chore: adding pay invoice example for lightning

TICKET: BTC-1963

Author: 007harshmahajan

examples/ts/btc/lightning/pay-invoice.ts

@@ -0,0 +1,110 @@
+/**
+ * Pay a Lightning invoice from a BitGo Lightning wallet.
+ *
+ * IMPORTANT: Your BitGo account must have the "custodyLightningWallet" license
+ * enabled to use this functionality.
+ *
+ * Copyright 2025, BitGo, Inc.  All Rights Reserved.
+ */
+
+import { BitGoAPI } from '@bitgo/sdk-api';
+import { Tlnbtc } from '@bitgo/sdk-coin-lnbtc';
+import { getLightningWallet, SubmitPaymentParams } from '@bitgo/abstract-lightning';
+
+// Set access token for testnet
+const accessToken = process.env.TESTNET_ACCESS_TOKEN || '';
+
+// Set your lightning wallet ID
+const walletId = process.env.LIGHTNING_WALLET_ID || '';
+
+// Set your wallet passphrase - needed for signing
+const passphrase = process.env.WALLET_PASSPHRASE || '';
+
+// Use tlnbtc for testnet, lnbtc for mainnet
+const coin = '';
+
+// The invoice you want to pay
+const invoiceToPay = ''; // BOLT11 encoded invoice string
+
+/**
+ * Pay a Lightning invoice
+ * @returns {Promise<any>} Payment result
+ */
+async function main(): Promise<void> {
+  try {
+    const bitgo = new BitGoAPI({
+      accessToken,
+      env: 'test',
+    });
+
+    // Register Lightning Bitcoin coin
+    bitgo.register(coin, Tlnbtc.createInstance);
+
+    //get the wallet
+    console.log(`Getting Lightning wallet with ID: ${walletId}`);
+
+    const wallet = await bitgo.coin(coin).wallets().get({ id: walletId });
+    const lightning = getLightningWallet(wallet);
+
+    // Set up payment parameters
+    const paymentParams: SubmitPaymentParams = {
+      invoice: invoiceToPay,
+      // If the invoice has an amount, this is optional
+      amountMsat: BigInt(50000), // 50,000 millisatoshis = 50 satoshis
+      passphrase: passphrase,
+      // Optional parameters
+      feeLimitMsat: BigInt(5000), // 5,000 millisatoshis = 5 satoshis maximum fee
+      comment: 'Payment for services',
+      sequenceId: `payment-${Date.now()}`, // Optional unique identifier
+    };
+
+    console.log('Paying Lightning invoice...');
+    const paymentResult = await lightning.payInvoice(paymentParams);
+
+    // Display payment information
+    console.log('\nPayment completed:');
+    console.log(`Transaction Request ID: ${paymentResult.txRequestId}`);
+    console.log(`Transaction Request State: ${paymentResult.txRequestState}`);
+
+    if (paymentResult.paymentStatus) {
+      console.log('\nPayment Status:');
+      console.log(`Status: ${paymentResult.paymentStatus.status}`);
+      console.log(`Payment Hash: ${paymentResult.paymentStatus.paymentHash}`);
+
+      if (paymentResult.paymentStatus.amountMsat) {
+        console.log(`Amount Paid: ${paymentResult.paymentStatus.amountMsat} msat`);
+      }
+
+      if (paymentResult.paymentStatus.feeMsat) {
+        console.log(`Fee Paid: ${paymentResult.paymentStatus.feeMsat} msat`);
+      }
+    }
+
+    // If payment requires approval
+    if (paymentResult.pendingApproval) {
+      console.log('\nPayment requires approval:');
+      console.log(`Pending Approval ID: ${paymentResult.pendingApproval.id}`);
+      console.log('Please approve the payment in the BitGo dashboard or via the API');
+    }
+  } catch (e) {
+    // Handle expected errors specifically
+    if (e.message && e.message.includes('invalid invoice')) {
+      console.error('\nINVALID INVOICE: The provided invoice string is not valid.');
+    } else if (e.message && e.message.includes('unauthorized')) {
+      console.error('\nAUTHENTICATION ERROR: Your access token is invalid or expired.');
+    }
+
+    throw e;
+  }
+}
+
+// Run the example
+main()
+  .then((result) => {
+    console.log('\nExample completed successfully.');
+    process.exit(0);
+  })
+  .catch((e) => {
+    console.error('Example failed with error:', e.message);
+    process.exit(-1);
+  });