import UIKit
import StoreKit

@MainActor
final class ReviewPromptService {
    static let shared = ReviewPromptService()

    private let reviewCompletedKey = "review_funnel_completed"
    private let lastPromptedCompletedWeeksKey = "review_funnel_last_prompted_completed_weeks"
    private let postPurchaseAskedKey = "review_post_purchase_asked"
    private let premiumUserAskedKey = "review_premium_user_asked"
    private let minimumCompletedWeeksToStart = 1
    private let promptIntervalWeeks = 2

    /// Write-review deep link: always opens the App Store review form, unlike
    /// `SKStoreReviewController` which Apple throttles to 3 prompts/year and
    /// silently no-ops the rest of the time.
    static let writeReviewURL = URL(string: "https://apps.apple.com/app/id6759255553?action=write-review")!

    private init() {}

    /// Asks for a rating right after a successful subscription purchase — the
    /// user just paid, so sentiment is at its peak. Once per user; the small
    /// delay lets the "premium active" state render before the system alert.
    func requestAfterPurchase() {
        guard !hasCompletedReviewFlow else { return }
        guard !UserDefaults.standard.bool(forKey: postPurchaseAskedKey) else { return }
        UserDefaults.standard.set(true, forKey: postPurchaseAskedKey)
        AnalyticsService.logEvent("review_prompt_post_purchase")
        Task { @MainActor in
            try? await Task.sleep(for: .seconds(2))
            requestReview()
            markReviewCompleted()
        }
    }

    /// One-time ask for users who were already premium before the post-purchase
    /// prompt existed — they never went through it, and a paying user is the
    /// most likely 5-star reviewer the app has.
    func requestForExistingPremiumUser() {
        guard !hasCompletedReviewFlow else { return }
        guard !UserDefaults.standard.bool(forKey: premiumUserAskedKey) else { return }
        UserDefaults.standard.set(true, forKey: premiumUserAskedKey)
        AnalyticsService.logEvent("review_prompt_premium_user")
        Task { @MainActor in
            try? await Task.sleep(for: .seconds(2))
            requestReview()
            markReviewCompleted()
        }
    }

    func shouldShowFunnelAfterWeekCompletion(completedWeeks: Int) -> Bool {
        guard !hasCompletedReviewFlow else { return false }
        guard completedWeeks >= minimumCompletedWeeksToStart else { return false }
        guard completedWeeks % promptIntervalWeeks == 0 else { return false }

        let lastPrompted = UserDefaults.standard.integer(forKey: lastPromptedCompletedWeeksKey)
        return completedWeeks > lastPrompted
    }

    func markFunnelShown(completedWeeks: Int) {
        UserDefaults.standard.set(completedWeeks, forKey: lastPromptedCompletedWeeksKey)
    }

    func markReviewCompleted() {
        UserDefaults.standard.set(true, forKey: reviewCompletedKey)
    }

    var hasCompletedReviewFlow: Bool {
        UserDefaults.standard.bool(forKey: reviewCompletedKey)
    }

    func requestReview() {
        guard let scene = UIApplication.shared.connectedScenes
            .compactMap({ $0 as? UIWindowScene })
            .first(where: { $0.activationState == .foregroundActive }) else { return }

        SKStoreReviewController.requestReview(in: scene)
    }
}