<?php

/**
 * Responsible for creating definition caches.
 */
class HTMLPurifier_DefinitionCacheFactory {
	/**
	 * @type array
	 */
	protected $caches = array (
			'Serializer' => array () 
	);
	
	/**
	 * @type array
	 */
	protected $implementations = array ();
	
	/**
	 * @type HTMLPurifier_DefinitionCache_Decorator[]
	 */
	protected $decorators = array ();
	
	/**
	 * Initialize default decorators
	 */
	public function setup() {
		$this->addDecorator ( 'Cleanup' );
	}
	
	/**
	 * Retrieves an instance of global definition cache factory.
	 * 
	 * @param HTMLPurifier_DefinitionCacheFactory $prototype        	
	 * @return HTMLPurifier_DefinitionCacheFactory
	 */
	public static function instance($prototype = null) {
		static $instance;
		if ($prototype !== null) {
			$instance = $prototype;
		} elseif ($instance === null || $prototype === true) {
			$instance = new HTMLPurifier_DefinitionCacheFactory ();
			$instance->setup ();
		}
		return $instance;
	}
	
	/**
	 * Registers a new definition cache object
	 * 
	 * @param string $short
	 *        	Short name of cache object, for reference
	 * @param string $long
	 *        	Full class name of cache object, for construction
	 */
	public function register($short, $long) {
		$this->implementations [$short] = $long;
	}
	
	/**
	 * Factory method that creates a cache object based on configuration
	 * 
	 * @param string $type
	 *        	Name of definitions handled by cache
	 * @param HTMLPurifier_Config $config
	 *        	Config instance
	 * @return mixed
	 */
	public function create($type, $config) {
		$method = $config->get ( 'Cache.DefinitionImpl' );
		if ($method === null) {
			return new HTMLPurifier_DefinitionCache_Null ( $type );
		}
		if (! empty ( $this->caches [$method] [$type] )) {
			return $this->caches [$method] [$type];
		}
		if (isset ( $this->implementations [$method] ) && class_exists ( $class = $this->implementations [$method], false )) {
			$cache = new $class ( $type );
		} else {
			if ($method != 'Serializer') {
				trigger_error ( "Unrecognized DefinitionCache $method, using Serializer instead", E_USER_WARNING );
			}
			$cache = new HTMLPurifier_DefinitionCache_Serializer ( $type );
		}
		foreach ( $this->decorators as $decorator ) {
			$new_cache = $decorator->decorate ( $cache );
			// prevent infinite recursion in PHP 4
			unset ( $cache );
			$cache = $new_cache;
		}
		$this->caches [$method] [$type] = $cache;
		return $this->caches [$method] [$type];
	}
	
	/**
	 * Registers a decorator to add to all new cache objects
	 * 
	 * @param HTMLPurifier_DefinitionCache_Decorator|string $decorator
	 *        	An instance or the name of a decorator
	 */
	public function addDecorator($decorator) {
		if (is_string ( $decorator )) {
			$class = "HTMLPurifier_DefinitionCache_Decorator_$decorator";
			$decorator = new $class ();
		}
		$this->decorators [$decorator->name] = $decorator;
	}
}

// vim: et sw=4 sts=4