payment redirect

src/modules/payments/services/payment-gateway.service.ts

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+import { Injectable, BadRequestException, Logger } from '@nestjs/common';
+import { ConfigService } from '@nestjs/config';
+import { RestaurantPaymentMethod } from '../entities/restaurant-payment-method.entity';
+import { Order } from '../../orders/entities/order.entity';
+
+export interface PaymentGatewayRedirect {
+  redirectUrl: string;
+  orderId: string;
+}
+
+@Injectable()
+export class PaymentGatewayService {
+  private readonly logger = new Logger(PaymentGatewayService.name);
+
+  constructor(private readonly configService: ConfigService) {}
+
+  /**
+   * Generate payment gateway redirect URL for online payment methods
+   */
+  generateRedirectUrl(order: Order, restaurantPaymentMethod: RestaurantPaymentMethod): Promise<PaymentGatewayRedirect> {
+    const paymentMethod = restaurantPaymentMethod.paymentMethod;
+
+    if (!paymentMethod.isOnline) {
+      throw new BadRequestException('Payment method is not online');
+    }
+
+    // Get base URL for callback
+    const baseUrl = this.configService.get<string>('APP_BASE_URL') || 'http://localhost:4000';
+    const callbackUrl = paymentMethod.callbackUrl || `${baseUrl}/public/payments/callback`;
+
+    // Generate payment gateway URL based on payment method keyName
+    const redirectUrl = this.generateGatewayUrl(paymentMethod.keyName, {
+      orderId: order.id,
+      amount: order.total,
+      merchantId: restaurantPaymentMethod.merchantId,
+      callbackUrl,
+      description: `Order #${order.id}`,
+    });
+
+    return {
+      redirectUrl,
+      orderId: order.id,
+    };
+  }
+
+  /**
+   * Generate gateway URL based on payment provider
+   * This can be extended to support multiple payment gateways (ZarinPal, Mellat, etc.)
+   */
+  private generateGatewayUrl(
+    paymentMethodKey: string,
+    params: {
+      orderId: string;
+      amount: number;
+      merchantId?: string;
+      callbackUrl: string;
+      description: string;
+    },
+  ) {
+    // Convert amount to smallest currency unit (e.g., Toman to Rials for Iranian gateways)
+    const amountInSmallestUnit = Math.round(params.amount * 10); // Assuming Toman to Rials conversion
+
+    switch (paymentMethodKey.toLowerCase()) {
+      case 'zarinpal':
+        return this.generateZarinPalUrl(params, amountInSmallestUnit);
+
+      case 'mellat':
+      case 'bankmellat':
+        return this.generateMellatUrl(params, amountInSmallestUnit);
+
+      default:
+        // Generic payment gateway URL structure
+        // You can customize this based on your payment gateway provider
+        this.logger.warn(`Unknown payment method: ${paymentMethodKey}, using generic URL structure`);
+        return this.generateGenericGatewayUrl(params, amountInSmallestUnit);
+    }
+  }
+
+  /**
+   * Generate ZarinPal payment gateway URL
+   */
+  private generateZarinPalUrl(
+    params: {
+      orderId: string;
+      merchantId?: string;
+      callbackUrl: string;
+      description: string;
+    },
+    amount: number,
+  ): string {
+    if (!params.merchantId) {
+      throw new BadRequestException('Merchant ID is required for ZarinPal payment gateway');
+    }
+
+    // ZarinPal payment gateway URL structure
+    // This is a simplified version - you may need to make an API call to get the actual redirect URL
+    const zarinPalBaseUrl =
+      this.configService.get<string>('ZARINPAL_BASE_URL') || 'https://www.zarinpal.com/pg/StartPay';
+
+    // For ZarinPal, you typically need to:
+    // 1. Call their API to create a payment request
+    // 2. Get an Authority token
+    // 3. Redirect to their payment page with the Authority
+
+    // For now, returning a placeholder URL structure
+    // TODO: Implement actual ZarinPal API integration
+    return `${zarinPalBaseUrl}/${params.orderId}?Amount=${amount}&MerchantID=${params.merchantId}&CallbackURL=${encodeURIComponent(params.callbackUrl)}&Description=${encodeURIComponent(params.description)}`;
+  }
+
+  /**
+   * Generate Bank Mellat payment gateway URL
+   */
+  private generateMellatUrl(
+    params: {
+      orderId: string;
+      merchantId?: string;
+      callbackUrl: string;
+      description: string;
+    },
+    amount: number,
+  ): string {
+    if (!params.merchantId) {
+      throw new BadRequestException('Merchant ID is required for Mellat payment gateway');
+    }
+
+    const mellatBaseUrl =
+      this.configService.get<string>('MELLAT_BASE_URL') || 'https://bpm.shaparak.ir/pgwchannel/startpay.mellat';
+
+    // TODO: Implement actual Mellat API integration
+    return `${mellatBaseUrl}?orderId=${params.orderId}&amount=${amount}&merchantId=${params.merchantId}&callbackUrl=${encodeURIComponent(params.callbackUrl)}`;
+  }
+
+  /**
+   * Generate generic payment gateway URL
+   */
+  private generateGenericGatewayUrl(
+    params: {
+      orderId: string;
+      merchantId?: string;
+      callbackUrl: string;
+      description: string;
+    },
+    amount: number,
+  ): string {
+    const genericBaseUrl =
+      this.configService.get<string>('PAYMENT_GATEWAY_BASE_URL') || 'https://payment.example.com/pay';
+
+    const queryParams = new URLSearchParams({
+      orderId: params.orderId,
+      amount: amount.toString(),
+      callbackUrl: params.callbackUrl,
+      description: params.description,
+    });
+
+    if (params.merchantId) {
+      queryParams.append('merchantId', params.merchantId);
+    }
+
+    return `${genericBaseUrl}?${queryParams.toString()}`;
+  }
+}