"use client";

import { type ReactNode, useMemo, useState } from "react";
import { formatPrice } from "@/data/sample";
import type { ProductStoreVariant, ProductVariation } from "@/lib/meshkee";
import { useAuth } from "@/context/AuthContext";
import { useCart } from "@/context/CartContext";

function CheckIcon({ className }: { className?: string }) {
  return (
    <svg viewBox="0 0 24 24" fill="none" className={className} aria-hidden>
      <path
        d="M5 12.5 9.5 17 19 7.5"
        stroke="currentColor"
        strokeWidth="2"
        strokeLinecap="round"
        strokeLinejoin="round"
      />
    </svg>
  );
}

export function ProductPurchasePanel({
  header,
  variations,
  storeVariants,
  fallbackPrice,
  inStock,
  contactPhone,
  storeName,
  initialSelections,
}: {
  header: ReactNode;
  variations: ProductVariation[];
  storeVariants: ProductStoreVariant[];
  fallbackPrice: {
    minPrice: number | null;
    maxPrice: number | null;
    oldPrice?: number | null;
    discount?: number;
  };
  inStock: boolean;
  contactPhone?: string;
  storeName?: string;
  // Pre-select the variant a shopper landed on directly (e.g. a store-item
  // detail page for one specific variant), instead of defaulting to the
  // first option of every variation.
  initialSelections?: Record<string, string>;
}) {
  const { user, openLoginModal } = useAuth();
  const { addItem } = useCart();
  const [selected, setSelected] = useState<Record<string, string>>(() => {
    if (initialSelections && Object.keys(initialSelections).length > 0) return initialSelections;
    const initial: Record<string, string> = {};
    for (const variation of variations) {
      if (variation.options[0]) initial[variation.id] = variation.options[0].id;
    }
    return initial;
  });
  const [quantity, setQuantity] = useState(1);
  const [cartStatus, setCartStatus] = useState<"idle" | "busy" | "done">("idle");
  const [cartError, setCartError] = useState<string | null>(null);

  const matchedVariant = useMemo(() => {
    if (storeVariants.length === 0) return null;
    if (variations.length === 0) return storeVariants[0] ?? null;
    return (
      storeVariants.find((variant) =>
        variations.every((variation) => {
          const selection = variant.selections.find((s) => s.variationId === variation.id);
          return selection?.optionId === selected[variation.id];
        }),
      ) ?? null
    );
  }, [variations, storeVariants, selected]);

  const hasVariations = variations.length > 0;
  const price = hasVariations
    ? (matchedVariant?.discountedPrice ?? matchedVariant?.price ?? null)
    : fallbackPrice.minPrice;
  const priceRangeLabel =
    !hasVariations &&
    fallbackPrice.minPrice != null &&
    fallbackPrice.maxPrice != null &&
    fallbackPrice.minPrice !== fallbackPrice.maxPrice
      ? `${formatPrice(fallbackPrice.minPrice)} - ${formatPrice(fallbackPrice.maxPrice)}`
      : null;

  const variantOldPrice =
    matchedVariant?.discountedPrice != null &&
    matchedVariant?.price != null &&
    matchedVariant.price !== matchedVariant.discountedPrice
      ? matchedVariant.price
      : null;
  const oldPrice = hasVariations ? variantOldPrice : (fallbackPrice.oldPrice ?? null);
  const discount = hasVariations
    ? (oldPrice != null && price != null ? Math.round((1 - price / oldPrice) * 100) : null)
    : (fallbackPrice.discount ?? null);

  const stockQuantity = matchedVariant ? matchedVariant.stockQuantity : null;
  const available = matchedVariant ? stockQuantity! > 0 : inStock;
  const maxQty = stockQuantity && stockQuantity > 0 ? stockQuantity : 99;

  const handleAddToCart = async () => {
    if (!matchedVariant) return;
    if (!user) {
      openLoginModal();
      return;
    }
    setCartError(null);
    setCartStatus("busy");
    const res = await addItem(matchedVariant.id, quantity);
    if (res.ok) {
      setCartStatus("done");
      setTimeout(() => setCartStatus("idle"), 1500);
    } else {
      setCartStatus("idle");
      setCartError(res.message ?? "افزودن به سبد ناموفق بود.");
    }
  };

  return (
    <>
      <div className="md:col-span-5">
        {header}

        {hasVariations && (
          <div className="mt-6 space-y-5">
            {variations.map((variation) => (
              <div key={variation.id}>
                <p className="mb-2 text-sm font-bold">
                  {variation.type === "color" ? "انتخاب رنگ" : variation.name}
                </p>
                <div className="flex flex-wrap gap-2">
                  {variation.options.map((option) => {
                    const isSelected = selected[variation.id] === option.id;
                    const swatch = option.colorHex ?? (variation.type === "color" ? option.value : null);
                    return (
                      <button
                        key={option.id}
                        type="button"
                        onClick={() =>
                          setSelected((prev) => ({ ...prev, [variation.id]: option.id }))
                        }
                        className={`flex items-center gap-1.5 rounded-lg border px-3 py-1.5 text-sm transition-colors ${
                          isSelected
                            ? "border-red text-red-dark"
                            : "border-border text-foreground hover:border-red-muted"
                        }`}
                      >
                        {swatch && (
                          <span
                            className="h-3 w-3 shrink-0 rounded-full border border-border"
                            style={{ backgroundColor: swatch }}
                            aria-hidden
                          />
                        )}
                        {option.label}
                        {isSelected && <CheckIcon className="h-3.5 w-3.5" />}
                      </button>
                    );
                  })}
                </div>
              </div>
            ))}
          </div>
        )}
      </div>

      <div className="md:col-span-3">
        <div className="sticky top-24 rounded-2xl border border-border bg-surface p-5">
          {storeName && <p className="mb-4 text-sm font-bold">{storeName}</p>}

          <div className="mb-4 flex items-center gap-2 text-sm">
            <span className="font-medium text-foreground">موجودی:</span>
            <span
              className={`rounded-full px-3 py-1 text-xs font-medium ${
                available ? "bg-green-50 text-green-700" : "bg-red-light text-red-dark"
              }`}
            >
              {available ? "موجود" : "ناموجود"}
            </span>
          </div>

          {price != null ? (
            <>
              <div className="mb-5 space-y-1.5">
                {!priceRangeLabel && oldPrice != null && (
                  <div className="flex items-center gap-2">
                    <span className="text-sm text-muted line-through">{formatPrice(oldPrice)}</span>
                    {discount != null && (
                      <span className="rounded-md bg-green-50 px-1.5 py-0.5 text-xs font-bold text-green-700">
                        {discount}٪
                      </span>
                    )}
                  </div>
                )}
                <p className="text-2xl font-bold text-red-dark">
                  {priceRangeLabel ?? formatPrice(price)}
                  <span className="mr-1 text-sm font-normal text-muted">تومان</span>
                </p>
              </div>

              <div className="mb-4 flex items-center gap-3">
                <span className="text-sm font-medium text-foreground">تعداد:</span>
                <div className="flex items-center rounded-xl border border-border">
                  <button
                    type="button"
                    onClick={() => setQuantity((q) => Math.min(maxQty, q + 1))}
                    disabled={quantity >= maxQty}
                    className="px-3 py-2 text-lg text-foreground transition-colors hover:text-red disabled:cursor-not-allowed disabled:text-muted"
                    aria-label="افزایش تعداد"
                  >
                    +
                  </button>
                  <span className="min-w-8 text-center text-sm font-medium">{quantity}</span>
                  <button
                    type="button"
                    onClick={() => setQuantity((q) => Math.max(1, q - 1))}
                    disabled={quantity <= 1}
                    className="px-3 py-2 text-lg text-foreground transition-colors hover:text-red disabled:cursor-not-allowed disabled:text-muted"
                    aria-label="کاهش تعداد"
                  >
                    −
                  </button>
                </div>
              </div>

              {cartError && <p className="mb-3 text-xs text-red-dark">{cartError}</p>}

              <button
                type="button"
                onClick={handleAddToCart}
                disabled={!available || cartStatus === "busy"}
                className="w-full rounded-xl bg-red py-3 text-sm font-medium text-white transition-colors hover:bg-red-dark disabled:cursor-not-allowed disabled:bg-red/60"
              >
                {cartStatus === "done" ? "به سبد اضافه شد ✓" : "افزودن به سبد خرید"}
              </button>
            </>
          ) : contactPhone ? (
            <a
              href={`tel:${contactPhone}`}
              className="flex w-full items-center justify-center gap-2 rounded-xl bg-red py-3 text-sm font-medium text-white transition-colors hover:bg-red-dark"
            >
              <span aria-hidden>📞</span>
              تماس با فروشگاه
            </a>
          ) : (
            <button
              type="button"
              disabled
              className="w-full cursor-not-allowed rounded-xl bg-red/60 py-3 text-sm font-medium text-white"
            >
              تماس با فروشگاه
            </button>
          )}
        </div>
      </div>
    </>
  );
}