import SwiftUI
import SwiftData

struct PaywallStepView: View {
    @Environment(\.modelContext) private var context
    @Query private var allSettings: [AppSettings]
    @StateObject private var storeManager = StoreManager()

    var onSkip: () -> Void
    var onConverted: () -> Void

    @State private var purchaseStatusMessageKey: String?

    var body: some View {
        ZStack {
            Color.mealMoodBackground.ignoresSafeArea()

            VStack(spacing: 24) {
                AppIconPlaceholder(size: 84)
                    .padding(.top, 20)

                VStack(spacing: 8) {
                    Text("onboarding_paywall_title")
                        .font(.mealMoodH1)
                        .foregroundColor(.mealMoodTextPrimary)
                        .multilineTextAlignment(.center)
                    Text("onboarding_paywall_subtitle")
                        .font(.mealMoodBody)
                        .foregroundColor(.mealMoodTextSecondary)
                        .multilineTextAlignment(.center)
                }
                .padding(.horizontal, 24)

                VStack(alignment: .leading, spacing: 10) {
                    benefitRow(text: String(localized: "premium_unlimited_dishes"))
                    benefitRow(text: String(localized: "premium_advanced_rules"))
                    benefitRow(text: String(localized: "premium_future_weeks"))
                    benefitRow(text: String(localized: "premium_no_ads"))
                }
                .padding(16)
                .background(Color.mealMoodSurface)
                .clipShape(RoundedRectangle(cornerRadius: 14))
                .padding(.horizontal, 24)

                Text("premium_social_proof")
                    .font(.mealMoodCaption)
                    .foregroundColor(.mealMoodTextSecondary)

                Spacer(minLength: 0)

                VStack(spacing: 12) {
                    PrimaryButton(
                        title: trialButtonTitle,
                        action: { Task { await startTrial() } },
                        isEnabled: !storeManager.isLoading
                    )
                    Button(action: skipPaywall) {
                        Text("onboarding_paywall_cta_skip")
                            .font(.mealMoodSmall)
                            .foregroundColor(.mealMoodTextSecondary)
                    }
                    .accessibilityIdentifier("onboarding_cta_paywall_skip")

                    // Required by guideline 3.1.2(c) in every purchase flow.
                    HStack(spacing: 16) {
                        Link(destination: URL(string: "https://mealmood.app/privacy.html")!) {
                            Text("premium_privacy_link")
                                .font(.mealMoodCaption)
                                .underline()
                                .foregroundColor(.mealMoodTextSecondary)
                        }
                        Link(destination: URL(string: "https://mealmood.app/terms.html")!) {
                            Text("premium_terms_link")
                                .font(.mealMoodCaption)
                                .underline()
                                .foregroundColor(.mealMoodTextSecondary)
                        }
                    }
                }
                .padding(.horizontal, 24)
                .padding(.bottom, 24)
            }
        }
        .task { await storeManager.loadProducts() }
        .onAppear { AnalyticsService.logPaywallViewed(source: "onboarding") }
        .alert("premium_title", isPresented: Binding(
            get: { purchaseStatusMessageKey != nil },
            set: { if !$0 { purchaseStatusMessageKey = nil } }
        )) {
            Button("dish_delete_blocked_ok", role: .cancel) {}
        } message: {
            Text(LocalizedStringKey(purchaseStatusMessageKey ?? ""))
        }
    }

    private var trialButtonTitle: String {
        if let yearly = storeManager.yearlyProduct {
            let format = String(localized: "premium_trial_note")
            let priceLabel = yearly.displayPrice + " / " + String(localized: "premium_year")
            return String(localized: "onboarding_paywall_cta_trial") + " — " + String(format: format, priceLabel)
        }
        return String(localized: "onboarding_paywall_cta_trial")
    }

    @ViewBuilder
    private func benefitRow(text: String) -> some View {
        HStack(spacing: 10) {
            Image(systemName: "checkmark.circle.fill")
                .foregroundColor(.mealMoodSuccess)
            Text(text)
                .font(.mealMoodBody)
                .foregroundColor(.mealMoodTextPrimary)
            Spacer()
        }
    }

    private func startTrial() async {
        let candidate = storeManager.yearlyProduct ?? storeManager.monthlyProduct
        guard let product = candidate else {
            purchaseStatusMessageKey = "premium_products_not_found"
            return
        }
        AnalyticsService.logPremiumUpgradeTapped(source: "onboarding")
        let result = await storeManager.purchase(product)
        switch result {
        case .success:
            if let settings = allSettings.first {
                settings.isPremium = true
                try? context.save()
            }
            AnalyticsService.logFreeTrialStarted(plan: product.id)
            onConverted()
        case .pending: purchaseStatusMessageKey = "premium_purchase_pending"
        case .cancelled: purchaseStatusMessageKey = "premium_purchase_cancelled"
        case .failed: purchaseStatusMessageKey = "premium_purchase_failed"
        }
    }

    private func skipPaywall() {
        AnalyticsService.logPaywallDismissed(source: "onboarding", secondsOnScreen: 0, didConvert: false)
        onSkip()
    }
}