolean isNight() {
             return mIsNight;
         }

         /**
          * Returns the time of yesterday's sunset in the System.currentTimeMillis() timebase,
          * or -1 if the sun never sets.
          */
         public long getYesterdaySunset() {
             return mYesterdaySunset;
         }

         /**
          * Returns the time of today's sunrise in the System.currentTimeMillis() timebase,
          * or -1 if the sun never rises.
          */
         public long getTodaySunrise() {
             return mTodaySunrise;
         }

         /**
          * Returns the time of today's sunset in the System.currentTimeMillis() timebase,
          * or -1 if the sun never sets.
          */
         public long getTodaySunset() {
             return mTodaySunset;
         }

         /**
          * Returns the time of tomorrow's sunrise in the System.currentTimeMillis() timebase,
          * or -1 if the sun never rises.
          */
         public long getTomorrowSunrise() {
             return mTomorrowSunrise;
         }

         @Override
         public boolean equals(Object o) {
             return o instanceof TwilightState && equals((TwilightState)o);
         }

         public boolean equals(TwilightState other) {
             return other != null
                     && mIsNight == other.mIsNight
                     && mYesterdaySunset == other.mYesterdaySunset
                     && mTodaySunrise == other.mTodaySunrise
                     && mTodaySunset == other.mTodaySunset
                     && mTomorrowSunrise == other.mTomorrowSunrise;
         }

         @Override
         public int hashCode() {
             return 0; // don't care
         }

         @Override
         public String toString() {
             DateFormat f = DateFormat.getDateTimeInstance();
             return "{TwilightState: isNight=" + mIsNight
                     + ", mYesterdaySunset=" + f.format(new Date(mYesterdaySunset))
                     + ", mTodaySunrise=" + f.format(new Date(mTodaySunrise))
                     + ", mTodaySunset=" + f.format(new Date(mTodaySunset))
                     + ", mTomorrowSunrise=" + f.format(new Date(mTomorrowSunrise))
                     + "}";
         }
     }

     /**
      * Listener for changes in twilight state.
      */
     public interface TwilightListener {
         public void onTwilightStateChanged();
     }

     private static final class TwilightListenerRecord implements Runnable {
         private final TwilightListener mListener;
         private final Handler mHandler;

         public TwilightListenerRecord(TwilightListener listener, Handler handler) {
             mListener = listener;
             mHandler = handler;
         }

         public void post() {
             mHandler.post(this);
         }

         @Override
         public void run() {
             mListener.onTwilightStateChanged();
         }
     }

     private final class LocationHandler extends Handler {
         private static final int MSG_ENABLE_LOCATION_UPDATES = 1;
         private static final int MSG_GET_NEW_LOCATION_UPDATE = 2;
         private static final int MSG_PROCESS_NEW_LOCATION = 3;
         private static final int MSG_DO_TWILIGHT_UPDATE = 4;

         private static final long LOCATION_UPDATE_MS = 24 * DateUtils.HOUR_IN_MILLIS;
         private static final long MIN_LOCATION_UPDATE_MS = 30 * DateUtils.MINUTE_IN_MILLIS;
         private static final float LOCATION_UPDATE_DISTANCE_METER = 1000 * 20;
         private static final long LOCATION_UPDATE_ENABLE_INTERVAL_MIN = 5000;
         private static final long LOCATION_UPDATE_ENABLE_INTERVAL_MAX =
                 15 * DateUtils.MINUTE_IN_MILLIS;
         private static final double FACTOR_GMT_OFFSET_LONGITUDE =
                 1000.0 * 360.0 / DateUtils.DAY_IN_MILLIS;

         private boolean mPassiveListenerEnabled;
         private boolean mNetworkListenerEnabled;
         private boolean mDidFirstInit;
         private long mLastNetworkRegisterTime = -MIN_LOCATION_UPDATE_MS;
         private long mLastUpdateInterval;
         private Location mLocation;
         private final TwilightCalculator mTwilightCalculator = new TwilightCalculator();

         public void processNewLocation(Location location) {
             Message msg = obtainMessage(MSG_PROCESS_NEW_LOCATION, location);
             sendMessage(msg);
         }

         public void enableLocationUpdates() {
             sendEmptyMessage(MSG_ENABLE_LOCATION_UPDATES);
         }

         public void requestLocationUpdate() {
             sendEmptyMessage(MSG_GET_NEW_LOCATION_UPDATE);
         }

         public void requestTwilightUpdate() {
             sendEmptyMessage(MSG_DO_TWILIGHT_UPDATE);
         }

         @Override
         public void handleMessage(Message msg) {
             switch (msg.what) {
                 case MSG_PROCESS_NEW_LOCATION: {
                     final Location location = (Location)msg.obj;
                     final boolean hasMoved = hasMoved(mLocation, location);
                     final boolean hasBetterAccuracy = mLocation == null
                             || location.getAccuracy() < mLocation.getAccuracy();
                     if (DEBUG) {
                         Slog.d(TAG, "Processing new location: " + location
                                + ", hasMoved=" + hasMoved
                                + ", hasBetterAccuracy=" + hasBetterAccuracy);
                     }
                     if (hasMoved || hasBetterAccuracy) {
                         setLocation(location);
                     }
                     break;
                 }

                 case MSG_GET_NEW_LOCATION_UPDATE:
                     if (!mNetworkListenerEnabled) {
                         // Don't do anything -- we are still trying to get a
                         // location.
                         return;
                     }
                     if ((mLastNetworkRegisterTime + MIN_LOCATION_UPDATE_MS) >=
                             SystemClock.elapsedRealtime()) {
                         // Don't do anything -- it hasn't been long enough
                         // since we last requested an update.
                         return;
                     }

                     // Unregister the current location monitor, so we can
                     // register a new one for it to get an immediate update.
                     mNetworkListenerEnabled = false;
                     mLocationManager.removeUpdates(mEmptyLocationListener);

                     // Fall through to re-register listener.
                 case MSG_ENABLE_LOCATION_UPDATES:
                     // enable network provider to receive at least location updates for a given
                     // distance.
                     boolean networkLocationEnabled;
                     try {
                         networkLocationEnabled =
                             mLocationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
                     } catch (Exception e) {
                         // we may get IllegalArgumentException if network location provider
                         // does not exist or is not yet installed.
                         networkLocationEnabled = false;
                     }
                     if (!mNetworkListenerEnabled && networkLocationEnabled) {
                         mNetworkListenerEnabled = true;
                         mLastNetworkRegisterTime = SystemClock.elapsedRealtime();
                         mLocationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,
                                 LOCATION_UPDATE_MS, 0, mEmptyLocationListener);

                         if (!mDidFirstInit) {
                             mDidFirstInit = true;
                             if (mLocation == null) {
                                 retrieveLocation();
                             }
                         }
                     }

                     // enable passive provider to receive updates from location fixes (gps
                     // and network).
                     boolean passiveLocationEnabled;
                     try {
                         passiveLocationEnabled =
                             mLocationManager.isProviderEnabled(LocationManager.PASSIVE_PROVIDER);
                     } catch (Exception e) {
                         // we may get IllegalArgumentException if passive location provider
                         // does not exist or is not yet installed.
                         passiveLocationEnabled = false;
                     }

                     if (!mPassiveListenerEnabled && passiveLocationEnabled) {
                         mPassiveListenerEnabled = true;
                         mLocationManager.requestLocationUpdates(LocationManager.PASSIVE_PROVIDER,
                                 0, LOCATION_UPDATE_DISTANCE_METER , mLocationListener);
                     }

                     if (!(mNetworkListenerEnabled && mPassiveListenerEnabled)) {
                         mLastUpdateInterval *= 1.5;
                         if (mLastUpdateInterval == 0) {
                             mLastUpdateInterval = LOCATION_UPDATE_ENABLE_INTERVAL_MIN;
                         } else if (mLastUpdateInterval > LOCATION_UPDATE_ENABLE_INTERVAL_MAX) {
                             mLastUpdateInterval = LOCATION_UPDATE_ENABLE_INTERVAL_MAX;
                         }
                         sendEmptyMessageDelayed(MSG_ENABLE_LOCATION_UPDATES, mLastUpdateInterval);
                     }
                     break;

                 case MSG_DO_TWILIGHT_UPDATE:
                     updateTwilightState();
                     break;
             }
         }

         private void retrieveLocation() {
             Location location = null;
             final Iterator<String> providers =
                     mLocationManager.getProviders(new Criteria(), true).iterator();
             while (providers.hasNext()) {
                 final Location lastKnownLocation =
                         mLocationManager.getLastKnownLocation(providers.next());
                 // pick the most recent location
                 if (location == null || (lastKnownLocation != null &&
                         location.getElapsedRealtimeNanos() <
                         lastKnownLocation.getElapsedRealtimeNanos())) {
                     location = lastKnownLocation;
                 }
             }

             // In the case there is no location available (e.g. GPS fix or network location
             // is not available yet), the longitude of the location is estimated using the timezone,
             // latitude and accuracy are set to get a good average.
             if (location == null) {
                 Time currentTime = new Time();
                 currentTime.set(System.currentTimeMillis());
                 double lngOffset = FACTOR_GMT_OFFSET_LONGITUDE *
                         (currentTime.gmtoff - (currentTime.isDst > 0 ? 3600 : 0));
                 location = new Location("fake");
                 location.setLongitude(lngOffset);
                 location.setLatitude(0);
                 location.setAccuracy(417000.0f);
                 location.setTime(System.currentTimeMillis());
                 location.setElapsedRealtimeNanos(SystemClock.elapsedRealtimeNanos());

                 if (DEBUG) {
                     Slog.d(TAG, "Estimated location from timezone: " + location);
                 }
             }

             setLocation(location);
         }

         private void setLocation(Location location) {
             mLocation = location;
             updateTwilightState();
         }

         private void updateTwilightState() {
             if (mLocation == null) {
                 setTwilightState(null);
                 return;
             }

             final long now = System.currentTimeMillis();

             // calculate yesterday's twilight
             mTwilightCalculator.calculateTwilight(now - DateUtils.DAY_IN_MILLIS,
                     mLocation.getLatitude(), mLocation.getLongitude());
             final long yesterdaySunset = mTwilightCalculator.mSunset;

             // calculate today's twilight
             mTwilightCalculator.calculateTwilight(now,
                     mLocation.getLatitude(), mLocation.getLongitude());
             final boolean isNight = (mTwilightCalculator.mState == TwilightCalculator.NIGHT);
             final long todaySunrise = mTwilightCalculator.mSunrise;
             final long todaySunset = mTwilightCalculator.mSunset;

             // calculate tomorrow's twilight
             mTwilightCalculator.calculateTwilight(now + DateUtils.DAY_IN_MILLIS,
                     mLocation.getLatitude(), mLocation.getLongitude());
             final long tomorrowSunrise = mTwilightCalculator.mSunrise;

             // set twilight state
             TwilightState state = new TwilightState(isNight, yesterdaySunset,
                     todaySunrise, todaySunset, tomorrowSunrise);
             if (DEBUG) {
                 Slog.d(TAG, "Updating twilight state: " + state);
             }
             setTwilightState(state);

             // schedule next update
             long nextUpdate = 0;
             if (todaySunrise == -1 || todaySunset == -1) {
                 // In the case the day or night never ends the update is scheduled 12 hours later.
                 nextUpdate = now + 12 * DateUtils.HOUR_IN_MILLIS;
             } else {
                 // add some extra time to be on the safe side.
                 nextUpdate += DateUtils.MINUTE_IN_MILLIS;

                 if (now > todaySunset) {
                     nextUpdate += tomorrowSunrise;
                 } else if (now > todaySunrise) {
                     nextUpdate += todaySunset;
                 } else {
                     nextUpdate += todaySunrise;
                 }
             }

             if (DEBUG) {
                 Slog.d(TAG, "Next update in " + (nextUpdate - now) + " ms");
             }

             Intent updateIntent = new Intent(ACTION_UPDATE_TWILIGHT_STATE);
             PendingIntent pendingIntent = PendingIntent.getBroadcast(mContext, 0, updateIntent, 0);
             mAlarmManager.cancel(pendingIntent);
             mAlarmManager.setExact(AlarmManager.RTC, nextUpdate, pendingIntent);
         }
     };

     private final BroadcastReceiver mUpdateLocationReceiver = new BroadcastReceiver() {
         @Override
         public void onReceive(Context context, Intent intent) {
             if (Intent.ACTION_AIRPLANE_MODE_CHANGED.equals(intent.getAction())
                     && !intent.getBooleanExtra("state", false)) {
                 // Airplane mode is now off!
                 mLocationHandler.requestLocationUpdate();
                 return;
             }

             // Time zone has changed or alarm expired.
             mLocationHandler.requestTwilightUpdate();
         }
     };

     // A LocationListener to initialize the network location provider. The location updates
     // are handled through the passive location provider.
     private final LocationListener mEmptyLocationListener =  new LocationListener() {
         public void onLocationChanged(Location location) {
         }

         public void onProviderDisabled(String provider) {
         }

         public void onProviderEnabled(String provider) {
         }

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

     private final LocationListener mLocationListener = new LocationListener() {
         public void onLocationChanged(Location location) {
             mLocationHandler.processNewLocation(location);
         }

         public void onProviderDisabled(String provider) {
         }

         public void onProviderEnabled(String provider) {
         }

         public void onStatusChanged(String provider, int status, Bundle extras) {
         }
     };
 }
	/*
	* Copyright (C) 2012 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package com.android.server;

	import android.app.AlarmManager;
	import android.app.PendingIntent;
	import android.content.BroadcastReceiver;
	import android.content.Context;
	import android.content.Intent;
	import android.content.IntentFilter;
	import android.location.Criteria;
	import android.location.Location;
	import android.location.LocationListener;
	import android.location.LocationManager;
	import android.os.Bundle;
	import android.os.Handler;
	import android.os.Message;
	import android.os.SystemClock;
	import android.text.format.DateUtils;
	import android.text.format.Time;
	import android.util.Slog;

	import java.text.DateFormat;
	import java.util.ArrayList;
	import java.util.Date;
	import java.util.Iterator;

	import libcore.util.Objects;

	/**
	* Figures out whether it's twilight time based on the user's location.
	*
	* Used by the UI mode manager and other components to adjust night mode
	* effects based on sunrise and sunset.
	*/
	public final class TwilightService {
	private static final String TAG = "TwilightService";

	private static final boolean DEBUG = false;

	private static final String ACTION_UPDATE_TWILIGHT_STATE =
	"com.android.server.action.UPDATE_TWILIGHT_STATE";

	private final Context mContext;
	private final AlarmManager mAlarmManager;
	private final LocationManager mLocationManager;
	private final LocationHandler mLocationHandler;

	private final Object mLock = new Object();

	private final ArrayList<TwilightListenerRecord> mListeners =
	new ArrayList<TwilightListenerRecord>();

	private boolean mSystemReady;

	private TwilightState mTwilightState;

	public TwilightService(Context context) {
	mContext = context;

	mAlarmManager = (AlarmManager)mContext.getSystemService(Context.ALARM_SERVICE);
	mLocationManager = (LocationManager)mContext.getSystemService(Context.LOCATION_SERVICE);
	mLocationHandler = new LocationHandler();
	}

	void systemReady() {
	synchronized (mLock) {
	mSystemReady = true;

	IntentFilter filter = new IntentFilter(Intent.ACTION_AIRPLANE_MODE_CHANGED);
	filter.addAction(Intent.ACTION_TIME_CHANGED);
	filter.addAction(Intent.ACTION_TIMEZONE_CHANGED);
	filter.addAction(ACTION_UPDATE_TWILIGHT_STATE);
	mContext.registerReceiver(mUpdateLocationReceiver, filter);

	if (!mListeners.isEmpty()) {
	mLocationHandler.enableLocationUpdates();
	}
	}
	}

	/**
	* Gets the current twilight state.
	*
	* @return The current twilight state, or null if no information is available.
	*/
	public TwilightState getCurrentState() {
	synchronized (mLock) {
	return mTwilightState;
	}
	}

	/**
	* Listens for twilight time.
	*
	* @param listener The listener.
	* @param handler The handler on which to post calls into the listener.
	*/
	public void registerListener(TwilightListener listener, Handler handler) {
	synchronized (mLock) {
	mListeners.add(new TwilightListenerRecord(listener, handler));

	if (mSystemReady && mListeners.size() == 1) {
	mLocationHandler.enableLocationUpdates();
	}
	}
	}

	private void setTwilightState(TwilightState state) {
	synchronized (mLock) {
	if (!Objects.equal(mTwilightState, state)) {
	if (DEBUG) {
	Slog.d(TAG, "Twilight state changed: " + state);
	}

	mTwilightState = state;
	int count = mListeners.size();
	for (int i = 0; i < count; i++) {
	mListeners.get(i).post();
	}
	}
	}
	}

	// The user has moved if the accuracy circles of the two locations don't overlap.
	private static boolean hasMoved(Location from, Location to) {
	if (to == null) {
	return false;
	}

	if (from == null) {
	return true;
	}

	// if new location is older than the current one, the device hasn't moved.
	if (to.getElapsedRealtimeNanos() < from.getElapsedRealtimeNanos()) {
	return false;
	}

	// Get the distance between the two points.
	float distance = from.distanceTo(to);

	// Get the total accuracy radius for both locations.
	float totalAccuracy = from.getAccuracy() + to.getAccuracy();

	// If the distance is greater than the combined accuracy of the two
	// points then they can't overlap and hence the user has moved.
	return distance >= totalAccuracy;
	}

	/**
	* Describes whether it is day or night.
	* This object is immutable.
	*/
	public static final class TwilightState {
	private final boolean mIsNight;
	private final long mYesterdaySunset;
	private final long mTodaySunrise;
	private final long mTodaySunset;
	private final long mTomorrowSunrise;

	TwilightState(boolean isNight,
	long yesterdaySunset,
	long todaySunrise, long todaySunset,
	long tomorrowSunrise) {
	mIsNight = isNight;
	mYesterdaySunset = yesterdaySunset;
	mTodaySunrise = todaySunrise;
	mTodaySunset = todaySunset;
	mTomorrowSunrise = tomorrowSunrise;
	}

	/**
	* Returns true if it is currently night time.
	*/
	public boolean isNight() {
	return mIsNight;
	}

	/**
	* Returns the time of yesterday's sunset in the System.currentTimeMillis() timebase,
	* or -1 if the sun never sets.
	*/
	public long getYesterdaySunset() {
	return mYesterdaySunset;
	}

	/**
	* Returns the time of today's sunrise in the System.currentTimeMillis() timebase,
	* or -1 if the sun never rises.
	*/
	public long getTodaySunrise() {
	return mTodaySunrise;
	}

	/**
	* Returns the time of today's sunset in the System.currentTimeMillis() timebase,
	* or -1 if the sun never sets.
	*/
	public long getTodaySunset() {
	return mTodaySunset;
	}

	/**
	* Returns the time of tomorrow's sunrise in the System.currentTimeMillis() timebase,
	* or -1 if the sun never rises.
	*/
	public long getTomorrowSunrise() {
	return mTomorrowSunrise;
	}

	@Override
	public boolean equals(Object o) {
	return o instanceof TwilightState && equals((TwilightState)o);
	}

	public boolean equals(TwilightState other) {
	return other != null
	&& mIsNight == other.mIsNight
	&& mYesterdaySunset == other.mYesterdaySunset
	&& mTodaySunrise == other.mTodaySunrise
	&& mTodaySunset == other.mTodaySunset
	&& mTomorrowSunrise == other.mTomorrowSunrise;
	}

	@Override
	public int hashCode() {
	return 0; // don't care
	}

	@Override
	public String toString() {
	DateFormat f = DateFormat.getDateTimeInstance();
	return "{TwilightState: isNight=" + mIsNight
	+ ", mYesterdaySunset=" + f.format(new Date(mYesterdaySunset))
	+ ", mTodaySunrise=" + f.format(new Date(mTodaySunrise))
	+ ", mTodaySunset=" + f.format(new Date(mTodaySunset))
	+ ", mTomorrowSunrise=" + f.format(new Date(mTomorrowSunrise))
	+ "}";
	}
	}

	/**
	* Listener for changes in twilight state.
	*/
	public interface TwilightListener {
	public void onTwilightStateChanged();
	}

	private static final class TwilightListenerRecord implements Runnable {
	private final TwilightListener mListener;
	private final Handler mHandler;

	public TwilightListenerRecord(TwilightListener listener, Handler handler) {
	mListener = listener;
	mHandler = handler;
	}

	public void post() {
	mHandler.post(this);
	}

	@Override
	public void run() {
	mListener.onTwilightStateChanged();
	}
	}

	private final class LocationHandler extends Handler {
	private static final int MSG_ENABLE_LOCATION_UPDATES = 1;
	private static final int MSG_GET_NEW_LOCATION_UPDATE = 2;
	private static final int MSG_PROCESS_NEW_LOCATION = 3;
	private static final int MSG_DO_TWILIGHT_UPDATE = 4;

	private static final long LOCATION_UPDATE_MS = 24 * DateUtils.HOUR_IN_MILLIS;
	private static final long MIN_LOCATION_UPDATE_MS = 30 * DateUtils.MINUTE_IN_MILLIS;
	private static final float LOCATION_UPDATE_DISTANCE_METER = 1000 * 20;
	private static final long LOCATION_UPDATE_ENABLE_INTERVAL_MIN = 5000;
	private static final long LOCATION_UPDATE_ENABLE_INTERVAL_MAX =
	15 * DateUtils.MINUTE_IN_MILLIS;
	private static final double FACTOR_GMT_OFFSET_LONGITUDE =
	1000.0 * 360.0 / DateUtils.DAY_IN_MILLIS;

	private boolean mPassiveListenerEnabled;
	private boolean mNetworkListenerEnabled;
	private boolean mDidFirstInit;
	private long mLastNetworkRegisterTime = -MIN_LOCATION_UPDATE_MS;
	private long mLastUpdateInterval;
	private Location mLocation;
	private final TwilightCalculator mTwilightCalculator = new TwilightCalculator();

	public void processNewLocation(Location location) {
	Message msg = obtainMessage(MSG_PROCESS_NEW_LOCATION, location);
	sendMessage(msg);
	}

	public void enableLocationUpdates() {
	sendEmptyMessage(MSG_ENABLE_LOCATION_UPDATES);
	}

	public void requestLocationUpdate() {
	sendEmptyMessage(MSG_GET_NEW_LOCATION_UPDATE);
	}

	public void requestTwilightUpdate() {
	sendEmptyMessage(MSG_DO_TWILIGHT_UPDATE);
	}

	@Override
	public void handleMessage(Message msg) {
	switch (msg.what) {
	case MSG_PROCESS_NEW_LOCATION: {
	final Location location = (Location)msg.obj;
	final boolean hasMoved = hasMoved(mLocation, location);
	final boolean hasBetterAccuracy = mLocation == null
	\|\| location.getAccuracy() < mLocation.getAccuracy();
	if (DEBUG) {
	Slog.d(TAG, "Processing new location: " + location
	+ ", hasMoved=" + hasMoved
	+ ", hasBetterAccuracy=" + hasBetterAccuracy);
	}
	if (hasMoved \|\| hasBetterAccuracy) {
	setLocation(location);
	}
	break;
	}

	case MSG_GET_NEW_LOCATION_UPDATE:
	if (!mNetworkListenerEnabled) {
	// Don't do anything -- we are still trying to get a
	// location.
	return;
	}
	if ((mLastNetworkRegisterTime + MIN_LOCATION_UPDATE_MS) >=
	SystemClock.elapsedRealtime()) {
	// Don't do anything -- it hasn't been long enough
	// since we last requested an update.
	return;
	}

	// Unregister the current location monitor, so we can
	// register a new one for it to get an immediate update.
	mNetworkListenerEnabled = false;
	mLocationManager.removeUpdates(mEmptyLocationListener);

	// Fall through to re-register listener.
	case MSG_ENABLE_LOCATION_UPDATES:
	// enable network provider to receive at least location updates for a given
	// distance.
	boolean networkLocationEnabled;
	try {
	networkLocationEnabled =
	mLocationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
	} catch (Exception e) {
	// we may get IllegalArgumentException if network location provider
	// does not exist or is not yet installed.
	networkLocationEnabled = false;
	}
	if (!mNetworkListenerEnabled && networkLocationEnabled) {
	mNetworkListenerEnabled = true;
	mLastNetworkRegisterTime = SystemClock.elapsedRealtime();
	mLocationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,
	LOCATION_UPDATE_MS, 0, mEmptyLocationListener);

	if (!mDidFirstInit) {
	mDidFirstInit = true;
	if (mLocation == null) {
	retrieveLocation();
	}
	}
	}

	// enable passive provider to receive updates from location fixes (gps
	// and network).
	boolean passiveLocationEnabled;
	try {
	passiveLocationEnabled =
	mLocationManager.isProviderEnabled(LocationManager.PASSIVE_PROVIDER);
	} catch (Exception e) {
	// we may get IllegalArgumentException if passive location provider
	// does not exist or is not yet installed.
	passiveLocationEnabled = false;
	}

	if (!mPassiveListenerEnabled && passiveLocationEnabled) {
	mPassiveListenerEnabled = true;
	mLocationManager.requestLocationUpdates(LocationManager.PASSIVE_PROVIDER,
	0, LOCATION_UPDATE_DISTANCE_METER , mLocationListener);
	}

	if (!(mNetworkListenerEnabled && mPassiveListenerEnabled)) {
	mLastUpdateInterval *= 1.5;
	if (mLastUpdateInterval == 0) {
	mLastUpdateInterval = LOCATION_UPDATE_ENABLE_INTERVAL_MIN;
	} else if (mLastUpdateInterval > LOCATION_UPDATE_ENABLE_INTERVAL_MAX) {
	mLastUpdateInterval = LOCATION_UPDATE_ENABLE_INTERVAL_MAX;
	}
	sendEmptyMessageDelayed(MSG_ENABLE_LOCATION_UPDATES, mLastUpdateInterval);
	}
	break;

	case MSG_DO_TWILIGHT_UPDATE:
	updateTwilightState();
	break;
	}
	}

	private void retrieveLocation() {
	Location location = null;
	final Iterator<String> providers =
	mLocationManager.getProviders(new Criteria(), true).iterator();
	while (providers.hasNext()) {
	final Location lastKnownLocation =
	mLocationManager.getLastKnownLocation(providers.next());
	// pick the most recent location
	if (location == null \|\| (lastKnownLocation != null &&
	location.getElapsedRealtimeNanos() <
	lastKnownLocation.getElapsedRealtimeNanos())) {
	location = lastKnownLocation;
	}
	}

	// In the case there is no location available (e.g. GPS fix or network location
	// is not available yet), the longitude of the location is estimated using the timezone,
	// latitude and accuracy are set to get a good average.
	if (location == null) {
	Time currentTime = new Time();
	currentTime.set(System.currentTimeMillis());
	double lngOffset = FACTOR_GMT_OFFSET_LONGITUDE *
	(currentTime.gmtoff - (currentTime.isDst > 0 ? 3600 : 0));
	location = new Location("fake");
	location.setLongitude(lngOffset);
	location.setLatitude(0);
	location.setAccuracy(417000.0f);
	location.setTime(System.currentTimeMillis());
	location.setElapsedRealtimeNanos(SystemClock.elapsedRealtimeNanos());

	if (DEBUG) {
	Slog.d(TAG, "Estimated location from timezone: " + location);
	}
	}

	setLocation(location);
	}

	private void setLocation(Location location) {
	mLocation = location;
	updateTwilightState();
	}

	private void updateTwilightState() {
	if (mLocation == null) {
	setTwilightState(null);
	return;
	}

	final long now = System.currentTimeMillis();

	// calculate yesterday's twilight
	mTwilightCalculator.calculateTwilight(now - DateUtils.DAY_IN_MILLIS,
	mLocation.getLatitude(), mLocation.getLongitude());
	final long yesterdaySunset = mTwilightCalculator.mSunset;

	// calculate today's twilight
	mTwilightCalculator.calculateTwilight(now,
	mLocation.getLatitude(), mLocation.getLongitude());
	final boolean isNight = (mTwilightCalculator.mState == TwilightCalculator.NIGHT);
	final long todaySunrise = mTwilightCalculator.mSunrise;
	final long todaySunset = mTwilightCalculator.mSunset;

	// calculate tomorrow's twilight
	mTwilightCalculator.calculateTwilight(now + DateUtils.DAY_IN_MILLIS,
	mLocation.getLatitude(), mLocation.getLongitude());
	final long tomorrowSunrise = mTwilightCalculator.mSunrise;

	// set twilight state
	TwilightState state = new TwilightState(isNight, yesterdaySunset,
	todaySunrise, todaySunset, tomorrowSunrise);
	if (DEBUG) {
	Slog.d(TAG, "Updating twilight state: " + state);
	}
	setTwilightState(state);

	// schedule next update
	long nextUpdate = 0;
	if (todaySunrise == -1 \|\| todaySunset == -1) {
	// In the case the day or night never ends the update is scheduled 12 hours later.
	nextUpdate = now + 12 * DateUtils.HOUR_IN_MILLIS;
	} else {
	// add some extra time to be on the safe side.
	nextUpdate += DateUtils.MINUTE_IN_MILLIS;

	if (now > todaySunset) {
	nextUpdate += tomorrowSunrise;
	} else if (now > todaySunrise) {
	nextUpdate += todaySunset;
	} else {
	nextUpdate += todaySunrise;
	}
	}

	if (DEBUG) {
	Slog.d(TAG, "Next update in " + (nextUpdate - now) + " ms");
	}

	Intent updateIntent = new Intent(ACTION_UPDATE_TWILIGHT_STATE);
	PendingIntent pendingIntent = PendingIntent.getBroadcast(mContext, 0, updateIntent, 0);
	mAlarmManager.cancel(pendingIntent);
	mAlarmManager.setExact(AlarmManager.RTC, nextUpdate, pendingIntent);
	}
	};

	private final BroadcastReceiver mUpdateLocationReceiver = new BroadcastReceiver() {
	@Override
	public void onReceive(Context context, Intent intent) {
	if (Intent.ACTION_AIRPLANE_MODE_CHANGED.equals(intent.getAction())
	&& !intent.getBooleanExtra("state", false)) {
	// Airplane mode is now off!
	mLocationHandler.requestLocationUpdate();
	return;
	}

	// Time zone has changed or alarm expired.
	mLocationHandler.requestTwilightUpdate();
	}
	};

	// A LocationListener to initialize the network location provider. The location updates
	// are handled through the passive location provider.
	private final LocationListener mEmptyLocationListener = new LocationListener() {
	public void onLocationChanged(Location location) {
	}

	public void onProviderDisabled(String provider) {
	}

	public void onProviderEnabled(String provider) {
	}

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

	private final LocationListener mLocationListener = new LocationListener() {
	public void onLocationChanged(Location location) {
	mLocationHandler.processNewLocation(location);
	}

	public void onProviderDisabled(String provider) {
	}

	public void onProviderEnabled(String provider) {
	}

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