middleware.js

import { NextResponse } from "next/server"
import getAvailableLocales, { getFallbackLocale } from "./app/i18n/settings"
import { match } from "@formatjs/intl-localematcher"
import Negotiator from "negotiator"

async function getLocale(request, locales) {
    const fallbackLng = await getFallbackLocale()
    const headers = new Headers(request.headers)
    const acceptLanguage = headers.get("accept-language")
    if (acceptLanguage) {
        headers.set("accept-language", acceptLanguage.replaceAll("_", "-"))
    }

    const headersObject = Object.fromEntries(headers.entries())
    const languages = new Negotiator({ headers: headersObject }).languages()
    return match(languages, locales, fallbackLng)
}

export async function middleware(request) {
    // Check if there is any supported locale in the pathname
    const pathname = request.nextUrl.pathname
    const locales = await getAvailableLocales()

    const pathnameIsMissingLocale = locales.every(
        locale => !pathname.startsWith(`/${locale}/`) && pathname !== `/${locale}`
    )

    //go to home in browser language if pathname & locale is missing
    if (pathname === "/") {
        const locale = await getLocale(request, locales)
        return NextResponse.redirect(new URL(`/${locale}/home`, request.url))
    }

    //go to the specific locale home if there is no pathname but the locale is set
    if (
        pathname.split("/").length === 2 &&
        locales.includes(pathname.split("/")[1])
    ) {
        return NextResponse.redirect(
            new URL(`/${pathname.split("/")[1]}/home`, request.url)
        )
    }

    //go to pathname in browser language if locale is missing but pathname is set
    if (pathnameIsMissingLocale) {
        const locale = await getLocale(request, locales)

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

export const config = {
    matcher: ["/((?!.*\\.|_next|api\\/).*)"]
}