class PaypalStrategy implements PaymentStrategy
{、
    private $clientId;

    private $clientSecret;

    private $environment;

    private $currency;

    private $apiContext;

    private $redirectUrl;

    public function __construct()
    {
        $this->clientId = Env::get("paypal.CLIENT_ID");
        $this->clientSecret = Env::get("paypal.CLIENT_SECRET");
        $this->environment = Env::get("paypal.ENVIRONMENT");
        $this->currency = "USD";
        $this->redirectUrl = "http://".Env::get("app.app_url") . "/api/order/paypalExecute";

        $this->apiContext = new ApiContext(
            new OAuthTokenCredential(
                $this->clientId,
                $this->clientSecret
            )
        );
      
       if ($env === "production") {
            $this->apiContext->setConfig([
                'mode' => 'live',         // 设置为生产环境
            ]);
        }
    }
    
    // 支付
    public function pay(array $orderInfo, array $paymentParams)
    {
        $payer = new \PayPal\Api\Payer();
        $payer->setPaymentMethod('paypal');

        $item = new Item();
        $item->setName("商品名称")
            ->setCurrency($this->currency)
            // 设置数量
            ->setQuantity(1)
            ->setPrice($orderInfo['paymentamount']);

        $itemList = new ItemList();
        $itemList->setItems([$item]);

        $amount = new \PayPal\Api\Amount();
        // 设置总价
        $amount->setTotal($orderInfo['paymentamount'])
            ->setCurrency($this->currency);

        $transaction = new \PayPal\Api\Transaction();
        $transaction->setAmount($amount)
            ->setItemList($itemList)
            ->setDescription("商品描述")
            ->setInvoiceNumber($orderInfo['orderno']);

        // 设置授权成功之后，重定向地址
        // 这个地址很重要，是 PayPal 授权成功之后，同步回调获取付款人 ID
        $redirectUrls = new RedirectUrls();
        $redirectUrls->setReturnUrl($this->redirectUrl . "?success=ture")
            ->setCancelUrl($this->redirectUrl . "?success=false");

        $payment = new Payment();
        $payment->setIntent('sale')
            ->setPayer($payer)
            ->setTransactions(array($transaction))
            ->setRedirectUrls($redirectUrls);

        try {
            // 创建交易
            $payment->create($this->apiContext);
            return [
                // Paypal payment id
                "third_order_no" => $payment->id,
                // Paypal 授权地址
                "approval_url"   => $payment->getApprovalLink(),
            ];
        } catch (\PayPal\Exception\PayPalConnectionException $exception) {
            throw new \Exception($exception->getData());
        }
    } 
}

// 同步支付回调（用于获取付款人 ID）
public function execute($payload)
{
    // 是否取消支付标识
    $success = $payload['success'] ?? false;
    // 支付ID
    $paymentId = $payload['paymentId'] ?? "";
    // 支付人ID
    $payerId = $payload['PayerID'] ?? "";

    if (empty($paymentId) || empty($payerId)) {
        // 支付失败
        return "fail";
    }

    if (false === $success) {
        // 取消支付
        
        return "cancel";
    }

    $payment = Payment::get($paymentId, $this->apiContext);
    $execute = new PaymentExecution();
    // 设置付款人 ID
    $execute->setPayerId($payerId);
    try {
        // 确认支付（真正发起支付请求的地方）
        $payment->execute($execute, $this->apiContext);
    } catch (\Exception $e) {
        // 支付失败
        return "fail";
    }
    // 支付成功
    return "success";
}

// 异步支付回调
public function webhook($payload)
{
    $payload = json_decode($payload, true);
    if (empty($payload)) {
        // 回调参数解析失败
        return false;
    }

    // todo 验签
  
    try {
        // 详细回调参数，参见 https://developer.paypal.com/api/rest/webhooks/#link-samplemessagepayload
        
        switch ($payload['event_type']) {
            // 支付订单创建成功
            case "PAYMENTS.PAYMENT.CREATED":
            
                break;
            
            // 买家完成支付
            case "PAYMENT.SALE.COMPLETED":
                // 记录买家 ID，后面退款会用到
                break;
        }
        // todo 业务逻辑处理
        
        return true;
    } catch (\Exception $e) {
        // 订单回调处理异常

        return false;
    }
}

// Paypal 退款
public function refund($orderInfo)
{
    try {
            $amount = new Amount();
            $amount->setCurrency($this->currency)
                ->setTotal($orderInfo['payment_amount']);

            $refundRequest = new RefundRequest();
            $refundRequest->setAmount($amount);

            $sale = new Sale();
            // 付款人 ID
            $sale->setId($orderInfo['payer_id']);

            $result = $sale->refundSale($refundRequest, $this->apiContext);
        } catch (\Exception $e) {
            // 退款失败
            return $e->getMessage();
        }
        // 退款完成
        return true;
}