<?php
	/**
	 * Elgg Entity Extender.
	 * This file contains ways of extending an Elgg entity in custom ways.
	 * 
	 * @package Elgg
	 * @subpackage Core
	 * @license http://www.gnu.org/licenses/old-licenses/gpl-2.0.html GNU Public License version 2
	 * @author Marcus Povey
	 * @copyright Curverider Ltd 2008
	 * @link http://elgg.org/
	 */

	/**
	 * ElggExtender 
	 * 
	 * @author Marcus Povey
	 * @package Elgg
	 * @subpackage Core
	 */
	abstract class ElggExtender
	{
		/**
		 * This contains the site's main properties (id, etc)
		 * @var array
		 */
		protected $attributes;
		
		/**
		 * Get an attribute
		 *
		 * @param string $name
		 * @return mixed
		 */
		protected function get($name) {
			if (isset($this->attributes[$name])) {
				
				// Sanitise value if necessary
				if ($name=='value')
				{
					switch ($this->attributes['value_type'])
					{
						case 'integer' :  return (int)$this->attributes['value'];
						//case 'tag' :
						//case 'file' :
						case 'text' : return sanitise_string($this->attributes['value']);
							
						default : throw new InstallationException("Type {$this->attributes['value_type']} is not supported. This indicates an error in your installation, most likely caused by an incomplete upgrade.");
					}
				}
				
				return $this->attributes[$name];
			}
			return null;
		}
		
		/**
		 * Set an attribute
		 *
		 * @param string $name
		 * @param mixed $value
		 * @param string $value_type
		 * @return boolean
		 */
		protected function set($name, $value, $value_type = "") {

			$this->attributes[$name] = $value;
			$this->attributes['value_type'] = detect_extender_valuetype($value, $value_type);
			
			return true;
		}	
		
		/**
		 * Return the owner of this annotation.
		 *
		 * @return mixed
		 */
		public function getOwner() 
		{ 
			return get_user($this->owner_guid); 
		}
		
		/**
		 * Save this data to the appropriate database table.
		 */
		abstract public function save();
		
		/**
		 * Delete this data.
		 */
		abstract public function delete();
		
		/**
		 * Determines whether or not the specified user can edit this
		 *
		 * @param int $user_guid The GUID of the user (defaults to currently logged in user)
		 * @return true|false
		 */
		public function canEdit($user_guid = 0) {
			return can_edit_extender($this->id,$this->type,$user_guid);
		}
		
	}
	
	/**
	 * Detect the value_type for a given value.
	 * Currently this is very crude.
	 * 
	 * TODO: Make better!
	 *
	 * @param mixed $value
	 * @param string $value_type If specified, overrides the detection.
	 * @return string
	 */
	function detect_extender_valuetype($value, $value_type = "")
	{
		if ($value_type!="")
			return $value_type;
			
		// This is crude
		if (is_int($value)) return 'integer';
		if (is_numeric($value)) return 'integer';
		
		return 'text';
	}
	
	/**
	 *  Handler called by trigger_plugin_hook on the "import" event.
	 */
	function import_extender_plugin_hook($hook, $entity_type, $returnvalue, $params)
	{
		$element = $params['element'];
		
		$tmp = NULL;
		
		if ($element instanceof ODDMetaData)
		{
			// Recall entity
			$entity_uuid = $element->getAttribute('entity_uuid');
			$entity = get_entity_from_uuid($entity_uuid);
			if (!$entity)
				throw new ImportException("Entity '$entity_uuid' could not be found.");
			
			// Get the type of extender (metadata, type, attribute etc)
			$type = $element->getAttribute('type');
			$attr_name = $element->getAttribute('name');
			$attr_val = $element->getBody();
		
			switch ($type)
			{
				case 'annotation' : 
					$entity->annotate($attr_name, $attr_val);
				break;
				case 'metadata' :
					$entity->setMetaData($attr_name, $attr_val, "", true);
				break;
				default : // Anything else assume attribute
					$entity->set($attr_name, $attr_val);			
			}
	
			// Save
			if (!$entity->save())
				throw new ImportException("There was a problem updating entity '$entity_uuid'");
			
			return true;
		}
	}
	
	/**
	 * Determines whether or not the specified user can edit the specified piece of extender
	 *
	 * @param int $extender_id The ID of the piece of extender
	 * @param string $type 'metadata' or 'annotation'
	 * @param int $user_guid The GUID of the user
	 * @return true|false
	 */
	function can_edit_extender($extender_id, $type, $user_guid = 0) {
		
		if ($user_guid == 0) {
			$user = $_SESSION['user'];
		} else {
			$user = get_entity($user_guid);
		}
		$functionname = "get_{$type}";
		if (is_callable($functionname)) {
			$extender = $functionname($extender_id);
		} else return false;
		
		if ($extender->getOwner() == $user->getGUID()) return true;
		
		return trigger_plugin_hook('permissions_check',$type,array('entity' => $entity, 'user' => $user),false);
		
	}
	
	/** Register the hook */
	register_plugin_hook("import", "all", "import_extender_plugin_hook", 2);
	
?>