import SwiftUI
#if canImport(LCEssentials) && os(iOS)
import LCEssentials
#endif
#if canImport(UIKit)
import UIKit
#endif

struct StoreDetailView: View {
    let storeId: String
    let storeName: String
    let storeCoverURL: String?
    let storeLogoURL: String?
    let storeCategory: String?
    let storeRating: Double?
    let storeDistance: String?
    @Binding var appState: AppState

    @Environment(\.dismiss) var dismiss

    @State var isLoading = true
    @State var errorMessage: String? = nil
    @State var info: StoreInfoResult? = nil
    @State var categories: [StoreCatalogCategory] = []
    @State var selectedCategoryId: String? = nil
    @State var selectedProduct: StoreCatalogProduct? = nil
    @State var selectedPizzaCategoryId: String? = nil
    @State var showSwitchStoreAlert = false
    @State var pendingCartItem: CartItemState? = nil
    @State var pendingProductSheet: StoreCatalogProduct? = nil
    @State var pendingPizzaCategoryId: String? = nil
    @State var pendingCartAction: CartAction = .add
    @State var didLoad = false
    @State var categoryHeaderOffsets: [String: CGFloat] = [:]
    @State var isProgrammaticCategoryScroll = false
    @State var scrollOffsetY: CGFloat = 0

    let cardTopInset: CGFloat = 168
    let summaryCardBaseHeight: CGFloat = 170
    let closedBannerHeight: CGFloat = 44
    let coverVisibleUntilY: CGFloat = 253
    let storeLogoSize: CGFloat = 84

    var body: some View {
        GeometryReader { geometry in
            let safeTop = geometry.safeAreaInsets.top
            ScrollViewReader { proxy in
                
                ZStack(alignment: .top) {
                    AppColors.backgroundLight.ignoresSafeArea()

                    ScrollView(showsIndicators: false) {
#if os(Android)
                        LazyVStack(spacing: 0) {
                            topSection

                            categoryTabs(proxy: proxy, safeTop: safeTop, isSticky: false)

                            sectionedProducts
                        }
#else
                        LazyVStack(spacing: 0, pinnedViews: [.sectionHeaders]) {
                            topSection

                            categoryTabs(proxy: proxy, safeTop: safeTop, isSticky: false)

                            sectionedProducts
                        }
#endif
                    }
                    .refreshable {
                        await loadStoreData(forceRefresh: true)
                    }
                    .ignoresSafeArea(edges: .top)
                    .background(ScrollOffsetReader(offsetY: $scrollOffsetY))
                }
                .ignoresSafeArea(edges: .top)
                .overlay(alignment: .top) {
                    if isCategoryTabsPinned(safeTop: safeTop) {
                        categoryTabs(proxy: proxy, safeTop: safeTop, isSticky: true)
                        .transition(.opacity)
                        .zIndex(20)
                    }
                }
                .saturation(isStoreOpen ? 1 : 0)
            }
        }
        .navigationBarBackButtonHidden(true)
        .appHiddenNavigationBar()
        .task {
            guard didLoad == false else { return }
            didLoad = true
            await loadStoreData(forceRefresh: false)
        }
        .sheet(item: $selectedProduct) { product in
            NavigationStack {
                ProductDetailSheet(
                    product: product,
                    imageURL: resolvedURL(product.image),
                    storeId: storeId,
                    currentQuantityForItemId: { itemId in
                        currentQuantity(forCartItemId: itemId)
                    },
                    onAdd: { item in
                        guard isStoreOpen else {
                            SnackbarCenter.shared.show(title: "Loja fechada no momento.", style: .warning, icon: "moon.zzz.fill", duration: 2.0)
                            return
                        }
                        requestSetCartItem(item)
                    }
                )
            }
        }
        .sheet(
            isPresented: Binding(
                get: { selectedPizzaCategoryId != nil },
                set: { isPresented in
                    if isPresented == false {
                        selectedPizzaCategoryId = nil
                    }
                }
            )
        ) {
            if let category = categories.first(where: { $0.id == selectedPizzaCategoryId }) {
                NavigationStack {
                    PizzaProductDetailSheet(
                        category: category,
                        storeId: storeId,
                        resolveImageURL: { raw in resolvedURL(raw) },
                        currentQuantityForItemId: { itemId in
                            currentQuantity(forCartItemId: itemId)
                        },
                        onAdd: { item in
                            guard isStoreOpen else {
                                SnackbarCenter.shared.show(title: "Loja fechada no momento.", style: .warning, icon: "moon.zzz.fill", duration: 2.0)
                                return
                            }
                            requestSetCartItem(item)
                        }
                    )
                }
            } else {
                ProgressView()
            }
        }
        .alert("Trocar de loja?", isPresented: $showSwitchStoreAlert) {
            Button("Cancelar", role: .cancel) {
                pendingCartItem = nil
                pendingProductSheet = nil
                pendingPizzaCategoryId = nil
            }
            Button("Limpar carrinho e adicionar", role: .destructive) {
                appState.cart.clear()
                switch pendingCartAction {
                case .add:
                    guard let pendingCartItem else { return }
                    applyAddToCart(pendingCartItem)
                case .set:
                    guard let pendingCartItem else { return }
                    applySetCartItem(pendingCartItem)
                case .openProductSheet:
                    guard let pendingProductSheet else { return }
                    selectedProduct = pendingProductSheet
                case .openPizzaSheet:
                    guard let pendingPizzaCategoryId else { return }
                    selectedPizzaCategoryId = pendingPizzaCategoryId
                }
                self.pendingCartItem = nil
                self.pendingProductSheet = nil
                self.pendingPizzaCategoryId = nil
            }
        } message: {
            Text("Seu carrinho tem itens de outra loja. Deseja limpar o carrinho atual para adicionar este produto?")
        }
        .onPreferenceChange(CategoryHeaderOffsetPreferenceKey.self) { offsets in
            categoryHeaderOffsets = offsets
            syncCategoryWithScroll()
        }
    }

    private var topSection: some View {
        ZStack(alignment: .top) {
            heroSection
                .frame(height: topSectionHeight)

            // Hard cut: cover cannot appear below this line.
            Rectangle()
                .fill(AppColors.backgroundLight)
                .frame(height: max(0, topSectionHeight - coverVisibleUntilY))
                .offset(y: coverVisibleUntilY)

            summaryCard
                .padding(.horizontal, 16)
                .padding(.top, cardTopInset)

            storeLogoBadge
                .padding(.top, cardTopInset - (storeLogoSize / 2))
        }
        .frame(height: topSectionHeight)
    }

    private var heroSection: some View {
        ZStack(alignment: .top) {
            AsyncStoreImage(imageURL: resolvedURL(storeCoverURL))
                .frame(height: topSectionHeight)
                .overlay(
                    LinearGradient(
                        colors: [Color.black.opacity(0.32), Color.black.opacity(0.05)],
                        startPoint: .top,
                        endPoint: .bottom
                    )
                )

            VStack(spacing: 0) {
                HStack {
                    heroIconButton(icon: "chevron.left") {
                        dismiss()
                    }
                    Spacer()
                    heroIconButton(icon: "magnifyingglass") {}
                    heroIconButton(icon: "heart") {}
                }
                .padding(.horizontal, 14)
                .padding(.top, UIDevice.topNotch)

                Spacer()

                Text("RESTAURANT")
                    .font(AppTypography.overline)
                    .tracking(1.8)
                    .foregroundStyle(Color.white.opacity(0.92))
                    .padding(.bottom, 14)
            }
        }
    }

    private var storeLogoBadge: some View {
        ZStack {
            Circle()
                .fill(AppColors.surface)
                .frame(width: storeLogoSize, height: storeLogoSize)
                .overlay(
                    Circle()
                        .stroke(Color.white, lineWidth: 0.1)
                )

            AsyncStoreImage(imageURL: resolvedURL(storeLogoURL))
                .frame(width: storeLogoSize - 10, height: storeLogoSize - 10)
                .clipShape(Circle())
        }
        .shadow(color: Color.black.opacity(0.10), radius: 8, y: 3)
    }

    private var summaryCard: some View {
        VStack(spacing: 0) {
            VStack(alignment: .leading, spacing: 14) {
                HStack(alignment: .top) {
                    VStack(alignment: .leading, spacing: 6) {
                        Text(storeName)
                            .font(AppTypography.heading2)
                            .foregroundStyle(AppColors.textPrimary)
                            .lineLimit(2)
                            .padding(.top, 30)

                        Text(storeSubtitle)
                            .font(.caption)
                            .foregroundStyle(AppColors.textMuted)
                            .lineLimit(1)
                    }

                    Spacer()

                    ratingChip
                }

                HStack(spacing: 0) {
                    statItem(title: "DISTÂNCIA", value: distanceValueLabel)
                    Divider().frame(height: 34)
                    statItem(title: "TEMPO", value: info?.deliveryTime ?? "25-35 min")
                    Divider().frame(height: 34)
                    statItem(title: "ENTREGA", value: deliveryValueLabel)
                }
                .padding(.vertical, 4)
            }
            .padding(16)

            if isStoreOpen == false {
                Text(closedStoreBannerText)
                    .font(AppTypography.heading3)
                    .foregroundStyle(Color.white)
                    .frame(maxWidth: .infinity, minHeight: closedBannerHeight)
                    .background(AppColors.brandDark)
            }
        }
        .frame(height: summaryCardHeight)
        .background(AppColors.surface)
        .clipShape(RoundedRectangle(cornerRadius: AppLayout.radiusXL, style: .continuous))
        .shadow(color: AppShadow.soft.color, radius: AppShadow.soft.radius, y: AppShadow.soft.y)
    }

    @ViewBuilder
    private var sectionedProducts: some View {
        if isLoading {
            ProgressView()
                .frame(maxWidth: .infinity, alignment: .center)
                .padding(.top, 26)
        } else if let errorMessage {
            VStack(alignment: .leading, spacing: 10) {
                Text(errorMessage)
                    .font(AppTypography.body)
                    .foregroundStyle(AppColors.textMuted)
                Button("Tentar novamente") {
                    Task { await loadStoreData() }
                }
                .font(AppTypography.heading3)
                .foregroundStyle(AppColors.primary)
            }
            .padding(.top, 16)
        } else if categories.isEmpty {
            Text("Cardápio indisponível no momento.")
                .font(AppTypography.body)
                .foregroundStyle(AppColors.textMuted)
                .padding(.top, 16)
                .padding(.horizontal, 16)
                .padding(.bottom, 120)
        } else {
            ForEach(categories, id: \.id) { category in
                Section {
                    VStack(spacing: 12) {
                        ForEach(listItems(for: category)) { item in
                            productCard(item, in: category)
                        }
                    }
                    .padding(.horizontal, 16)
                    .padding(.bottom, 8)
                } header: {
                    Text(category.name)
                        .font(AppTypography.heading2)
                        .foregroundStyle(AppColors.textPrimary)
                        .id(sectionAnchorId(for: category.id))
                        .frame(maxWidth: .infinity, alignment: .leading)
                        .padding(.horizontal, 16)
                        .padding(.top, 8)
                        .padding(.bottom, 8)
                        .background(AppColors.backgroundLight)
                        .background(
                            GeometryReader { geometry in
                                Color.clear.preference(
                                    key: CategoryHeaderOffsetPreferenceKey.self,
                                    value: [category.id: geometry.frame(in: .global).minY]
                                )
                            }
                        )
                }
            }
            Color.clear.frame(height: 120)
        }
    }

    private func categoryTabs(proxy: ScrollViewProxy, safeTop: CGFloat, isSticky: Bool) -> some View {
        ScrollView(.horizontal, showsIndicators: false) {
            HStack(spacing: 10) {
                ForEach(categories, id: \.id) { category in
                    let active = selectedCategoryId == category.id
                    Button {
                        selectedCategoryId = category.id
                        isProgrammaticCategoryScroll = true
                        withAnimation(.easeInOut(duration: 0.25)) {
                            proxy.scrollTo(sectionAnchorId(for: category.id), anchor: .top)
                        }
                        DispatchQueue.main.asyncAfter(deadline: .now() + 0.35) {
                            isProgrammaticCategoryScroll = false
                        }
                    } label: {
                        Text(category.name)
                            .font(AppTypography.heading3)
                            .foregroundStyle(active ? AppColors.textInverse : AppColors.textMuted)
                            .padding(.horizontal, 16)
                            .padding(.vertical, 9)
                            .background(active ? AppColors.primary : AppColors.surface)
                            .clipShape(Capsule())
                    }
                    .buttonStyle(.plain)
                }
            }
            .padding(.horizontal, 16)
            .padding(.bottom, 10)
            .padding(.top, isSticky ? categoryTabsPinnedInset(safeTop: safeTop) : 10)
        }
        .background(AppColors.backgroundLight)
    }

    private func isCategoryTabsPinned(safeTop: CGFloat) -> Bool {
        scrollOffsetY >= categoryTabsPinThreshold(safeTop: safeTop)
    }

    private func categoryTabsPinThreshold(safeTop: CGFloat) -> CGFloat {
        max(0, topSectionHeight + 10 - safeTop)
    }

    private func categoryTabsPinnedInset(safeTop: CGFloat) -> CGFloat {
        max(8, safeTop - 44)
    }

    private func productCard(_ item: StoreCatalogListItem, in category: StoreCatalogCategory) -> some View {
        let product = item.product
        let hasSelectableAddons = product.addonGroups.contains { $0.items.isEmpty == false }

        return HStack(spacing: 12) {
            VStack(alignment: .leading, spacing: 8) {
                Text(item.title)
                    .font(AppTypography.heading3)
                    .foregroundStyle(AppColors.textPrimary)
                    .lineLimit(2)
                    .multilineTextAlignment(.leading)

                if let description = item.description, description.isEmpty == false {
                    Text(description)
                        .font(.caption)
                        .foregroundStyle(AppColors.textMuted)
                        .lineLimit(2)
                        .multilineTextAlignment(.leading)
                }

                Text(listPriceLabel(for: product, in: category))
                    .font(AppTypography.heading3)
                    .foregroundStyle(AppColors.textPrimary)
            }

            Spacer()

            ZStack(alignment: .bottomTrailing) {
                AsyncStoreImage(imageURL: resolvedURL(item.imageURL))
                    .frame(width: 92, height: 92)
                    .clipShape(RoundedRectangle(cornerRadius: AppLayout.radiusLG, style: .continuous))

                Button {
                    guard isStoreOpen else {
                        SnackbarCenter.shared.show(title: "Loja fechada no momento.", style: .warning, icon: "moon.zzz.fill", duration: 2.0)
                        return
                    }
                    if item.isPizzaSummary, let pizzaCategoryId = item.pizzaCategoryId {
                        requestOpenPizzaSheet(categoryId: pizzaCategoryId)
                        return
                    }
                    if hasSelectableAddons == false {
                        let basePrice = product.price ?? 0
                        let item = CartItemState(
                            id: "\(storeId)::\(product.id)::base",
                            productId: product.id,
                            storeId: storeId,
                            name: product.name,
                            imageURL: resolvedURL(product.image),
                            quantity: 1,
                            unitPrice: basePrice
                        )
                        requestAddToCart(item)
                    } else {
                        requestOpenProductSheet(product)
                    }
                } label: {
                    ZStack(alignment: .leading) {
                        Image(systemName: "plus")
                            .font(.system(size: 16, weight: .bold))
                            .foregroundStyle(AppColors.textPrimary)
                            .frame(width: 30, height: 30)
                            .background(AppColors.tertiary)
                            .clipShape(Circle())

                        let qty = quantityInCart(for: item)
                        if qty > 0 {
                            Text("\(qty)")
                                .font(.system(size: 10, weight: .bold))
                                .foregroundStyle(Color.white)
                                .padding(.horizontal, 5)
                                .padding(.vertical, 2)
                                .background(Color.red)
                                .clipShape(Capsule())
                                .offset(x: -6, y: -10)
                                .zIndex(1)
                        }                        
                    }
                    .offset(x: 3, y: -3)
                    .frame(width: 30, height: 30)
                    .appContentShape(Circle())
                }
                .buttonStyle(.plain)
                .frame(width: 30, height: 30)
                .disabled(isStoreOpen == false)
                .opacity(isStoreOpen ? 1 : 0.65)
                .offset(x: 7, y: 7)
            }
        }
        .padding(12)
        .background(AppColors.surface)
        .clipShape(RoundedRectangle(cornerRadius: AppLayout.radiusLG, style: .continuous))
        .appContentShape(RoundedRectangle(cornerRadius: AppLayout.radiusLG, style: .continuous))
        .onTapGesture {
            guard isStoreOpen else {
                SnackbarCenter.shared.show(title: "Loja fechada no momento.", style: .warning, icon: "moon.zzz.fill", duration: 2.0)
                return
            }
            if item.isPizzaSummary, let pizzaCategoryId = item.pizzaCategoryId {
                requestOpenPizzaSheet(categoryId: pizzaCategoryId)
                return
            }
            guard hasSelectableAddons else { return }
            requestOpenProductSheet(product)
        }
    }

}