@pelag/nts/dist/templates/middleware.txt

Creation and support of the multilingual project Next.js

import { NextRequest, NextResponse } from 'next/server';
import { match as matchLocale } from '@formatjs/intl-localematcher';
import Negotiator from 'negotiator';

import { langConfig } from '{{PATH}}';

function getLocale(request: NextRequest): string {
  const negotiatorHeaders: Record<string, string> = {};
  request.headers.forEach((value, key) => {
    negotiatorHeaders[key] = value;
  });

  const languages = new Negotiator({ headers: negotiatorHeaders }).languages(
      [...langConfig.locales]
  );

  return matchLocale(languages, [...langConfig.locales], langConfig.defaultLocale);
}

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

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

  if (!pathnameHasLocale) {
    const locale = getLocale(request);

    return NextResponse.redirect(
        new URL(`/${locale}${pathname}`, request.url)
    );
  }
}

export const config = {
  matcher: [
    '/((?!api|_next/static|_next/image|favicon.ico|manifest.json).*)'
  ]
};