add: weglot header to middleware

apps/web/src/middleware.ts

@@ -1,9 +1,10 @@
 import { jwtVerify } from "jose";
 import type { NextRequest } from "next/server";
 import { NextResponse } from "next/server";
+import { headers } from 'next/headers'
 
 // List of public paths that don't require authentication
-const publicPaths = [
+const PUBLIC_PATHS = [
   "/sign-in",
   "/api/auth/session",
   "/api/user",
@@ -31,6 +32,20 @@ interface JWTPayload {
   exp?: number;
 }
 
+// Add supported languages
+const SUPPORTED_LANGUAGES = ['en', 'fr', 'es', 'de']
+
+// Helper to extract primary language from Accept-Language header
+function getPrimaryLanguage(acceptLanguage: string | null): string {
+  if (!acceptLanguage) return 'en'
+
+  // Get first language code (e.g. 'fr-FR,fr;q=0.9,en;q=0.8' -> 'fr')
+  const primaryLang = acceptLanguage.split(',')[0].split('-')[0].toLowerCase()
+
+  // Return primary language if supported, otherwise default to 'en'
+  return SUPPORTED_LANGUAGES.includes(primaryLang) ? primaryLang : 'en'
+}
+
 // Function to verify JWT token
 async function verifyToken(token: string) {
   try {
@@ -59,13 +74,55 @@ async function verifyToken(token: string) {
   }
 }
 
+// Helper to check if path is public (including language prefixes)
+function isPublicPath(path: string): boolean {
+  // Remove language prefix if it exists
+  const pathWithoutLang = SUPPORTED_LANGUAGES.some(lang => path.startsWith(`/${lang}/`))
+    ? path.substring(3) // Remove /{lang}/ prefix
+    : path
+
+  return PUBLIC_PATHS.some(publicPath => pathWithoutLang.startsWith(publicPath))
+}
+
+// Helper to get language from URL or Accept-Language header
+function getLanguageFromPath(pathname: string): string | null {
+  const firstSegment = pathname.split('/')[1]
+  return SUPPORTED_LANGUAGES.includes(firstSegment) ? firstSegment : null
+}
+
 // Middleware function
 export async function middleware(request: NextRequest) {
-  const { pathname } = request.nextUrl;
+  const { pathname, search } = request.nextUrl;
+
+  // Get language from URL or Accept-Language header
+  const urlLanguage = getLanguageFromPath(pathname)
+  const acceptLanguage = request.headers.get('Accept-Language')
+  const preferredLanguage = urlLanguage || getPrimaryLanguage(acceptLanguage)
+
+  // Create response object that we'll modify
+  let response = NextResponse.next()
+
+  // Set Weglot language header
+  response.headers.set('Weglot-Language-Preference', preferredLanguage)
+
+  // Function to add language prefix to URL if needed
+  const addLanguagePrefix = (url: string): string => {
+    if (urlLanguage || SUPPORTED_LANGUAGES.some(lang => url.startsWith(`/${lang}/`))) {
+      return url
+    }
+    return `/${preferredLanguage}${url.startsWith('/') ? url : `/${url}`}`
+  }
+
+  // Redirect to language-prefixed URL if no language prefix exists
+  if (!urlLanguage && !pathname.startsWith('/api/')) {
+    const url = new URL(request.url)
+    url.pathname = addLanguagePrefix(pathname)
+    return NextResponse.redirect(url)
+  }
 
   // Allow public paths
-  if (publicPaths.some((path) => pathname.startsWith(path))) {
-    return NextResponse.next();
+  if (isPublicPath(pathname)) {
+    return response
   }
 
   // Get session token and registration status
@@ -74,50 +131,65 @@ export async function middleware(request: NextRequest) {
 
   // For all protected routes
   if (!sessionToken) {
-    return NextResponse.redirect(new URL("/sign-in", request.url));
+    const signInUrl = new URL(addLanguagePrefix("/sign-in"), request.url)
+    response = NextResponse.redirect(signInUrl)
+    response.headers.set('Weglot-Language-Preference', preferredLanguage)
+    return response
   }
 
   try {
-    const decoded = await verifyToken(sessionToken);
+    const decoded = await verifyToken(sessionToken)
     if (!decoded) {
-      const response = NextResponse.redirect(new URL("/sign-in", request.url));
-      response.cookies.delete("session");
-      response.cookies.delete("registration_status");
-      return response;
+      const signInUrl = new URL(addLanguagePrefix("/sign-in"), request.url)
+      response = NextResponse.redirect(signInUrl)
+      response.cookies.delete("session")
+      response.cookies.delete("registration_status")
+      response.headers.set('Weglot-Language-Preference', preferredLanguage)
+      return response
     }
 
     // Handle registration flow
     if (pathname !== "/register" && registrationStatus !== "complete") {
-      const url = new URL("/register", request.url);
+      const registerUrl = new URL(addLanguagePrefix("/register"), request.url)
       if (decoded.walletAddress) {
-        url.searchParams.set("walletAddress", decoded.walletAddress);
+        registerUrl.searchParams.set("walletAddress", decoded.walletAddress)
       }
-      return NextResponse.redirect(url);
+      response = NextResponse.redirect(registerUrl)
+      response.headers.set('Weglot-Language-Preference', preferredLanguage)
+      return response
     }
 
     // Add user info to request headers for API routes
     if (pathname.startsWith("/api/")) {
-      const requestHeaders = new Headers(request.headers);
-      requestHeaders.set("x-user-id", decoded.sub as string);
-      requestHeaders.set("x-wallet-address", decoded.walletAddress as string);
+      const requestHeaders = new Headers(request.headers)
+      requestHeaders.set("x-user-id", decoded.sub as string)
+      requestHeaders.set("x-wallet-address", decoded.walletAddress as string)
+      requestHeaders.set("x-preferred-language", preferredLanguage)
 
       return NextResponse.next({
         request: {
           headers: requestHeaders,
         },
-      });
+      })
     }
 
-    return NextResponse.next();
+    return response
+
   } catch {
     // Clear invalid session
-    const response = NextResponse.redirect(new URL("/sign-in", request.url));
-    response.cookies.delete("session");
-    response.cookies.delete("registration_status");
-    return response;
+    const signInUrl = new URL(addLanguagePrefix("/sign-in"), request.url)
+    response = NextResponse.redirect(signInUrl)
+    response.cookies.delete("session")
+    response.cookies.delete("registration_status")
+    response.headers.set('Weglot-Language-Preference', preferredLanguage)
+    return response
   }
 }
 
+// Update matcher to include language prefixes
 export const config = {
-  matcher: ["/((?!_next/static|_next/image|favicon.ico).*)"],
+  matcher: [
+    "/((?!_next/static|_next/image|favicon.ico).*)",
+    "/:lang(en|fr|es|de)/:path*"
+  ]
 };