/*
 * extend Leaflet's LatLng class
 * giving it the ability to calculate the bearing to another LatLng
 * Usage example:
 *     here  = map.getCenter();   / some latlng
 *     there = L.latlng([37.7833,-122.4167]);
 *     var whichway = here.bearingWordTo(there);
 *     var howfar   = (here.distanceTo(there) / 1609.34).toFixed(2);
 *     alert("San Francisco is " + howfar + " miles, to the " + whichway );
 * 
 * Greg Allensworth   <greg.allensworth@gmail.com>
 * No license, use as you will, kudos welcome but not required, etc.
 */


L.LatLng.prototype.bearingTo = function(other) {
    var d2r  = L.LatLng.DEG_TO_RAD;
    var r2d  = L.LatLng.RAD_TO_DEG;
    var lat1 = this.lat * d2r;
    var lat2 = other.lat * d2r;
    var dLon = (other.lng-this.lng) * d2r;
    var y    = Math.sin(dLon) * Math.cos(lat2);
    var x    = Math.cos(lat1)*Math.sin(lat2) - Math.sin(lat1)*Math.cos(lat2)*Math.cos(dLon);
    var brng = Math.atan2(y, x);
    brng = parseInt( brng * r2d );
    brng = (brng + 360) % 360;
    return brng;
};

L.LatLng.prototype.bearingWordTo = function(other) {
    var bearing = this.bearingTo(other);
    var bearingword = '';
    if      (bearing >=  22 && bearing <=  67) bearingword = 'NE';
    else if (bearing >=  67 && bearing <= 112) bearingword =  'E';
    else if (bearing >= 112 && bearing <= 157) bearingword = 'SE';
    else if (bearing >= 157 && bearing <= 202) bearingword =  'S';
    else if (bearing >= 202 && bearing <= 247) bearingword = 'SW';
    else if (bearing >= 247 && bearing <= 292) bearingword =  'W';
    else if (bearing >= 292 && bearing <= 337) bearingword = 'NW';
    else if (bearing >= 337 || bearing <=  22) bearingword =  'N';
    return bearingword;
};