import { useEffect, useState } from "react";
import { Link, useNavigate, useParams } from "react-router-dom";
import { apiFetch } from "../../api/client";
import { formatCents, type Category, type PriceTier, type Product, type Unit } from "../../api/types";
import { useCart } from "./CartContext";
import { useMediaUrl } from "./useMediaUrl";
import { useSiteSettings } from "./SiteSettingsContext";
import GalleryThumb from "./GalleryThumb";
import { useI18n } from "../../i18n/LanguageContext";

export default function ProductDetailPage() {
  const { t } = useI18n();
  const site = useSiteSettings();
  const { id } = useParams<{ id: string }>();
  const navigate = useNavigate();
  const { addItem } = useCart();

  const [product, setProduct] = useState<Product | null>(null);
  const [categories, setCategories] = useState<Category[]>([]);
  const [siblings, setSiblings] = useState<Product[]>([]);
  const [tiers, setTiers] = useState<PriceTier[]>([]);
  const [units, setUnits] = useState<Unit[]>([]);
  const [gallery, setGallery] = useState<string[]>([]);
  const [loading, setLoading] = useState(true);
  const [notFound, setNotFound] = useState(false);
  const [selectedTierId, setSelectedTierId] = useState("");
  const [multiplier, setMultiplier] = useState(1);
  const [added, setAdded] = useState(false);

  const primaryImage = useMediaUrl(product?.primary_media_id);

  useEffect(() => {
    if (!id) return;
    setLoading(true);
    setNotFound(false);
    setAdded(false);
    apiFetch<Product>(`/api/products/${id}`)
      .then((p) => {
        setProduct(p);
        return Promise.all([
          apiFetch<{ price_tiers: PriceTier[] }>(`/api/price-tiers/by-product/${p.id}`),
          apiFetch<{ units: Unit[] }>("/api/units"),
          apiFetch<{ gallery: { media_id: string }[] }>(`/api/product-gallery/${p.id}`),
          apiFetch<{ categories: Category[] }>("/api/categories"),
          apiFetch<{ products: Product[] }>(`/api/products?category_id=${p.category_id}`),
        ]);
      })
      .then(([t, u, g, c, siblingList]) => {
        setTiers(t.price_tiers);
        setUnits(u.units);
        setGallery(g.gallery.map((item) => item.media_id));
        setSelectedTierId(t.price_tiers[0]?.id ?? "");
        setCategories(c.categories);
        setSiblings(siblingList.products);
      })
      .catch(() => setNotFound(true))
      .finally(() => setLoading(false));
  }, [id]);

  function unitSymbol(unitId: string) {
    return units.find((u) => u.id === unitId)?.symbol ?? "";
  }

  function tierLabel(t: PriceTier) {
    return `${t.quantity} ${unitSymbol(t.unit_id)} — ${formatCents(t.price_cents)}`;
  }

  function handleAddToCart() {
    if (!product) return;
    const tier = tiers.find((t) => t.id === selectedTierId);
    if (!tier) return;
    addItem({
      productId: product.id,
      productName: product.name,
      priceTierId: tier.id,
      unitLabel: `${tier.quantity} ${unitSymbol(tier.unit_id)}`,
      unitPriceCents: tier.price_cents,
      multiplier,
    });
    setAdded(true);
  }

  if (loading) return <div className="page-loading">{t("common.loading")}</div>;
  if (notFound || !product) return <p>{t("storefront.productDetail.notFound")}</p>;

  const category = categories.find((c) => c.id === product.category_id);
  const siblingIndex = siblings.findIndex((p) => p.id === product.id);
  const previousProduct = siblingIndex > 0 ? siblings[siblingIndex - 1] : undefined;
  const nextProduct = siblingIndex >= 0 && siblingIndex < siblings.length - 1 ? siblings[siblingIndex + 1] : undefined;

  return (
    <div>
      <p>
        <Link to="/">&larr; {t("storefront.productDetail.backLink")}</Link>
      </p>
      <div className="product-detail">
        <div>
          {primaryImage && <img src={primaryImage} alt={product.name} className="product-detail-image" />}
          {gallery.length > 0 && (
            <div className="product-gallery">
              {gallery.map((mediaId) => (
                <GalleryThumb key={mediaId} mediaId={mediaId} alt={product.name} />
              ))}
            </div>
          )}
        </div>
        <div>
          <h1>{product.name}</h1>
          {category && (
            <Link to={`/?category_id=${category.id}`} className="badge badge-link">
              {category.name}
            </Link>
          )}
          {product.description && <p>{product.description}</p>}

          {tiers.length === 0 ? (
            <p>{t("storefront.productDetail.notAvailable")}</p>
          ) : !(site.orders_enabled && site.customer_login_enabled) ? (
            <div className="panel">
              <h2>{t("storefront.productDetail.chooseQuantity")}</h2>
              <ul>
                {tiers.map((tier) => (
                  <li key={tier.id}>{tierLabel(tier)}</li>
                ))}
              </ul>
            </div>
          ) : (
            <div className="panel">
              <h2>{t("storefront.productDetail.chooseQuantity")}</h2>
              <div className="field">
                <select value={selectedTierId} onChange={(e) => setSelectedTierId(e.target.value)}>
                  {tiers.map((t) => (
                    <option key={t.id} value={t.id}>
                      {tierLabel(t)}
                    </option>
                  ))}
                </select>
              </div>
              <div className="field">
                <label htmlFor="multiplier">{t("storefront.productDetail.quantityLabel")}</label>
                <input
                  id="multiplier"
                  type="number"
                  min="1"
                  value={multiplier}
                  onChange={(e) => setMultiplier(Math.max(1, Number(e.target.value)))}
                />
              </div>
              <div className="form-actions">
                <button className="btn btn-primary" onClick={handleAddToCart}>
                  {t("storefront.productDetail.addToCart")}
                </button>
                {added && (
                  <button className="btn" onClick={() => navigate("/cart")}>
                    {t("storefront.productDetail.viewCart")}
                  </button>
                )}
              </div>
              {added && <p>{t("storefront.productDetail.added")}</p>}
            </div>
          )}
        </div>
      </div>

      {(previousProduct || nextProduct) && (
        <div className="product-nav">
          {previousProduct ? (
            <Link to={`/products/${previousProduct.id}`} className="product-nav-link product-nav-prev">
              <span className="product-nav-label">← {t("storefront.productDetail.previousProduct")}</span>
              <span className="product-nav-name">{previousProduct.name}</span>
            </Link>
          ) : (
            <span />
          )}
          {nextProduct && (
            <Link to={`/products/${nextProduct.id}`} className="product-nav-link product-nav-next">
              <span className="product-nav-label">{t("storefront.productDetail.nextProduct")} →</span>
              <span className="product-nav-name">{nextProduct.name}</span>
            </Link>
          )}
        </div>
      )}
    </div>
  );
}