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

export type Locales = 'en' | 'zh'
export const locales: Locales[] = ['en', 'zh']
export const localeLabels: Record<Locales, string> = {
    'en': 'English',
    'zh': '中文',
}
const defaultLocale: Locales = 'en'


// Get the preferred locale, similar to the above or using a library
function getLocale(request: NextRequest) {
    const headers = { 'accept-language': request.headers.get('accept-language') ?? '' }
    const languages = new Negotiator({ headers }).languages()
    return match(languages, locales, defaultLocale)
}

export function middleware(request: NextRequest) {
    const { pathname } = request.nextUrl
    const pathnameHasLocale = locales.some(
        (locale) => pathname.startsWith(`/${locale}/`) || pathname === `/${locale}`
    )

    if (pathnameHasLocale) return

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

export const config = {
    matcher: [
        // Skip all internal paths (_next)
        '/((?!_next).*)',
        // Optional: only run on root (/) URL
        // '/'
    ],
}