/*var crs = new L.Proj.CRS(
    'EPSG:27700',
    '+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +datum=OSGB36 +units=m +no_defs',
    {
        resolutions: [1600,800,400,200,100,50,25,10,5,2.5,1,0.5,0.25,0.125,0.0625]
    }
);*/

// Setup the EPSG:27700 (British National Grid) projection.
    const crsnew = new L.Proj.CRS('EPSG:27700', '+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 +units=m +no_defs', {
        resolutions: [ 896.0, 448.0, 224.0, 112.0, 56.0, 28.0, 14.0, 7.0, 3.5, 1.75 ],
        origin: [ 100000000, 100000000 ]
    });



//const map = L.map('map').setView([82.35, -168.4], 19);
//good for uk !!!const map = L.map('map').setView([83.9, -174.5], 5);
//const map = L.map('map').setView([53.199375, -1.4341342], 19);
//const map = L.map('map').setView([53.199478, -1.4347414], 15);

const cartoSatellite = L.tileLayer('https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}', {
  attribution: '&copy; <a href="https://www.esri.com">ESRI</a>',
  subdomains: 'abcd',
  maxZoom: 19,
  crs: crsnew
});

const cartoMappingGB = L.tileLayer('https://mappinggb.com/xyztiles?x={x}&y={y}&z={z}', {
  attribution: '&copy; <a href="https://mappinggb.com">MappingGB</a>',
  subdomains: 'abcd',
  maxZoom: 19,
  crs: crsnew
});

const cartoOpenStreetMap = L.tileLayer('https://tile.openstreetmap.org/{z}/{x}/{y}.png', {
  attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a>',
  subdomains: 'abcd',
  maxZoom: 19,
  crs: crsnew
});

var map = L.map('map', {
            center: [51.494, 0.042],
            zoom: 13,
            //layers: [cartoMappingGB, cartoSatellite, cartoOpenStreetMap]
            layers: [cartoOpenStreetMap, cartoSatellite, cartoMappingGB]
          });


//const map = L.map('map').setView([70, -168.4], 10);
//const map = L.map('map').setView([-100, -100], 10);

map.on('click', function(e) {
    //alert("Lat, Lon : " + e.latlng.lat + ", " + e.latlng.lng);
    //alert(transformCoords([e.latlng.lng, e.latlng.lat]));
    url = getTileURL(e.latlng.lat, e.latlng.lng, map.getZoom())
	//console.log(url);
    //alert(url);
});

map.addControl(
  L.control.locate({
    locateOptions: {
      enableHighAccuracy: true
    }
  })
);

var baseMaps = { "Satellite": cartoSatellite, "OpenStreetMap": cartoOpenStreetMap, "MappingGB": cartoMappingGB };
L.control.layers(baseMaps).addTo(map);

function getTileURL(lat, lon, zoom)
{
	var xtile = parseInt(Math.floor( (lon + 180) / 360 * (1<<zoom) ));
	var ytile = parseInt(Math.floor( (1 - Math.log(Math.tan(toRad(lat)) + 1 / Math.cos(toRad(lat))) / Math.PI) / 2 * (1<<zoom) ));
	return "" + zoom + "/" + xtile + "/" + ytile;
}

function toRad(a)
{
	return a * Math.PI / 180;
}

// Transform coordinates.
const transformCoords = function(arr) {
	//return proj4('EPSG:27700', 'EPSG:4326', arr).reverse();
	return proj4('EPSG:4326', 'EPSG:27700', arr).reverse();
};