//Taken from github.com/leaflet-extras/leaflet-providers (function (root, factory) {

if (typeof define === 'function' && define.amd) {
        // AMD. Register as an anonymous module.
        define(['leaflet'], factory);
} else if (typeof modules === 'object' && module.exports) {
        // define a Common JS module that relies on 'leaflet'
        module.exports = factory(require('leaflet'));
} else {
        // Assume Leaflet is loaded into global object L already
        factory(L);
}

}(this, function (L) {

'use strict';

L.TileLayer.Provider = L.TileLayer.extend({
        initialize: function (arg, options) {
                var providers = L.TileLayer.Provider.providers;

                var parts = arg.split('.');

                var providerName = parts[0];
                var variantName = parts[1];

                if (!providers[providerName]) {
                        throw 'No such provider (' + providerName + ')';
                }

                var provider = {
                        url: providers[providerName].url,
                        options: providers[providerName].options
                };

                // overwrite values in provider from variant.
                if (variantName && 'variants' in providers[providerName]) {
                        if (!(variantName in providers[providerName].variants)) {
                                throw 'No such variant of ' + providerName + ' (' + variantName + ')';
                        }
                        var variant = providers[providerName].variants[variantName];
                        var variantOptions;
                        if (typeof variant === 'string') {
                                variantOptions = {
                                        variant: variant
                                };
                        } else {
                                variantOptions = variant.options;
                        }
                        provider = {
                                url: variant.url || provider.url,
                                options: L.Util.extend({}, provider.options, variantOptions)
                        };
                }

                // replace attribution placeholders with their values from toplevel provider attribution,
                // recursively
                var attributionReplacer = function (attr) {
                        if (attr.indexOf('{attribution.') === -1) {
                                return attr;
                        }
                        return attr.replace(/\{attribution.(\w*)\}/g,
                                function (match, attributionName) {
                                        return attributionReplacer(providers[attributionName].options.attribution);
                                }
                        );
                };
                provider.options.attribution = attributionReplacer(provider.options.attribution);

                // Compute final options combining provider options with any user overrides
                var layerOpts = L.Util.extend({}, provider.options, options);
                L.TileLayer.prototype.initialize.call(this, provider.url, layerOpts);
        }
});

/**
 * Definition of providers.
 * see http://leafletjs.com/reference.html#tilelayer for options in the options map.
 */

L.TileLayer.Provider.providers = {
        OpenStreetMap: {
                url: 'https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png',
                options: {
                        maxZoom: 19,
                        attribution:
                                '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
                },
                variants: {
                        Mapnik: {},
                        DE: {
                                url: 'https://{s}.tile.openstreetmap.de/tiles/osmde/{z}/{x}/{y}.png',
                                options: {
                                        maxZoom: 18
                                }
                        },
                        CH: {
                                url: 'https://tile.osm.ch/switzerland/{z}/{x}/{y}.png',
                                options: {
                                        maxZoom: 18,
                                        bounds: [[45, 5], [48, 11]]
                                }
                        },
                        France: {
                                url: 'https://{s}.tile.openstreetmap.fr/osmfr/{z}/{x}/{y}.png',
                                options: {
                                        maxZoom: 20,
                                        attribution: '&copy; Openstreetmap France | {attribution.OpenStreetMap}'
                                }
                        },
                        HOT: {
                                url: 'https://{s}.tile.openstreetmap.fr/hot/{z}/{x}/{y}.png',
                                options: {
                                        attribution:
                                                '{attribution.OpenStreetMap}, ' +
                                                'Tiles style by <a href="https://www.hotosm.org/" target="_blank">Humanitarian OpenStreetMap Team</a> ' +
                                                'hosted by <a href="https://openstreetmap.fr/" target="_blank">OpenStreetMap France</a>'
                                }
                        },
                        BZH: {
                                url: 'https://tile.openstreetmap.bzh/br/{z}/{x}/{y}.png',
                                options: {
                                        attribution: '{attribution.OpenStreetMap}, Tiles courtesy of <a href="http://www.openstreetmap.bzh/" target="_blank">Breton OpenStreetMap Team</a>',
                                        bounds: [[46.2, -5.5], [50, 0.7]]
                                }
                        }
                }
        },
        OpenSeaMap: {
                url: 'https://tiles.openseamap.org/seamark/{z}/{x}/{y}.png',
                options: {
                        attribution: 'Map data: &copy; <a href="http://www.openseamap.org">OpenSeaMap</a> contributors'
                }
        },
        OpenPtMap: {
                url: 'http://openptmap.org/tiles/{z}/{x}/{y}.png',
                options: {
                        maxZoom: 17,
                        attribution: 'Map data: &copy; <a href="http://www.openptmap.org">OpenPtMap</a> contributors'
                }
        },
        OpenTopoMap: {
                url: 'https://{s}.tile.opentopomap.org/{z}/{x}/{y}.png',
                options: {
                        maxZoom: 17,
                        attribution: 'Map data: {attribution.OpenStreetMap}, <a href="http://viewfinderpanoramas.org">SRTM</a> | Map style: &copy; <a href="https://opentopomap.org">OpenTopoMap</a> (<a href="https://creativecommons.org/licenses/by-sa/3.0/">CC-BY-SA</a>)'
                }
        },
        OpenRailwayMap: {
                url: 'https://{s}.tiles.openrailwaymap.org/standard/{z}/{x}/{y}.png',
                options: {
                        maxZoom: 19,
                        attribution: 'Map data: {attribution.OpenStreetMap} | Map style: &copy; <a href="https://www.OpenRailwayMap.org">OpenRailwayMap</a> (<a href="https://creativecommons.org/licenses/by-sa/3.0/">CC-BY-SA</a>)'
                }
        },
        OpenFireMap: {
                url: 'http://openfiremap.org/hytiles/{z}/{x}/{y}.png',
                options: {
                        maxZoom: 19,
                        attribution: 'Map data: {attribution.OpenStreetMap} | Map style: &copy; <a href="http://www.openfiremap.org">OpenFireMap</a> (<a href="https://creativecommons.org/licenses/by-sa/3.0/">CC-BY-SA</a>)'
                }
        },
        SafeCast: {
                url: 'https://s3.amazonaws.com/te512.safecast.org/{z}/{x}/{y}.png',
                options: {
                        maxZoom: 16,
                        attribution: 'Map data: {attribution.OpenStreetMap} | Map style: &copy; <a href="https://blog.safecast.org/about/">SafeCast</a> (<a href="https://creativecommons.org/licenses/by-sa/3.0/">CC-BY-SA</a>)'
                }
        },
        Thunderforest: {
                url: 'https://{s}.tile.thunderforest.com/{variant}/{z}/{x}/{y}.png?apikey={apikey}',
                options: {
                        attribution:
                                '&copy; <a href="http://www.thunderforest.com/">Thunderforest</a>, {attribution.OpenStreetMap}',
                        variant: 'cycle',
                        apikey: '<insert your api key here>',
                        maxZoom: 22
                },
                variants: {
                        OpenCycleMap: 'cycle',
                        Transport: {
                                options: {
                                        variant: 'transport'
                                }
                        },
                        TransportDark: {
                                options: {
                                        variant: 'transport-dark'
                                }
                        },
                        SpinalMap: {
                                options: {
                                        variant: 'spinal-map'
                                }
                        },
                        Landscape: 'landscape',
                        Outdoors: 'outdoors',
                        Pioneer: 'pioneer'
                }
        },
        OpenMapSurfer: {
                url: 'https://maps.heigit.org/openmapsurfer/tiles/{variant}/webmercator/{z}/{x}/{y}.png',
                options: {
                        maxZoom: 19,
                        variant: 'roads',
                        attribution: 'Imagery from <a href="http://giscience.uni-hd.de/">GIScience Research Group @ University of Heidelberg</a> | Map data '
                },
                variants: {
                        Roads: {
                                options: {
                                        variant: 'roads',
                                        attribution: '{attribution.OpenMapSurfer}{attribution.OpenStreetMap}'
                                }
                        },
                        Hybrid: {
                                options: {
                                        variant: 'hybrid',
                                        attribution: '{attribution.OpenMapSurfer}{attribution.OpenStreetMap}'
                                }
                        },
                        AdminBounds: {
                                options: {
                                        variant: 'adminb',
                                        maxZoom: 18,
                                        attribution: '{attribution.OpenMapSurfer}{attribution.OpenStreetMap}'
                                }
                        },
                        ContourLines: {
                                options: {
                                        variant: 'asterc',
                                        maxZoom: 18,
                                        minZoom: 13,
                                        attribution: '{attribution.OpenMapSurfer} <a href="https://lpdaac.usgs.gov/products/aster_policies">ASTER GDEM</a>'
                                }
                        },
                        Hillshade: {
                                options: {
                                        variant: 'asterh',
                                        maxZoom: 18,
                                        attribution: '{attribution.OpenMapSurfer} <a href="https://lpdaac.usgs.gov/products/aster_policies">ASTER GDEM</a>, <a href="http://srtm.csi.cgiar.org/">SRTM</a>'
                                }
                        },
                        ElementsAtRisk: {
                                options: {
                                        variant: 'elements_at_risk',
                                        attribution: '{attribution.OpenMapSurfer}{attribution.OpenStreetMap}'
                                }
                        }
                }
        },
        Hydda: {
                url: 'https://{s}.tile.openstreetmap.se/hydda/{variant}/{z}/{x}/{y}.png',
                options: {
                        maxZoom: 18,
                        variant: 'full',
                        attribution: 'Tiles courtesy of <a href="http://openstreetmap.se/" target="_blank">OpenStreetMap Sweden</a> &mdash; Map data {attribution.OpenStreetMap}'
                },
                variants: {
                        Full: 'full',
                        Base: 'base',
                        RoadsAndLabels: 'roads_and_labels'
                }
        },
        MapBox: {
                url: 'https://api.tiles.mapbox.com/v4/{id}/{z}/{x}/{y}{r}.png?access_token={accessToken}',
                options: {
                        attribution:
                                '<a href="https://www.mapbox.com/about/maps/" target="_blank">&copy; Mapbox</a> ' +
                                '{attribution.OpenStreetMap} ' +
                                '<a href="https://www.mapbox.com/map-feedback/" target="_blank">Improve this map</a>',
                        subdomains: 'abcd',
                        id: 'mapbox.streets',
                        accessToken: '<insert your access token here>',
                }
        },
        Stamen: {
                url: 'https://stamen-tiles-{s}.a.ssl.fastly.net/{variant}/{z}/{x}/{y}{r}.{ext}',
                options: {
                        attribution:
                                'Map tiles by <a href="http://stamen.com">Stamen Design</a>, ' +
                                '<a href="http://creativecommons.org/licenses/by/3.0">CC BY 3.0</a> &mdash; ' +
                                'Map data {attribution.OpenStreetMap}',
                        subdomains: 'abcd',
                        minZoom: 0,
                        maxZoom: 20,
                        variant: 'toner',
                        ext: 'png'
                },
                variants: {
                        Toner: 'toner',
                        TonerBackground: 'toner-background',
                        TonerHybrid: 'toner-hybrid',
                        TonerLines: 'toner-lines',
                        TonerLabels: 'toner-labels',
                        TonerLite: 'toner-lite',
                        Watercolor: {
                                url: 'https://stamen-tiles-{s}.a.ssl.fastly.net/{variant}/{z}/{x}/{y}.{ext}',
                                options: {
                                        variant: 'watercolor',
                                        ext: 'jpg',
                                        minZoom: 1,
                                        maxZoom: 16
                                }
                        },
                        Terrain: {
                                options: {
                                        variant: 'terrain',
                                        minZoom: 0,
                                        maxZoom: 18
                                }
                        },
                        TerrainBackground: {
                                options: {
                                        variant: 'terrain-background',
                                        minZoom: 0,
                                        maxZoom: 18
                                }
                        },
                        TopOSMRelief: {
                                url: 'https://stamen-tiles-{s}.a.ssl.fastly.net/{variant}/{z}/{x}/{y}.{ext}',
                                options: {
                                        variant: 'toposm-color-relief',
                                        ext: 'jpg',
                                        bounds: [[22, -132], [51, -56]]
                                }
                        },
                        TopOSMFeatures: {
                                options: {
                                        variant: 'toposm-features',
                                        bounds: [[22, -132], [51, -56]],
                                        opacity: 0.9
                                }
                        }
                }
        },
        Esri: {
                url: 'https://server.arcgisonline.com/ArcGIS/rest/services/{variant}/MapServer/tile/{z}/{y}/{x}',
                options: {
                        variant: 'World_Street_Map',
                        attribution: 'Tiles &copy; Esri'
                },
                variants: {
                        WorldStreetMap: {
                                options: {
                                        attribution:
                                                '{attribution.Esri} &mdash; ' +
                                                'Source: Esri, DeLorme, NAVTEQ, USGS, Intermap, iPC, NRCAN, Esri Japan, METI, Esri China (Hong Kong), Esri (Thailand), TomTom, 2012'
                                }
                        },
                        DeLorme: {
                                options: {
                                        variant: 'Specialty/DeLorme_World_Base_Map',
                                        minZoom: 1,
                                        maxZoom: 11,
                                        attribution: '{attribution.Esri} &mdash; Copyright: &copy;2012 DeLorme'
                                }
                        },
                        WorldTopoMap: {
                                options: {
                                        variant: 'World_Topo_Map',
                                        attribution:
                                                '{attribution.Esri} &mdash; ' +
                                                'Esri, DeLorme, NAVTEQ, TomTom, Intermap, iPC, USGS, FAO, NPS, NRCAN, GeoBase, Kadaster NL, Ordnance Survey, Esri Japan, METI, Esri China (Hong Kong), and the GIS User Community'
                                }
                        },
                        WorldImagery: {
                                options: {
                                        variant: 'World_Imagery',
                                        attribution:
                                                '{attribution.Esri} &mdash; ' +
                                                'Source: Esri, i-cubed, USDA, USGS, AEX, GeoEye, Getmapping, Aerogrid, IGN, IGP, UPR-EGP, and the GIS User Community'
                                }
                        },
                        WorldTerrain: {
                                options: {
                                        variant: 'World_Terrain_Base',
                                        maxZoom: 13,
                                        attribution:
                                                '{attribution.Esri} &mdash; ' +
                                                'Source: USGS, Esri, TANA, DeLorme, and NPS'
                                }
                        },
                        WorldShadedRelief: {
                                options: {
                                        variant: 'World_Shaded_Relief',
                                        maxZoom: 13,
                                        attribution: '{attribution.Esri} &mdash; Source: Esri'
                                }
                        },
                        WorldPhysical: {
                                options: {
                                        variant: 'World_Physical_Map',
                                        maxZoom: 8,
                                        attribution: '{attribution.Esri} &mdash; Source: US National Park Service'
                                }
                        },
                        OceanBasemap: {
                                options: {
                                        variant: 'Ocean_Basemap',
                                        maxZoom: 13,
                                        attribution: '{attribution.Esri} &mdash; Sources: GEBCO, NOAA, CHS, OSU, UNH, CSUMB, National Geographic, DeLorme, NAVTEQ, and Esri'
                                }
                        },
                        NatGeoWorldMap: {
                                options: {
                                        variant: 'NatGeo_World_Map',
                                        maxZoom: 16,
                                        attribution: '{attribution.Esri} &mdash; National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, iPC'
                                }
                        },
                        WorldGrayCanvas: {
                                options: {
                                        variant: 'Canvas/World_Light_Gray_Base',
                                        maxZoom: 16,
                                        attribution: '{attribution.Esri} &mdash; Esri, DeLorme, NAVTEQ'
                                }
                        }
                }
        },
        OpenWeatherMap: {
                url: 'http://{s}.tile.openweathermap.org/map/{variant}/{z}/{x}/{y}.png?appid={apiKey}',
                options: {
                        maxZoom: 19,
                        attribution: 'Map data &copy; <a href="http://openweathermap.org">OpenWeatherMap</a>',
                        apiKey:'<insert your api key here>',
                        opacity: 0.5
                },
                variants: {
                        Clouds: 'clouds',
                        CloudsClassic: 'clouds_cls',
                        Precipitation: 'precipitation',
                        PrecipitationClassic: 'precipitation_cls',
                        Rain: 'rain',
                        RainClassic: 'rain_cls',
                        Pressure: 'pressure',
                        PressureContour: 'pressure_cntr',
                        Wind: 'wind',
                        Temperature: 'temp',
                        Snow: 'snow'
                }
        },
        HERE: {
                /*
                 * HERE maps, formerly Nokia maps.
                 * These basemaps are free, but you need an API key. Please sign up at
                 * https://developer.here.com/plans
                 */
                url:
                        'https://{s}.{base}.maps.api.here.com/maptile/2.1/' +
                        '{type}/{mapID}/{variant}/{z}/{x}/{y}/{size}/{format}?' +
                        'app_id={app_id}&app_code={app_code}&lg={language}',
                options: {
                        attribution:
                                'Map &copy; 1987-' + new Date().getFullYear() + ' <a href="http://developer.here.com">HERE</a>',
                        subdomains: '1234',
                        mapID: 'newest',
                        'app_id': '<insert your app_id here>',
                        'app_code': '<insert your app_code here>',
                        base: 'base',
                        variant: 'normal.day',
                        maxZoom: 20,
                        type: 'maptile',
                        language: 'eng',
                        format: 'png8',
                        size: '256'
                },
                variants: {
                        normalDay: 'normal.day',
                        normalDayCustom: 'normal.day.custom',
                        normalDayGrey: 'normal.day.grey',
                        normalDayMobile: 'normal.day.mobile',
                        normalDayGreyMobile: 'normal.day.grey.mobile',
                        normalDayTransit: 'normal.day.transit',
                        normalDayTransitMobile: 'normal.day.transit.mobile',
                        normalNight: 'normal.night',
                        normalNightMobile: 'normal.night.mobile',
                        normalNightGrey: 'normal.night.grey',
                        normalNightGreyMobile: 'normal.night.grey.mobile',
                        normalNightTransit: 'normal.night.transit',
                        normalNightTransitMobile: 'normal.night.transit.mobile',
                        reducedDay: 'reduced.day',
                        reducedNight: 'reduced.night',
                        basicMap: {
                                options: {
                                        type: 'basetile'
                                }
                        },
                        mapLabels: {
                                options: {
                                        type: 'labeltile',
                                        format: 'png'
                                }
                        },
                        trafficFlow: {
                                options: {
                                        base: 'traffic',
                                        type: 'flowtile'
                                }
                        },
                        carnavDayGrey: 'carnav.day.grey',
                        hybridDay: {
                                options: {
                                        base: 'aerial',
                                        variant: 'hybrid.day'
                                }
                        },
                        hybridDayMobile: {
                                options: {
                                        base: 'aerial',
                                        variant: 'hybrid.day.mobile'
                                }
                        },
                        hybridDayTransit: {
                                options: {
                                        base: 'aerial',
                                        variant: 'hybrid.day.transit'
                                }
                        },
                        hybridDayGrey: {
                                options: {
                                        base: 'aerial',
                                        variant: 'hybrid.grey.day'
                                }
                        },
                        pedestrianDay: 'pedestrian.day',
                        pedestrianNight: 'pedestrian.night',
                        satelliteDay: {
                                options: {
                                        base: 'aerial',
                                        variant: 'satellite.day'
                                }
                        },
                        terrainDay: {
                                options: {
                                        base: 'aerial',
                                        variant: 'terrain.day'
                                }
                        },
                        terrainDayMobile: {
                                options: {
                                        base: 'aerial',
                                        variant: 'terrain.day.mobile'
                                }
                        }
                }
        },
        FreeMapSK: {
                url: 'http://t{s}.freemap.sk/T/{z}/{x}/{y}.jpeg',
                options: {
                        minZoom: 8,
                        maxZoom: 16,
                        subdomains: '1234',
                        bounds: [[47.204642, 15.996093], [49.830896, 22.576904]],
                        attribution:
                                '{attribution.OpenStreetMap}, vizualization CC-By-SA 2.0 <a href="http://freemap.sk">Freemap.sk</a>'
                }
        },
        MtbMap: {
                url: 'http://tile.mtbmap.cz/mtbmap_tiles/{z}/{x}/{y}.png',
                options: {
                        attribution:
                                '{attribution.OpenStreetMap} &amp; USGS'
                }
        },
        CartoDB: {
                url: 'https://{s}.basemaps.cartocdn.com/{variant}/{z}/{x}/{y}{r}.png',
                options: {
                        attribution: '{attribution.OpenStreetMap} &copy; <a href="https://carto.com/attributions">CARTO</a>',
                        subdomains: 'abcd',
                        maxZoom: 19,
                        variant: 'light_all'
                },
                variants: {
                        Positron: 'light_all',
                        PositronNoLabels: 'light_nolabels',
                        PositronOnlyLabels: 'light_only_labels',
                        DarkMatter: 'dark_all',
                        DarkMatterNoLabels: 'dark_nolabels',
                        DarkMatterOnlyLabels: 'dark_only_labels',
                        Voyager: 'rastertiles/voyager',
                        VoyagerNoLabels: 'rastertiles/voyager_nolabels',
                        VoyagerOnlyLabels: 'rastertiles/voyager_only_labels',
                        VoyagerLabelsUnder: 'rastertiles/voyager_labels_under'
                }
        },
        HikeBike: {
                url: 'https://tiles.wmflabs.org/{variant}/{z}/{x}/{y}.png',
                options: {
                        maxZoom: 19,
                        attribution: '{attribution.OpenStreetMap}',
                        variant: 'hikebike'
                },
                variants: {
                        HikeBike: {},
                        HillShading: {
                                options: {
                                        maxZoom: 15,
                                        variant: 'hillshading'
                                }
                        }
                }
        },
        BasemapAT: {
                url: 'https://maps{s}.wien.gv.at/basemap/{variant}/normal/google3857/{z}/{y}/{x}.{format}',
                options: {
                        maxZoom: 19,
                        attribution: 'Datenquelle: <a href="https://www.basemap.at">basemap.at</a>',
                        subdomains: ['', '1', '2', '3', '4'],
                        format: 'png',
                        bounds: [[46.358770, 8.782379], [49.037872, 17.189532]],
                        variant: 'geolandbasemap'
                },
                variants: {
                        basemap: {
                                options: {
                                        maxZoom: 20, // currently only in Vienna
                                        variant: 'geolandbasemap'
                                }
                        },
                        grau: 'bmapgrau',
                        overlay: 'bmapoverlay',
                        highdpi: {
                                options: {
                                        variant: 'bmaphidpi',
                                        format: 'jpeg'
                                }
                        },
                        orthofoto: {
                                options: {
                                        maxZoom: 20, // currently only in Vienna
                                        variant: 'bmaporthofoto30cm',
                                        format: 'jpeg'
                                }
                        }
                }
        },
        nlmaps: {
                url: 'https://geodata.nationaalgeoregister.nl/tiles/service/wmts/{variant}/EPSG:3857/{z}/{x}/{y}.png',
                options: {
                        minZoom: 6,
                        maxZoom: 19,
                        bounds: [[50.5, 3.25], [54, 7.6]],
                        attribution: 'Kaartgegevens &copy; <a href="kadaster.nl">Kadaster</a>'
                },
                variants: {
                        'standaard': 'brtachtergrondkaart',
                        'pastel': 'brtachtergrondkaartpastel',
                        'grijs': 'brtachtergrondkaartgrijs',
                        'luchtfoto': {
                                'url': 'https://geodata.nationaalgeoregister.nl/luchtfoto/rgb/wmts/1.0.0/2016_ortho25/EPSG:3857/{z}/{x}/{y}.png',
                        }
                }
        },
        NASAGIBS: {
                url: 'https://map1.vis.earthdata.nasa.gov/wmts-webmerc/{variant}/default/{time}/{tilematrixset}{maxZoom}/{z}/{y}/{x}.{format}',
                options: {
                        attribution:
                                'Imagery provided by services from the Global Imagery Browse Services (GIBS), operated by the NASA/GSFC/Earth Science Data and Information System ' +
                                '(<a href="https://earthdata.nasa.gov">ESDIS</a>) with funding provided by NASA/HQ.',
                        bounds: [[-85.0511287776, -179.999999975], [85.0511287776, 179.999999975]],
                        minZoom: 1,
                        maxZoom: 9,
                        format: 'jpg',
                        time: '',
                        tilematrixset: 'GoogleMapsCompatible_Level'
                },
                variants: {
                        ModisTerraTrueColorCR: 'MODIS_Terra_CorrectedReflectance_TrueColor',
                        ModisTerraBands367CR: 'MODIS_Terra_CorrectedReflectance_Bands367',
                        ViirsEarthAtNight2012: {
                                options: {
                                        variant: 'VIIRS_CityLights_2012',
                                        maxZoom: 8
                                }
                        },
                        ModisTerraLSTDay: {
                                options: {
                                        variant: 'MODIS_Terra_Land_Surface_Temp_Day',
                                        format: 'png',
                                        maxZoom: 7,
                                        opacity: 0.75
                                }
                        },
                        ModisTerraSnowCover: {
                                options: {
                                        variant: 'MODIS_Terra_Snow_Cover',
                                        format: 'png',
                                        maxZoom: 8,
                                        opacity: 0.75
                                }
                        },
                        ModisTerraAOD: {
                                options: {
                                        variant: 'MODIS_Terra_Aerosol',
                                        format: 'png',
                                        maxZoom: 6,
                                        opacity: 0.75
                                }
                        },
                        ModisTerraChlorophyll: {
                                options: {
                                        variant: 'MODIS_Terra_Chlorophyll_A',
                                        format: 'png',
                                        maxZoom: 7,
                                        opacity: 0.75
                                }
                        }
                }
        },
        NLS: {
                // NLS maps are copyright National library of Scotland.
                // http://maps.nls.uk/projects/api/index.html
                // Please contact NLS for anything other than non-commercial low volume usage
                //
                // Map sources: Ordnance Survey 1:1m to 1:63K, 1920s-1940s
                //   z0-9  - 1:1m
                //  z10-11 - quarter inch (1:253440)
                //  z12-18 - one inch (1:63360)
                url: 'https://nls-{s}.tileserver.com/nls/{z}/{x}/{y}.jpg',
                options: {
                        attribution: '<a href="http://geo.nls.uk/maps/">National Library of Scotland Historic Maps</a>',
                        bounds: [[49.6, -12], [61.7, 3]],
                        minZoom: 1,
                        maxZoom: 18,
                        subdomains: '0123',
                }
        },
        JusticeMap: {
                // Justice Map (http://www.justicemap.org/)
                // Visualize race and income data for your community, county and country.
                // Includes tools for data journalists, bloggers and community activists.
                url: 'http://www.justicemap.org/tile/{size}/{variant}/{z}/{x}/{y}.png',
                options: {
                        attribution: '<a href="http://www.justicemap.org/terms.php">Justice Map</a>',
                        // one of 'county', 'tract', 'block'
                        size: 'county',
                        // Bounds for USA, including Alaska and Hawaii
                        bounds: [[14, -180], [72, -56]]
                },
                variants: {
                        income: 'income',
                        americanIndian: 'indian',
                        asian: 'asian',
                        black: 'black',
                        hispanic: 'hispanic',
                        multi: 'multi',
                        nonWhite: 'nonwhite',
                        white: 'white',
                        plurality: 'plural'
                }
        },
        Wikimedia: {
                url: 'https://maps.wikimedia.org/osm-intl/{z}/{x}/{y}{r}.png',
                options: {
                        attribution: '<a href="https://wikimediafoundation.org/wiki/Maps_Terms_of_Use">Wikimedia</a>',
                        minZoom: 1,
                        maxZoom: 19
                }
        },
        GeoportailFrance: {
                url: 'https://wxs.ign.fr/{apikey}/geoportail/wmts?REQUEST=GetTile&SERVICE=WMTS&VERSION=1.0.0&STYLE={style}&TILEMATRIXSET=PM&FORMAT={format}&LAYER={variant}&TILEMATRIX={z}&TILEROW={y}&TILECOL={x}',
                options: {
                        attribution: '<a target="_blank" href="https://www.geoportail.gouv.fr/">Geoportail France</a>',
                        bounds: [[-75, -180], [81, 180]],
                        minZoom: 2,
                        maxZoom: 18,
                        // Get your own geoportail apikey here : http://professionnels.ign.fr/ign/contrats/
                        // NB : 'choisirgeoportail' is a demonstration key that comes with no guarantee
                        apikey: 'choisirgeoportail',
                        format: 'image/jpeg',
                        style : 'normal',
                        variant: 'GEOGRAPHICALGRIDSYSTEMS.MAPS.SCAN-EXPRESS.STANDARD'
                },
                variants: {
                        parcels: {
                                options : {
                                        variant: 'CADASTRALPARCELS.PARCELS',
                                        maxZoom: 20,
                                        style : 'bdparcellaire',
                                        format: 'image/png'
                                }
                        },
                        ignMaps: 'GEOGRAPHICALGRIDSYSTEMS.MAPS',
                        maps: 'GEOGRAPHICALGRIDSYSTEMS.MAPS.SCAN-EXPRESS.STANDARD',
                        orthos: {
                                options: {
                                        maxZoom: 19,
                                        variant: 'ORTHOIMAGERY.ORTHOPHOTOS'
                                }
                        }
                }
        },
        OneMapSG: {
                url: 'https://maps-{s}.onemap.sg/v3/{variant}/{z}/{x}/{y}.png',
                options: {
                        variant: 'Default',
                        minZoom: 11,
                        maxZoom: 18,
                        bounds: [[1.56073, 104.11475], [1.16, 103.502]],
                        attribution: '<img src="https://docs.onemap.sg/maps/images/oneMap64-01.png" style="height:20px;width:20px;"/> New OneMap | Map data &copy; contributors, <a href="http://SLA.gov.sg">Singapore Land Authority</a>'
                },
                variants: {
                        Default: 'Default',
                        Night: 'Night',
                        Original: 'Original',
                        Grey: 'Grey',
                        LandLot: 'LandLot'
                }
        }
};

L.tileLayer.provider = function (provider, options) {
        return new L.TileLayer.Provider(provider, options);
};

return L;

}));