import SwiftUI

struct SettingsView: View {
    @EnvironmentObject var iapService: IAPService
    @StateObject private var viewModel: SettingsViewModel

    init() {
        _viewModel = StateObject(wrappedValue: SettingsViewModel(iapService: IAPService()))
    }

    var body: some View {
        NavigationStack {
            List {
                // Premium Section
                premiumSection

                // Notifications Section
                notificationsSection

                // Data Section
                dataSection

                // About Section
                aboutSection

                // Danger Zone
                dangerZoneSection
            }
            .navigationTitle("Settings")
            .sheet(isPresented: $viewModel.showingPaywall) {
                PaywallView()
            }
            .sheet(isPresented: $viewModel.showingExportOptions) {
                ExportOptionsSheet(viewModel: viewModel)
            }
            .confirmationDialog(
                "Reset All Data",
                isPresented: $viewModel.showingResetConfirmation,
                titleVisibility: .visible
            ) {
                Button("Reset Everything", role: .destructive) {
                    viewModel.resetAllData()
                }
            } message: {
                Text("This will permanently delete all your investment data. This action cannot be undone.")
            }
            .alert("Success", isPresented: .constant(viewModel.successMessage != nil)) {
                Button("OK") {
                    viewModel.successMessage = nil
                }
            } message: {
                Text(viewModel.successMessage ?? "")
            }
            .alert("Error", isPresented: .constant(viewModel.errorMessage != nil)) {
                Button("OK") {
                    viewModel.errorMessage = nil
                }
            } message: {
                Text(viewModel.errorMessage ?? "")
            }
        }
    }

    // MARK: - Premium Section

    private var premiumSection: some View {
        Section {
            if viewModel.isPremium {
                HStack {
                    ZStack {
                        Circle()
                            .fill(Color.yellow.opacity(0.2))
                            .frame(width: 44, height: 44)

                        Image(systemName: "crown.fill")
                            .foregroundStyle(
                                LinearGradient(
                                    colors: [.yellow, .orange],
                                    startPoint: .topLeading,
                                    endPoint: .bottomTrailing
                                )
                            )
                    }

                    VStack(alignment: .leading, spacing: 2) {
                        Text("Premium Active")
                            .font(.headline)

                        if viewModel.isFamilyShared {
                            Text("Family Sharing")
                                .font(.caption)
                                .foregroundColor(.secondary)
                        }
                    }

                    Spacer()

                    Image(systemName: "checkmark.seal.fill")
                        .foregroundColor(.positiveGreen)
                }
            } else {
                Button {
                    viewModel.upgradeToPremium()
                } label: {
                    HStack {
                        ZStack {
                            Circle()
                                .fill(Color.appPrimary.opacity(0.1))
                                .frame(width: 44, height: 44)

                            Image(systemName: "crown.fill")
                                .foregroundColor(.appPrimary)
                        }

                        VStack(alignment: .leading, spacing: 2) {
                            Text("Upgrade to Premium")
                                .font(.headline)
                                .foregroundColor(.primary)

                            Text("Unlock all features for €4.69")
                                .font(.caption)
                                .foregroundColor(.secondary)
                        }

                        Spacer()

                        Image(systemName: "chevron.right")
                            .foregroundColor(.secondary)
                    }
                }

                Button {
                    Task {
                        await viewModel.restorePurchases()
                    }
                } label: {
                    Text("Restore Purchases")
                }
            }
        } header: {
            Text("Subscription")
        } footer: {
            if !viewModel.isPremium {
                Text("Free: \(viewModel.sourceLimitText) • \(viewModel.historyLimitText)")
            }
        }
    }

    // MARK: - Notifications Section

    private var notificationsSection: some View {
        Section {
            HStack {
                Text("Notifications")
                Spacer()
                Text(viewModel.notificationsEnabled ? "Enabled" : "Disabled")
                    .foregroundColor(.secondary)
            }
            .contentShape(Rectangle())
            .onTapGesture {
                if !viewModel.notificationsEnabled {
                    Task {
                        await viewModel.requestNotificationPermission()
                    }
                } else {
                    viewModel.openSystemSettings()
                }
            }

            if viewModel.notificationsEnabled {
                DatePicker(
                    "Default Reminder Time",
                    selection: $viewModel.defaultNotificationTime,
                    displayedComponents: .hourAndMinute
                )
                .onChange(of: viewModel.defaultNotificationTime) { _, newTime in
                    viewModel.updateNotificationTime(newTime)
                }
            }
        } header: {
            Text("Notifications")
        } footer: {
            Text("Set when you'd like to receive investment update reminders.")
        }
    }

    // MARK: - Data Section

    private var dataSection: some View {
        Section {
            Button {
                if viewModel.canExport {
                    viewModel.showingExportOptions = true
                } else {
                    viewModel.showingPaywall = true
                }
            } label: {
                HStack {
                    Label("Export Data", systemImage: "square.and.arrow.up")

                    Spacer()

                    if !viewModel.canExport {
                        Image(systemName: "lock.fill")
                            .font(.caption)
                            .foregroundColor(.appWarning)
                    }
                }
            }

            HStack {
                Text("Total Sources")
                Spacer()
                Text("\(viewModel.totalSources)")
                    .foregroundColor(.secondary)
            }

            HStack {
                Text("Total Snapshots")
                Spacer()
                Text("\(viewModel.totalSnapshots)")
                    .foregroundColor(.secondary)
            }

            HStack {
                Text("Storage Used")
                Spacer()
                Text(viewModel.storageUsedText)
                    .foregroundColor(.secondary)
            }
        } header: {
            Text("Data")
        }
    }

    // MARK: - About Section

    private var aboutSection: some View {
        Section {
            HStack {
                Text("Version")
                Spacer()
                Text(viewModel.appVersion)
                    .foregroundColor(.secondary)
            }

            Link(destination: URL(string: AppConstants.URLs.privacyPolicy)!) {
                HStack {
                    Text("Privacy Policy")
                    Spacer()
                    Image(systemName: "arrow.up.right")
                        .font(.caption)
                        .foregroundColor(.secondary)
                }
            }

            Link(destination: URL(string: AppConstants.URLs.termsOfService)!) {
                HStack {
                    Text("Terms of Service")
                    Spacer()
                    Image(systemName: "arrow.up.right")
                        .font(.caption)
                        .foregroundColor(.secondary)
                }
            }

            Link(destination: URL(string: AppConstants.URLs.support)!) {
                HStack {
                    Text("Support")
                    Spacer()
                    Image(systemName: "arrow.up.right")
                        .font(.caption)
                        .foregroundColor(.secondary)
                }
            }

            Button {
                requestAppReview()
            } label: {
                HStack {
                    Text("Rate App")
                    Spacer()
                    Image(systemName: "star.fill")
                        .foregroundColor(.yellow)
                }
            }
        } header: {
            Text("About")
        }
    }

    // MARK: - Danger Zone Section

    private var dangerZoneSection: some View {
        Section {
            Button(role: .destructive) {
                viewModel.showingResetConfirmation = true
            } label: {
                HStack {
                    Image(systemName: "trash")
                    Text("Reset All Data")
                }
            }
        } header: {
            Text("Danger Zone")
        } footer: {
            Text("This will permanently delete all your investment sources, snapshots, and settings.")
        }
    }

    // MARK: - Helpers

    private func requestAppReview() {
        guard let scene = UIApplication.shared.connectedScenes.first as? UIWindowScene else { return }
        import StoreKit
        SKStoreReviewController.requestReview(in: scene)
    }
}

// MARK: - Export Options Sheet

struct ExportOptionsSheet: View {
    @Environment(\.dismiss) private var dismiss
    @ObservedObject var viewModel: SettingsViewModel

    var body: some View {
        NavigationStack {
            List {
                Section {
                    Button {
                        viewModel.exportData(format: .csv)
                        dismiss()
                    } label: {
                        HStack {
                            Image(systemName: "tablecells")
                                .foregroundColor(.positiveGreen)
                                .frame(width: 30)

                            VStack(alignment: .leading) {
                                Text("CSV")
                                    .font(.headline)
                                Text("Compatible with Excel, Google Sheets")
                                    .font(.caption)
                                    .foregroundColor(.secondary)
                            }
                        }
                    }

                    Button {
                        viewModel.exportData(format: .json)
                        dismiss()
                    } label: {
                        HStack {
                            Image(systemName: "doc.text")
                                .foregroundColor(.appPrimary)
                                .frame(width: 30)

                            VStack(alignment: .leading) {
                                Text("JSON")
                                    .font(.headline)
                                Text("Full data structure for backup")
                                    .font(.caption)
                                    .foregroundColor(.secondary)
                            }
                        }
                    }
                } header: {
                    Text("Select Format")
                }
            }
            .navigationTitle("Export Data")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .navigationBarTrailing) {
                    Button("Cancel") {
                        dismiss()
                    }
                }
            }
        }
        .presentationDetents([.medium])
    }
}

#Preview {
    SettingsView()
        .environmentObject(IAPService())
}