const ISSLayer = {
    _viewer: null, _entity: null, _interval: null, _count: 0,

    start(viewer) {
        if (this._entity) return;
        this._viewer = viewer;
        this._entity = viewer.entities.add({
            name: 'ISS - International Space Station',
            position: Cesium.Cartesian3.fromDegrees(0, 0, 420000),
            point: { pixelSize: 18, color: Cesium.Color.fromCssColorString('#ff4444'),
                outlineColor: Cesium.Color.WHITE, outlineWidth: 2 },
            label: { text: 'ISS', font: '12px monospace bold',
                fillColor: Cesium.Color.fromCssColorString('#ff4444'),
                outlineColor: Cesium.Color.BLACK, outlineWidth: 3,
                style: Cesium.LabelStyle.FILL_AND_OUTLINE,
                pixelOffset: new Cesium.Cartesian2(12, -6) },
            description: '<div style="font-family:monospace;font-size:13px;color:#ff4444;padding:8px"><strong>International Space Station</strong><br>Hoehe: ~420 km<br>Geschwindigkeit: ~27.600 km/h</div>',
        });
        this._count = 1;
        this._fetch();
        var self = this;
        this._interval = setInterval(function() { self._fetch(); }, 5000);
    },

    stop() {
        if (this._interval) { clearInterval(this._interval); this._interval = null; }
        if (this._entity && this._viewer) { this._viewer.entities.remove(this._entity); this._entity = null; }
        this._count = 0;
    },

    _fetch() {
        var self = this;
        fetch('/api/iss')
        .then(function(r) { return r.json(); })
        .then(function(data) {
            if (!self._entity || data.message !== 'success') return;
            var pos = data.iss_position;
            self._entity.position = Cesium.Cartesian3.fromDegrees(
                parseFloat(pos.longitude), parseFloat(pos.latitude), 420000
            );
        }).catch(function() {});
    },
};