import SwiftUI
#if canImport(LCEssentials)
import LCEssentials
#endif

/// State -> city picker for anonymous browsing (public store locator).
/// Replaces AddressesView in the address-picker modal when the user is
/// not authenticated — see docs/plans/public-store-locator-sdd.md.
struct PublicLocationPickerView: View {
    @Binding var appState: AppState
    @Environment(\.dismiss) var dismiss

    private enum Step {
        case state
        case city
    }

    @State private var step: Step = .state
    @State private var locations: PublicLocationsResult = [:]
    @State private var selectedState: String? = nil
    @State private var isLoading = false
    @State private var errorMessage: String? = nil

    private var states: [String] {
        locations.keys.sorted()
    }

    private var cities: [String] {
        guard let selectedState else { return [] }
        return (locations[selectedState] ?? []).sorted()
    }

    var body: some View {
        LCENavigationView {
            content
        }
        .setLeftButton(image: AnyView(AppBackButtonIcon())) { back() }
        .setTitle(text: Text(step == .state ? "Escolha seu estado" : "Escolha sua cidade").font(AppTypography.heading2).foregroundStyle(AppColors.textPrimary))
        .setNavigationBarBackgroundColor(AppColors.backgroundLight)
        .buttonStyle(.plain)
    }

    private var content: some View {
        ZStack {
            AppColors.backgroundLight.ignoresSafeArea()

            VStack(spacing: 20) {
                if isLoading {
                    ProgressView()
                        .padding(.top, 40)
                } else if let errorMessage {
                    VStack(spacing: 12) {
                        Text(errorMessage)
                            .font(AppTypography.body)
                            .foregroundStyle(AppColors.textMuted)
                            .multilineTextAlignment(.center)
                        Button("Tentar novamente") {
                            Task { await loadLocations() }
                        }
                        .font(AppTypography.heading3)
                        .foregroundStyle(AppColors.primary)
                    }
                    .padding(.horizontal, 20)
                    .padding(.top, 40)
                } else {
                    list
                }

                Spacer(minLength: 0)
            }
            .padding(.top, 18)
        }
        .navigationBarBackButtonHidden(true)
        .appHiddenNavigationBar()
        .task {
            await loadLocations()
        }
    }

    private var list: some View {
        ScrollView(showsIndicators: false) {
            LazyVStack(spacing: 12) {
                switch step {
                case .state:
                    ForEach(states, id: \.self) { state in
                        rowButton(title: state) {
                            selectedState = state
                            step = .city
                        }
                    }
                case .city:
                    ForEach(cities, id: \.self) { city in
                        rowButton(title: city) {
                            confirmSelection(city: city)
                        }
                    }
                }
            }
            .padding(.horizontal, 20)
            .padding(.top, 8)
        }
    }

    private func rowButton(title: String, action: @escaping () -> Void) -> some View {
        Button(action: action) {
            HStack {
                Text(title)
                    .font(AppTypography.body)
                    .foregroundStyle(AppColors.textPrimary)
                Spacer()
                Image(systemName: "chevron.right")
                    .font(.system(size: 14, weight: .semibold))
                    .foregroundStyle(AppColors.textMuted)
            }
            .padding(.horizontal, 18)
            .padding(.vertical, 16)
            .background(AppColors.surface)
            .clipShape(RoundedRectangle(cornerRadius: 16, style: .continuous))
        }
        .buttonStyle(.plain)
    }

    private func back() {
        switch step {
        case .city:
            step = .state
            errorMessage = nil
        case .state:
            dismiss()
        }
    }

    private func confirmSelection(city: String) {
        guard let selectedState else { return }
        GuestLocationStore.shared.selectedState = selectedState
        GuestLocationStore.shared.selectedCity = city
        appState.address.display = "\(city), \(selectedState)"
        appState.address.onboardingMessage = nil
        dismiss()
    }

    @MainActor
    private func loadLocations() async {
        isLoading = true
        errorMessage = nil
        do {
            locations = try await PublicLocationService.shared.fetchLocations()
            if locations.isEmpty {
                errorMessage = "Nenhum estado disponível no momento."
            }
        } catch {
            print("[PublicLocationPickerView] loadLocations failed: \(error)")
            errorMessage = "Não foi possível carregar. Tente novamente."
        }
        isLoading = false
    }
}

#Preview {
    NavigationStack {
        PublicLocationPickerView(appState: .constant(AppState()))
    }
}