/**
 * Imagery Switcher: Verschiedene Satellitenbilder + historische Aufnahmen.
 * Unterstuetzt URL-Template (Esri, Sentinel, OSM) und WMTS (NASA GIBS).
 */
const ImagerySwitch = {
    _viewer: null,
    _currentLayer: null,
    _currentId: 'default',

    _sources: {
        'default': { name: 'Cesium Ion (Standard)' },
        'esri': {
            name: 'Esri World Imagery',
            url: 'https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}',
        },
        'nasa-modis': {
            name: 'NASA MODIS Terra (Heute)',
            gibs: {
                layer: 'MODIS_Terra_CorrectedReflectance_TrueColor',
                tileMatrixSet: '250m',
                ext: 'jpg',
                time: 'today',
                maxLevel: 8,
            },
        },
        'nasa-viirs': {
            name: 'NASA VIIRS SNPP (Heute)',
            gibs: {
                layer: 'VIIRS_SNPP_CorrectedReflectance_TrueColor',
                tileMatrixSet: '250m',
                ext: 'jpg',
                time: 'today',
                maxLevel: 8,
            },
        },
        'nasa-goes-east': {
            name: 'NASA GOES East (Live)',
            gibs: {
                layer: 'GOES-East_ABI_GeoColor',
                tileMatrixSet: '2km',
                ext: 'jpg',
                time: 'today',
                maxLevel: 5,
            },
        },
        'nasa-goes-west': {
            name: 'NASA GOES West (Live)',
            gibs: {
                layer: 'GOES-West_ABI_GeoColor',
                tileMatrixSet: '2km',
                ext: 'jpg',
                time: 'today',
                maxLevel: 5,
            },
        },
        's2-2024': {
            name: 'Sentinel-2 (2024)',
            url: 'https://tiles.maps.eox.at/wmts/1.0.0/s2cloudless-2024_3857/default/GoogleMapsCompatible/{z}/{x}/{y}.jpg',
        },
        's2-2023': {
            name: 'Sentinel-2 (2023)',
            url: 'https://tiles.maps.eox.at/wmts/1.0.0/s2cloudless-2023_3857/default/GoogleMapsCompatible/{z}/{x}/{y}.jpg',
        },
        's2-2022': {
            name: 'Sentinel-2 (2022)',
            url: 'https://tiles.maps.eox.at/wmts/1.0.0/s2cloudless-2022_3857/default/GoogleMapsCompatible/{z}/{x}/{y}.jpg',
        },
        's2-2020': {
            name: 'Sentinel-2 (2020)',
            url: 'https://tiles.maps.eox.at/wmts/1.0.0/s2cloudless-2020_3857/default/GoogleMapsCompatible/{z}/{x}/{y}.jpg',
        },
        's2-2018': {
            name: 'Sentinel-2 (2018)',
            url: 'https://tiles.maps.eox.at/wmts/1.0.0/s2cloudless-2018_3857/default/GoogleMapsCompatible/{z}/{x}/{y}.jpg',
        },
        'topo': {
            name: 'OpenTopoMap',
            url: 'https://tile.opentopomap.org/{z}/{x}/{y}.png',
        },
        'osm': {
            name: 'OpenStreetMap',
            url: 'https://a.tile.openstreetmap.org/{z}/{x}/{y}.png',
        },
    },

    init(viewer) {
        this._viewer = viewer;
    },

    _buildGibsProvider(g) {
        var today = new Date().toISOString().slice(0, 10);
        var time = (g.time === 'today') ? today : g.time;
        var labels = [];
        for (var i = 0; i <= g.maxLevel; i++) labels.push(String(i));

        // REST-URL (gleicher Ansatz wie nightlights.js -- bewaehrt)
        var restUrl = 'https://gibs.earthdata.nasa.gov/wmts/epsg4326/best/'
            + g.layer + '/default/' + time + '/' + g.tileMatrixSet
            + '/{TileMatrix}/{TileRow}/{TileCol}.' + g.ext;

        return new Cesium.WebMapTileServiceImageryProvider({
            url: restUrl,
            layer: g.layer,
            style: 'default',
            tileMatrixSetID: g.tileMatrixSet,
            tileMatrixLabels: labels,
            format: 'image/' + g.ext,
            tilingScheme: new Cesium.GeographicTilingScheme(),
            tileWidth: 512,
            tileHeight: 512,
            credit: 'NASA GIBS',
        });
    },

    switchTo(id) {
        if (!this._viewer || this._currentId === id) return;
        var src = this._sources[id];
        if (!src) return;

        // Alten Layer entfernen
        if (this._currentLayer) {
            this._viewer.imageryLayers.remove(this._currentLayer);
            this._currentLayer = null;
        }

        if (id === 'default') {
            // Cesium Ion Default -- nichts hinzufuegen
            this._currentId = id;
        } else if (src.gibs) {
            // NASA GIBS WMTS (REST-URL)
            this._currentLayer = this._viewer.imageryLayers.addImageryProvider(
                this._buildGibsProvider(src.gibs)
            );
            this._viewer.imageryLayers.lower(this._currentLayer);
            this._currentId = id;
        } else if (src.url) {
            // URL Template (Esri, Sentinel, OSM)
            this._currentLayer = this._viewer.imageryLayers.addImageryProvider(
                new Cesium.UrlTemplateImageryProvider({
                    url: src.url,
                    maximumLevel: 18,
                    credit: src.name,
                })
            );
            this._viewer.imageryLayers.lower(this._currentLayer);
            this._currentId = id;
        }

        var sel = document.getElementById('imagery-select');
        if (sel) sel.value = id;
        var label = document.getElementById('imagery-label');
        if (label) label.textContent = src.name;
    },
};