/** Базовые тайловые слои Leaflet для портала (CARTO + fallback OSM). */
(function (global) {
    var OSM = {
        url: 'https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png',
        options: {
            attribution: '&copy; <a href="https://openstreetmap.org/copyright">OpenStreetMap</a>',
            maxZoom: 19,
        },
    };

    function cartoApiKey() {
        return (global.ACORE_MAP_CONFIG && global.ACORE_MAP_CONFIG.cartoApiKey) || '';
    }

    function cartoLightSource() {
        var key = cartoApiKey();
        if (!key) return null;
        return {
            url: 'https://{s}.basemaps.cartocdn.com/light_all/{z}/{x}/{y}{r}.png?key=' + encodeURIComponent(key),
            options: {
                attribution: '&copy; OpenStreetMap contributors &copy; CARTO',
                maxZoom: 20,
                subdomains: 'abcd',
            },
        };
    }

    function tileSources() {
        var carto = cartoLightSource();
        return carto ? [carto, OSM] : [OSM];
    }

    global.acoreMapTileSources = tileSources;

    global.acoreAddMapBaseLayer = function (map) {
        var sources = tileSources();
        var idx = 0;
        var layer = null;

        function mount() {
            if (idx >= sources.length) return;
            var src = sources[idx];
            layer = global.L.tileLayer(src.url, src.options).addTo(map);
            layer.on('tileerror', function () {
                if (idx + 1 >= sources.length) return;
                map.removeLayer(layer);
                idx += 1;
                mount();
            });
        }

        mount();
        return layer;
    };
}(window));