import { useCallback, useState, useRef, useEffect } from "react";
import { useTranslation } from "react-i18next";
import * as Y from "yjs";
import type { YjsState } from "~/lib/use-yjs";
import { generateGpx } from "@trails-cool/gpx";
import type { TrackPoint, NoGoArea } from "@trails-cool/gpx";

function getTracks(yjs: YjsState): TrackPoint[][] {
  const geojsonStr = yjs.routeData.get("geojson") as string | undefined;
  if (!geojsonStr) return [];
  try {
    const geojson = JSON.parse(geojsonStr);
    const coords: number[][] = geojson.features?.[0]?.geometry?.coordinates ?? [];
    if (coords.length > 0) {
      return [coords.map((c) => ({ lat: c[1]!, lon: c[0]!, ele: c[2] }))];
    }
  } catch { /* invalid geojson */ }
  return [];
}

function getWaypoints(yjs: YjsState) {
  return yjs.waypoints.toArray().map((yMap: Y.Map<unknown>) => ({
    lat: yMap.get("lat") as number,
    lon: yMap.get("lon") as number,
    name: yMap.get("name") as string | undefined,
  }));
}

function getNoGoAreas(yjs: YjsState): NoGoArea[] {
  return yjs.noGoAreas.toArray().map((yMap: Y.Map<unknown>) => ({
    points: (yMap.get("points") as Array<{ lat: number; lon: number }>) ?? [],
  })).filter((a) => a.points.length >= 3);
}

function download(gpx: string, filename: string) {
  const blob = new Blob([gpx], { type: "application/gpx+xml" });
  const url = URL.createObjectURL(blob);
  const a = document.createElement("a");
  a.href = url;
  a.download = filename;
  a.click();
  URL.revokeObjectURL(url);
}

export function ExportButton({ yjs }: { yjs: YjsState }) {
  const { t } = useTranslation("planner");
  const [open, setOpen] = useState(false);
  const ref = useRef<HTMLDivElement>(null);

  // Close dropdown on outside click
  useEffect(() => {
    if (!open) return;
    const handler = (e: MouseEvent) => {
      if (ref.current && !ref.current.contains(e.target as Node)) setOpen(false);
    };
    document.addEventListener("click", handler);
    return () => document.removeEventListener("click", handler);
  }, [open]);

  const handleExportRoute = useCallback(() => {
    const tracks = getTracks(yjs);
    const gpx = generateGpx({ name: "trails.cool route", waypoints: [], tracks });
    download(gpx, "route.gpx");
    setOpen(false);
  }, [yjs]);

  const handleExportPlan = useCallback(() => {
    const tracks = getTracks(yjs);
    const waypoints = getWaypoints(yjs);
    const noGoAreas = getNoGoAreas(yjs);
    const gpx = generateGpx({ name: "trails.cool route", waypoints, tracks, noGoAreas });
    download(gpx, "route-plan.gpx");
    setOpen(false);
  }, [yjs]);

  return (
    <div ref={ref} className="relative">
      <div className="flex">
        <button
          onClick={handleExportRoute}
          className="rounded-l bg-gray-100 px-3 py-1 text-sm text-gray-700 hover:bg-gray-200"
        >
          {t("exportGpx")}
        </button>
        <button
          onClick={() => setOpen((v) => !v)}
          className="rounded-r border-l border-gray-300 bg-gray-100 px-1.5 py-1 text-sm text-gray-700 hover:bg-gray-200"
        >
          ▾
        </button>
      </div>
      {open && (
        <div className="absolute right-0 top-full z-50 mt-1 w-44 rounded border border-gray-200 bg-white py-1 shadow-lg">
          <button
            onClick={handleExportRoute}
            className="block w-full px-3 py-1.5 text-left text-sm text-gray-700 hover:bg-gray-100"
          >
            {t("exportRoute")}
          </button>
          <button
            onClick={handleExportPlan}
            className="block w-full px-3 py-1.5 text-left text-sm text-gray-700 hover:bg-gray-100"
          >
            {t("exportPlan")}
          </button>
        </div>
      )}
    </div>
  );
}