import { useEffect, useMemo, useState } from "react";
import { useParams, useSearchParams } from "react-router-dom";
import { getJSON, itemsOrEmpty, type Category, type Resource } from "../api";
import { ResourceCard } from "../components/ResourceCard";
import { ResourceListFooter } from "../components/ResourceListFooter";
import { useI18n } from "../i18n";
import { typeFilterLabel } from "../resourceTypeLabels";

const TYPE_FILTERS = [
  "all",
  "image",
  "video",
  "ppt",
  "pdf",
  "text",
  "link",
  "archive",
] as const;
const resourceLangCodes = ["", "zh-TW", "zh-CN", "en"] as const;

function resourceLangLabel(t: (k: string) => string, code: string) {
  if (!code) return t("filterLanguageAll");
  if (code === "zh-TW") return t("lang_zh_TW");
  if (code === "zh-CN") return t("lang_zh_CN");
  return t("lang_en");
}

export function CategoryPage() {
  const { slug } = useParams();
  const { t, lang } = useI18n();
  const [sp, setSp] = useSearchParams();
  const type = sp.get("type") || "all";
  const resourceLang = sp.get("language") || "";
  const page = Math.max(1, parseInt(sp.get("page") || "1", 10) || 1);
  const limit = 24;

  const [items, setItems] = useState<Resource[]>([]);
  const [total, setTotal] = useState(0);
  const [categoryTitle, setCategoryTitle] = useState<string>("");
  const [err, setErr] = useState<string | null>(null);

  const query = useMemo(() => {
    const p = new URLSearchParams();
    p.set("lang", lang);
    p.set("category", slug || "");
    p.set("limit", String(limit));
    p.set("page", String(page));
    if (type !== "all") p.set("type", type);
    if (resourceLang) p.set("language", resourceLang);
    return p.toString();
  }, [lang, slug, type, resourceLang, page]);

  useEffect(() => {
    if (!slug) return;
    setErr(null);
    getJSON<{ items: Resource[]; total?: number }>(`/api/resources?${query}`)
      .then((r) => {
        setItems(itemsOrEmpty(r.items));
        setTotal(typeof r.total === "number" ? r.total : 0);
      })
      .catch((e) => setErr(String(e)));
  }, [query, slug]);

  useEffect(() => {
    if (!slug) return;
    const langQ = encodeURIComponent(lang);
    getJSON<Category[]>(`/api/categories?lang=${langQ}`)
      .then((cats) => {
        const c = itemsOrEmpty(cats).find((x) => x.slug === slug);
        setCategoryTitle(c?.name ?? slug);
      })
      .catch(() => setCategoryTitle(slug));
  }, [slug, lang]);

  const setPage = (next: number) => {
    const n = new URLSearchParams(sp);
    if (next <= 1) n.delete("page");
    else n.set("page", String(next));
    setSp(n);
  };

  return (
    <div className="space-y-6">
      <h1 className="text-2xl font-bold">{categoryTitle || slug}</h1>
      <div className="flex flex-wrap gap-2">
        {TYPE_FILTERS.map((tp) => (
          <button
            key={tp}
            type="button"
            className={`rounded-full border px-3 py-1 text-xs outline-none focus-visible:ring-2 focus-visible:ring-ark-gold/80 focus-visible:ring-offset-2 focus-visible:ring-offset-ark-bg ${
              type === tp || (tp === "all" && !sp.get("type"))
                ? "border-ark-gold text-ark-gold2"
                : "border-ark-line"
            }`}
            onClick={() => {
              const n = new URLSearchParams(sp);
              n.delete("page");
              if (tp === "all") n.delete("type");
              else n.set("type", tp);
              setSp(n);
            }}
          >
            {typeFilterLabel(t, tp)}
          </button>
        ))}
      </div>

      <div className="space-y-2">
        <div className="text-xs font-medium uppercase tracking-wide text-neutral-500">
          {t("resourceLangFilter")}
        </div>
        <div className="flex flex-wrap gap-2">
          {resourceLangCodes.map((code) => (
            <button
              key={code || "all"}
              type="button"
              onClick={() => {
                const n = new URLSearchParams(sp);
                n.delete("page");
                if (!code) n.delete("language");
                else n.set("language", code);
                setSp(n);
              }}
              className={`rounded-full border px-3 py-1 text-xs outline-none focus-visible:ring-2 focus-visible:ring-ark-gold/80 focus-visible:ring-offset-2 focus-visible:ring-offset-ark-bg ${
                (code === "" && !resourceLang) || resourceLang === code
                  ? "border-ark-gold text-ark-gold2"
                  : "border-ark-line"
              }`}
            >
              {resourceLangLabel(t, code)}
            </button>
          ))}
        </div>
      </div>

      {err ? <div className="text-red-300">{err}</div> : null}
      {!err && items.length === 0 ? (
        <p className="text-neutral-400">{t("noResults")}</p>
      ) : null}
      <div className="grid gap-4 md:grid-cols-2 lg:grid-cols-3">
        {items.map((r) => (
          <ResourceCard key={r.id} r={r} />
        ))}
      </div>

      <ResourceListFooter
        page={page}
        limit={limit}
        total={total}
        t={t}
        onPrev={() => setPage(page - 1)}
        onNext={() => setPage(page + 1)}
      />
    </div>
  );
}