<?php


/**
 * Base Factory abstract class.
 * This class implements all the common behaviour of
 * it's specialized classes (ProcessFactory and WorkflowFactory).
 *
 * @author Pedro Eugênio Rocha
 * @package Factory
 * @abstract
 */
abstract class BaseFactory {

	/**
	 * @var array Store what classes we can instantiate.
	 * @access private
	 */
	private $_fileInfo;


	/**
	 * Registers classes into '$_fileInfo' private
	 * atribute.
	 *
	 * @todo Maybe here we should receive more parameters...
	 * @access protected
	 * @return void
	 */
	protected final function registerFileInfo($className, $fileName, $relativePath) {

		/* default is to override */
		$this->_fileInfo[$className] = array(	'filename' => $fileName,
												'path' => $relativePath,
												'instance' => null);
	}


	/**
	 * Here we should do all the factory stuff.
	 * The classes instatiated here will be stored
	 * into our private object cache. If there is no
	 * object of the given type into the cache, 'newInstance'
	 * will be called.
	 *
	 * @access public
	 * @return object
	 */
	public function &getInstance(){

		/* at least the class name */
		if (func_num_args() <= 0)
			return null;

		$args = func_get_args();

		/* recovering class data */
		if ($entry = $this->_getEntry($args[0])) {

			if (is_null($entry['instance'])) {

				/* must instantiate it */
                if (($obj = call_user_func_array(array($this, "newInstance"), $args)) == null)
					throw new Exception("Unable to instantiate '".$args[0]."'");

				/* saving the object reference */
				$this->_setEntryInstance($args[0], $obj);
				return $obj;
			}
			return $entry['instance'];

		}
		/* class not allowed */
		else
			throw new Exception("You are not allowed to instantiate class '".$args[0]."'.");
	}

	/**
	 * Instantiate classes.
	 *
	 * @todo I think that we don't need to use the reflection
	 *		 class here. Future work...
	 * @access public
	 * @return object
	 */
	public function &newInstance(){

		/* at least the class name */
		if (func_num_args() <= 0)
			return null;

		$args = func_get_args();

		$className = array_shift($args);
		if(!$this->_import($className))
			return null;

		/* I dont know.. maybe we could do better here.. */
		$reflectionObj = new ReflectionClass($className);

		if (count($args) == 0)
			return $reflectionObj->newInstance();
		return $reflectionObj->newInstanceArgs($args);
	}


	/**
	 * Private stuff. Handles the cache and information
	 * '$_fileInfo' array.
	 *
	 * @access private
	 * @return array
	 */
	private function _getEntry($className){
		return $this->_fileInfo[$className];
	}


	/**
	 * Stores the given object into the internal cache
	 * for upcoming requests.
	 *
	 * @access private
	 * @return boolean
	 */
	private function _setEntryInstance($className, $obj){

		if (is_array($this->_fileInfo[$className])) {
			$this->_fileInfo[$className]['instance'] = $obj;
			return true;
		}
		return false;
	}


	/**
	 * Including (requiring_once ;P ) the file(s) itself. Ideally,
	 * it could be the only place to include files.
	 *
	 * @access private
	 * @return boolean
	 */
	private function _import($className){

		/* not found */
		if (!($entry = $this->_getEntry($className)))
			throw new Exception('You are not allowed to instantiate '.$className.' class.');

		$fullPath = WF_SERVER_ROOT . $entry['path'] . SEP . $entry['filename'];

		/* file not found */
		if (!file_exists($fullPath))
			throw new Exception("File '".$fullPath."' not found.");

		/* including file */
		require_once $fullPath;
		return true;
	}
}
?>