Add VERCEL_URl to env with URL parsing & transformation

src/env.mjs

@@ -1,5 +1,5 @@
 /* eslint-disable @typescript-eslint/ban-ts-comment */
-import { z } from "zod";
+import {z} from "zod";
 
 /**
  * Specify your server-side environment variables schema here.
@@ -15,6 +15,12 @@ const server = z.object({
  * To expose them to the client, prefix them with `NEXT_PUBLIC_`.
  */
 const client = z.object({
+    NEXT_PUBLIC_APP_URL: z.string().transform(url => {
+        // Add a HTTPS url prefix automatically, for vercel.
+        if (!(url.startsWith("http://") || url.startsWith("https://")))
+            return `https://${url}`;
+        return url;
+    })
     // NEXT_PUBLIC_CLIENTVAR: z.string().min(1),
 });
 
@@ -25,6 +31,7 @@ const client = z.object({
  */
 const processEnv = {
     NODE_ENV: process.env.NODE_ENV,
+    NEXT_PUBLIC_APP_URL: process.env.VERCEL_URL ?? process.env.APP_URL
     // NEXT_PUBLIC_CLIENTVAR: process.env.NEXT_PUBLIC_CLIENTVAR,
 };
 
@@ -70,4 +77,4 @@ if (!!process.env.SKIP_ENV_VALIDATION == false) {
     });
 }
 
-export { env };
+export {env};