import UIKit
import StoreKit

@objc public protocol JXIAPManagerDelegate {
    /// 购买成功
    @objc optional func jx_iapPaySuccess(productId: String, receipt: String, transactionIdentifier: String)
    /// 购买失败
    @objc optional func jx_iapPayFailed(productId: String, code: JXIAPManagerCode, msg: String?)
    /// 恢复商品（仅限永久有效商品）
    @objc optional func iapPayRestore(productIds: [String], transactionIds: [String])
//    /// 加载
//    @objc optional func iapPayShowHud()
//    /// 系统错误
//    @objc optional func iapSysWrong()
//    /// 验证成功
//    @objc optional func verifySuccess()
//    /// 验证失败
//    @objc optional func verifyFailed()
}

@objc public enum JXIAPManagerCode: Int {
    ///未知错误
    case unknown
    ///取消交易
    case cancelled
    ///没有商品
    case noProduct
}

public class JXIAPManager: NSObject {
    
    
    public static let manager: JXIAPManager = JXIAPManager()
    
    public weak var delegate: JXIAPManagerDelegate?
    
    private var payment: SKPayment?
    
    private var product: SKProduct?
    private var productId: String?

    private var discount: SKPaymentDiscount?
    private var orderId: String?
    private var applicationUsername: String?
    
    private var receiptCompletion: ((URL?) -> Void)?
    
    override init() {
        super.init()
        SKPaymentQueue.default().add(self)
    }

    
    public func start(productId: String, orderId: String, applicationUsername: String?, discount: SKPaymentDiscount? = nil) {
        self.product = nil
        self.productId = productId
        self.orderId = orderId
        self.discount = discount
        self.applicationUsername = applicationUsername
        
        let set = Set([productId])
        let productsRequest = SKProductsRequest(productIdentifiers: set)
        productsRequest.delegate = self
        productsRequest.start()
    }
    
    /// 购买商品
    private func buyProduct() {
        guard let product = self.product else { return }
        
        // 要购买商品，开个小票
        let payment = SKMutablePayment(product: product)
        payment.applicationUsername = self.applicationUsername
        if let discount = self.discount {
            payment.paymentDiscount = discount
            self.discount = nil
        }
        
        self.payment = payment
        
        // 去收银台排队，准备购买
        SKPaymentQueue.default().add(payment)
    }
    
}

//MARK: --------------   SKProductsRequestDelegate  --------------
extension JXIAPManager: SKProductsRequestDelegate {
    public func productsRequest(_ request: SKProductsRequest, didReceive response: SKProductsResponse) {
        guard let product = response.products.first else {
            DispatchQueue.main.async {
                if let productId = self.productId {
                    self.productId = nil
                    self.delegate?.jx_iapPayFailed?(productId: productId, code: .noProduct, msg: nil)
                }
            }
            return
        }
        self.product = product
        
        self.buyProduct()
        
    }
}

//MARK: --------------   SKPaymentTransactionObserver  --------------
extension JXIAPManager: SKPaymentTransactionObserver {
    ///购买回调
    public func paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction]) {
        
        for transaction in transactions {
            switch transaction.transactionState {
            case .purchased:
                DispatchQueue.main.async {
                    self.completeTransaction(transaction: transaction)
                }
                SKPaymentQueue.default().finishTransaction(transaction)
                
            case .failed:
                DispatchQueue.main.async {
                    self.failedTransaction(transaction: transaction)
                }
                SKPaymentQueue.default().finishTransaction(transaction)
//            case .restored:
//                self.restoreTransaction(transaction: transaction)
                
            case .purchasing:
                break
            default:
                SKPaymentQueue.default().finishTransaction(transaction)
                break
            }

            
        }
    }
    
//    func paymentQueue(_ queue: SKPaymentQueue, shouldAddStorePayment payment: SKPayment, for product: SKProduct) -> Bool {
//        return true
//    }
    
    /// 恢复购买回调
    public func paymentQueueRestoreCompletedTransactionsFinished(_ queue: SKPaymentQueue) {
        
    }
    
}

extension JXIAPManager {

    
    private func completeTransaction(transaction: SKPaymentTransaction) {
        guard let encodeStr = getAppStoreReceipt() else { return }
        guard let transactionIdentifier = transaction.transactionIdentifier else { return }
        
        guard let productId = self.productId, productId == transaction.payment.productIdentifier else { return }
        self.productId = nil
        self.delegate?.jx_iapPaySuccess?(productId: productId, receipt: encodeStr, transactionIdentifier: transactionIdentifier)
        
    }
    
    private func failedTransaction(transaction: SKPaymentTransaction) {
        let error = transaction.error as? SKError
        guard let productId = self.productId else { return }
        self.productId = nil
        
        switch error?.code {
        case SKError.paymentCancelled:
            self.delegate?.jx_iapPayFailed?(productId: productId, code: .cancelled, msg: error?.localizedDescription)
        default:
            self.delegate?.jx_iapPayFailed?(productId: productId, code: .unknown, msg: error?.localizedDescription)
        }
        
    }
    
    
    
}

extension JXIAPManager: SKRequestDelegate {
    
    public func getAppStoreReceipt() -> String? {
        guard let receiptURL = Bundle.main.appStoreReceiptURL else { return nil }
        let receiptData = NSData(contentsOf: receiptURL)
        return receiptData?.base64EncodedString(options: .endLineWithLineFeed)
    }
    
    ///获取凭证
    public func fetchReceipt(completion: @escaping (URL?) -> Void) {
        let receiptURL = Bundle.main.appStoreReceiptURL
        if let url = receiptURL, FileManager.default.fileExists(atPath: url.path) {
            completion(url)
            return
        }
        
        let request = SKReceiptRefreshRequest()
        request.delegate = self
        request.start()
        // 在 delegate 回调里处理
        self.receiptCompletion = completion
    }
    
    public func requestDidFinish(_ request: SKRequest) {
        let receiptURL = Bundle.main.appStoreReceiptURL
        if let url = receiptURL, FileManager.default.fileExists(atPath: url.path) {
            receiptCompletion?(url)
        } else {
            receiptCompletion?(nil)
        }
    }
    
    public func request(_ request: SKRequest, didFailWithError error: Error) {
        print("Receipt request failed: \(error)")
        receiptCompletion?(nil)
    }
}