import maplibregl from "maplibre-gl";
import { Geometry } from "@/lib/useEditorState";

type ModeGetter = () => "idle" | "draw" | "select" | "add-point" | "add-line" | "add-path" | "add-circle";

export function initDrawing(
    map: maplibregl.Map,
    getMode: ModeGetter,
    onComplete: (geometry: Geometry) => void
) {
    let coords: [number, number][] = [];

    /**
     * Close polygon ring if not closed.
     */
    function closePolygon(c: [number, number][]) {
        if (c.length < 3) return c;
        const first = c[0];
        const last = c[c.length - 1];

        if (first[0] !== last[0] || first[1] !== last[1]) {
            return [...c, first];
        }
        return c;
    }

    /**
     * Update preview layer while drawing.
     */
    function update(c: [number, number][]) {
        const closed = closePolygon(c);

        (map.getSource("draw-preview") as maplibregl.GeoJSONSource)?.setData({
            type: "FeatureCollection",
            features: [
                {
                    type: "Feature",
                    properties: {},
                    geometry: {
                        type: "Polygon",
                        coordinates: [closed],
                    },
                },
            ],
        });
    }

    function onClick(e: maplibregl.MapLayerMouseEvent) {
        if (getMode() !== "draw") return;

        coords.push([e.lngLat.lng, e.lngLat.lat] as [number, number]);
        update(coords);
    }

    function onMove(e: maplibregl.MapLayerMouseEvent) {
        if (getMode() !== "draw" || coords.length === 0) return;

        const preview: [number, number][] = [
            ...coords,
            [e.lngLat.lng, e.lngLat.lat] as [number, number],
        ];
        update(preview);
    }

    /**
     * Finalize polygon, emit geometry to caller, reset preview.
     */
    function finishDrawing() {
        if (getMode() !== "draw" || coords.length < 3) return;

        const geometry: Geometry = {
            type: "Polygon",
            coordinates: [closePolygon(coords)],
        };

        onComplete(geometry);

        coords = [];

        (map.getSource("draw-preview") as maplibregl.GeoJSONSource | undefined)?.setData({
            type: "FeatureCollection",
            features: [],
        });
    }

    function onKeyDown(e: KeyboardEvent) {
        if (e.key === "Enter") {
            finishDrawing();
        }
    }

    map.on("click", onClick);
    map.on("mousemove", onMove);
    document.addEventListener("keydown", onKeyDown);

    return () => {
        map.off("click", onClick);
        map.off("mousemove", onMove);
        document.removeEventListener("keydown", onKeyDown);
    };
}