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import { MmgCheckoutUtil } from "mobile-money-sdk"; // Import the custom utility
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import express from "express";
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const app = express();
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// Initialize the Checkout Utility
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/** 
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    process.env.* returns string | undefined — TypeScript will complain if you pass those directly to fields typed as string. The ! non-null assertion (or
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    runtime validation) is needed for publicKey, secretKey, merchantId, and clientId.
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**/
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  const checkoutUtil = new MmgCheckoutUtil({
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      environment: "Live", // or "Sandbox"
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      publicKey: process.env.MMG_PUBLIC_KEY!,
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      privateKey: process.env.MMG_PRIVATE_KEY,
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  });
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app.post("/api/checkout", async (req, res) => {
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    try {
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        // 2. Generate a unique Transaction ID for this order
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        const merchantTxnId = `ORD-${Date.now()}`;
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        // 3. Define the payload
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        const payload = {
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            secretKey: process.env.MMG_SECRET_KEY,
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            merchantId: process.env.MMG_MERCHANT_ID,
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            amount: "3000", // Amount in GYD
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            merchantTransactionId: merchantTxnId,
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            merchantName: "My Ecommerce Store",
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            productDescription: "Shopping Cart Checkout",
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            requestInitiationTime: Date.now().toString(),
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        };
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        // 4. Generate the Redirect URL
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        // The utility automatically encrypts the payload and appends the required query parameters
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        const redirectUrl = checkoutUtil.generateRedirectUrl(
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            payload, 
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            process.env.MMG_CLIENT_ID
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        );
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        // 5. Send the URL to the frontend, or trigger the redirect directly
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        res.json({ redirectUrl: redirectUrl });
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    } catch (error) {
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        console.error("Failed to generate checkout URL", error);
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        res.status(500).json({ error: "Internal Server Error" });
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    }
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});