<?php

namespace App\Http\Middleware;

use Closure;

/**
 * 設定網站語系
 *
 * Class SetAppLanguage
 * @package App\Http\Middleware
 */
class SetAppLanguage
{
    /**
     * Cookie及Session存放Locale資訊的Key
     *
     * @var string
     */
    private $cookieAndSessionKey = 'appLocale';

    /**
     * 設定Locale時的參數Key
     *
     * @var string
     */
    private $localeRequestKey = 'locale';
    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        //取得所有語言清單
        $availableLocales = (array)config('languages');
        //要被回傳的Cookie
        $setLocaleCookie = false;
        //要被設定的語言
        $setLocale = false;
        //如果有Locale參數
        if($request->get($this->localeRequestKey) !== null) {
            //取得傳入的Locale值
            $requestLocale = $request->get($this->localeRequestKey);
            //如果有在語言清單內
            if(array_key_exists($requestLocale, $availableLocales)) {
                //設定session
                $request->session()->put($this->cookieAndSessionKey, $requestLocale);
                //設定要被回傳的Cookie及目標Locale
                $setLocale = $setLocaleCookie = $requestLocale;
            }
        }
        //假如沒有目標Locale，再讀取Session、Cookie、瀏覽器的Locale
        if(!$setLocale) {
            $cookieLocale = $request->cookies->get($this->cookieAndSessionKey);
            $sessionLocale = $request->session()->get($this->cookieAndSessionKey);
            if(array_key_exists($sessionLocale, $availableLocales)) {
                //設定要被回傳的Cookie及目標Locale
                $setLocale = $sessionLocale;
                if(!$cookieLocale) {
                    $setLocaleCookie = $sessionLocale;
                }
            } elseif(array_key_exists($cookieLocale, $availableLocales)) {
                //設定Session及目標Locale
                $request->session()->put($this->cookieAndSessionKey, $cookieLocale);
                $setLocale = $cookieLocale;
            } else {
                //Session及Cookie都沒有Locale值時，讀取HTTP Header的資訊
                $browserLocales = $request->server('HTTP_ACCEPT_LANGUAGE');
                $browserLocales = preg_replace('/;q=0\.\d+/', '', $browserLocales);
                $browserLocales = explode(',', $browserLocales);
                $browserLocales = array_map(function($lang){
                    return strtolower($lang);
                }, $browserLocales);

                //與語言清單比對
                $validBrowserLocales = array_intersect($browserLocales, array_keys($availableLocales));

                if(!empty($validBrowserLocales)) {
                    //取得第一個瀏覽器Locale
                    $validBrowserLocale = head($validBrowserLocales);
                    //設定Session及目標Locale
                    $request->session()->put($this->cookieAndSessionKey, $validBrowserLocale);
                    $setLocale = $setLocaleCookie = $validBrowserLocale;
                }
            }
        }

        if($setLocale) {
            //如果有目標Locale
            app()->setLocale($setLocale);
        } else {
            //如果沒有目標Locale，則設定成預設語言
            app()->setLocale(config('app.fallback_locale'));
        }

        //如果有Cookie，則帶入request
        if($setLocaleCookie) {
            return $next($request)->withCookie(cookie()->forever($this->cookieAndSessionKey, $setLocaleCookie));
        } else {
            return $next($request);
        }
    }
}