<?php

/**

 * @version 	$Id: factory.php 3540 2011-06-20 15:00:35Z johanjanssens $

 * @category	Koowa

 * @package		Koowa_Factory

 * @copyright	Copyright (C) 2007 - 2010 Johan Janssens. All rights reserved.

 * @license		GNU GPLv3 <http://www.gnu.org/licenses/gpl.html>

 * @link        http://www.nooku.org

 */



//Instantiate the factory singleton

KFactory::instantiate();



/**

 * KFactory class

 *

 * @author		Johan Janssens <johan@nooku.org>

 * @category	Koowa

 * @package     Koowa_Factory

 * @static

 * @uses 		KIdentifier

 * @uses		KCommandContext

 */

class KFactory

{

	/**

	 * The object container

	 *

	 * @var	array

	 */

	protected static $_registry = null;

	

	/**

	 * The commandchain

	 *

	 * @var	KLoaderChain

	 */

	protected static $_chain = null;

	

	/**

	 * The identifier alias map

	 *

	 * @var	array

	 */

	protected static $_identifier_map = array();

	

	/**

	 * The mixin map

	 *

	 * @var	array

	 */

	protected static $_mixin_map = array();



	/**

	 * Constructor

	 *

	 * Prevent creating instances of this class by making the contructor private

	 */

	final private function __construct(KConfig $config) 

	{ 

		self::$_registry = new ArrayObject();

        self::$_chain     = new KFactoryChain();

	}

	

	/**

	 * Clone 

	 *

	 * Prevent creating clones of this class

	 */

	final private function __clone() { }

	

	/**

	 * Force creation of a singleton

	 *

	 * @return void

	 */

	public static function instantiate($config = array())

	{

		static $instance;

		

		if ($instance === NULL) 

		{

			if(!$config instanceof KConfig) {

				$config = new KConfig($config);

			}

			

			$instance = new self($config);

		}

		

		return $instance;

	}



	/**

	 * Returns an identifier string. 

	 * 

	 * Accepts various types of parameters and returns a valid identifier. Parameters can either be an 

	 * object that implements KObjectIdentifiable, or a KIdentifierInterface, or valid identifier 

	 * string. Function will also check for identifier mappings and return the mapped identifier.

	 *

	 * @param	mixed	An object that implements KObjectIdentifiable, an object that 

	 *                  implements KIdentifierInterface or valid identifier string

	 * @return KIdentifier

	 */

	public static function identify($identifier)

	{		

		if(!is_string($identifier)) 

		{

			if($identifier instanceof KObjectIdentifiable) {

			    $identifier = $identifier->getIdentifier();

		    }   

		} 

		

		$alias = (string) $identifier;

		if(array_key_exists($alias, self::$_identifier_map)) {

			$identifier = self::$_identifier_map[$alias];

		}

		

		if(is_string($identifier)) {

		    $identifier = new KIdentifier($identifier);

		}

		

		return $identifier;

	}



	/**

	 * Get an instance of a class based on a class identifier only creating it

	 * if it doesn't exist yet.

	 *

	 * @param	string|object	The class identifier or identifier object

	 * @param	array  			An optional associative array of configuration settings.

	 * @throws	KFactoryException

	 * @return	object  		Return object on success, throws exception on failure

	 */

	public static function get($identifier, array $config = array())

	{

		$objIdentifier = self::identify($identifier);

		$strIdentifier = (string) $objIdentifier;

		

		if(!self::$_registry->offsetExists($strIdentifier))

		{

			//Instantiate the identifier

			$instance = self::_instantiate($objIdentifier, $config);

		

			//Perform the mixin 

			self::_mixin($strIdentifier, $instance);

			

			self::$_registry->offsetSet($strIdentifier, $instance);

		}

		

		return self::$_registry->offsetGet($strIdentifier);

	}



	/**

	 * Get an instance of a class based on a class identifier always creating a

	 * new instance.

	 *

	 * @param	string|object	The class identifier or an identifier object

	 * @param 	array  			An optional associative array of configuration settings.

	 * @throws 	KFactoryException

	 * @return 	object  		Return object on success, throws exception on failure

	 */

	public static function tmp($identifier, array $config = array())

	{

		$objIdentifier = self::identify($identifier);

		$strIdentifier = (string) $objIdentifier;

	

		//Instantiate the identifier

		$instance = self::_instantiate($objIdentifier, $config);

		

		//Perform the mixin 

		self::_mixin($strIdentifier, $instance);

		

		return $instance;

	}



	/**

	 * Insert the object instance using the identifier

	 *

	 * @param mixed  The class identifier

	 * @param object The object instance to store

	 */

	public static function set($identifier, $object)

	{

		$objIdentifier = self::identify($identifier);

		$strIdentifier = (string) $objIdentifier;

		

		self::$_registry->offsetSet($strIdentifier, $object);

	}



	/**

	 * Remove the object instance using the identifier

	 *

	 * @param mixed  The class identifier

	 * @return boolean Returns TRUE on success or FALSE on failure.

	 */

	public static function del($identifier)

	{

		$objIdentifier = self::identify($identifier);

		$strIdentifier = (string) $objIdentifier;



		if(self::$_registry->offsetExists($strIdentifier)) {

			self::$_registry->offsetUnset($strIdentifier);

			return true;

		}



		return false;

	}



	/**

	 * Check if the object instance exists based on the identifier

	 *

	 * @param mixed  The class identifier

	 * @return boolean Returns TRUE on success or FALSE on failure.

	 */

	public static function has($identifier)

	{

		try 

		{

	        $objIdentifier = self::identify($identifier);

	        $strIdentifier = (string) $objIdentifier;

	        $result = (bool) self::$_registry->offsetExists($strIdentifier);

		

		} catch (KIdentifierException $e) {

		    $result = false;

		}

 		

		return $result;

	}

	

	/**

	 * Creates an alias for an identifier

	 *

	 * @param mixed  The alias 

	 * @param mixed  The class indentifier or identifier object

	 */

	public static function map($alias, $identifier)

	{		

		$identifier = self::identify($identifier);

		

		self::$_identifier_map[$alias] = $identifier;

	}

	

	/**

     * Set a mixin or an array of mixins for an identifier

     * 

     * The mixins are mixed when the indentified object is first instantiated see {@linkk get} and 

     * {$link tmp} Mixins are also added to existing singleton objects that already exist in the

     * object store.

     *

     * @param  mixed        An identifier string, KIdentfier object or an array of identifiers 

     * @param  string|array A mixin identifier or a array of mixin identifiers

     * @see KObject::mixin

     */

    public static function mix($identifiers, $mixins)

    {

        settype($identifiers, 'array');

        settype($mixins,      'array');



        foreach($identifiers as $identifier) 

        {

            $objIdentifier = self::identify($identifier);

            $strIdentifier = (string) $objIdentifier;

            

            if (!isset(self::$_mixin_map[$strIdentifier]) ) {

                self::$_mixin_map[$strIdentifier] = array();

            }



            self::$_mixin_map[$strIdentifier] = array_unique(array_merge(self::$_mixin_map[$strIdentifier], $mixins));



            if (self::$_registry->offsetExists($strIdentifier)) 

            {

                $instance = self::$_registry->offsetGet($strIdentifier);

                

                //Perform the mixin 

                self::_mixin($strIdentifier, $instance);

            }

        }

    }



    /**

     * Add a factory adapter

     *

     * @param object    A KFactoryAdapter

     * @return void

     */

    public static function addAdapter(KFactoryAdapterInterface $adapter)

    {

        self::$_chain->enqueue($adapter);

    }

    

    /**

     * Perform the actual mixin of all registered mixins with an object 

     * 

     * @param   string  The identifier string

     * @param   object  A KObject instance to used as the mixer

     * @return void

     */

    protected static function _mixin($identifier, $instance)

    {

        if(isset(self::$_mixin_map[$identifier]) && $instance instanceof KObject)

        {

            $mixins = self::$_mixin_map[$identifier];

            foreach($mixins as $mixin) 

            {

                $mixin = KFactory::tmp($mixin, array('mixer'=> $instance));

                $instance->mixin($mixin);

            }

        }

    }

    

    /**

     * Get an instance of a class based on a class identifier

     *

     * @param   string          The identifier string 

     * @param   array           An optional associative array of configuration settings.

     * @throws  KFactoryException

     * @return  object          Return object on success, throws exception on failure

     */

    protected static function _instantiate($identifier, array $config = array())

    {           

        $context =  self::$_chain->getContext();

        $config  =  new KConfig($config);

        $context->config = $config;

        

        $result = self::$_chain->run($identifier, $context);

    

        //If we get a string returned we assume it's a classname

        if(is_string($result)) 

        {

            //Set the classname

            $identifier->classname = $result;

            

            //Set the filepath

            $identifier->filepath = KLoader::path($identifier);

            

            //If the object is indentifiable push the identifier in through the constructor

            if(array_key_exists('KObjectIdentifiable', class_implements($identifier->classname))) {

                $config->identifier = $identifier;

            }

                            

            // If the class has an instantiate method call it

            if(is_callable(array($identifier->classname, 'instantiate'), false)) {

                $result = call_user_func(array($identifier->classname, 'instantiate'), $config);

            } 

            else {

                $result = new $identifier->classname($config);

            }

        }

        

        if(!is_object($result)) {

            throw new KFactoryException('Cannot create object from identifier : '.$identifier);

        }

                

        return $result;

    }

}