import { useEffect, useMemo, useState } from "react";
import { Link } from "react-router-dom";
import { api } from "../api";
import { useAuth } from "../auth";
import Icon from "../components/Icon";
import DataTable from "../components/DataTable";
import { ProduktThumb } from "../components/ProduktBild";
import { locationOptions, locationPathById } from "../locationPath";
import { categoryInfoMap } from "../categoryPath";
import CategoryPathLabel, { pathParts } from "../components/CategoryPathLabel";

/**
 * Liste aller Einzelstücke (physische Exemplare, jedes mit eigener UID/Lagerort) –
 * anders als „Produkte", das nur die Katalog-Typen zeigt. Über die DataTable je
 * Spalte filterbar, u.a. nach Lagerort. Lagerort und Shop sind inline änderbar.
 */
export default function ItemList() {
  const { isAdmin } = useAuth();
  const [items, setItems] = useState([]);
  const [locations, setLocations] = useState([]);
  const [shops, setShops] = useState([]);
  const [categories, setCategories] = useState([]);
  const [error, setError] = useState(null);
  const [loading, setLoading] = useState(true);

  async function load() {
    setLoading(true);
    try {
      const [is, ls, ss, cs] = await Promise.all([
        api.listAllItems(), api.listLocations(), api.listShops(), api.listCategories(),
      ]);
      setItems(is); setLocations(ls); setShops(ss); setCategories(cs);
    } catch (err) { setError(err.message); } finally { setLoading(false); }
  }
  useEffect(() => { load(); }, []);

  // Kategorie als Pfad + Tokens (jede Ebene), damit "Klamotten" auch die
  // Unterkategorien findet und die Oberkategorie im Filter wählbar ist.
  const catInfo = useMemo(() => categoryInfoMap(categories), [categories]);

  async function patch(it, body) {
    try { await api.updateItem(it.id, body); await load(); }
    catch (err) { setError(err.message); }
  }

  const preis = (it) => (it.price_cents != null
    ? `${(it.price_cents / 100).toFixed(2)} ${it.currency || ""}`.trim() : "");

  const columns = [
    { key: "thumb", header: "", label: "Bild", fixed: true, width: 56,
      render: (it) => <ProduktThumb productId={it.product_id} alt={it.product_name} /> },
    { key: "uid", header: "UID", width: 110, filterText: (it) => it.uid, sortValue: (it) => it.uid,
      render: (it) => <span className="strong nowrap">{it.uid}</span> },
    { key: "product", header: "Produkt", grow: true, min: 180,
      filterText: (it) => it.product_name || "", sortValue: (it) => it.product_name || "",
      render: (it) => it.product_name || "–" },
    { key: "brand", header: "Marke", width: 140, filterText: (it) => it.product_brand || "",
      render: (it) => <span className="muted">{it.product_brand || "–"}</span> },
    { key: "category", header: "Kategorie", width: 200,
      filterText: (it) => catInfo.get(it.category_id)?.path || it.category_name || "",
      filterValues: (it) => catInfo.get(it.category_id)?.tokens || (it.category_name ? [it.category_name] : [""]),
      filterOptionLabel: (v) => (v === "" ? "(Leere)" : <CategoryPathLabel parts={pathParts(v)} />),
      sortValue: (it) => catInfo.get(it.category_id)?.path || it.category_name || "",
      render: (it) => <CategoryPathLabel parts={catInfo.get(it.category_id)?.parts} fallback={it.category_name || "–"} /> },
    { key: "location", header: "Lagerort", width: 220,
      filterText: (it) => locationPathById(it.location_id, locations),
      render: (it) => (isAdmin ? (
        <select value={it.location_id ?? ""} style={{ marginTop: 0 }}
          onChange={(e) => patch(it, { location_id: e.target.value === "" ? null : e.target.value })}>
          <option value="">– ohne –</option>
          {locationOptions(locations).map((o) => <option key={o.id} value={o.id}>{o.label}</option>)}
        </select>
      ) : (locationPathById(it.location_id, locations) || "–")) },
    { key: "shop", header: "Gekauft bei", width: 150, filterText: (it) => it.shop_name || "",
      render: (it) => (isAdmin ? (
        <select value={it.shop_id ?? ""} style={{ marginTop: 0 }}
          onChange={(e) => patch(it, { shop_id: e.target.value === "" ? null : Number(e.target.value) })}>
          <option value="">– unbekannt –</option>
          {shops.map((s) => <option key={s.id} value={s.id}>{s.name}</option>)}
        </select>
      ) : (it.shop_name || "–")) },
    { key: "acquired", header: "Gekauft am", width: 120, filterText: (it) => it.acquired_on || "",
      sortValue: (it) => it.acquired_on || "", render: (it) => it.acquired_on || "–" },
    { key: "warranty", header: "Garantie bis", width: 120, filterText: (it) => it.warranty_until || "",
      sortValue: (it) => it.warranty_until || "", render: (it) => it.warranty_until || "–" },
    { key: "price", header: "Preis", width: 110, align: "num",
      sortValue: (it) => it.price_cents ?? -1, filterText: preis,
      render: (it) => preis(it) || "–" },
    { key: "note", header: "Notiz", width: 160, filterText: (it) => it.note || "",
      render: (it) => <span className="muted">{it.note || "–"}</span> },
    { key: "open", header: "", label: "Produkt öffnen", fixed: true, width: 84, align: "num",
      render: (it) => <Link to={`/products/${it.product_id}`}>Produkt</Link> },
  ];

  return (
    <div>
      <div className="page-head">
        <div>
          <h1>Einzelstücke</h1>
          <div className="sub">{items.length} Exemplare · nach Lagerort, Produkt, Kategorie u.a. filterbar</div>
        </div>
      </div>
      {error && <div className="alert error"><Icon name="alert" size={16} />{error}</div>}
      <div className="card">
        <DataTable id="items" columns={columns} rows={items} loading={loading}
          getRowKey={(it) => it.id} empty="Noch keine Einzelstücke." />
      </div>
    </div>
  );
}