<?php

/**
 * @package KantPHP
 * @author  Zhenqiang Zhang <zhenqiang.zhang@hotmail.com>
 * @copyright (c) KantPHP Studio, All rights reserved.
 * @license http://www.opensource.org/licenses/BSD-3-Clause  The BSD 3-Clause License
 */
namespace Kant\Registry;

use ArrayObject;

class KantRegistry extends ArrayObject
{

    /**
     * Registry object provides storage for shared objects.
     * 
     * @var Kant_Registry
     */
    private static $_registry = null;

    /**
     * Retrieves the default registry instance.
     *
     * @return Kant_Registry
     */
    public static function getInstance()
    {
        if (self::$_registry === null) {
            self::$_registry = new self();
        }
        
        return self::$_registry;
    }

    /**
     * Unset the default registry instance.
     * Primarily used in tearDown() in unit tests.
     * 
     * @return s void
     */
    public static function _unsetInstance()
    {
        self::$_registry = null;
    }

    /**
     * getter method, basically same as offsetGet().
     *
     * This method can be called from an object of type Kant_Registry, or it
     * can be called statically. In the latter case, it uses the default
     * static instance stored in the class.
     *
     * @param string $index
     *            - get the value associated with $index
     * @return mixed
     * @throws Exception if no entry is registerd for $index.
     */
    public static function get($index)
    {
        $instance = self::getInstance();
        
        if (!$instance->offsetExists($index)) {
            // do nothing;
            // throw new Exception("No entry is registered for key '$index'");
        }
        
        return $instance->offsetGet($index);
    }

    /**
     * setter method, basically same as offsetSet().
     *
     * This method can be called from an object of type Kant_Registry, or it
     * can be called statically. In the latter case, it uses the default
     * static instance stored in the class.
     *
     * @param string $index
     *            The location in the ArrayObject in which to store
     *            the value.
     * @param mixed $value
     *            The object to store in the ArrayObject.
     * @return void
     */
    public static function set($index, $value)
    {
        $instance = self::getInstance();
        $instance->offsetSet($index, $value);
    }

    /**
     * Returns TRUE if the $index is a named value in the registry,
     * or FALSE if $index was not found in the registry.
     *
     * @param string $index            
     * @return boolean
     */
    public static function isRegistered($index)
    {
        if (self::$_registry === null) {
            return false;
        }
        return self::$_registry->offsetExists($index);
    }

    /**
     * Constructs a parent ArrayObject with default
     * ARRAY_AS_PROPS to allow acces as an object
     *
     * @param array $array
     *            data array
     * @param integer $flags
     *            ArrayObject flags
     */
    public function __construct($array = array(), $flags = parent::ARRAY_AS_PROPS)
    {
        parent::__construct($array, $flags);
    }

    /**
     *
     * @param string $index            
     * @return s mixed
     *        
     *         Workaround for http://bugs.php.net/bug.php?id=40442 (ZF-960).
     */
    public function offsetExists($index)
    {
        return array_key_exists($index, $this);
    }
}
