From b42ce08b4c8ad79ed4e689e3f601cdf8cd9a0e97 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Feyzanur=20ATE=C5=9E?=
 <123100654+Feyzanur25@users.noreply.github.com>
Date: Sun, 22 Mar 2026 21:10:56 +0300
Subject: [PATCH] Refactor signTransaction with error handling and comments

Added error handling for missing parameters and improved documentation.
---
 lib/stellar.ts | 45 ++++++++++++++++++++++++++++++++++++---------
 1 file changed, 36 insertions(+), 9 deletions(-)

diff --git a/lib/stellar.ts b/lib/stellar.ts
index 1d66b91d..784e36f6 100644
--- a/lib/stellar.ts
+++ b/lib/stellar.ts
@@ -1,9 +1,36 @@
-import { Keypair, TransactionBuilder } from "stellar-sdk";
-
-export const signTransaction = (txXDR: string, networkPassphrase: string) => {
-    const keypair = Keypair.fromSecret(`${process.env.STELLAR_PRIVATE_KEY}`);
-    const transaction = TransactionBuilder.fromXDR(txXDR, networkPassphrase);
-    transaction.sign(keypair);
-    return transaction.toXDR();
-  };
-  
\ No newline at end of file
+/// <reference types="node" />
+
+import { Keypair, TransactionBuilder } from "@stellar/stellar-sdk";
+
+/**
+ * Signs a Stellar transaction XDR string using the private key
+ * stored in environment variables.
+ */
+export const signTransaction = (
+  txXDR: string,
+  networkPassphrase: string
+): string => {
+  const secretKey = process.env.STELLAR_PRIVATE_KEY;
+
+  if (!secretKey) {
+    throw new Error("Missing STELLAR_PRIVATE_KEY in environment variables");
+  }
+
+  if (!txXDR) {
+    throw new Error("txXDR parameter is required");
+  }
+
+  if (!networkPassphrase) {
+    throw new Error("networkPassphrase parameter is required");
+  }
+
+  const keypair = Keypair.fromSecret(secretKey);
+  const transaction = TransactionBuilder.fromXDR(
+    txXDR,
+    networkPassphrase
+  );
+
+  transaction.sign(keypair);
+
+  return transaction.toXDR();
+};