/**
 * Author: Simon-Pierre Boucher
 * Contact: contact@spboucher.ai
 * Project: Hilmacorp.ai — Web Platform
 * File: middleware.ts
 * Description: Locale-prefix middleware — redirects unprefixed paths to /fr or /en
 *              based on the NEXT_LOCALE cookie or the Accept-Language header
 */

import { NextRequest, NextResponse } from "next/server";

const LOCALES = ["fr", "en"];
const DEFAULT_LOCALE = "fr";

function detectLocale(request: NextRequest): string {
  const cookie = request.cookies.get("NEXT_LOCALE")?.value;
  if (cookie && LOCALES.includes(cookie)) return cookie;
  const header = request.headers.get("accept-language") ?? "";
  for (const part of header.split(",")) {
    const code = part.split(";")[0].trim().slice(0, 2).toLowerCase();
    if (LOCALES.includes(code)) return code;
  }
  return DEFAULT_LOCALE;
}

export function middleware(request: NextRequest) {
  const { pathname } = request.nextUrl;
  const hasLocale = LOCALES.some(
    (locale) => pathname === `/${locale}` || pathname.startsWith(`/${locale}/`)
  );
  if (hasLocale) return NextResponse.next();

  const locale = detectLocale(request);
  const url = request.nextUrl.clone();
  url.pathname = `/${locale}${pathname === "/" ? "" : pathname}`;
  return NextResponse.redirect(url);
}

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