fix oidc callback behind reverse proxy

proxy.test.ts

@@ -0,0 +1,26 @@
+import { describe, expect, test } from "bun:test";
+import { NextRequest } from "next/server";
+import { buildPublicRequestUrl } from "./proxy";
+
+describe("public request URL", () => {
+  test("uses NEXTAUTH_URL for OIDC callback URLs behind Docker reverse proxies", () => {
+    const request = new NextRequest("http://0.0.0.0:8019/logs?range=7d");
+
+    expect(
+      buildPublicRequestUrl(request, {
+        NEXTAUTH_URL: "https://analytics.example.com",
+      }).href
+    ).toBe("https://analytics.example.com/logs?range=7d");
+  });
+
+  test("falls back to forwarded proxy headers when no public URL is configured", () => {
+    const request = new NextRequest("http://0.0.0.0:8019/", {
+      headers: {
+        "x-forwarded-host": "analytics.example.com",
+        "x-forwarded-proto": "https",
+      },
+    });
+
+    expect(buildPublicRequestUrl(request).href).toBe("https://analytics.example.com/");
+  });
+});