LocationHelper.java

/*
 	LogMyNight - Android app for logging night activities. 
 	Copyright (c) 2010 Michael Greifeneder <mikegr@gmx.net>, Oliver Selinger <oliver.selinger@gmail.com>
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package at.madexperts.logmynight;

import static java.lang.Math.abs;
import static java.lang.Math.pow;
import static java.lang.Math.sqrt;

import java.util.ArrayList;
import java.util.List;
import java.util.SortedMap;
import java.util.TreeMap;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationManager;
import android.util.Log;
import android.widget.ArrayAdapter;

public class LocationHelper {

	private static final String TAG = LocationHelper.class.getName();
	
	private SQLiteDatabase db;
	private Context ctx;
	public LocationHelper(Context ctx, SQLiteDatabase db) {
		this.ctx = ctx;
		this.db = db;
		
		
	}
	
    private SortedMap<Double, List<String>> getSortedLocations(Location location) {
    	double latNow = 0.0;
    	double lonNow = 0.0;
    	if (location != null) {
    		latNow = location.getLatitude() + 90.0;
    		lonNow = location.getLongitude() + 180.0;
    	}
	
    	Cursor c = db.rawQuery("SELECT _id, name, longitude, latitude FROM location", null);
    	TreeMap<Double, List<String>> map = new TreeMap<Double, List<String>>();
    	while (c.moveToNext()) {
			double latRow = c.getDouble(c.getColumnIndex("longitude")) + 90.0;
			double lonRow = c.getDouble(c.getColumnIndex("latitude")) + 180.0;
			String name = c.getString(c.getColumnIndex("name"));
			double distance = euklidDistance(latNow, lonNow, latRow, lonRow);
			List<String> list = map.get(distance);
			if (list == null) {
				list = new ArrayList<String>();
				map.put(distance, list);
			}
			list.add(name);
			Log.d(TAG, name + " has distance of " + distance);
		}
    	return map;
    }
    
    public String getNearestLocation() {
    	Location now = getLocation();
    	return getNearestLocation(now);
    }
    /**
     * Returns name of nearest location
     * @param now location for calculation distance to 
     * @return
     */
    public String getNearestLocation(Location now) {
    	SortedMap<Double, List<String>> map = getSortedLocations(now);
    	if (map.isEmpty()) {
    		return null;
    	}
    	List<String> list = map.get(map.firstKey());
    	if (list == null || list.isEmpty()) {
    		return null;
    	}
    	String name = list.get(0);
    	return name;
    	/*
    	Cursor c = db.rawQuery("SELECT _id, name, longitude, latitude FROM location WHERE name = ?", new String[] {name});
    	if (!c.moveToFirst()) {
    		return null;
    	}
    	double latitude = c.getDouble(c.getColumnIndex("latitude"));
    	double longitude = c.getDouble(c.getColumnIndex("longitude"));
    	Location result = new Location("LOGMYNIGHT");
    	result.setTime(new Date().getTime());
    	result.setLatitude(latitude);
    	result.setLongitude(longitude);
    	return result;
    	*/
    }
    
    public double euklidDistance(double x1, double y1, double x2, double y2) {
    	return sqrt( pow(abs(x1 - x2),2) * pow(abs(y1 - y2),2) );
    }

    
    public String getBestProvider(LocationManager lm) {
    	List<String> provs = lm.getAllProviders();
    	for (String prov : provs) {
    		Log.d(TAG, "Provider: " + prov);
    	}
    	Criteria c = new Criteria();
    	c.setAccuracy(Criteria.ACCURACY_COARSE);
    	c.setAltitudeRequired(false);
    	c.setBearingRequired(false);
    	c.setCostAllowed(false);
    	c.setPowerRequirement(Criteria.NO_REQUIREMENT);
    	c.setSpeedRequired(false);
    	String provider = lm.getBestProvider(c, true);
    	return provider;
    }
	

    /**
     * Returns last know location with best provider 
     * @return
     */
	public Location getLocation() {
		LocationManager lm = (LocationManager) ctx.getSystemService(ctx.LOCATION_SERVICE);
		String provider = getBestProvider(lm);
		Log.d(TAG, "Used provider: " + provider);
		return lm.getLastKnownLocation(provider);
    }
    

	/**
	 * Returns adapter with sorted list of location names, sorted by closed distance 
	 * @return
	 */
	public ArrayAdapter<String> getSortedNameAdapter() {
		Location location = getLocation();
		return getSortedNameAdapter(location);
	}
	
    public ArrayAdapter<String> getSortedNameAdapter(Location location) {
    	SortedMap<Double, List<String>> map = getSortedLocations(location);
		ArrayList<String> values = new ArrayList<String>();
		for (List<String> list: map.values()) {
			for(String value:list) {
				values.add(value);
				Log.d(TAG, "Sorted:" + value);
			}
		}
		ArrayAdapter<String> adapter = new ArrayAdapter<String>(ctx, android.R.layout.simple_dropdown_item_1line, values);
    	return adapter;
    	
    }
	
}