/*****************************************************************************
* Copyright [2013] [Jules White] *
* *
* 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 org.magnum.soda.ctx;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.HashMap;
import java.util.List;
import org.magnum.soda.SodaContext;
public class SodaLocation implements SodaContext {
private double latitude_;
private double longitude_;
private String geohash_;
private Proximity proximity_;
private Accuracy accuracy_;
private PositionUpdates positionUpdates_;
public enum Proximity {
ZERO, TWENTY_METERS
}
public enum Accuracy {
FINE
}
public enum PositionUpdates {
EVERY_HUNDRED_METERS
}
public static SodaLocation at(double lat, double lon) {
SodaLocation sodaLocation = new SodaLocation();
try {
sodaLocation.latitude_ = lat;
sodaLocation.longitude_ = lon;
sodaLocation.proximity_ = Proximity.ZERO;
sodaLocation.geohash_ = encode(lat,lon);
} catch (Exception e) {
throw new RuntimeException();
}
return sodaLocation;
}
public static SodaLocation at(String geohash) {
SodaLocation sodaLocation = new SodaLocation();
try {
sodaLocation.geohash_ = geohash;
sodaLocation.proximity_ = Proximity.ZERO;
double[] latlon = decode(geohash);
sodaLocation.latitude_ = latlon[0];
sodaLocation.longitude_ = latlon[1];
} catch (Exception e) {
throw new RuntimeException();
}
return sodaLocation;
}
public static SodaLocation within(Proximity range) {
SodaLocation sodaLocation = new SodaLocation();
try {
sodaLocation.proximity_ = range;
} catch (Exception e) {
throw new RuntimeException();
}
return sodaLocation;
}
public SodaLocation of(double lat, double lon) {
try {
latitude_ = lat;
longitude_ = lon;
geohash_ = encode(lat,lon);
} catch (Exception e) {
throw new RuntimeException();
}
return this;
}
public SodaLocation of(String geohash) {
try {
geohash_ = geohash;
double[] latlon = decode(geohash);
latitude_ = latlon[0];
longitude_ = latlon[1];
} catch (Exception e) {
throw new RuntimeException();
}
return this;
}
public SodaLocation atAccuracy(Accuracy accuracy) {
try {
this.accuracy_ = accuracy;
} catch (Exception e) {
throw new RuntimeException();
}
return this;
}
@Override
public boolean equals(Object obj) {
SodaLocation l = (SodaLocation) obj;
double range = proximityToNum(l.proximity_)
+ proximityToNum(this.proximity_);
double dist = distFrom(l.latitude_, l.longitude_, this.latitude_,
this.longitude_);
if (dist <= range)
return true;
else
return false;
}
public double proximityToNum(Proximity proximity) {
if (proximity == Proximity.TWENTY_METERS)
return 20;
else if (proximity == Proximity.ZERO)
return 0;
else
return -1;
}
public double distFrom(double lat1, double lng1, double lat2, double lng2) {
double earthRadius = 63710100; // in meters
double dLat = Math.toRadians(lat2 - lat1);
double dLng = Math.toRadians(lng2 - lng1);
double sindLat = Math.sin(dLat / 2);
double sindLng = Math.sin(dLng / 2);
double a = Math.pow(sindLat, 2) + Math.pow(sindLng, 2)
* Math.cos(Math.toRadians(lat1))
* Math.cos(Math.toRadians(lat2));
double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
double dist = earthRadius * c;
return dist;
}
private static int numbits = 6 * 5;
final static char[] digits = { '0', '1', '2', '3', '4', '5', '6', '7', '8',
'9', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'j', 'k', 'm', 'n', 'p',
'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z' };
final static HashMap<Character, Integer> lookup = new HashMap<Character, Integer>();
static {
int i = 0;
for (char c : digits)
lookup.put(c, i++);
}
// convert from geohash string to lat,lon double
public static double[] decode(String geohash) {
StringBuilder buffer = new StringBuilder();
for (char c : geohash.toCharArray()) {
int i = lookup.get(c) + 32;
buffer.append(Integer.toString(i, 2).substring(1));
}
BitSet lonset = new BitSet();
BitSet latset = new BitSet();
// even bits
int j = 0;
for (int i = 0; i < numbits * 2; i += 2) {
boolean isSet = false;
if (i < buffer.length())
isSet = buffer.charAt(i) == '1';
lonset.set(j++, isSet);
}
// odd bits
j = 0;
for (int i = 1; i < numbits * 2; i += 2) {
boolean isSet = false;
if (i < buffer.length())
isSet = buffer.charAt(i) == '1';
latset.set(j++, isSet);
}
double lon = decode(lonset, -180, 180);
double lat = decode(latset, -90, 90);
return new double[] { lat, lon };
}
private static double decode(BitSet bs, double floor, double ceiling) {
double mid = 0;
for (int i = 0; i < bs.length(); i++) {
mid = (floor + ceiling) / 2;
if (bs.get(i))
floor = mid;
else
ceiling = mid;
}
return mid;
}
public static String encode(double lat, double lon) {
BitSet latbits = getBits(lat, -90, 90);
BitSet lonbits = getBits(lon, -180, 180);
StringBuilder buffer = new StringBuilder();
for (int i = 0; i < numbits; i++) {
buffer.append((lonbits.get(i)) ? '1' : '0');
buffer.append((latbits.get(i)) ? '1' : '0');
}
return base32(Long.parseLong(buffer.toString(), 2));
}
private static BitSet getBits(double lat, double floor, double ceiling) {
BitSet buffer = new BitSet(numbits);
for (int i = 0; i < numbits; i++) {
double mid = (floor + ceiling) / 2;
if (lat >= mid) {
buffer.set(i);
floor = mid;
} else {
ceiling = mid;
}
}
return buffer;
}
public static String base32(long i) {
char[] buf = new char[65];
int charPos = 64;
boolean negative = (i < 0);
if (!negative)
i = -i;
while (i <= -32) {
buf[charPos--] = digits[(int) (-(i % 32))];
i /= 32;
}
buf[charPos] = digits[(int) (-i)];
if (negative)
buf[--charPos] = '-';
return new String(buf, charPos, (65 - charPos));
}
}