/**
 * Nachtlicht-Layer: NASA VIIRS Black Marble Nighttime Lights (NRT).
 * Verwendet tagesaktuelle Daten statt statischem Datum.
 */
const NightlightsLayer = {
    _viewer: null,
    _layer: null,

    start: function(viewer) {
        if (this._layer) return;
        this._viewer = viewer;
        // NRT-Daten brauchen ~12-24h Processing, daher Datum von gestern
        var yesterday = new Date(Date.now() - 86400000).toISOString().slice(0, 10);
        this._layer = viewer.imageryLayers.addImageryProvider(
            new Cesium.WebMapTileServiceImageryProvider({
                url: "https://gibs.earthdata.nasa.gov/wmts/epsg4326/best/VIIRS_Black_Marble/default/" + yesterday + "/500m/{TileMatrix}/{TileRow}/{TileCol}.png",
                layer: "VIIRS_Black_Marble",
                style: "default",
                tileMatrixSetID: "500m",
                tileMatrixLabels: [
                    "0", "1", "2", "3", "4", "5", "6", "7", "8",
                ],
                format: "image/png",
                tilingScheme: new Cesium.GeographicTilingScheme(),
                tileWidth: 512,
                tileHeight: 512,
                credit: "NASA VIIRS Black Marble (NRT)",
            })
        );
        this._layer.alpha = 0.85;
    },

    stop: function() {
        if (this._layer && this._viewer) {
            this._viewer.imageryLayers.remove(this._layer);
            this._layer = null;
        }
    },
};