/**
 * Zeitzonen-Overlay: Vertikale Linien alle 15 Grad + aktuelle Uhrzeit.
 */
const TimezonesLayer = {
    _viewer: null,
    _primitives: null,
    _labels: null,
    _interval: null,
    _count: 0,

    start(viewer) {
        if (this._primitives) return;
        this._viewer = viewer;
        this._primitives = viewer.scene.primitives.add(new Cesium.PolylineCollection());
        this._labels = viewer.scene.primitives.add(new Cesium.LabelCollection());
        this._render();
        this._count = 24;
        var self = this;
        this._interval = setInterval(function() { self._updateLabels(); }, 60000);
    },

    stop() {
        if (this._interval) { clearInterval(this._interval); this._interval = null; }
        if (this._primitives && this._viewer) { this._viewer.scene.primitives.remove(this._primitives); this._primitives = null; }
        if (this._labels && this._viewer) { this._viewer.scene.primitives.remove(this._labels); this._labels = null; }
        this._count = 0;
    },

    _render() {
        if (!this._primitives) return;
        var lineColor = Cesium.Color.fromCssColorString('#ffffff').withAlpha(0.08);
        // 24 Zeitzonen-Linien (alle 15 Grad)
        for (var tz = -12; tz <= 12; tz++) {
            var lon = tz * 15;
            var positions = [];
            for (var lat = -80; lat <= 80; lat += 10) {
                positions.push(Cesium.Cartesian3.fromDegrees(lon, lat, 0));
            }
            this._primitives.add({
                positions: positions,
                width: 1,
                material: Cesium.Material.fromType('Color', { color: lineColor }),
            });
        }
        this._updateLabels();
    },

    _updateLabels() {
        if (!this._labels) return;
        this._labels.removeAll();
        var now = new Date();
        var utcH = now.getUTCHours();
        var utcM = now.getUTCMinutes();

        for (var tz = -12; tz <= 12; tz++) {
            var lon = tz * 15;
            var h = (utcH + tz + 24) % 24;
            var timeStr = ('0' + h).slice(-2) + ':' + ('0' + utcM).slice(-2);
            var label = 'UTC' + (tz >= 0 ? '+' : '') + tz + '  ' + timeStr;

            this._labels.add({
                position: Cesium.Cartesian3.fromDegrees(lon, 0, 0),
                text: label,
                font: '10px monospace',
                fillColor: Cesium.Color.WHITE.withAlpha(0.4),
                outlineColor: Cesium.Color.BLACK,
                outlineWidth: 2,
                style: Cesium.LabelStyle.FILL_AND_OUTLINE,
                scale: 0.7,
                horizontalOrigin: Cesium.HorizontalOrigin.CENTER,
                distanceDisplayCondition: new Cesium.DistanceDisplayCondition(0, 8000000),
            });
        }
    },
};