<?php
namespace LanguageSwitcher;
/**
* @usage:
*   $lang = isset($_GET['lang'])?$_GET['lang']:'ru';
*   (new \LanguageSwitcher\LanguageFileSwitcher(__DIR__ .'/languages/'))->includeLanguage($lang);
*/
class LanguageFileSwitcher{

    const DEFAULT_CODE = 'en';
    const DEFAULT_EXT = '.php';

    protected $sourcePath;
    protected $extention ;

    public function __construct($sourcePath, $extention = self::DEFAULT_EXT){
        $this->sourcePath = $sourcePath;
        $this->extention = $extention;
    }

    public function inludeLanguage($code = self::DEFAULT_CODE){
        $filename = $this->getFilenameByCode($code);
        if(in_array($filename, $this->getAvailableLanguagesFiles())){
            include $filename;
            return;
        }else{
            $defaultSource = $this->getFilenameByCode(self::DEFAULT_CODE);
            if(file_exists($defaultSource)){
                include $defaultSource;
                return;
            }else{
                throw new Exception("Not found default language file! ");
            }
        }
    }

    protected function getFilenameByCode($code){
        return $this->sourcePath . $code . $this->extention;
    }

    protected function getAvailableLanguagesFiles(){
        return glob($this->sourcePath . '*' . $this->extention);
    }
}

class Exception extends \RuntimeException {}