php translator

translation.php

<?php

class TranslationMissing extends \Exception
{
    public function __construct($lang, $trans)
    {
        parent::__construct("translation missing of $trans in language $lang");
    }
}

class FailedToLoad extends \Exception
{
	public function __construct(string $strategy)
	{
		parent::__construct("Failed to load $strategy");
	}
}

class Translation
{
	/** @var string */
    public $lang;
	
	/** @var string */
    public $key;
	
	/** @var string */
    public $value;
	
	/**
	 * @param string $lang
	 * @param string $key
	 * @param string $value
	 */
    public function __construct($lang, $key, $value)
    {
        $this->lang = $lang;
        $this->key = $key;
        $this->value = $value;
    }
}

/**
 * Load strategy
 */
interface TranslationLoadStrategy
{
	/**
	 * @param string $lang
	 * @param mixed $resource
	 * @return array
	 * @throws FailedToLoad
	 */
    public function load($lang, $resource): array;
}

class TranslationArrayLoader implements TranslationLoadStrategy
{
	/**
	 * @param string $lang
	 * @param mixed $resource
	 * @return array
	 * @throws FailedToLoad
	 */
    public function load($lang, $resource): array
    {
		if (!is_array($resource)) {
			throw new FailedToLoad('TranslationArrayLoader');
		}

        $result = [];
        foreach($resource as $key => $value)
        {
            $result[] = new Translation($lang, $key, $value);
        }
        
        return $result;
    }
}

class Translator
{
	/** @var array */
    protected $translations = [];

	/**
	 * @param string $lang
	 */
    public function __construct($lang)
    {
        $this->lang = $lang;
    }
	
	/**
	 * translate
	 * 
	 * @param string $key
	 * @return string
	 * @throws TranslationMissing
	 */
    public function trans($key)
    {
        $key = strtolower($key);
        
        if (!isset($this->translations[$key])) {
            throw new TranslationMissing($this->lang, $key);
        }
        
        return $this->translations[$key];
    }
	
	/**
	 * add translation
	 *
	 * @param Translation $translation
	 * @return self
	 */
    public function add(Translation $translation)
    {
        if ($this->lang != $translation->lang) {
            return $this;
        }
        
		$this->translations[strtolower($translation->key)] = $translation->value;
		
		return $this;
    }
	
	/**
	 * load by load strategy
	 *
	 * @param mixed $resource
	 * @param TranslationLoadStrategy $strategy
	 * @return self
	 */
    public function load($resource, TranslationLoadStrategy $strategy)
    {
        foreach($strategy->load($this->lang, $resource) as $translation) {
            $this->add($translation);
		}
		
		return $this;
    }
}

$lang = 'nl';
$data = [
    'Dog' => 'hond',
    'cat' => 'kat',
    'fridge' => 'koelkast'
];

$translator = new Translator($lang);
$translator->load($data, new TranslationArrayLoader());

echo $translator->trans('dog');