proxy.ts

import { defaultLocale, locales } from "@/lib/i18n";
import { NextResponse, type NextRequest } from "next/server";

const PUBLIC_FILE = /\.[^/]+$/;

function getPreferredLocale(request: NextRequest) {
  const header = request.headers.get("accept-language");
  if (!header) return defaultLocale;

  const languages = header
    .split(",")
    .map((part) => part.split(";")[0]?.trim())
    .filter(Boolean);

  for (const language of languages) {
    const base = language.split("-")[0];
    if (locales.includes(base as (typeof locales)[number])) {
      return base as (typeof locales)[number];
    }
  }

  return defaultLocale;
}

export function proxy(request: NextRequest) {
  const { pathname } = request.nextUrl;

  if (
    pathname.startsWith("/_next") ||
    pathname.startsWith("/api") ||
    pathname.startsWith("/favicon.ico") ||
    pathname.startsWith("/sitemap.xml") ||
    pathname.startsWith("/robots.txt") ||
    PUBLIC_FILE.test(pathname)
  ) {
    return;
  }

  const pathnameHasLocale = locales.some(
    (locale) => pathname === `/${locale}` || pathname.startsWith(`/${locale}/`),
  );

  if (!pathnameHasLocale) {
    const locale = getPreferredLocale(request);
    const url = request.nextUrl.clone();
    url.pathname = `/${locale}${pathname}`;
    return NextResponse.redirect(url);
  }

  return NextResponse.next();
}

export const config = {
  matcher: [
    "/((?!_next/static|_next/image|favicon.ico|sitemap.xml|robots.txt|.*\\.png$).*)",
  ],
};