//
//  OnboardingPaywallView.swift
//  SportsTime
//
//  First-launch upsell with feature pages.
//

import SwiftUI
import StoreKit

struct OnboardingPaywallView: View {
    @Environment(\.colorScheme) private var colorScheme
    @Binding var isPresented: Bool

    @State private var currentPage = 0
    @State private var selectedProduct: Product?
    @State private var isPurchasing = false
    @State private var errorMessage: String?

    private let storeManager = StoreManager.shared

    private let pages: [(icon: String, title: String, description: String, color: Color)] = [
        ("suitcase.fill", "Unlimited Trips", "Plan as many road trips as you want. Never lose your itineraries.", Theme.warmOrange),
        ("doc.fill", "Export & Share", "Generate beautiful PDF itineraries to share with friends.", Theme.routeGold),
        ("trophy.fill", "Track Your Journey", "Log stadium visits, earn badges, complete your bucket list.", .green)
    ]

    var body: some View {
        VStack(spacing: 0) {
            // Page content
            TabView(selection: $currentPage) {
                ForEach(0..<pages.count, id: \.self) { index in
                    featurePage(index: index)
                        .tag(index)
                }

                // Pricing page
                pricingPage
                    .tag(pages.count)
            }
            .tabViewStyle(.page(indexDisplayMode: .never))
            .animation(.easeInOut, value: currentPage)

            // Page indicator
            HStack(spacing: 8) {
                ForEach(0...pages.count, id: \.self) { index in
                    Circle()
                        .fill(currentPage == index ? Theme.warmOrange : Theme.textMuted(colorScheme))
                        .frame(width: 8, height: 8)
                }
            }
            .padding(.bottom, Theme.Spacing.lg)

            // Bottom buttons
            bottomButtons
                .padding(.horizontal, Theme.Spacing.lg)
                .padding(.bottom, Theme.Spacing.xl)
        }
        .background(Theme.backgroundGradient(colorScheme))
        .task {
            await storeManager.loadProducts()
            selectedProduct = storeManager.annualProduct ?? storeManager.monthlyProduct
        }
    }

    // MARK: - Feature Page

    private func featurePage(index: Int) -> some View {
        let page = pages[index]

        return VStack(spacing: Theme.Spacing.xl) {
            Spacer()

            ZStack {
                Circle()
                    .fill(page.color.opacity(0.15))
                    .frame(width: 120, height: 120)

                Image(systemName: page.icon)
                    .font(.system(size: 50))
                    .foregroundStyle(page.color)
            }

            VStack(spacing: Theme.Spacing.md) {
                Text(page.title)
                    .font(.title.bold())
                    .foregroundStyle(Theme.textPrimary(colorScheme))

                Text(page.description)
                    .font(.body)
                    .foregroundStyle(Theme.textSecondary(colorScheme))
                    .multilineTextAlignment(.center)
                    .padding(.horizontal, Theme.Spacing.xl)
            }

            Spacer()
            Spacer()
        }
    }

    // MARK: - Pricing Page

    private var pricingPage: some View {
        VStack(spacing: Theme.Spacing.lg) {
            Spacer()

            Text("Choose Your Plan")
                .font(.title.bold())
                .foregroundStyle(Theme.textPrimary(colorScheme))

            if storeManager.isLoading {
                ProgressView()
            } else {
                VStack(spacing: Theme.Spacing.md) {
                    // Annual (recommended)
                    if let annual = storeManager.annualProduct {
                        OnboardingPricingRow(
                            product: annual,
                            title: "Annual",
                            subtitle: "Best Value - Save 17%",
                            isSelected: selectedProduct?.id == annual.id,
                            isRecommended: true
                        ) {
                            selectedProduct = annual
                        }
                    }

                    // Monthly
                    if let monthly = storeManager.monthlyProduct {
                        OnboardingPricingRow(
                            product: monthly,
                            title: "Monthly",
                            subtitle: "Flexible billing",
                            isSelected: selectedProduct?.id == monthly.id,
                            isRecommended: false
                        ) {
                            selectedProduct = monthly
                        }
                    }
                }
                .padding(.horizontal, Theme.Spacing.lg)
            }

            if let error = errorMessage {
                Text(error)
                    .font(.caption)
                    .foregroundStyle(.red)
            }

            Spacer()
            Spacer()
        }
    }

    // MARK: - Bottom Buttons

    private var bottomButtons: some View {
        VStack(spacing: Theme.Spacing.md) {
            if currentPage < pages.count {
                // Next button
                Button {
                    withAnimation {
                        currentPage += 1
                    }
                } label: {
                    Text("Next")
                        .fontWeight(.semibold)
                        .frame(maxWidth: .infinity)
                        .padding(Theme.Spacing.md)
                        .background(Theme.warmOrange)
                        .foregroundStyle(.white)
                        .clipShape(RoundedRectangle(cornerRadius: Theme.CornerRadius.medium))
                }

                // Skip
                Button {
                    markOnboardingSeen()
                    isPresented = false
                } label: {
                    Text("Continue with Free")
                        .font(.subheadline)
                        .foregroundStyle(Theme.textMuted(colorScheme))
                }
            } else {
                // Subscribe button
                Button {
                    Task {
                        await purchase()
                    }
                } label: {
                    HStack {
                        if isPurchasing {
                            ProgressView()
                                .tint(.white)
                        } else {
                            Text("Subscribe")
                                .fontWeight(.semibold)
                        }
                    }
                    .frame(maxWidth: .infinity)
                    .padding(Theme.Spacing.md)
                    .background(Theme.warmOrange)
                    .foregroundStyle(.white)
                    .clipShape(RoundedRectangle(cornerRadius: Theme.CornerRadius.medium))
                }
                .disabled(selectedProduct == nil || isPurchasing)

                // Continue free
                Button {
                    markOnboardingSeen()
                    isPresented = false
                } label: {
                    Text("Continue with Free")
                        .font(.subheadline)
                        .foregroundStyle(Theme.textMuted(colorScheme))
                }
            }
        }
    }

    // MARK: - Actions

    private func purchase() async {
        guard let product = selectedProduct else { return }

        isPurchasing = true
        errorMessage = nil

        do {
            try await storeManager.purchase(product)
            markOnboardingSeen()
            isPresented = false
        } catch StoreError.userCancelled {
            // User cancelled
        } catch {
            errorMessage = error.localizedDescription
        }

        isPurchasing = false
    }

    private func markOnboardingSeen() {
        UserDefaults.standard.set(true, forKey: "hasSeenOnboardingPaywall")
    }
}

// MARK: - Pricing Row

struct OnboardingPricingRow: View {
    let product: Product
    let title: String
    let subtitle: String
    let isSelected: Bool
    let isRecommended: Bool
    let onSelect: () -> Void

    @Environment(\.colorScheme) private var colorScheme

    var body: some View {
        Button(action: onSelect) {
            HStack {
                VStack(alignment: .leading, spacing: 4) {
                    HStack(spacing: Theme.Spacing.xs) {
                        Text(title)
                            .font(.body.bold())
                            .foregroundStyle(Theme.textPrimary(colorScheme))

                        if isRecommended {
                            Text("BEST")
                                .font(.caption2.bold())
                                .foregroundStyle(.white)
                                .padding(.horizontal, 6)
                                .padding(.vertical, 2)
                                .background(Theme.warmOrange, in: Capsule())
                        }
                    }

                    Text(subtitle)
                        .font(.caption)
                        .foregroundStyle(Theme.textSecondary(colorScheme))
                }

                Spacer()

                Text(product.displayPrice)
                    .font(.title3.bold())
                    .foregroundStyle(Theme.textPrimary(colorScheme))

                Image(systemName: isSelected ? "checkmark.circle.fill" : "circle")
                    .foregroundStyle(isSelected ? Theme.warmOrange : Theme.textMuted(colorScheme))
            }
            .padding(Theme.Spacing.lg)
            .background(Theme.cardBackground(colorScheme))
            .clipShape(RoundedRectangle(cornerRadius: Theme.CornerRadius.large))
            .overlay {
                RoundedRectangle(cornerRadius: Theme.CornerRadius.large)
                    .stroke(isSelected ? Theme.warmOrange : Theme.surfaceGlow(colorScheme), lineWidth: isSelected ? 2 : 1)
            }
        }
        .buttonStyle(.plain)
    }
}

#Preview {
    OnboardingPaywallView(isPresented: .constant(true))
}