// The MIT License (MIT)
// 
// Copyright (c) 2014 Federal Office of Topography swisstopo, Wabern, CH
// Copyright (c) 2016 Sacha Bron https://github.com/BinaryBrain
// Copyright (c) 2016 Basile Vu https://github.com/Flagoul
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
//	of this software and associated documentation files (the "Software"), to deal
//	in the Software without restriction, including without limitation the rights
//	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//	copies of the Software, and to permit persons to whom the Software is
//	furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
//	all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//	THE SOFTWARE.
// 
	
// Source: http://www.swisstopo.admin.ch/internet/swisstopo/en/home/topics/survey/sys/refsys/projections.html (see PDFs under "Documentation")
// Updated 9 dec 2014
// Please validate your results with NAVREF on-line service: http://www.swisstopo.admin.ch/internet/swisstopo/en/home/apps/calc/navref.html (difference ~ 1-2m)

var Swisstopo = {
	WGStoCH: function (lat, lng) {
		return [
			this.WGStoCHy(lat, lng),
			this.WGStoCHx(lat, lng)
		]
	},

	// Convert WGS lat/lng (° dec) to CH x
	WGStoCHx: function (lat, lng) {
		
		// Convert decimal degrees to sexagesimal seconds
		lat = this.DECtoSEX(lat);
		lng = this.DECtoSEX(lng);
		
		// Auxiliary values (% Bern)
		var lat_aux = (lat - 169028.66)/10000;
		var lng_aux = (lng - 26782.5)/10000;

		// Process X
		x = 200147.07 +
			308807.95 * lat_aux  +
			3745.25 * Math.pow(lng_aux,2) +
			76.63 * Math.pow(lat_aux,2) -
			194.56 * Math.pow(lng_aux,2) * lat_aux +
			119.79 * Math.pow(lat_aux,3);

		return x;		
	},

	// Convert WGS lat/lng (° dec) to CH y
	WGStoCHy: function (lat, lng) {
		// Convert decimal degrees to sexagesimal seconds
		lat = this.DECtoSEX(lat);
		lng = this.DECtoSEX(lng);

		// Auxiliary values (% Bern)
		var lat_aux = (lat - 169028.66)/10000;
		var lng_aux = (lng - 26782.5)/10000;
		
		// Process Y
		y = 600072.37 +
			211455.93 * lng_aux -
			10938.51 * lng_aux * lat_aux -
			0.36 * lng_aux * Math.pow(lat_aux,2) -
			44.54 * Math.pow(lng_aux,3);

		return y;
	},

	CHtoWGS: function (y, x) {
		return [
			this.CHtoWGSlng(y, x),
			this.CHtoWGSlat(y, x)
		]
	},

	// Convert CH y/x to WGS lat
	CHtoWGSlat: function (y, x) {
		// Converts military to civil and to unit = 1000km
		// Auxiliary values (% Bern)
		var y_aux = (y - 600000)/1000000;
		var x_aux = (x - 200000)/1000000;

		// Process lat
		var lat = 16.9023892 +
			3.238272 * x_aux -
			0.270978 * Math.pow(y_aux, 2) -
			0.002528 * Math.pow(x_aux, 2) -
			0.0447	 * Math.pow(y_aux, 2) * x_aux -
			0.0140	 * Math.pow(x_aux, 3);

		// Unit 10000" to 1 " and converts seconds to degrees (dec)
		lat = lat * 100 / 36;

		return lat;
	},

	// Convert CH y/x to WGS lng
	CHtoWGSlng: function (y, x) {
		// Converts military to civil and	to unit = 1000km
		// Auxiliary values (% Bern)
		var y_aux = (y - 600000)/1000000;
		var x_aux = (x - 200000)/1000000;

		// Process lng
		var lng = 2.6779094 +
			4.728982 * y_aux +
			0.791484 * y_aux * x_aux +
			0.1306	 * y_aux * Math.pow(x_aux, 2) -
			0.0436	 * Math.pow(y_aux, 3);

		// Unit 10000" to 1 " and converts seconds to degrees (dec)
		lng = lng * 100 / 36;

		return lng;
	},

	// Convert angle in decimal degrees to sexagesimal seconds
	DECtoSEX: function (angle) {

		// Extract DMS
		var deg = parseInt(angle);
		var min = parseInt((angle-deg)*60);
		var sec = (((angle-deg)*60)-min)*60;	 

		// Result sexagesimal seconds
		return sec + min*60.0 + deg*3600.0;
		
	}
}