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