import { useEffect, useRef } from 'react';
import L from 'leaflet';

import { createCachedTileLayer } from '@/lib/cachedTileLayer';
import { cn } from '@/lib/utils';

export interface LatLng {
  lat: number;
  lng: number;
}

interface SpotLocationPickerProps {
  value: LatLng | null;
  onChange: (coords: LatLng) => void;
  className?: string;
}

/** Fallback center before the user has a location (NYC, same as the map default). */
const DEFAULT_CENTER: [number, number] = [40.7128, -74.006];

/**
 * A small, tappable Leaflet map for choosing a spot's location.
 *
 * Tap anywhere to drop the pin, or drag the pin to fine-tune. This replaces the
 * raw latitude/longitude text boxes as the PRIMARY way to set a location — those
 * move behind an "enter coordinates manually" toggle for power users. Uses the
 * same cached tile layer as the main map, so the basemap still draws offline.
 */
export function SpotLocationPicker({ value, onChange, className }: SpotLocationPickerProps) {
  const containerRef = useRef<HTMLDivElement>(null);
  const mapRef = useRef<L.Map | null>(null);
  const markerRef = useRef<L.Marker | null>(null);
  const onChangeRef = useRef(onChange);
  // Captured once so the init effect doesn't depend on `value` (which changes
  // constantly) — the marker-sync effect below handles later updates.
  const initialValueRef = useRef(value);

  useEffect(() => {
    onChangeRef.current = onChange;
  }, [onChange]);

  // Create the map once.
  useEffect(() => {
    const el = containerRef.current;
    if (!el || mapRef.current) return;

    const initial = initialValueRef.current;
    const center: [number, number] = initial ? [initial.lat, initial.lng] : DEFAULT_CENTER;
    const map = L.map(el, {
      center,
      zoom: initial ? 15 : 12,
      zoomControl: true,
      attributionControl: true,
    });

    createCachedTileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
      attribution: '',
      subdomains: 'abc',
      minZoom: 2,
      maxZoom: 19,
      noWrap: true,
      className: 'skatespots-dark-tiles',
    }).addTo(map);

    map.on('click', (e: L.LeafletMouseEvent) => {
      onChangeRef.current({ lat: e.latlng.lat, lng: e.latlng.lng });
    });

    mapRef.current = map;

    const ro = new ResizeObserver(() => map.invalidateSize());
    ro.observe(el);
    // Leaflet can mis-measure inside a freshly-laid-out page — nudge it once.
    const t = window.setTimeout(() => map.invalidateSize(), 0);

    return () => {
      window.clearTimeout(t);
      ro.disconnect();
      map.remove();
      mapRef.current = null;
      markerRef.current = null;
    };
  }, []);

  // Draw / move the draggable pin to match `value`.
  useEffect(() => {
    const map = mapRef.current;
    if (!map) return;

    if (!value) {
      if (markerRef.current) {
        markerRef.current.remove();
        markerRef.current = null;
      }
      return;
    }

    const latlng: [number, number] = [value.lat, value.lng];
    if (markerRef.current) {
      markerRef.current.setLatLng(latlng);
      return;
    }

    const marker = L.marker(latlng, {
      draggable: true,
      icon: L.divIcon({
        className: '',
        html:
          '<div style="display:flex;flex-direction:column;align-items:center;transform:translateY(-4px)">' +
          '<div style="width:22px;height:22px;border-radius:50%;background:#ff0040;border:3px solid #fff;box-shadow:0 2px 10px rgba(0,0,0,.55)"></div>' +
          '<div style="width:0;height:0;border-left:7px solid transparent;border-right:7px solid transparent;border-top:11px solid #fff;margin-top:-1px"></div>' +
          '</div>',
        iconSize: [22, 34],
        iconAnchor: [11, 34],
      }),
    }).addTo(map);

    marker.on('dragend', () => {
      const p = marker.getLatLng();
      onChangeRef.current({ lat: p.lat, lng: p.lng });
    });

    markerRef.current = marker;
    map.setView(latlng, Math.max(map.getZoom(), 15), { animate: true });
  }, [value]);

  return (
    <div
      ref={containerRef}
      className={cn('h-64 w-full overflow-hidden rounded-xl border-2 border-white/10', className)}
    />
  );
}