chore: wire Carplace into dev and production stacks

apps/carplace/src/proxy.ts

@@ -0,0 +1,47 @@
+import { NextResponse } from 'next/server'
+import type { NextRequest } from 'next/server'
+
+const SHARED_LANGUAGE_COOKIE = 'rentaldrivego-language'
+
+type Language = 'en' | 'fr' | 'ar'
+
+function isValidLanguage(value: string | null | undefined): value is Language {
+  return value === 'en' || value === 'fr' || value === 'ar'
+}
+
+function detectFromAcceptLanguage(header: string | null): Language {
+  if (!header) return 'en'
+  for (const entry of header.split(',')) {
+    const code = entry.split(';')[0].trim().split('-')[0].toLowerCase()
+    if (isValidLanguage(code)) return code
+  }
+  return 'en'
+}
+
+export function proxy(request: NextRequest) {
+  if (request.headers.has('x-middleware-subrequest')) {
+    return new NextResponse('Unsupported internal request header', { status: 400 })
+  }
+
+  const currentLanguage = request.cookies.get(SHARED_LANGUAGE_COOKIE)?.value
+  if (isValidLanguage(currentLanguage)) return NextResponse.next()
+
+  const language = detectFromAcceptLanguage(request.headers.get('accept-language'))
+  const requestHeaders = new Headers(request.headers)
+  const existingCookies = request.headers.get('cookie') ?? ''
+  const languageCookie = `${SHARED_LANGUAGE_COOKIE}=${language}`
+  requestHeaders.set('cookie', existingCookies ? `${existingCookies}; ${languageCookie}` : languageCookie)
+
+  const response = NextResponse.next({ request: { headers: requestHeaders } })
+  response.cookies.set(SHARED_LANGUAGE_COOKIE, language, {
+    maxAge: 365 * 24 * 60 * 60,
+    path: '/',
+    sameSite: 'lax',
+    secure: process.env.NODE_ENV === 'production',
+  })
+  return response
+}
+
+export const config = {
+  matcher: ['/((?!_next/static|_next/image|_next/webpack-hmr|favicon\\.ico|.*\\.(?:png|ico|jpg|jpeg|svg|webp)$).*)'],
+}