import { useEffect, useRef, useState } from "react";
import { useTranslation } from "react-i18next";
import { API_URL, getImageUrl } from "../config/authConstants";
import { useGeolocation, GEO_STATUS } from "../hooks/useGeolocation";

const MARKER_COLORS = {
  LOST: "#ff3b30",
  LOSS: "#ff3b30",
  FOUND: "#34c759",
};

function createMarkerLayout(color, imageUrl) {
  const bgStyle = imageUrl
      ? `background-image:url('${imageUrl}');background-size:cover;background-position:center;`
      : "";

  return window.ymaps.templateLayoutFactory.createClass(
      `<div style="
      width:40px;height:40px;
      border-radius:50%;
      border:3px solid ${color};
      box-shadow:0 2px 8px rgba(0,0,0,.35);
      overflow:hidden;
      background:${imageUrl ? "transparent" : color};
      display:flex;align-items:center;justify-content:center;
      cursor:pointer;
    ">
      <div style="
        width:100%;height:100%;border-radius:50%;
        ${bgStyle}
      "></div>
    </div>`,
      {
        build() {
          this.constructor.superclass.build.call(this);
        },
      }
  );
}

const FOCUS_ZOOM = 16;
const COORD_MATCH_TOLERANCE = 0.005;

export default function MapView({ focusPostId, focusLat, focusLng, onPostClick, onBack }) {
  const { t } = useTranslation();
  const mapRef = useRef(null);
  const ymapRef = useRef(null);
  const userMarkerRef = useRef(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState(null);

  const { coords: geoCoords, status: geoStatus } = useGeolocation({ onMount: true });

  const onPostClickRef = useRef(onPostClick);
  onPostClickRef.current = onPostClick;

  useEffect(() => {
    let map;
    const destroyed = { current: false };

    const init = async () => {
      if (!mapRef.current || destroyed.current) return;

      try {
        const res = await fetch(`${API_URL}/api/v1/posts/map`);
        if (!res.ok) throw new Error("Failed to fetch map markers");
        const markers = await res.json();

        if (destroyed.current) return;

        map = new window.ymaps.Map(mapRef.current, {
          center: [55.751574, 37.573856],
          zoom: 11,
          controls: ["zoomControl", "geolocationControl"],
        });
        ymapRef.current = map;

        const placemarksById = new Map();

        markers.forEach((m) => {
          if (m.latitude == null || m.longitude == null) return;

          const color = MARKER_COLORS[m.type] || MARKER_COLORS.LOST;
          const typeLabel = m.type === "FOUND" ? "Находка" : "Потеря";
          const imgSrc = m.imageUrl ? getImageUrl(m.imageUrl) : null;
          const iconLayout = createMarkerLayout(color, imgSrc);
          const coords = [m.latitude, m.longitude];

          const placemark = new window.ymaps.Placemark(
              coords,
              {},
              {
                iconLayout,
                iconImageSize: [40, 40],
                iconImageOffset: [-20, -20],
                // Без явного iconShape карта не может корректно вычислить
                // кликабельную область для кастомного HTML-лейаута —
                // маркер рисуется, но клики по нему не срабатывают.
                iconShape: {
                  type: "Circle",
                  coordinates: [20, 20],
                  radius: 20,
                },
                hasBalloon: false,
                hasHint: true,
                hintContent: m.title || typeLabel,
              }
          );

          map.geoObjects.add(placemark);
          if (m.id != null) {
            const postId = String(m.id);
            placemarksById.set(postId, { placemark, coords });
            placemark.events.add("click", () => {
              if (onPostClickRef.current) {
                onPostClickRef.current(postId);
              }
            });
          }
        });

        let target = focusPostId != null
            ? placemarksById.get(String(focusPostId))
            : null;

        if (!target && Number.isFinite(focusLat) && Number.isFinite(focusLng)) {
          let best = null;
          let bestDist = Infinity;
          placemarksById.forEach((entry) => {
            const d =
                Math.pow(entry.coords[0] - focusLat, 2) +
                Math.pow(entry.coords[1] - focusLng, 2);
            if (d < bestDist) {
              bestDist = d;
              best = entry;
            }
          });
          if (best && bestDist < COORD_MATCH_TOLERANCE * COORD_MATCH_TOLERANCE) {
            target = best;
          }
        }

        if (target) {
          map.setCenter(target.coords, FOCUS_ZOOM);
        } else if (placemarksById.size > 0) {
          map.setBounds(
              map.geoObjects.getBounds(),
              { checkZoomRange: true, zoomMargin: 40 }
          );
        }
      } catch (e) {
        if (!destroyed.current) setError(e.message);
      } finally {
        if (!destroyed.current) setLoading(false);
      }
    };

    if (window.ymaps?.ready) {
      window.ymaps.ready(init);
    }

    return () => {
      destroyed.current = true;
      ymapRef.current?.destroy();
      ymapRef.current = null;
      userMarkerRef.current = null;
    };
  }, [focusPostId, focusLat, focusLng]);

  // Геолокация: если юзер разрешил и карта уже создана — центр на его месте.
  // Не трогаем, если карта была открыта с фокусом на конкретном объявлении.
  const hasFocus = focusPostId != null || (Number.isFinite(focusLat) && Number.isFinite(focusLng));
  useEffect(() => {
    if (hasFocus) return;
    if (geoStatus !== GEO_STATUS.SUCCESS || !geoCoords) return;
    const map = ymapRef.current;
    if (!map) return;

    const [lat, lng] = [geoCoords.latitude, geoCoords.longitude];
    map.setCenter([lat, lng], 14);

    if (userMarkerRef.current) {
      userMarkerRef.current.geometry.setCoordinates([lat, lng]);
    } else {
      const pm = new window.ymaps.Placemark(
          [lat, lng],
          {},
          { preset: "islands#blueCircleIcon" }
      );
      map.geoObjects.add(pm);
      userMarkerRef.current = pm;
    }
  }, [hasFocus, geoStatus, geoCoords, loading]);

  return (
      <div className="f-mapview">
        {loading && (
            <div className="f-mapview-status">
              <div className="f-spinner" />
            </div>
        )}
        {error && (
            <div className="f-mapview-status f-mapview-error">
              Ошибка загрузки карты
            </div>
        )}
        <div ref={mapRef} className="f-mapview-canvas" />
        {geoStatus === GEO_STATUS.LOADING && !hasFocus && (
            <div className="f-mapview-geo f-mapview-geo-info">Определение местоположения…</div>
        )}
        {geoStatus === GEO_STATUS.DENIED && (
            <div className="f-mapview-geo f-mapview-geo-warn">Доступ к геолокации запрещён</div>
        )}
        {geoStatus === GEO_STATUS.TIMEOUT && (
            <div className="f-mapview-geo f-mapview-geo-warn">Геолокация не определилась</div>
        )}
        {geoStatus === GEO_STATUS.UNSUPPORTED && (
            <div className="f-mapview-geo f-mapview-geo-warn">Геолокация недоступна</div>
        )}
        {onBack && (
            <button type="button" className="f-mapview-back" onClick={onBack}>
              <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth={2.2} strokeLinecap="round" strokeLinejoin="round" className="f-mapview-back-icon">
                <path d="M19 12H5" />
                <path d="m12 19-7-7 7-7" />
              </svg>
              {t('map.backToListings')}
            </button>
        )}
      </div>
  );
}