Multilanguage class that detects and sets language

I have been learning object oriented programming for quite a while. I understand many concepts about it but I quickly realized that I made a big mistake just reading theory and not doing any actual coding . There was no practise at all and when I started to write some code, I felt it was harder to think and come up with great ideas of what exactly my code should do before I blindly go to write some code.

I'm trying to improve my multilanguage class and this is how it works:

• It first checks if a language from the lang= GET parameter is set and if that value exists in possible languages array. I then set that language to the currentLang property and cookie to remember that language for a longer time.

If I'm getting a language from $_GET, then I assume that the user manually switched to another language.

-
Almost the same check is made in the second if statement, but this time checking if COOKIE['lang'] is set. This condition is needed to check if the language was set previously.

-
If $_GET['lang'] or $_COOKIE['lang'] is not set then I assume that no language was chosen manually nor last time user visited page, inside that condition I check if current browser language value can be found in possible languages array if so then I set current language from browser language string.
If language from browser HTTP_ACCEPT_LANGUAGE can't be found then I set current language to 'English' as a default option.

```
class Langs {

// for detecting current language
public $currentLang = '';

// all possible languages
private $allLangs = ['lt', 'en'];

public function __construct() {

// get first two letters from string
$browserLang = substr($_SERVER['HTTP_ACCEPT_LANGUAGE'], 0, 2);

// if language in url is set and if that language value exists in possible languages array and if language file exists
if(isset($_GET['lang']) && in_array($_GET['lang'], $this->allLangs) && $this->_langFileExist($_GET['lang'])) {

The class is small and simple but I just made some changes for better reading.

• I'm a fan of exit early so if an if statement is checked and there is nothing more to do, exit the function. the rest of the function is not necessary.

• I also moved the duplicated check in_array($lang, $this->allLangs) && $this->_langFileExist($lang) in an own function, DRY.

• Next thing is adding typehints for your IDE to detect your variable methods.

• The last thing is to add a getter for $currentLang, I like this more than get a public attribute.

If you want, you can move each if statedments in the construct to an own function but in this case i would leave it like it is.

Hope this will help you.

_langIsAvailable($_GET['lang'])) {
            setcookie("lang", $_GET['lang'], time() + 3600 * 24 * 30);

            // store current language
            $this->currentLang = $_GET['lang'];

            return;
        }

        // get lang from cookie
        if(isset($_COOKIE['lang']) && $this->_langIsAvailable($_COOKIE['lang'])) {

            // store current language from COOKIE
            $this->currentLang = $_COOKIE['lang'];
            return;
        }

        // if no lang is set
        if(empty($this->currentLang)) {
            // get first two letters from string
            $browserLang = substr($_SERVER['HTTP_ACCEPT_LANGUAGE'], 0, 2);

            // tries to detect browser language, if browser language exists in possible languages array and if language file exists
            if($this->_langIsAvailable($browserLang)) {

                // set current language from browser language
                $this->currentLang = $browserLang;
                return;
            }
        }

        // set it to english by default
        $this->currentLang = 'en';
    }

    /**
     * @return string
     */
    public function getCurrentLang()
    {
        return $this->currentLang;
    }

    /**
     * @param string $lang
     * @return bool
     */
    private function _langIsAvailable($lang) 
    {
        return in_array($lang, $this->allLangs) && $this->_langFileExist($lang);
    }

    /**
     * @param string $lang
     * @return bool
     */
    private function _langFileExist($lang) 
    {
        return file_exists('langs/'.strtolower($lang.'.php'));

    }
}

StackExchange Code Review Q#121737, answer score: 2