import StoreKit
import UIKit

final class ReviewPromptService {
    static let shared = ReviewPromptService()

    private let lastPromptKey = "reviewPromptLastDate"
    private let checkInCountKey = "reviewPromptCheckinCount"
    private let minCheckInsBetweenPrompts = 3
    private let minDaysBetweenPrompts = 90
    private let userDefaults: UserDefaults
    private let dateProvider: () -> Date
    private let reviewRequestHandler: () -> Void

    private init() {
        userDefaults = .standard
        dateProvider = Date.init
        reviewRequestHandler = ReviewPromptService.defaultReviewRequestHandler
    }

    init(
        userDefaults: UserDefaults,
        dateProvider: @escaping () -> Date,
        reviewRequestHandler: @escaping () -> Void
    ) {
        self.userDefaults = userDefaults
        self.dateProvider = dateProvider
        self.reviewRequestHandler = reviewRequestHandler
    }

    func recordMonthlyCheckInCompleted() {
        let currentCount = userDefaults.integer(forKey: checkInCountKey)
        userDefaults.set(currentCount + 1, forKey: checkInCountKey)
        requestReviewIfEligible()
    }

    private func requestReviewIfEligible() {
        let now = dateProvider()
        if let lastPrompt = userDefaults.object(forKey: lastPromptKey) as? Date {
            let daysSince = now.timeIntervalSince(lastPrompt) / 86_400
            if daysSince < Double(minDaysBetweenPrompts) {
                return
            }
        }

        let count = userDefaults.integer(forKey: checkInCountKey)
        guard count >= minCheckInsBetweenPrompts else { return }

        requestReview()
    }

    private func requestReview() {
        reviewRequestHandler()
        userDefaults.set(dateProvider(), forKey: lastPromptKey)
        userDefaults.set(0, forKey: checkInCountKey)
    }

    private static func defaultReviewRequestHandler() {
        guard let scene = UIApplication.shared.connectedScenes.first as? UIWindowScene else { return }
        if #available(iOS 18.0, *) {
            AppStore.requestReview(in: scene)
        } else {
            SKStoreReviewController.requestReview(in: scene)
        }
    }
}