<script lang="ts">
	import { getContext } from 'svelte';
	import MapLibreGL from 'maplibre-gl';
	import { generateUUID } from '$lib/utils/uuid';

	interface Props {
		/** Optional unique identifier for the route layer */
		id?: string;
		/** Array of [longitude, latitude] coordinate pairs defining the route */
		coordinates: [number, number][];
		/** Line color as CSS color value (default: "#4285F4") */
		color?: string;
		/** Line width in pixels (default: 3) */
		width?: number;
		/** Line opacity from 0 to 1 (default: 0.8) */
		opacity?: number;
		/** Dash pattern [dash length, gap length] for dashed lines */
		dashArray?: [number, number];
		/** Callback when the route line is clicked */
		onclick?: () => void;
		/** Callback when mouse enters the route line */
		onmouseenter?: () => void;
		/** Callback when mouse leaves the route line */
		onmouseleave?: () => void;
		/** Whether the route is interactive - shows pointer cursor on hover (default: true) */
		interactive?: boolean;
	}

	const {
		coordinates,
		color = '#4285F4',
		width = 3,
		opacity = 0.8,
		dashArray,
		onclick,
		onmouseenter,
		onmouseleave,
		interactive = true,
		id = generateUUID()
	}: Props = $props();

	const mapCtx = getContext<{
		getMap: () => MapLibreGL.Map | null;
		isStyleReady: () => boolean;
	}>('map');

	const sourceId = $derived(`route-source-${id}`);
	const layerId = $derived(`route-layer-${id}`);

	// Add route when map is ready
	$effect(() => {
		const map = mapCtx.getMap();
		const loaded = mapCtx.isStyleReady();

		if (!loaded || !map || coordinates.length < 2) return;

		// Remove existing layer and source if they exist
		if (map.getLayer(layerId)) map.removeLayer(layerId);
		if (map.getSource(sourceId)) map.removeSource(sourceId);

		// Add source
		map.addSource(sourceId, {
			type: 'geojson',
			data: {
				type: 'Feature',
				properties: {},
				geometry: {
					type: 'LineString',
					coordinates
				}
			}
		});

		// Build paint options with transition definitions
		// Use default values here - they'll be updated by the paint property effect
		const paint: MapLibreGL.LineLayerSpecification['paint'] = {
			'line-color': '#94a3b8', // Start with gray (unselected color)
			'line-width': 5, // Start with unselected width
			'line-opacity': 0.6, // Start with unselected opacity
			'line-color-transition': { duration: 300, delay: 0 },
			'line-width-transition': { duration: 300, delay: 0 },
			'line-opacity-transition': { duration: 300, delay: 0 }
		};

		if (dashArray) {
			paint['line-dasharray'] = dashArray;
		}

		// Add layer
		map.addLayer({
			id: layerId,
			type: 'line',
			source: sourceId,
			layout: {
				'line-join': 'round',
				'line-cap': 'round'
			},
			paint
		});

		return () => {
			try {
				if (map.getLayer(layerId)) map.removeLayer(layerId);
				if (map.getSource(sourceId)) map.removeSource(sourceId);
			} catch {
				// Ignore errors during cleanup
			}
		};
	});

	// Update route data when coordinates change
	$effect(() => {
		const map = mapCtx.getMap();
		const loaded = mapCtx.isStyleReady();

		if (!loaded || !map || coordinates.length < 2) return;

		const source = map.getSource(sourceId) as MapLibreGL.GeoJSONSource | undefined;
		if (source) {
			source.setData({
				type: 'Feature',
				properties: {},
				geometry: {
					type: 'LineString',
					coordinates
				}
			});
		}
	});

	// Update paint properties when they change
	$effect(() => {
		const map = mapCtx.getMap();
		const loaded = mapCtx.isStyleReady();

		if (!loaded || !map || !map.getLayer(layerId)) return;

		map.setPaintProperty(layerId, 'line-color', color);
		map.setPaintProperty(layerId, 'line-width', width);
		map.setPaintProperty(layerId, 'line-opacity', opacity);

		if (dashArray) {
			map.setPaintProperty(layerId, 'line-dasharray', dashArray);
		}

		// Move selected routes to top (when opacity is 1, it's selected)
		if (opacity === 1) {
			try {
				map.moveLayer(layerId);
			} catch {
				// Layer might not exist yet
			}
		}
	});

	// Handle click and hover events
	$effect(() => {
		const map = mapCtx.getMap();
		const loaded = mapCtx.isStyleReady();

		if (!loaded || !map || !interactive) return;

		const handleClick = () => {
			onclick?.();
		};
		const handleMouseEnter = () => {
			map.getCanvas().style.cursor = 'pointer';
			onmouseenter?.();
		};
		const handleMouseLeave = () => {
			map.getCanvas().style.cursor = '';
			onmouseleave?.();
		};

		map.on('click', layerId, handleClick);
		map.on('mouseenter', layerId, handleMouseEnter);
		map.on('mouseleave', layerId, handleMouseLeave);

		return () => {
			map.off('click', layerId, handleClick);
			map.off('mouseenter', layerId, handleMouseEnter);
			map.off('mouseleave', layerId, handleMouseLeave);
		};
	});
</script>
