import { useCallback, useEffect, useMemo, useRef, type RefObject } from 'react';
import { CircleMarker, MapContainer, TileLayer, useMap, useMapEvents } from 'react-leaflet';
import { Box, Text } from '@mantine/core';
import { OSM_ATTRIBUTION, OSM_TILE_URL } from './osm';
import {
  DEFAULT_MAP_CENTER,
  DEFAULT_MAP_ZOOM,
  locationFromLatLng,
  SELECTED_MAP_ZOOM,
  toLocationLatLng,
} from './location-point';
import 'leaflet/dist/leaflet.css';
import './leaflet-stacking.css';

export interface LocationMapProps {
  latitude?: unknown;
  longitude?: unknown;
  onChange?: (point: { latitude: number; longitude: number }) => void;
  height?: number;
  emptyLabel?: string;
  helperLabel?: string;
  defaultCenter?: [number, number];
  defaultZoom?: number;
  tileUrl?: string;
  attribution?: string;
}

function SyncMapView({
  latitude,
  longitude,
  lastPickedRef,
}: {
  latitude: unknown;
  longitude: unknown;
  lastPickedRef: RefObject<{ latitude: number; longitude: number } | null>;
}) {
  const map = useMap();
  const point = toLocationLatLng(latitude, longitude);
  const lat = point?.[0] ?? null;
  const lng = point?.[1] ?? null;
  const hasCentered = useRef(false);

  useEffect(() => {
    const id = window.setTimeout(() => map.invalidateSize(), 0);
    return () => window.clearTimeout(id);
  }, [map]);

  useEffect(() => {
    if (lat === null || lng === null) return;
    const picked = lastPickedRef.current;
    if (picked && picked.latitude === lat && picked.longitude === lng) {
      return;
    }
    if (!hasCentered.current) {
      hasCentered.current = true;
      map.setView([lat, lng], SELECTED_MAP_ZOOM);
      return;
    }
    map.panTo([lat, lng]);
  }, [map, lat, lng, lastPickedRef]);

  return null;
}

function MapClickPicker({ onPick }: { onPick: (lat: number, lng: number) => void }) {
  const onPickRef = useRef(onPick);
  onPickRef.current = onPick;
  const handlers = useMemo(
    () => ({
      click(event: { latlng: { lat: number; lng: number } }) {
        onPickRef.current(event.latlng.lat, event.latlng.lng);
      },
    }),
    [],
  );
  useMapEvents(handlers);
  return null;
}

export function LocationMap({
  latitude,
  longitude,
  onChange,
  height = 280,
  emptyLabel = 'No location',
  helperLabel,
  defaultCenter = DEFAULT_MAP_CENTER,
  defaultZoom = DEFAULT_MAP_ZOOM,
  tileUrl = OSM_TILE_URL,
  attribution = OSM_ATTRIBUTION,
}: LocationMapProps) {
  const interactive = Boolean(onChange);
  const position = toLocationLatLng(latitude, longitude);
  const lastPickedRef = useRef<{ latitude: number; longitude: number } | null>(null);
  const center = position ?? defaultCenter;
  const zoom = position ? SELECTED_MAP_ZOOM : defaultZoom;

  const handlePick = useCallback(
    (lat: number, lng: number) => {
      const point = locationFromLatLng(lat, lng);
      lastPickedRef.current = point;
      onChange?.(point);
    },
    [onChange],
  );

  if (!interactive && !position) {
    return (
      <Box h={height} bdrs="md" bd="1px solid var(--mantine-color-default-border)" p="md">
        <Text size="sm" c="dimmed">
          {emptyLabel}
        </Text>
      </Box>
    );
  }

  return (
    <Box>
      <Box
        h={height}
        bdrs="md"
        bd="1px solid var(--mantine-color-default-border)"
        className="tg-map-viewport"
        style={{ cursor: interactive ? 'crosshair' : undefined }}
      >
        <MapContainer
          center={center}
          zoom={zoom}
          style={{ height: '100%', width: '100%' }}
          scrollWheelZoom={interactive}
        >
          <TileLayer attribution={attribution} url={tileUrl} />
          {position ? (
            <CircleMarker
              center={position}
              radius={10}
              pathOptions={{ color: 'var(--mantine-color-blue-8)', fillOpacity: 0.9 }}
            />
          ) : null}
          <SyncMapView latitude={latitude} longitude={longitude} lastPickedRef={lastPickedRef} />
          {onChange ? <MapClickPicker onPick={handlePick} /> : null}
        </MapContainer>
      </Box>
      {interactive && helperLabel ? (
        <Text size="xs" c="dimmed" mt="xs">
          {helperLabel}
        </Text>
      ) : null}
    </Box>
  );
}