import Foundation
import SwiftUI

struct ProductDetailSheet: View {
    let product: StoreCatalogProduct
    let imageURL: String?
    let storeId: String
    let currentQuantityForItemId: (String) -> Int
    let onAdd: (CartItemState) -> Void
    @Environment(\.dismiss) var dismiss
    @State var selectedAddonItemIds: Set<String> = []
    @State var quantity: Int = 0

    private var selectedAddonItems: [StoreAddonItem] {
        product.addonGroups
            .flatMap(\.items)
            .filter { selectedAddonItemIds.contains($0.id) }
    }

    private var addonsTotal: Double {
        selectedAddonItems.reduce(0) { $0 + ($1.price ?? 0) }
    }

    private var unitPrice: Double {
        (product.price ?? 0) + addonsTotal
    }

    private var totalPrice: Double {
        unitPrice * Double(quantity)
    }

    private var cartItemId: String {
        let addonKey = selectedAddonItemIds.sorted().joined(separator: ",")
        return "\(storeId)::\(product.id)::\(addonKey)"
    }

    private var selectedAddonsSummary: String? {
        let names = selectedAddonItems.map(\.name)
        if names.isEmpty { return nil }
        return names.joined(separator: ", ")
    }

    private var addButtonTitle: String {
        if quantity <= 0 {
            return "Remover do carrinho"
        }
        return "Atualizar • \(formatCurrency(totalPrice))"
    }

    var body: some View {
        ScrollView(showsIndicators: false) {
            VStack(alignment: .leading, spacing: 16) {
                AsyncStoreImage(imageURL: imageURL)
                    .frame(height: 220)
                    .clipShape(RoundedRectangle(cornerRadius: AppLayout.radiusXL, style: .continuous))

                Text(product.name)
                    .font(AppTypography.heading2)
                    .foregroundStyle(AppColors.textPrimary)

                if let description = product.description, description.isEmpty == false {
                    Text(description)
                        .font(AppTypography.body)
                        .foregroundStyle(AppColors.textMuted)
                }

                Text(formatCurrency(unitPrice))
                    .font(AppTypography.heading2)
                    .foregroundStyle(AppColors.primary)

                if addonsTotal > 0 {
                    Text("Inclui adicionais: \(formatCurrency(addonsTotal))")
                        .font(.caption)
                        .foregroundStyle(AppColors.textMuted)
                }

                if product.addonGroups.isEmpty == false {
                    Text("Adicionais")
                        .font(AppTypography.heading3)
                        .foregroundStyle(AppColors.textPrimary)

                    ForEach(product.addonGroups) { group in
                        VStack(alignment: .leading, spacing: 8) {
                            Text(group.name)
                                .font(AppTypography.heading3)
                                .foregroundStyle(AppColors.textPrimary)

                            ForEach(group.items) { item in
                                Button {
                                    if selectedAddonItemIds.contains(item.id) {
                                        selectedAddonItemIds.remove(item.id)
                                    } else {
                                        selectedAddonItemIds.insert(item.id)
                                    }
                                } label: {
                                    HStack {
                                        Image(systemName: selectedAddonItemIds.contains(item.id) ? "checkmark.circle.fill" : "circle")
                                            .font(.system(size: 18, weight: .semibold))
                                            .foregroundStyle(selectedAddonItemIds.contains(item.id) ? AppColors.primary : AppColors.textMuted)

                                        Text(item.name)
                                            .font(AppTypography.body)
                                            .foregroundStyle(AppColors.textMuted)
                                        Spacer()
                                        Text(String(format: "+ R$ %.2f", item.price ?? 0).replacingOccurrences(of: ".", with: ","))
                                            .font(AppTypography.body)
                                            .foregroundStyle(AppColors.textPrimary)
                                    }
                                }
                                .buttonStyle(.plain)
                            }
                        }
                        .padding(12)
                        .background(AppColors.surface)
                        .clipShape(RoundedRectangle(cornerRadius: AppLayout.radiusLG, style: .continuous))
                    }
                }
            }
            .padding(20)
            .padding(.bottom, 80)
        }
        .safeAreaInset(edge: .bottom) {
            HStack(spacing: 12) {
                HStack(spacing: 10) {
                    Button(action: { if quantity > 0 { quantity -= 1 } }) {
                        Image(systemName: "minus")
                            .font(.system(size: 14, weight: .bold))
                            .foregroundStyle(AppColors.textPrimary)
                            .frame(width: 32, height: 32)
                            .background(AppColors.surface)
                            .clipShape(Circle())
                    }
                    .buttonStyle(.plain)
                    .disabled(quantity <= 0)

                    Text("\(quantity)")
                        .font(AppTypography.heading3)
                        .foregroundStyle(AppColors.textPrimary)
                        .frame(minWidth: 20)

                    Button(action: { quantity += 1 }) {
                        Image(systemName: "plus")
                            .font(.system(size: 14, weight: .bold))
                            .foregroundStyle(AppColors.textPrimary)
                            .frame(width: 32, height: 32)
                            .background(AppColors.surface)
                            .clipShape(Circle())
                    }
                    .buttonStyle(.plain)
                }
                .padding(.horizontal, 8)
                .frame(height: 48)
                .background(AppColors.surface)
                .clipShape(RoundedRectangle(cornerRadius: 14, style: .continuous))
                .buttonStyle(.plain)

                PrimaryButton(title: addButtonTitle) {
                    let item = CartItemState(
                        id: cartItemId,
                        productId: product.id,
                        storeId: storeId,
                        name: product.name,
                        details: selectedAddonsSummary,
                        quantity: quantity,
                        unitPrice: unitPrice
                    )
                    onAdd(item)
                    dismiss()
                }
            }
            .padding(.horizontal, 20)
            .padding(.top, 8)
            .padding(.bottom, 12)
            .background(.ultraThinMaterial)
        }
        .background(AppColors.backgroundLight.ignoresSafeArea())
        .navigationTitle("Detalhes")
        .navigationBarTitleDisplayMode(.inline)
        .toolbar {
            ToolbarItem(placement: .topBarTrailing) {
                Button("Fechar") { dismiss() }
                    .foregroundStyle(AppColors.primary)
            }
        }
        .onAppear {
            quantity = currentQuantityForItemId(cartItemId)
        }
        .onChange(of: selectedAddonItemIds) { _, _ in
            quantity = currentQuantityForItemId(cartItemId)
        }
    }

    private func formatCurrency(_ value: Double) -> String {
        String(format: "R$ %.2f", value).replacingOccurrences(of: ".", with: ",")
    }
}