middleware.js

import { NextResponse } from 'next/server'

import { i18n } from './i18n-config'

import { match } from '@formatjs/intl-localematcher'
import Negotiator from 'negotiator'

function getLocale(request) {
    // Negotiator expects plain object so we need to transform headers
    const negotiatorHeaders = {}
    request.headers.forEach((value, key) => (negotiatorHeaders[key] = value))

    // @ts-ignore locales are readonly
    const locales = i18n.locales

    // Use negotiator and intl-localematcher to get best locale
    let languages = new Negotiator({ headers: negotiatorHeaders }).languages(
        locales
    )

    const locale = match(languages, locales, i18n.defaultLocale)

    return locale
}

export function middleware(request) {

    const pathname = request.nextUrl.pathname

    // // `/_next/` and `/api/` are ignored by the watcher, but we need to ignore files in `public` manually.
    // If you have one
    if (
        [
            '/filter.svg',
            '/jordan.png',
            '/sofa.svg',
            '/bed.svg',
            '/bathtub.svg',
            '/favourite.svg',
            '/logo.png'
            // Your other files in `public`
        ].includes(pathname)
    )
        return

    // Check if there is any supported locale in the pathname
    const pathnameIsMissingLocale = i18n.locales.every(
        (locale) => !pathname.startsWith(`/${locale}/`) && pathname !== `/${locale}`
    )

    // Redirect if there is no locale
    if (pathnameIsMissingLocale) {
        const locale = getLocale(request)

        // e.g. incoming request is /products
        // The new URL is now /en-US/products
        return NextResponse.redirect(
            new URL(
                `/${locale}${pathname.startsWith('/') ? '' : '/'}${pathname}`,
                request.url
            )
        )
    }
}

export const config = {
    // Matcher ignoring `/_next/` and `/api/`
    matcher: ['/((?!api|_next/static|_next/image|favicon.ico).*)'],
}