fix: reading callback url from env (#3)

* fix: reading callback url from env

* refacor: added fail option when evironment variables are missing

---------

Co-authored-by: Amos Machora<81857018+AmosMachora@users.noreply.github.com>

app/api/mpesa/stk-push/route.ts

@@ -3,6 +3,7 @@ import { payments } from "@/app/db/schema";
 import { db } from "@/app/db/drizzle-client";
 import { stkPushRequest } from "@/daraja/stk-push";
 import { allowedOrigins, corsOptions } from "@/utils/cors";
+import { MPESA_APP_BASE_URL } from "@/config/env";
 
 type RequestBody = {
   accountReference: string;
@@ -18,7 +19,7 @@ export const POST = async (request: NextRequest) => {
   const requestBody: RequestBody = {
     accountReference,
     amount,
-    callbackURL: `https://billing.kenyahmis.org/api/mpesa/stk-push-callback`,
+    callbackURL: `${MPESA_APP_BASE_URL}/api/mpesa/stk-push-callback`,
     phoneNumber,
     transactionDesc: "HMIS Payment",
   };

config/env.ts

@@ -0,0 +1,12 @@
+export const MPESA_APP_BASE_URL = assertValue(
+  process.env.MPESA_APP_BASE_URL,
+  "Missing environment variable: MPESA_APP_BASE_URL"
+);
+
+function assertValue<T>(v: T | undefined, errorMessage: string): T {
+  if (v === undefined) {
+    throw new Error(errorMessage);
+  }
+
+  return v;
+}