fix(WEB-132): absolute seamless login return urls

app/[lang]/(live)/(public)/login/route.ts

@@ -3,7 +3,7 @@ import { AuthError } from "next-auth"
 
 import { Lang } from "@/constants/languages"
 import { env } from "@/env/server"
-import { badRequest, internalServerError } from "@/server/errors/next"
+import { badRequest } from "@/server/errors/next"
 
 import { signIn } from "@/auth"
 
@@ -11,21 +11,41 @@ export async function GET(
   request: NextRequest,
   context: { params: { lang: Lang } }
 ) {
+  let redirectHeaders: Headers | undefined = undefined
+  let redirectTo: string
+
   const returnUrl = request.headers.get("x-returnurl")
+  if (returnUrl) {
+    // Seamless login request from Current web
+    redirectTo = returnUrl
+  } else {
+    // Normal login request from New web
+    redirectTo =
+      request.cookies.get("redirectTo")?.value || // Cookie gets set by authRequired middleware
+      request.headers.get("x-redirect-to") ||
+      request.nextUrl.searchParams.get("redirectTo") ||
+      request.headers.get("Referer") ||
+      ""
 
-  // If all else fails, always redirect to startpage
-  const finalDestination =
-    returnUrl ||
-    request.headers.get("x-redirect-to") ||
-    request.nextUrl.searchParams.get("redirectTo") ||
-    request.headers.get("Referer") ||
-    "/"
+    // If above fails, always redirect to startpage
+    if (!redirectTo) {
+      const proto = request.headers.get("x-forwarded-proto") ?? "http"
+      const host =
+        request.headers.get("x-forwarded-host") ??
+        request.headers.get("host") ??
+        env.URL
+      redirectTo = `${proto}://${host}/`
+    }
+
+    // Clean up cookie from authRequired middleware
+    redirectHeaders = new Headers()
+    redirectHeaders.append(
+      "set-cookie",
+      "redirectTo=; Expires=Thu, 01 Jan 1970 00:00:00 UTC; Path=/; HttpOnly; SameSite=Lax"
+    )
 
-  let redirectTo = finalDestination
-  if (!returnUrl) {
-    // This is a regular login request, not a seamless login request
-    // We should initiate the seamless login flow
     try {
+      // Initiate the seamless login flow
       let redirectUrlValue
       switch (context.params.lang) {
         case Lang.da:
@@ -48,12 +68,13 @@ export async function GET(
           break
       }
       const redirectUrl = new URL(redirectUrlValue)
-      redirectUrl.searchParams.set("returnurl", finalDestination)
+      redirectUrl.searchParams.set("returnurl", redirectTo)
       redirectTo = redirectUrl.toString()
     } catch (e) {
-      console.error("Unable to create URL for seamless login")
+      console.error(
+        "Unable to create URL for seamless login, proceeding without it."
+      )
       console.error(e)
-      return internalServerError()
     }
   }
 
@@ -63,7 +84,7 @@ export async function GET(
      * automatically redirecting to it inside of `signIn`.
      * https://github.com/nextauthjs/next-auth/blob/3c035ec/packages/next-auth/src/lib/actions.ts#L76
      */
-    const url = await signIn(
+    const redirectUrl = await signIn(
       "curity",
       {
         redirectTo,
@@ -74,8 +95,10 @@ export async function GET(
       }
     )
 
-    if (url) {
-      return NextResponse.redirect(url)
+    if (redirectUrl) {
+      return NextResponse.redirect(redirectUrl, {
+        headers: redirectHeaders,
+      })
     }
   } catch (error) {
     if (error instanceof AuthError) {

env/server.ts

@@ -34,6 +34,7 @@ export const env = createEnv({
     SEAMLESS_LOGIN_FI: z.string(),
     SEAMLESS_LOGIN_NO: z.string(),
     SEAMLESS_LOGIN_SV: z.string(),
+    URL: z.string().optional(),
     WEBVIEW_ENCRYPTION_KEY: z.string(),
   },
   emptyStringAsUndefined: true,
@@ -63,6 +64,7 @@ export const env = createEnv({
     SEAMLESS_LOGIN_FI: process.env.SEAMLESS_LOGIN_FI,
     SEAMLESS_LOGIN_NO: process.env.SEAMLESS_LOGIN_NO,
     SEAMLESS_LOGIN_SV: process.env.SEAMLESS_LOGIN_SV,
+    URL: process.env.URL,
     WEBVIEW_ENCRYPTION_KEY: process.env.WEBVIEW_ENCRYPTION_KEY,
   },
 })

middleware.ts

@@ -1,11 +1,11 @@
 import { NextMiddleware } from "next/server"
 
-import * as handleAuth from "./middlewares/handleAuth"
 import * as authRequired from "./middlewares/authRequired"
+import * as cmsContent from "./middlewares/cmsContent"
 import * as currentWebLogin from "./middlewares/currentWebLogin"
 import * as ensureLang from "./middlewares/ensureLang"
-import * as cmsContent from "@/middlewares/cmsContent"
-import * as webView from "@/middlewares/webView"
+import * as handleAuth from "./middlewares/handleAuth"
+import * as webView from "./middlewares/webView"
 
 export const middleware: NextMiddleware = async (request, event) => {
   const middlewares = [

middlewares/authRequired.ts

@@ -1,10 +1,11 @@
 import { NextResponse } from "next/server"
 
-import { auth } from "@/auth"
 import { findLang } from "@/constants/languages"
 import { authRequired } from "@/constants/routes/authRequired"
 import { login } from "@/constants/routes/handleAuth"
 
+import { auth } from "@/auth"
+
 import type { NextMiddleware } from "next/server"
 
 import type { MiddlewareMatcher } from "@/types/middleware"
@@ -44,8 +45,15 @@ export const middleware = auth(async (request) => {
     return NextResponse.next()
   }
 
+  const headers = new Headers()
+  headers.append(
+    "set-cookie",
+    `redirectTo=${encodeURIComponent(nextUrl.href)}; Path=/; HttpOnly; SameSite=Lax`
+  )
   const loginUrl = login[lang]
-  return NextResponse.redirect(new URL(loginUrl, request.nextUrl))
+  return NextResponse.redirect(new URL(loginUrl, request.nextUrl), {
+    headers,
+  })
 }) as NextMiddleware // See comment above
 
 export const matcher: MiddlewareMatcher = (request) => {

next.config.js

@@ -23,6 +23,10 @@ jiti("./env/client")
 /** @type {import('next').NextConfig} */
 const nextConfig = {
   env: {
+    URL:
+      process.env.CONTEXT === "production"
+        ? process.env.URL
+        : process.env.DEPLOY_PRIME_URL,
     NEXTAUTH_URL:
       (process.env.CONTEXT === "production"
         ? process.env.URL