package net.osmand.util;


import java.util.Collections;
import java.util.Comparator;
import java.util.List;

import net.osmand.data.LatLon;
import net.osmand.data.MapObject;


/**
 * This utility class includes : 
 * 1. distance algorithms
 * 2. finding center for array of nodes
 * 3. tile evaluation algorithms
 *   
 *
 */
public class MapUtils {
	
	private static final String BASE_SHORT_OSM_URL = "http://osm.org/go/";
	
	/**
     * This array is a lookup table that translates 6-bit positive integer
     * index values into their "Base64 Alphabet" equivalents as specified
     * in Table 1 of RFC 2045.
     */
    private static final char intToBase64[] = {
        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
        'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
        'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
        'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '_', '@'
    };

	public static double getDistance(LatLon l, double latitude, double longitude){
		return getDistance(l.getLatitude(), l.getLongitude(), latitude, longitude);
	}
	
	private static double scalarMultiplication(double xA, double yA, double xB, double yB, double xC, double yC) {
		// Scalar multiplication between (AB, AC)
		double multiple = (xB - xA) * (xC - xA) + (yB- yA) * (yC -yA);
		return multiple;
	}

	public static double getOrthogonalDistance(double lat, double lon, double fromLat, double fromLon, double toLat, double toLon) {
		return getDistance(getProjection(lat, lon, fromLat, fromLon, toLat, toLon), lat, lon);
	}
	
	public static LatLon getProjection(double lat, double lon, double fromLat, double fromLon, double toLat, double toLon) {
		// not very accurate computation on sphere but for distances < 1000m it is ok
		double mDist = (fromLat - toLat) * (fromLat - toLat) + (fromLon - toLon) * (fromLon - toLon);
		double projection = scalarMultiplication(fromLat, fromLon, toLat, toLon, lat, lon);
		double prlat;
		double prlon;
		if (projection < 0) {
			prlat = fromLat;
			prlon = fromLon;
		} else if (projection >= mDist) {
			prlat = toLat;
			prlon = toLon;
		} else {
			prlat = fromLat + (toLat - fromLat) * (projection / mDist);
			prlon = fromLon + (toLon - fromLon) * (projection / mDist);
		}
		return new LatLon(prlat, prlon);
	}
	
	private static double toRadians(double angdeg) {
//		return Math.toRadians(angdeg);
		return angdeg / 180.0 * Math.PI;
	}
	
	/**
	 * Gets distance in meters
	 */
	public static double getDistance(double lat1, double lon1, double lat2, double lon2){
		double R = 6372.8; // for haversine use R = 6372.8 km instead of 6371 km
		double dLat = toRadians(lat2-lat1);
		double dLon = toRadians(lon2-lon1); 
		double a = Math.sin(dLat/2) * Math.sin(dLat/2) +
		        Math.cos(toRadians(lat1)) * Math.cos(toRadians(lat2)) * 
		        Math.sin(dLon/2) * Math.sin(dLon/2); 
		//double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
		//return R * c * 1000;
		// simplyfy haversine:
		double c = 2 * R * 1000 * Math.asin(Math.sqrt(a));
		return c;
	}
	
	
	/**
	 * Gets distance in meters
	 */
	public static double getDistance(LatLon l1, LatLon l2){
		return getDistance(l1.getLatitude(), l1.getLongitude(), l2.getLatitude(), l2.getLongitude());
	}
	
	public static double checkLongitude(double longitude) {
		while (longitude < -180 || longitude > 180) {
			if (longitude < 0) {
				longitude += 360;
			} else {
				longitude -= 360;
			}
		}
		return longitude;
	}
	
	public static double checkLatitude(double latitude) {
		while (latitude < -90 || latitude > 90) {
			if (latitude < 0) {
				latitude += 180;
			} else {
				latitude -= 180;
			}
		}
		if(latitude < -85.0511) {
			return -85.0511;
 		} else if(latitude > 85.0511){
 			return 85.0511;
 		}
		return latitude;
	}
	
	public static int get31TileNumberX(double longitude){
		longitude = checkLongitude(longitude);
		long l = 1l << 31;
		return (int)((longitude + 180d)/360d * l);
	}
	public static int get31TileNumberY( double latitude){
		latitude = checkLatitude(latitude);
		double eval = Math.log( Math.tan(toRadians(latitude)) + 1/Math.cos(toRadians(latitude)) );
		long l = 1l << 31;
		if(eval > Math.PI){
			eval = Math.PI;
		}
		return  (int) ((1 - eval / Math.PI) / 2 * l);
	}
	
	public static double get31LongitudeX(int tileX){
		return MapUtils.getLongitudeFromTile(21, tileX /1024f);
	}
	
	public static double get31LatitudeY(int tileY){
		return MapUtils.getLatitudeFromTile(21, tileY /1024f);
	}
	
	
	
	/**
	 * 
	 * Theses methods operate with degrees (evaluating tiles & vice versa) 
	 * degree longitude measurements (-180, 180) [27.56 Minsk]
	// degree latitude measurements (90, -90) [53.9]
	 */
	
	public static double getTileNumberX(float zoom, double longitude){
		if(longitude == 180d) {
			return getPowZoom(zoom) - 1;
		}
		longitude = checkLongitude(longitude);
		return (longitude + 180d)/360d * getPowZoom(zoom);
	}
	
	public static double getTileNumberY(float zoom,  double latitude){
		latitude = checkLatitude(latitude);
		double eval = Math.log( Math.tan(toRadians(latitude)) + 1/Math.cos(toRadians(latitude)) );
		if (Double.isInfinite(eval) || Double.isNaN(eval)) {
			latitude = latitude < 0 ? - 89.9 : 89.9;
			eval = Math.log( Math.tan(toRadians(latitude)) + 1/Math.cos(toRadians(latitude)) );
		}
		double result = (1 - eval / Math.PI) / 2 * getPowZoom(zoom);
		return  result;
	}
	
	public static double getTileEllipsoidNumberY(float zoom, double latitude){
		final double E2 = (double) latitude * Math.PI / 180;
		final long sradiusa = 6378137;
		final long sradiusb = 6356752;
		final double J2 = (double) Math.sqrt(sradiusa * sradiusa - sradiusb * sradiusb)	/ sradiusa;
		final double M2 = (double) Math.log((1 + Math.sin(E2))
				/ (1 - Math.sin(E2)))/ 2- J2	* Math.log((1 + J2 * Math.sin(E2))/ (1 - J2 * Math.sin(E2))) / 2;
		final double B2 = getPowZoom(zoom);
		return B2 / 2 - M2 * B2 / 2 / Math.PI;
	}
	
	public static double getLatitudeFromEllipsoidTileY(float zoom, float tileNumberY){
		final double MerkElipsK = 0.0000001;
		final long sradiusa = 6378137;
		final long sradiusb = 6356752;
		final double FExct = (double) Math.sqrt(sradiusa * sradiusa
				- sradiusb * sradiusb)
				/ sradiusa;
		final double TilesAtZoom = getPowZoom(zoom);
		double result = (tileNumberY - TilesAtZoom / 2)
				/ -(TilesAtZoom / (2 * Math.PI));
		result = (2 * Math.atan(Math.exp(result)) - Math.PI / 2) * 180
				/ Math.PI;
		double Zu = result / (180 / Math.PI);
		double yy = (tileNumberY - TilesAtZoom / 2);

		double Zum1 = Zu;
		Zu = Math.asin(1 - ((1 + Math.sin(Zum1)) * Math.pow(1 - FExct * Math.sin(Zum1), FExct))
				/ (Math.exp((2 * yy) / -(TilesAtZoom / (2 * Math.PI))) * Math.pow(1 + FExct * Math.sin(Zum1), FExct)));
		while (Math.abs(Zum1 - Zu) >= MerkElipsK) {
			Zum1 = Zu;
			Zu = Math.asin(1 - ((1 + Math.sin(Zum1)) * Math.pow(1 - FExct * Math.sin(Zum1), FExct))
					/ (Math.exp((2 * yy) / -(TilesAtZoom / (2 * Math.PI))) * Math.pow(1 + FExct * Math.sin(Zum1), FExct)));
		}

		return Zu * 180 / Math.PI;
	}
	
	
	public static double getLongitudeFromTile(float zoom, double x) {
		return x / getPowZoom(zoom) * 360.0 - 180.0;
	}
	
	public static double getPowZoom(float zoom){
		if(zoom >= 0 && zoom - Math.floor(zoom) < 0.05f){
			return 1 << ((int)zoom); 
		} else {
			return Math.pow(2, zoom);
		}
	}
	

	
	public static float calcDiffPixelX(float rotateSin, float rotateCos, float dTileX, float dTileY, float tileSize){
		return (rotateCos * dTileX - rotateSin * dTileY) * tileSize ;
	}
	
	public static float calcDiffPixelY(float rotateSin, float rotateCos, float dTileX, float dTileY, float tileSize){
		return (rotateSin * dTileX + rotateCos * dTileY) * tileSize ;
	}
	
	public static double getLatitudeFromTile(float zoom, double y){
		int sign = y < 0 ? -1 : 1;
		double result = Math.atan(sign*Math.sinh(Math.PI * (1 - 2 * y / getPowZoom(zoom)))) * 180d / Math.PI;
		return result;
	}
	
	
	public static int getPixelShiftX(int zoom, double long1, double long2, int tileSize){
		return (int) ((getTileNumberX(zoom, long1) - getTileNumberX(zoom, long2)) * tileSize);
	}
	
	
	public static int getPixelShiftY(int zoom, double lat1, double lat2, int tileSize){
		return (int) ((getTileNumberY(zoom, lat1) - getTileNumberY(zoom, lat2)) * tileSize);
	}
	
	
	
	public static void sortListOfMapObject(List<? extends MapObject> list, final double lat, final double lon){
		Collections.sort(list, new Comparator<MapObject>() {
			@Override
			public int compare(MapObject o1, MapObject o2) {
				return Double.compare(MapUtils.getDistance(o1.getLocation(), lat, lon), MapUtils.getDistance(o2.getLocation(),
						lat, lon));
			}
		});
	}
	
	
	// Examples
//	System.out.println(buildShortOsmUrl(51.51829d, 0.07347d, 16)); // http://osm.org/go/0EEQsyfu
//	System.out.println(buildShortOsmUrl(52.30103d, 4.862927d, 18)); // http://osm.org/go/0E4_JiVhs
//	System.out.println(buildShortOsmUrl(40.59d, -115.213d, 9)); // http://osm.org/go/TelHTB--
	public static String buildShortOsmUrl(double latitude, double longitude, int zoom){
		StringBuilder str = new StringBuilder(10);
		str.append(BASE_SHORT_OSM_URL);
		str.append(createShortLocString(latitude, longitude, zoom));
		str.append("?m");
		return str.toString();
	}

	public static String createShortLocString(double latitude, double longitude, int zoom) {
		long lat = (long) (((latitude + 90d)/180d)*(1l << 32));
		long lon = (long) (((longitude + 180d)/360d)*(1l << 32));
		long code = interleaveBits(lon, lat);
		String str = "";
	    // add eight to the zoom level, which approximates an accuracy of one pixel in a tile.
		for (int i = 0; i < Math.ceil((zoom + 8) / 3d); i++) {
		    str += intToBase64[(int) ((code >> (58 - 6 * i)) & 0x3f)];
		}
		// append characters onto the end of the string to represent
		// partial zoom levels (characters themselves have a granularity of 3 zoom levels).
		for (int j = 0; j < (zoom + 8) % 3; j++) {
			str += '-';
		}
		return str;
	}
	
	@SuppressWarnings("unused")
	public static LatLon decodeShortLocString(String s) {
		long x = 0;
		long y = 0;
	    int z = 0;
		int z_offset = 0;

		for (int i = 0; i < s.length(); i++) {
			if (s.charAt(i) == '-') {
				z_offset--;
				continue;
			}
			char c = s.charAt(i);
			for (int j = 0; j < intToBase64.length; j++) {
				if (c == intToBase64[j]) {
					for (int k = 0; k < 3; k++) {
						x <<= 1;
						if ((j & 32) != 0) {
							x = x | 1;
						}
						j <<= 1;
						y <<= 1;
						if ((j & 32) != 0) {
							y = y | 1;
						}
						j <<= 1;
					}
					z += 3;
					break;
				}
			}
		}
		x <<= (32 - z);
		y <<= (32 - z);
//		int zoom = z - 8 - ((3 + z_offset) % 3);
		double dlat = (180d * (y) / ((double)(1l << 32))) - 90d;
		double dlon = (360d * (x)/ ((double)(1l << 32))) - 180d;
		return new LatLon(dlat, dlon);
	}
	
	/**	
	 * interleaves the bits of two 32-bit numbers. the result is known as a Morton code.	   
	 */
	private static long interleaveBits(long x, long y){
		long c = 0;
		for(byte b = 31; b>=0; b--){
			c = (c << 1) | ((x >> b) & 1);
			c = (c << 1) | ((y >> b) & 1);
		}
		return c;
	}

	/**
	 * Calculate rotation diff D, that R (rotate) + D = T (targetRotate)
	 * D is between -180, 180 
	 * @param rotate
	 * @param targetRotate
	 * @return 
	 */
	public static float unifyRotationDiff(float rotate, float targetRotate) {
		float d = targetRotate - rotate;
		while(d >= 180){
			d -= 360;
		}
		while(d < -180){
			d += 360;
		}
		return d;
	}
	
	/**
	 * Calculate rotation diff D, that R (rotate) + D = T (targetRotate)
	 * D is between -180, 180 
	 * @param rotate
	 * @param targetRotate
	 * @return 
	 */
	public static float unifyRotationTo360(float rotate) {
		while(rotate < 0){
			rotate += 360;
		}
		while(rotate > 360){
			rotate -= 360;
		}
		return rotate;
	}

	/**
	 * @param diff align difference between 2 angles ]-PI, PI] 
	 * @return 
	 */
	public static double alignAngleDifference(double diff) {
		while(diff > Math.PI) {
			diff -= 2 * Math.PI;
		}
		while(diff <=-Math.PI) {
			diff += 2 * Math.PI;
		}
		return diff;
		
	}
	
	/**
	 * @param diff align difference between 2 angles ]-180, 180] 
	 * @return 
	 */
	public static double degreesDiff(double a1, double a2) {
		double diff = a1 - a2;
		while(diff > 180) {
			diff -= 360;
		}
		while(diff <=-180) {
			diff += 360;
		}
		return diff;
		
	}	

	
	public static double squareDist31TileMetric(int x1, int y1, int x2, int y2) {
		// translate into meters 
		double dy = convert31YToMeters(y1, y2);
		double dx = convert31XToMeters(x1, x2);
		return dx * dx + dy * dy;
	}
	public static double convert31YToMeters(float y1, float y2) {
		// translate into meters 
		return (y1 - y2) * 0.01863d;
	}
	
	public static double convert31XToMeters(float x1, float x2) {
		// translate into meters 
		return (x1 - x2) * 0.011d;
	}
   
	
	public static double calculateProjection31TileMetric(int xA, int yA, int xB, int yB, int xC, int yC) {
		// Scalar multiplication between (AB, AC)
		double multiple = convert31XToMeters(xB, xA) * convert31XToMeters(xC, xA) + convert31YToMeters(yB, yA) * convert31YToMeters(yC, yA);
		return multiple;
	}
	
}