import { useState, useEffect, useCallback } from "react";
import { useSearchPosts } from "./useSearchPosts";

/**
 * Поиск объявлений по нескольким выбранным городам, с объединением
 * результатов без дублей. Автоматически перезапускается при смене
 * selectedCities.
 */
export function useCityFeed(selectedCities) {
  const { loading: cityLoading, searchPosts } = useSearchPosts();
  const [cityAds, setCityAds] = useState([]);

  const searchCities = useCallback((citiesToSearch) => {
    if (!citiesToSearch.length) return Promise.resolve([]);
    return Promise.all(citiesToSearch.map(c => searchPosts(c))).then(results => {
      const seen = new Set();
      const merged = [];
      results.flat().forEach(ad => {
        if (!seen.has(ad.id)) {
          seen.add(ad.id);
          merged.push(ad);
        }
      });
      return merged;
    });
  }, [searchPosts]);

  useEffect(() => {
    if (selectedCities.length === 0) {
      setCityAds([]);
      return;
    }
    let cancelled = false;
    searchCities(selectedCities).then(result => {
      if (!cancelled) setCityAds(result);
    });
    return () => { cancelled = true; };
  }, [selectedCities, searchCities]);

  return { cityAds, cityLoading, searchCities };
}