import SwiftUI

struct PaywallView: View {
    @Environment(\.dismiss) private var dismiss
    @EnvironmentObject var iapService: IAPService

    @State private var isPurchasing = false
    @State private var errorMessage: String?
    @State private var showingError = false

    var body: some View {
        NavigationStack {
            ScrollView {
                VStack(spacing: 24) {
                    // Header
                    headerSection

                    // Features List
                    featuresSection

                    // Price Card
                    priceCard

                    // Purchase Button
                    purchaseButton

                    // Restore Button
                    restoreButton

                    // Legal
                    legalSection
                }
                .padding()
            }
            .navigationTitle("Upgrade to Premium")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .navigationBarLeading) {
                    Button {
                        dismiss()
                    } label: {
                        Image(systemName: "xmark")
                            .foregroundColor(.secondary)
                    }
                }
            }
            .alert("Error", isPresented: $showingError) {
                Button("OK", role: .cancel) {}
            } message: {
                Text(errorMessage ?? "An error occurred")
            }
            .onChange(of: iapService.isPremium) { _, isPremium in
                if isPremium {
                    dismiss()
                }
            }
        }
    }

    // MARK: - Header Section

    private var headerSection: some View {
        VStack(spacing: 16) {
            // Crown icon
            ZStack {
                Circle()
                    .fill(
                        LinearGradient(
                            colors: [Color.yellow.opacity(0.3), Color.orange.opacity(0.3)],
                            startPoint: .topLeading,
                            endPoint: .bottomTrailing
                        )
                    )
                    .frame(width: 80, height: 80)

                Image(systemName: "crown.fill")
                    .font(.system(size: 36))
                    .foregroundStyle(
                        LinearGradient(
                            colors: [.yellow, .orange],
                            startPoint: .topLeading,
                            endPoint: .bottomTrailing
                        )
                    )
            }

            Text("Unlock Full Potential")
                .font(.title.weight(.bold))

            Text("Get unlimited access to all features with a one-time purchase")
                .font(.subheadline)
                .foregroundColor(.secondary)
                .multilineTextAlignment(.center)
        }
    }

    // MARK: - Features Section

    private var featuresSection: some View {
        VStack(spacing: 12) {
            ForEach(IAPService.premiumFeatures, id: \.title) { feature in
                FeatureRow(
                    icon: feature.icon,
                    title: feature.title,
                    description: feature.description
                )
            }
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }

    // MARK: - Price Card

    private var priceCard: some View {
        VStack(spacing: 8) {
            HStack(alignment: .top, spacing: 4) {
                Text("€")
                    .font(.title2.weight(.semibold))
                    .foregroundColor(.appPrimary)

                Text("4.69")
                    .font(.system(size: 48, weight: .bold, design: .rounded))
                    .foregroundColor(.appPrimary)
            }

            Text("One-time purchase")
                .font(.subheadline)
                .foregroundColor(.secondary)

            HStack(spacing: 4) {
                Image(systemName: "person.2.fill")
                    .font(.caption)
                Text("Includes Family Sharing")
                    .font(.caption)
            }
            .foregroundColor(.appSecondary)
            .padding(.top, 4)
        }
        .frame(maxWidth: .infinity)
        .padding(.vertical, 24)
        .background(
            RoundedRectangle(cornerRadius: AppConstants.UI.cornerRadius)
                .fill(Color.appPrimary.opacity(0.1))
                .overlay(
                    RoundedRectangle(cornerRadius: AppConstants.UI.cornerRadius)
                        .stroke(Color.appPrimary, lineWidth: 2)
                )
        )
    }

    // MARK: - Purchase Button

    private var purchaseButton: some View {
        Button {
            purchase()
        } label: {
            HStack {
                if isPurchasing {
                    ProgressView()
                        .tint(.white)
                } else {
                    Text("Upgrade Now")
                        .font(.headline)
                }
            }
            .frame(maxWidth: .infinity)
            .padding()
            .background(Color.appPrimary)
            .foregroundColor(.white)
            .cornerRadius(AppConstants.UI.cornerRadius)
        }
        .disabled(isPurchasing)
    }

    // MARK: - Restore Button

    private var restoreButton: some View {
        Button {
            restore()
        } label: {
            Text("Restore Purchases")
                .font(.subheadline)
                .foregroundColor(.appPrimary)
        }
        .disabled(isPurchasing)
    }

    // MARK: - Legal Section

    private var legalSection: some View {
        VStack(spacing: 8) {
            Text("Payment will be charged to your Apple ID account. By purchasing, you agree to our Terms of Service and Privacy Policy.")
                .font(.caption2)
                .foregroundColor(.secondary)
                .multilineTextAlignment(.center)

            HStack(spacing: 16) {
                Link("Terms", destination: URL(string: AppConstants.URLs.termsOfService)!)
                    .font(.caption)

                Link("Privacy", destination: URL(string: AppConstants.URLs.privacyPolicy)!)
                    .font(.caption)
            }
        }
        .padding(.top, 8)
    }

    // MARK: - Actions

    private func purchase() {
        isPurchasing = true
        FirebaseService.shared.logPurchaseAttempt(productId: IAPService.premiumProductID)

        Task {
            do {
                try await iapService.purchase()
            } catch {
                errorMessage = error.localizedDescription
                showingError = true
            }
            isPurchasing = false
        }
    }

    private func restore() {
        isPurchasing = true

        Task {
            await iapService.restorePurchases()

            if !iapService.isPremium {
                errorMessage = "No purchases found to restore"
                showingError = true
            }
            isPurchasing = false
        }
    }
}

// MARK: - Feature Row

struct FeatureRow: View {
    let icon: String
    let title: String
    let description: String

    var body: some View {
        HStack(spacing: 16) {
            ZStack {
                Circle()
                    .fill(Color.appPrimary.opacity(0.1))
                    .frame(width: 44, height: 44)

                Image(systemName: icon)
                    .font(.system(size: 18))
                    .foregroundColor(.appPrimary)
            }

            VStack(alignment: .leading, spacing: 2) {
                Text(title)
                    .font(.subheadline.weight(.semibold))

                Text(description)
                    .font(.caption)
                    .foregroundColor(.secondary)
            }

            Spacer()

            Image(systemName: "checkmark.circle.fill")
                .foregroundColor(.positiveGreen)
        }
    }
}

// MARK: - Compact Paywall (for inline use)

struct CompactPaywallBanner: View {
    @Binding var showingPaywall: Bool

    var body: some View {
        HStack(spacing: 12) {
            Image(systemName: "crown.fill")
                .font(.title2)
                .foregroundStyle(
                    LinearGradient(
                        colors: [.yellow, .orange],
                        startPoint: .topLeading,
                        endPoint: .bottomTrailing
                    )
                )

            VStack(alignment: .leading, spacing: 2) {
                Text("Unlock Premium")
                    .font(.subheadline.weight(.semibold))

                Text("Get unlimited access to all features")
                    .font(.caption)
                    .foregroundColor(.secondary)
            }

            Spacer()

            Button {
                showingPaywall = true
            } label: {
                Text("€4.69")
                    .font(.caption.weight(.semibold))
                    .padding(.horizontal, 12)
                    .padding(.vertical, 6)
                    .background(Color.appPrimary)
                    .foregroundColor(.white)
                    .cornerRadius(16)
            }
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
    }
}

// MARK: - Premium Lock Overlay

struct PremiumLockOverlay: View {
    let feature: String
    @Binding var showingPaywall: Bool

    var body: some View {
        VStack(spacing: 16) {
            Image(systemName: "lock.fill")
                .font(.system(size: 32))
                .foregroundColor(.appWarning)

            Text("Premium Feature")
                .font(.headline)

            Text(feature)
                .font(.subheadline)
                .foregroundColor(.secondary)
                .multilineTextAlignment(.center)

            Button {
                showingPaywall = true
            } label: {
                Label("Unlock", systemImage: "crown.fill")
                    .font(.subheadline.weight(.semibold))
                    .padding(.horizontal, 20)
                    .padding(.vertical, 10)
                    .background(Color.appPrimary)
                    .foregroundColor(.white)
                    .cornerRadius(20)
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(Color(.systemBackground).opacity(0.95))
    }
}

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