"use client";

import { use, useCallback, useEffect, useState } from "react";
import Link from "next/link";

import { formatDate, formatMoney, getErrorMessage } from "@/components/inventory/inventory-utils";
import { Button } from "@/components/ui/button";
import { api } from "@/lib/api";
import type { InventoryItem, InventoryStockMovement } from "@/types/inventory";

type PageProps = {
  params: Promise<{
    id: string;
  }>;
};

const movementLabels: Record<string, string> = {
  initial: "Anfangsbestand",
  purchase: "Einkauf",
  adjustment: "Anpassung",
  reservation: "Reservierung",
  release: "Freigabe",
  consumption: "Verbrauch",
  return: "Rückgabe",
  correction: "Korrektur",
};

export default function InventoryItemDetailPage({ params }: PageProps) {
  const { id } = use(params);
  const [item, setItem] = useState<InventoryItem | null>(null);
  const [movements, setMovements] = useState<InventoryStockMovement[]>([]);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState("");

  const loadItem = useCallback(async () => {
    setLoading(true);
    setError("");
    try {
      const [itemResponse, movementResponse] = await Promise.all([
        api.get<InventoryItem>(`/inventory/items/${id}`),
        api.get<InventoryStockMovement[]>(`/inventory/items/${id}/movements`),
      ]);
      setItem(itemResponse.data);
      setMovements(movementResponse.data);
    } catch (err) {
      setError(getErrorMessage(err));
    } finally {
      setLoading(false);
    }
  }, [id]);

  useEffect(() => {
    queueMicrotask(() => {
      void loadItem();
    });
  }, [loadItem]);

  if (loading) {
    return <div className="rounded-lg border bg-white p-8 text-slate-500">Artikel wird geladen...</div>;
  }

  if (error || !item) {
    return <div className="rounded-lg border bg-white p-8 text-red-600">{error || "Artikel nicht gefunden"}</div>;
  }

  return (
    <div className="space-y-6">
      <div className="flex flex-col gap-4 lg:flex-row lg:items-center lg:justify-between">
        <div>
          <p className="text-sm font-medium text-slate-500">{item.sku}</p>
          <h1 className="text-3xl font-bold text-slate-950">{item.name}</h1>
          <p className="mt-1 text-sm text-slate-500">{item.category?.name ?? "Keine Kategorie"} · {item.is_active ? "Aktiv" : "Inaktiv"}</p>
        </div>
        <Link href="/inventory"><Button type="button" variant="outline">Zurück zum Lager</Button></Link>
      </div>

      <div className="grid gap-4 xl:grid-cols-3">
        <section className="rounded-lg border bg-white p-5 xl:col-span-2">
          <h2 className="font-semibold text-slate-950">Stammdaten</h2>
          <dl className="mt-4 grid gap-4 md:grid-cols-2">
            <Info label="Beschreibung" value={item.description ?? "Keine Angabe"} />
            <Info label="Hersteller" value={item.manufacturer ?? "Keine Angabe"} />
            <Info label="Hersteller-Teilenummer" value={item.manufacturer_part_number ?? "Keine Angabe"} />
            <Info label="Lieferanten-Teilenummer" value={item.supplier_part_number ?? "Keine Angabe"} />
            <Info label="Lieferant" value={item.supplier?.name ?? "Kein Lieferant"} />
            <Info label="Lagerort" value={item.location?.name ?? "Kein Lagerort"} />
            <Info label="Kompatible Geräte" value={item.compatible_devices ?? "Keine Angabe"} />
            <Info label="Notizen" value={item.notes ?? "Keine Notizen"} />
          </dl>
        </section>

        <section className="rounded-lg border bg-white p-5">
          <h2 className="font-semibold text-slate-950">Bestand</h2>
          <dl className="mt-4 grid gap-3">
            <Metric label="Bestand" value={`${item.quantity_on_hand} ${item.unit}`} />
            <Metric label="Reserviert" value={`${item.quantity_reserved} ${item.unit}`} />
            <Metric label="Verfügbar" value={`${item.quantity_available} ${item.unit}`} />
            <Metric label="Mindestbestand" value={`${item.reorder_level} ${item.unit}`} />
          </dl>
        </section>
      </div>

      <div className="grid gap-4 xl:grid-cols-3">
        <section className="rounded-lg border bg-white p-5">
          <h2 className="font-semibold text-slate-950">Preise</h2>
          <dl className="mt-4 grid gap-3">
            <Metric label="Einkaufspreis" value={formatMoney(item.purchase_price_cents, item.currency)} />
            <Metric label="Verkaufspreis" value={formatMoney(item.selling_price_cents, item.currency)} />
            <Metric label="MwSt." value={`${item.tax_rate_percent} %`} />
          </dl>
        </section>

        <section className="rounded-lg border bg-white p-5 xl:col-span-2">
          <h2 className="font-semibold text-slate-950">Bewegungen</h2>
          {movements.length === 0 ? (
            <p className="mt-4 text-sm text-slate-500">Noch keine Bewegungen vorhanden.</p>
          ) : (
            <div className="mt-4 divide-y">
              {movements.map((movement) => (
                <div key={movement.id} className="py-3">
                  <div className="flex flex-col gap-1 sm:flex-row sm:items-center sm:justify-between">
                    <p className="font-medium text-slate-950">{movementLabels[movement.movement_type] ?? movement.movement_type} · {movement.quantity}</p>
                    <time className="text-xs text-slate-500" dateTime={movement.created_at}>{formatDate(movement.created_at)}</time>
                  </div>
                  <p className="mt-1 text-sm text-slate-500">{movement.reason}{movement.note ? ` · ${movement.note}` : ""}</p>
                  {movement.actor_username && <p className="mt-1 text-xs text-slate-400">Gebucht von {movement.actor_username}</p>}
                </div>
              ))}
            </div>
          )}
        </section>
      </div>
    </div>
  );
}

function Info({ label, value }: { label: string; value: string }) {
  return (
    <div>
      <dt className="text-xs font-semibold uppercase text-slate-500">{label}</dt>
      <dd className="mt-1 whitespace-pre-wrap text-sm text-slate-950">{value}</dd>
    </div>
  );
}

function Metric({ label, value }: { label: string; value: string }) {
  return (
    <div className="rounded-lg border bg-slate-50 p-3">
      <dt className="text-xs font-semibold uppercase text-slate-500">{label}</dt>
      <dd className="mt-1 text-lg font-semibold text-slate-950">{value}</dd>
    </div>
  );
}