final class IAPManager: NSObject, SKProductsRequestDelegate, SKPaymentTransactionObserver {
    static let shared = IAPManager()
    static var enabled = true

    private var products = [SKProduct]()
    private var completion: (() -> Void)?
    private var productBeingPurchased: SKProduct?

    enum Product: String, CaseIterable {
        case removeAds = "JokesRUs.RemoveAds1"
        case summerIcon = "JokesRUs.Icons.Summer"
        case tacoIcon = "JokesRUs.Icons.Taco"
        case pizzaIcon = "JokesRUs.Icons.Pizza"
        case hotdogIcon = "JokesRUs.Icons.HotDog"
        case hamburgerIcon = "JokesRUs.Icons.Hamburger"
        case doughnutIcon = "JokesRUs.Icons.Doughnut"
        case support1 = "JokesRUs.Support.One"
        case support5 = "JokesRUs.Support.Five"
        case support10 = "JokesRUs.Support.Ten"
        case support20 = "JokesRUs.Support.Twenty"
    }
    let group = DispatchGroup()
    
    public func fetchProducts() {
        let request = SKProductsRequest(productIdentifiers: Set(Product.allCases.compactMap(({ $0.rawValue }))))
        request.delegate = self
        request.start()
    }
    func productsRequest(_ request: SKProductsRequest, didReceive response: SKProductsResponse) {
        print("products returned = \(response.products.count )")
        products = response.products
    }
    func request(_ request: SKRequest, didFailWithError error: Error) {
        guard request is SKProductsRequest else {
            return
        }

        print("Product fetch request failed")
    }
    public func purchase(product: Product, completion: @escaping (() -> Void)) {
        print("product = \(product)")
        print("can make payments = \(SKPaymentQueue.canMakePayments())")
        guard SKPaymentQueue.canMakePayments() else {
            return
        }
        print("product = \(product.rawValue)")
        guard let storeKitProduct = products.first(where: { $0.productIdentifier == product.rawValue }) else {
            return
        }
        Utilities.purchaseFailed = false
        print("call purchase")
        let paymentRequest = SKPayment(product: storeKitProduct)
        SKPaymentQueue.default().add(self)
        SKPaymentQueue.default().add(paymentRequest)
        print("Payments pending = \(SKPaymentQueue.default().transactions)")
//        completion()
        self.completion = completion
    }
    public func restore() {
        print("start restore")
        Utilities.restoredPurchases = false
        SKPaymentQueue.default().restoreCompletedTransactions()
    }
    
    func paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction]) {
        transactions.forEach({ transaction in
            print("id = \(transaction.payment.productIdentifier), state = \(transaction.transactionState)")
            switch transaction.transactionState {
            case .purchasing:
                //No op
                print("purchasing")
                break
            case .purchased:
                handlePurchase(transaction.payment.productIdentifier)
                Utilities.purchaseFailed = false
                break
            case .failed:
                print("purchase failed")
                Utilities.purchaseFailed = true
                Utilities.restoredPurchases = false
                NotificationCenter.default.post(name: NSNotification.Name(rawValue: "checkFailedPurchase"), object: nil)
                completion?()
                break
            case .restored:
                print("purchases restored")
                handlePurchase(transaction.payment.productIdentifier)
                Utilities.restoredPurchases = true
                print("finish restore")
                NotificationCenter.default.post(name: NSNotification.Name(rawValue: "checkRestored"), object: nil)
                SKPaymentQueue.default().finishTransaction(transaction)
                break
            case .deferred:
                print("purchase deferred")
                completion?()
                break
            @unknown default:
                print("default")
                completion?()
                break
            }
        })
}
    private func handlePurchase(_ id: String) {
        print("Pass on Icon = \(IconChange.passOnIcon)")
        Analytics.logEvent("Purchase", parameters: [
            "Purchase ID" : id
        ])
        UserDefaults.standard.setValue(true, forKey: id)
        print("id = \(id)")
        Utilities.purchaseID = id
        if id.contains("support") {
            completion?()
        }
        
        if id == "JokesRUs.RemoveAds" {
            Utilities.ShowAds = false
            NotificationCenter.default.post(name: NSNotification.Name(rawValue: "AdsRemoved"), object: nil)
            completion?()
        }
        if id == "JokesRUs.Icons.Summer" {
            print("summer bought")
            IconChange.setIconPurchased = true
            IconChange.summerIconUnlocked = true
            IconChange.numUnlocked = IconChange.numUnlocked + 1
            UserDefaults.standard.setValue(IconChange.numUnlocked + 1, forKey: "numUnlocked")
            UserDefaults.standard.setValue(true, forKey: "summerIconUnlocked")
            NotificationCenter.default.post(name: NSNotification.Name(rawValue: "setIcon"), object: nil)
            completion?()
        }