"use client";

import { useState, useCallback, useMemo, useRef, useEffect } from "react";
import { Skeleton } from "@/components/ui/skeleton";
import {
  useProductsBySlug,
  useRelatedProducts,
  useSubmitReview,
} from "@/features/products/hooks/useProducts";
import {
  useAddToCart,
  useUpdateCartItemQuantity,
  useRemoveFromCart,
  useCart,
  cartEvents,
} from "@/features/cart/hooks/useCart";
import { useTranslations } from "next-intl";
import { toast } from "sonner";
import { ProductImageGallery } from "./ProductImageGallery";
import { ProductInfoCard } from "./ProductInfoCard";
import { ProductPurchaseCard } from "./ProductPurchaseCard";
import { ProductReviewsSection } from "./ProductReviewsSection";
import { RelatedProductsSection } from "./RelatedProductsSection";
import { ReviewModal } from "./ReviewModal";
import { StockLimitModal } from "./StockLimitModal";
import {
  useIsFavorite,
  useToggleFavorite,
} from "@/features/favorites/hooks/useFavorites";
interface ProductDetailProps {
  slug: string;
}

const PENDING_PRODUCT_UPDATES_KEY = "pendingProductUpdates";

interface PendingUpdate {
  quantity: number;
  timestamp: number;
  retryCount: number;
}


export default function ProductPageContent({ slug }: ProductDetailProps) {
  const [localQuantity, setLocalQuantity] = useState(1);

  const [isSyncing, setIsSyncing] = useState(false);
  const [syncError, setSyncError] = useState(false);
  const [showStockModal, setShowStockModal] = useState(false);
  const [showReviewModal, setShowReviewModal] = useState(false);
  const [isInitialized, setIsInitialized] = useState(false);

  const t = useTranslations();

  const debounceTimerRef = useRef<NodeJS.Timeout | undefined>(undefined);
  const isRequestInFlightRef = useRef(false);
  const pendingQuantityRef = useRef<number | null>(null);
  const retryCountRef = useRef(0);
  const retryTimerRef = useRef<NodeJS.Timeout | undefined>(undefined);
  const syncToServerRef = useRef<((quantity: number) => void) | null>(null);
  const retrySyncRef = useRef<((quantity: number) => void) | null>(null);
  const shouldSyncFromCartRef = useRef(true);
  const lastSyncedQuantityRef = useRef<number | null>(null);

  const {
    data: product,
    isLoading: productLoading,
    error,
    refetch: refetchProduct,
  } = useProductsBySlug(slug);
  const { isFavorite, isLoading: isFavLoading } = useIsFavorite(
    product?.id || 0
  );
  const cartOptions = useMemo(
    () => ({
      refetchOnMount: true,
      refetchOnWindowFocus: true,
      staleTime: 0,
    }),
    []
  );
  const { mutate: toggleFavoriteMutation } = useToggleFavorite();
  const {
    data: cartData,
    refetch: refetchCart,
    isFetching: isCartFetching,
  } = useCart(cartOptions);

  const { data: relatedProducts } = useRelatedProducts(product?.id || 0, {
    enabled: !!product?.id,
  });

  const addToCartMutation = useAddToCart();
  const updateCartMutation = useUpdateCartItemQuantity();
  const removeFromCartMutation = useRemoveFromCart();
  const submitReviewMutation = useSubmitReview();

  const cartItem = useMemo(() => {
    const item = cartData?.data?.find(
      (item: any) => item.product?.id === product?.id
    );

    return item;
  }, [cartData, product, isInitialized]);

  const isInCart = !!cartItem;
  const availableStock = product?.stock || 0;

  const imageUrls = useMemo(
    () =>
      product?.media?.map(
        (m) => m.images_800x800 || m.images_720x720 || m.thumbnail
      ) || [],
    [product]
  );

  const reviews = useMemo(() => product?.reviews_resources || [], [product]);
  const averageRating = useMemo(
    () =>
      product?.reviews?.rating ? Number.parseFloat(product.reviews.rating) : 0,
    [product]
  );

  const transformedRelatedProducts = useMemo(() => {
    if (!relatedProducts) return [];
    return relatedProducts.map((p) => ({
      id: p.id,
      slug: p.slug,
      name: p.name,
      price_amount: p.price_amount,
      old_price_amount: p.old_price_amount ?? undefined,
      struct_price_text: `${p.price_amount} TMT`,
      discount: null,
      discount_text: null,
      stock: p.stock,
      media: p.media,
      labels: [],
      price_color: undefined,
    }));
  }, [relatedProducts]);

  useEffect(() => {
    if (!product?.id || isInitialized) return;

    if (cartItem?.product_quantity) {
      const serverQuantity = cartItem.product_quantity;
      setLocalQuantity(serverQuantity);
      lastSyncedQuantityRef.current = serverQuantity;
    }

    setIsInitialized(true);
  }, [product?.id, cartItem, isInitialized]);

  useEffect(() => {
    setLocalQuantity(cartItem?.product_quantity || 1);
  }, [cartItem]);

  const savePendingUpdate = useCallback(
    (quantity: number) => {
      if (!product?.id) return;
      try {
        const stored = sessionStorage.getItem(PENDING_PRODUCT_UPDATES_KEY);
        const pending: Record<number, PendingUpdate> = stored
          ? JSON.parse(stored)
          : {};
        pending[product.id] = {
          quantity,
          timestamp: Date.now(),
          retryCount: retryCountRef.current,
        };
        sessionStorage.setItem(
          PENDING_PRODUCT_UPDATES_KEY,
          JSON.stringify(pending)
        );
      } catch (error) {
        console.error("Failed to save pending update:", error);
      }
    },
    [product?.id]
  );

  const clearPendingUpdate = useCallback(() => {
    if (!product?.id) return;
    try {
      const stored = sessionStorage.getItem(PENDING_PRODUCT_UPDATES_KEY);
      if (stored) {
        const pending: Record<number, PendingUpdate> = JSON.parse(stored);
        delete pending[product.id];
        if (Object.keys(pending).length === 0) {
          sessionStorage.removeItem(PENDING_PRODUCT_UPDATES_KEY);
        } else {
          sessionStorage.setItem(
            PENDING_PRODUCT_UPDATES_KEY,
            JSON.stringify(pending)
          );
        }
      }
    } catch (error) {
      console.error("Failed to clear pending update:", error);
    }
  }, [product?.id]);

  const retrySync = useCallback(
    (quantity: number) => {
      const maxRetries = 4;
      const retryCount = retryCountRef.current;

      if (retryCount >= maxRetries) {
        setSyncError(true);
        setIsSyncing(false);
        shouldSyncFromCartRef.current = true;
        toast.error(t("error"), {
          description: t("update_quantity_failed"),
        });
        return;
      }

      const delay = Math.min(1000 * Math.pow(2, retryCount), 16000);
      retryCountRef.current++;

      retryTimerRef.current = setTimeout(() => {
        syncToServerRef.current?.(quantity);
      }, delay);
    },
    [t]
  );

  retrySyncRef.current = retrySync;

  const syncToServer = useCallback(
    async (quantity: number) => {
      if (!product?.id) return;

      if (isRequestInFlightRef.current) {
        pendingQuantityRef.current = quantity;
        return;
      }

      isRequestInFlightRef.current = true;
      setIsSyncing(true);
      setSyncError(false);

      try {
        if (quantity === 0) {
          await removeFromCartMutation.mutateAsync(product.id);
          toast.success(t("removed_from_cart"));
        } else if (isInCart) {
          await updateCartMutation.mutateAsync({
            productId: product.id,
            quantity: quantity,
          });
        } else {
          await addToCartMutation.mutateAsync({
            productId: product.id,
            quantity: quantity,
          });
        }

        retryCountRef.current = 0;
        clearPendingUpdate();

        if (pendingQuantityRef.current !== null) {
          const nextQuantity = pendingQuantityRef.current;
          pendingQuantityRef.current = null;
          setTimeout(() => syncToServerRef.current?.(nextQuantity), 100);
        }
      } catch (error) {
        setLocalQuantity(cartItem?.product_quantity || 1);
        toast.error(t("failed_to_update_quantity"), {
          description: "Please try again",
        });

        retrySyncRef.current?.(quantity);
      } finally {
        isRequestInFlightRef.current = false;
        setIsSyncing(false);
      }
    },
    [
      product?.id,
      isInCart,
      updateCartMutation,
      addToCartMutation,
      removeFromCartMutation,
      cartItem,
      clearPendingUpdate,
      t,
    ]
  );

  syncToServerRef.current = syncToServer;

  useEffect(() => {
    if (!isInCart || !product?.id) return;

    if (localQuantity === (cartItem?.product_quantity || 1)) {
      return;
    }

    if (debounceTimerRef.current) {
      clearTimeout(debounceTimerRef.current);
    }

    debounceTimerRef.current = setTimeout(() => {
      syncToServerRef.current?.(localQuantity);
    }, 800);

    return () => {
      if (debounceTimerRef.current) {
        clearTimeout(debounceTimerRef.current);
      }
    };
  }, [localQuantity, isInCart, product?.id, cartItem?.product_quantity]);

  useEffect(() => {
    return () => {
      if (debounceTimerRef.current) clearTimeout(debounceTimerRef.current);
      if (retryTimerRef.current) clearTimeout(retryTimerRef.current);
    };
  }, []);

  const handleAddToCart = useCallback(async () => {
    if (!product?.id) return;

    if (localQuantity > availableStock) {
      setShowStockModal(true);
      return;
    }

    setIsSyncing(true);
    shouldSyncFromCartRef.current = false;

    try {
      await addToCartMutation.mutateAsync({
        productId: product.id,
        quantity: localQuantity,
      });

      lastSyncedQuantityRef.current = localQuantity;

      setTimeout(() => {
        shouldSyncFromCartRef.current = true;
      }, 150);

      setIsSyncing(false);

      toast.success(t("added_to_cart"), {
        description: `${product.name} ${t("added_to_cart_description")}`,
      });
    } catch (error) {
      console.error("Add to cart error:", error);
      setIsSyncing(false);
      shouldSyncFromCartRef.current = true;
      toast.error(t("error"), {
        description: t("add_to_cart_failed"),
      });
    }
  }, [product, localQuantity, availableStock, addToCartMutation, t]);

  const handleQuantityIncrease = useCallback(() => {
    if (localQuantity >= availableStock) {
      setShowStockModal(true);
      return;
    }
    setLocalQuantity((prev) => {
      const newVal = prev + 1;
      return newVal;
    });
  }, [localQuantity, availableStock]);

  const handleQuantityDecrease = useCallback(() => {
    if (localQuantity <= 0) return;
    setLocalQuantity((prev) => {
      const newVal = prev - 1;
      return newVal;
    });
  }, [localQuantity]);

  const handleToggleFavorite = useCallback(
    (e?: React.MouseEvent<HTMLButtonElement>) => {
      e?.preventDefault();
      e?.stopPropagation();

      if (!product?.id) {
        toast.error(t("error"), {
          description: "Product ID not found",
        });
        return;
      }

      toggleFavoriteMutation(
        {
          productId: product.id,
          isFavorite,
        },
        {
          onSuccess: (data) => {
            toast.success(
              data?.wasAdded
                ? t("added_to_favorites")
                : t("removed_from_favorites")
            );
          },
          onError: () => {
            toast.error(t("error"), {
              description: "Try again later",
            });
          },
        }
      );
    },
    [product?.id, isFavorite, toggleFavoriteMutation, t]
  );

  const handleSubmitReview = useCallback(
    async (rating: number, text: string) => {
      if (!product?.id || rating === 0 || !text.trim()) {
        toast.error(t("error"), {
          description: "Please provide rating and review text",
        });
        return;
      }

      try {
        await submitReviewMutation.mutateAsync({
          productId: product.id,
          rating: rating,
          title: text,
          source: "site",
        });

        await refetchProduct();

        toast.success("Review submitted successfully!");
        setShowReviewModal(false);
      } catch (error) {
        toast.error(t("error"), {
          description: "Failed to submit review",
        });
      }
    },
    [product?.id, submitReviewMutation, refetchProduct, t]
  );

  const loadingSkeleton = useMemo(
    () => (
      <div className=" mx-auto px-4 py-8">
        <div className="flex flex-col lg:flex-row gap-8">
          <div className="flex-1 max-w-2xl">
            <Skeleton className="aspect-square w-full rounded-2xl" />
            <div className="mt-4 flex gap-2">
              {[1, 2, 3].map((i) => (
                <Skeleton key={i} className="w-16 h-16 rounded" />
              ))}
            </div>
          </div>
          <div className="flex-1 space-y-6">
            <Skeleton className="h-10 w-64" />
            <Skeleton className="h-20 w-full" />
          </div>
        </div>
      </div>
    ),
    []
  );

  if (productLoading) return loadingSkeleton;

  if (error || !product) {
    return (
      <div className=" mx-auto px-4 py-8 text-center">
        <h2 className="text-2xl font-bold text-red-600">
          {t("product_not_found")}
        </h2>
        <p className="text-gray-500 mt-2">
          {t("product_not_found_description")}
        </p>
      </div>
    );
  }

  return (
    <>
      <div className="px-2 md:px-4 lg:px-6 rounded-lg mb-18 space-y-8 max-w-[1504px] mx-auto">
        <div className="flex flex-col lg:flex-row gap-8 rounded-b-lg bg-white p-4">
          <ProductImageGallery
            images={imageUrls}
            productName={product.name}
            noImageText={t("no_image")}
          />

          <ProductInfoCard
            name={product.name}
            brandName={product.brand?.name ?? undefined}
            stock={product.stock}
            barcode={product.barcode}
            colour={product.colour ?? undefined}
            properties={product.properties}
            description={product.description}
            averageRating={averageRating}
            reviewsCount={product.reviews?.count || 0}
            t={t}
          />

          <ProductPurchaseCard
            price={product.price_amount}
            oldPrice={product.old_price_amount ?? undefined}
            isInCart={isInCart}
            localQuantity={localQuantity}
            availableStock={availableStock}
            isSyncing={isSyncing}
            syncError={syncError}
            isFavorite={isFavorite}
            productStock={product.stock}
            channelName={product.channel?.[0]?.name}
            onAddToCart={handleAddToCart}
            onQuantityIncrease={handleQuantityIncrease}
            onQuantityDecrease={handleQuantityDecrease}
            onToggleFavorite={handleToggleFavorite}
            t={t}
          />
        </div>

        {/* <ProductReviewsSection
          reviews={reviews}
          averageRating={averageRating}
          isLoading={false}
          onWriteReview={() => setShowReviewModal(true)}
        />

        <RelatedProductsSection products={transformedRelatedProducts} /> */}
      </div>

      <StockLimitModal
        open={showStockModal}
        onOpenChange={setShowStockModal}
        productName={product.name}
        availableStock={availableStock}
        t={t}
      />

      <ReviewModal
        open={showReviewModal}
        onOpenChange={setShowReviewModal}
        onSubmit={handleSubmitReview}
        isSubmitting={submitReviewMutation.isPending}
      />
    </>
  );
}