"use client";
import { useState, useMemo } from "react";
import { useSearchParams } from "next/navigation";
import { mockCourses } from "@/data/mockCourses";

function toggleItem(arr: string[], val: string): string[] {
  return arr.includes(val) ? arr.filter((x) => x !== val) : [...arr, val];
}

export function useFilters() {
  const searchParams = useSearchParams();

  const [search, setSearch] = useState(searchParams.get("q") ?? "");
  const [selectedCategories, setSelectedCategories] = useState<string[]>(() => {
    const cat = searchParams.get("cat");
    return cat ? [cat] : [];
  });
  const [selectedLevels, setSelectedLevels] = useState<string[]>([]);
  const [minRating, setMinRating] = useState<number | null>(null);
  const [maxPrice, setMaxPrice] = useState<number | null>(null);
  const [sort, setSort] = useState("popular");

  const toggleCategory = (val: string) => setSelectedCategories((prev) => toggleItem(prev, val));
  const toggleLevel    = (val: string) => setSelectedLevels((prev) => toggleItem(prev, val));
  const toggleRating   = (r: number)   => setMinRating((prev) => (prev === r ? null : r));
  const togglePrice    = (p: number)   => setMaxPrice((prev) => (prev === p ? null : p));

  const activeFiltersCount =
    selectedCategories.length + selectedLevels.length + (minRating ? 1 : 0) + (maxPrice ? 1 : 0);

  const clearAll = () => {
    setSearch("");
    setSelectedCategories([]);
    setSelectedLevels([]);
    setMinRating(null);
    setMaxPrice(null);
  };

  const filtered = useMemo(() => {
    let list = [...mockCourses];
    if (search)
      list = list.filter(
        (c) =>
          c.title.toLowerCase().includes(search.toLowerCase()) ||
          c.subtitle.toLowerCase().includes(search.toLowerCase()),
      );
    if (selectedCategories.length) list = list.filter((c) => selectedCategories.includes(c.category));
    if (selectedLevels.length)     list = list.filter((c) => selectedLevels.includes(c.level));
    if (minRating)                 list = list.filter((c) => c.rating >= minRating);
    if (maxPrice)                  list = list.filter((c) => c.price <= maxPrice);
    switch (sort) {
      case "rating":   list.sort((a, b) => b.rating - a.rating); break;
      case "price_lo": list.sort((a, b) => a.price - b.price);   break;
      case "price_hi": list.sort((a, b) => b.price - a.price);   break;
      case "newest":   list.sort((a, b) => (b.badge === "Nuevo" ? 1 : 0) - (a.badge === "Nuevo" ? 1 : 0)); break;
      default:         list.sort((a, b) => b.studentsCount - a.studentsCount);
    }
    return list;
  }, [search, selectedCategories, selectedLevels, minRating, maxPrice, sort]);

  return {
    search, setSearch,
    selectedCategories, toggleCategory,
    selectedLevels, toggleLevel,
    minRating, toggleRating,
    maxPrice, togglePrice,
    sort, setSort,
    activeFiltersCount, clearAll, filtered,
  };
}