import SwiftUI

struct FavoritesScreen: View {
    @EnvironmentObject var appState: AppState
    @State private var favorites: [Product] = []
    @State private var isLoading = true
    @State private var selectedProduct: Product?

    var body: some View {
        NavigationStack {
            Group {
                if !appState.isAuthenticated {
                    // Not logged in
                    VStack(spacing: 20) {
                        Spacer()
                        Image(systemName: "heart.fill")
                            .font(.system(size: 60))
                            .foregroundColor(.gray)

                        Text("Save Your Favorites")
                            .font(.title2.bold())

                        Text("Log in to save products you love and access them anytime.")
                            .font(.subheadline)
                            .foregroundColor(.secondary)
                            .multilineTextAlignment(.center)
                            .padding(.horizontal, 40)

                        Button {
                            appState.showLoginSheet = true
                        } label: {
                            Text("Log In")
                                .font(.headline)
                                .foregroundColor(.black)
                                .frame(maxWidth: .infinity)
                                .padding()
                                .background(Color.green)
                                .cornerRadius(12)
                        }
                        .padding(.horizontal, 40)

                        Spacer()
                    }
                } else if isLoading {
                    ProgressView("Loading favorites...")
                } else if favorites.isEmpty {
                    VStack(spacing: 20) {
                        Spacer()
                        Image(systemName: "heart")
                            .font(.system(size: 60))
                            .foregroundColor(.gray)

                        Text("No Favorites Yet")
                            .font(.title2.bold())

                        Text("Scan products and tap the heart icon to save them here.")
                            .font(.subheadline)
                            .foregroundColor(.secondary)
                            .multilineTextAlignment(.center)
                            .padding(.horizontal, 40)

                        Spacer()
                    }
                } else {
                    ScrollView {
                        LazyVStack(spacing: 12) {
                            ForEach(favorites) { product in
                                ProductCard(product: product)
                                    .onTapGesture {
                                        selectedProduct = product
                                    }
                            }
                        }
                        .padding()
                    }
                }
            }
            .navigationTitle("Favorites")
            .navigationDestination(isPresented: Binding(
                get: { selectedProduct != nil },
                set: { if !$0 { selectedProduct = nil } }
            )) {
                if let product = selectedProduct {
                    ProductScreen(product: product)
                        .environmentObject(appState)
                }
            }
            .task {
                if appState.isAuthenticated {
                    await loadFavorites()
                }
            }
            .refreshable {
                await loadFavorites()
            }
        }
    }

    private func loadFavorites() async {
        isLoading = true
        do {
            let result = try await APIService.shared.getFavorites()
            await MainActor.run {
                favorites = result
                isLoading = false
            }
        } catch {
            await MainActor.run {
                isLoading = false
                appState.showError(error.localizedDescription)
            }
        }
    }
}