Fixes #1986, #2170, #2225, #2759. Integrated ElggPluginPackage and ElggPluginManifest with ElggPlugin. System now uses ElggPlugin objects to determin plugins. Order is stored in private settings. This absolutely requires running upgrade.php.

git-svn-id: http://code.elgg.org/elgg/trunk@7817 36083f99-b078-4883-b0ff-0f9b5a30f544

2 files changed, 756 insertions, 453 deletions

diff --git a/engine/lib/plugins.php b/engine/lib/plugins.php
index 29f55926c..cd74353de 100644
--- a/engine/lib/plugins.php
+++ b/engine/lib/plugins.php
@@ -7,202 +7,296 @@
  * @subpackage Plugins
  */
 
-/// Cache enabled plugins per page
-$ENABLED_PLUGINS_CACHE = NULL;
+/**
+ * Tells ElggPlugin::start() to include the start.php file.
+ */
+define('ELGG_PLUGIN_INCLUDE_START', 1);
 
 /**
- * Returns a list of plugins to load, in the order that they should be loaded.
+ * Tells ElggPlugin::start() to automatically register the plugin's views.
+ */
+define('ELGG_PLUGIN_REGISTER_VIEWS', 2);
+
+/**
+ * Tells ElggPlugin::start() to automatically register the plugin's languages.
+ */
+define('ELGG_PLUGIN_REGISTER_LANGUAGES', 4);
+
+/**
+ * Tells ElggPlugin::start() to automatically register the plugin's classes.
+ */
+define('ELGG_PLUGIN_REGISTER_CLASSES', 8);
+
+/**
+ * Prefix for plugin setting names
  *
- * @return array List of plugins
+ * @todo Can't namespace these because many plugins directly call
+ * private settings via $entity->$name.
  */
-function get_plugin_list() {
-	global $CONFIG;
+//define('ELGG_PLUGIN_SETTING_PREFIX', 'plugin:setting:');
 
-	if (!empty($CONFIG->pluginlistcache)) {
-		return $CONFIG->pluginlistcache;
-	}
+/**
+ * Prefix for plugin user setting names
+ */
+define('ELGG_PLUGIN_USER_SETTING_PREFIX', 'plugin:user_setting:');
 
-	if ($site = get_entity($CONFIG->site_guid)) {
-		$pluginorder = $site->pluginorder;
-		if (!empty($pluginorder)) {
-			$plugins = unserialize($pluginorder);
+/**
+ * Internal settings prefix
+ *
+ * @todo This could be resolved by promoting ElggPlugin to a 5th type.
+ */
+define('ELGG_PLUGIN_INTERNAL_PREFIX', 'elgg:internal:');
 
-			$CONFIG->pluginlistcache = $plugins;
-			return $plugins;
-		} else {
-			// this only runs on install, otherwise uses serialized plugin order
-			$plugins = array();
-
-			if ($handle = opendir($CONFIG->pluginspath)) {
-				while ($mod = readdir($handle)) {
-					// must be directory and not begin with a .
-					if (substr($mod, 0, 1) !== '.' && is_dir($CONFIG->pluginspath . "/" . $mod)) {
-						$plugins[] = $mod;
-					}
-				}
-			}
 
-			sort($plugins);
+/**
+ * Returns a list of plugin IDs (dir names) from a dir.
+ *
+ * @param string $dir A dir to scan for plugins. Defaults to config's plugins_path.
+ *
+ * @return array
+ */
+function elgg_get_plugin_ids_in_dir($dir = null) {
+	if (!$dir) {
+		$dir = elgg_get_plugin_path();
+	}
+
+	$plugin_idss = array();
+	$handle = opendir($dir);
 
-			$CONFIG->pluginlistcache = $plugins;
-			return $plugins;
+	if ($handle) {
+		while ($plugin_id = readdir($handle)) {
+			// must be directory and not begin with a .
+			if (substr($plugin_id, 0, 1) !== '.' && is_dir($dir . $plugin_id)) {
+				$plugin_ids[] = $plugin_id;
+			}
 		}
 	}
 
-	return false;
+	sort($plugin_ids);
+
+	return $plugin_ids;
 }
 
 /**
- * Regenerates the list of known plugins and saves it to the current site
- *
- * Important: You should regenerate simplecache and the viewpath cache after executing this function
- * otherwise you may experience view display artifacts. Do this with the following code:
+ * Discovers plugins in the plugins_path setting and creates ElggPlugin
+ * entities for them if they don't exist.  If there are plugins with entities
+ * but not actual files, will disable the ElggPlugin entities and mark as inactive.
+ * The ElggPlugin object holds config data, so don't delete.
  *
- * 		elgg_view_regenerate_simplecache();
- *		elgg_filepath_cache_reset();
- *
- * @param array $pluginorder Optionally, a list of existing plugins and their orders
- *
- * @return array The new list of plugins and their orders
+ * @todo Crappy name?
+ * @return bool
  */
-function regenerate_plugin_list($pluginorder = FALSE) {
-	global $CONFIG;
-
-	$CONFIG->pluginlistcache = NULL;
+function elgg_generate_plugin_entities() {
+	$site = get_config('site');
+	$dir = elgg_get_plugin_path();
+
+	$options = array(
+		'type' => 'object',
+		'subtype' => 'plugin',
+		'limit' => ELGG_ENTITIES_NO_VALUE
+	);
+
+	$old_ia = elgg_set_ignore_access(true);
+	$old_access = access_get_show_hidden_status();
+	access_show_hidden_entities(true);
+	$known_plugins = elgg_get_entities_from_relationship($options);
+
+	if (!$known_plugins) {
+		$known_plugins = array();
+	}
 
-	if ($site = get_entity($CONFIG->site_guid)) {
-		if (empty($pluginorder)) {
-			$pluginorder = $site->pluginorder;
-			$pluginorder = unserialize($pluginorder);
-		} else {
-			ksort($pluginorder);
+	// map paths to indexes
+	$id_map = array();
+	foreach ($known_plugins as $i => $plugin) {
+		// if the ID is wrong, delete the plugin because we can never load it.
+		$id = $plugin->getID();
+		if (!$id) {
+			$plugin->delete();
+			unset($known_plugins[$i]);
+			continue;
 		}
+		$id_map[$plugin->getID()] = $i;
+	}
 
-		if (empty($pluginorder)) {
-			$pluginorder = array();
-		}
+	$physical_plugins = elgg_get_plugin_ids_in_dir($dir);
 
-		$max = 0;
-		if (sizeof($pluginorder)) {
-			foreach ($pluginorder as $key => $plugin) {
-				if (is_dir($CONFIG->pluginspath . "/" . $plugin)) {
-					if ($key > $max) {
-						$max = $key;
-					}
-				} else {
-					unset($pluginorder[$key]);
-				}
-			}
-		}
-		// Add new plugins to the end
-		if ($handle = opendir($CONFIG->pluginspath)) {
-			while ($mod = readdir($handle)) {
-				// must be directory and not begin with a .
-				if (substr($mod, 0, 1) !== '.' && is_dir($CONFIG->pluginspath . "/" . $mod)) {
-					if (!in_array($mod, $pluginorder)) {
-						$max = $max + 10;
-						$pluginorder[$max] = $mod;
-					}
-				}
+	if (!$physical_plugins) {
+		return false;
+	}
+
+	$new_plugin_priority = elgg_get_max_plugin_priority() + 1;
+
+	// check real plugins against known ones
+	foreach ($physical_plugins as $plugin_id) {
+		// is this already in the db?
+		if (array_key_exists($plugin_id, $id_map)) {
+			$index = $id_map[$plugin_id];
+			$plugin = $known_plugins[$index];
+			// was this plugin deleted and its entity disabled?
+			if ($plugin->enabled != 'yes') {
+				$plugin->enable();
+				$plugin->deactivate();
 			}
-		}
 
-		ksort($pluginorder);
+			// remove from the list of plugins to disable
+			unset($known_plugins[$index]);
+		} else {
+			// add new plugins
+			$plugin = new ElggPlugin($plugin_id);
+			$plugin->save();
+			$plugin->setPriority($new_plugin_priority);
 
-		// Now reorder the keys ..
-		$key = 10;
-		$plugins = array();
-		if (sizeof($pluginorder)) {
-			foreach ($pluginorder as $plugin) {
-				$plugins[$key] = $plugin;
-				$key = $key + 10;
-			}
+			$new_plugin_priority++;
 		}
+	}
 
-		$plugins = serialize($plugins);
+	// everything remaining in $known_plugins needs to be disabled
+	// because they are entities, but their dirs were removed.
+	// don't delete the entities because they hold settings.
+	foreach ($known_plugins as $plugin) {
+		$plugin->deactivate();
+		$plugin->disable();
+	}
+
+	access_show_hidden_entities($old_access);
+	elgg_set_ignore_access($old_ia);
 
-		$site->pluginorder = $plugins;
+	return true;
+}
 
-		return $plugins;
+/**
+ * Returns an ElggPlugin object with the path $path.
+ *
+ * @param string $id The id (dir name) of the plugin. NOT the guid.
+ * @return mixed ElggPlugin or false.
+ */
+function elgg_get_plugin_from_id($id) {
+	$id = sanitize_string($id);
+	$db_prefix = get_config('dbprefix');
+
+	$options = array(
+		'type' => 'object',
+		'subtype' => 'plugin',
+		'joins' => array("JOIN {$db_prefix}objects_entity oe on oe.guid = e.guid"),
+		'wheres' => array("oe.title = '$id'"),
+		'limit' => 1
+	);
+
+	$plugins = elgg_get_entities($options);
+
+	if ($plugins) {
+		return $plugins[0];
 	}
 
-	return FALSE;
+	return false;
+}
+
+/**
+ * Returns if a plugin exists in the system.
+ *
+ * @warning This checks only plugins that are registered in the system!
+ * If the plugin cache is outdated, be sure to regenerate it with
+ * {@link elgg_generate_plugin_objects()} first.
+ *
+ * @param string $id The plugin ID.
+ * @return bool
+ */
+function elgg_plugin_exists($id) {
+	$plugin = elgg_get_plugin_from_id($id);
+
+	return ($plugin) ? true : false;
 }
 
+/**
+ * Returns the highest priority of the plugins
+ *
+ * @return int
+ */
+function elgg_get_max_plugin_priority() {
+	$db_prefix = get_config('dbprefix');
+	$priority = elgg_namespace_plugin_private_setting('internal', 'priority');
+	$plugin_subtype = get_subtype_id('object', 'plugin');
+
+	$q = "SELECT MAX(CAST(ps.value AS unsigned)) as max
+		FROM {$db_prefix}entities e, {$db_prefix}private_settings ps
+		WHERE ps.name = '$priority'
+		AND ps.entity_guid = e.guid
+		AND e.type = 'object' and e.subtype = $plugin_subtype";
+
+	$data = get_data($q);
+	if ($data) {
+		return $data[0]->max;
+	}
+
+	// can't have a priority of 0.
+	return 1;
+}
 
 /**
- * For now, loads plugins directly
+ * Loads all active plugins in the order specified in the tool admin panel.
  *
- * @todo Add proper plugin handler that launches plugins in an
- * admin-defined order and activates them on admin request
+ * @note This is called on every page load and includes additional checking that plugins
+ * are fit to be loaded.  If a plugin is active and problematic, it will be disabled
+ * and a visible error emitted.
  *
- * @return void
+ * @return bool
  */
-function load_plugins() {
+function elgg_load_plugins() {
 	global $CONFIG;
 
-	if (empty($CONFIG->pluginspath)) {
-		return;
+	$plugins_path = elgg_get_plugin_path();
+	$start_flags =	ELGG_PLUGIN_INCLUDE_START
+					| ELGG_PLUGIN_REGISTER_VIEWS
+					| ELGG_PLUGIN_REGISTER_LANGUAGES
+					| ELGG_PLUGIN_REGISTER_CLASSES;
+
+	if (!$plugins_path) {
+		return false;
 	}
 
 	// temporary disable all plugins if there is a file called 'disabled' in the plugin dir
-	if (file_exists($CONFIG->pluginspath . "disabled")) {
-		return;
+	if (file_exists("$plugins_path/disabled")) {
+		return false;
 	}
-	
-	// See if we have cached values for things
+
+	// Load view caches if available
 	$cached_view_paths = elgg_filepath_cache_load('views');
 	$cached_view_types = elgg_filepath_cache_load('view_types');
 	$cached_view_info = is_string($cached_view_paths) && is_string($cached_view_types);
+
 	if ($cached_view_info) {
 		$CONFIG->views = unserialize($cached_view_paths);
 		$CONFIG->view_types = unserialize($cached_view_types);
+
+		// don't need to register views
+		$start_flags = $start_flags & ~ELGG_PLUGIN_REGISTER_VIEWS;
 	}
 
-	$plugins = get_plugin_list();
-
-	if (sizeof($plugins)) {
-		foreach ($plugins as $mod) {
-			if (is_plugin_enabled($mod)) {
-				if (file_exists($CONFIG->pluginspath . $mod)) {
-					if (!include($CONFIG->pluginspath . $mod . "/start.php")) {
-						// automatically disable the bad plugin
-						disable_plugin($mod);
-
-						// register error rather than rendering the site unusable with exception
-						register_error(sprintf(elgg_echo('PluginException:MisconfiguredPlugin'), $mod));
-
-						// continue loading remaining plugins
-						continue;
-					}
-
-					if (!$cached_view_info) {
-						$view_dir = $CONFIG->pluginspath . $mod . '/views/';
-
-						if (is_dir($view_dir) && ($handle = opendir($view_dir))) {
-							while (FALSE !== ($view_type = readdir($handle))) {
-								$view_type_dir = $view_dir . $view_type;
-
-								if ('.' !== substr($view_type, 0, 1) && is_dir($view_type_dir)) {
-									if (autoregister_views('', $view_type_dir, $view_dir, $view_type)) {
-										// add the valid view type.
-										if (!in_array($view_type, $CONFIG->view_types)) {
-											$CONFIG->view_types[] = $view_type;
-										}
-									}
-								}
-							}
-						}
-					}
-
-					if (is_dir($CONFIG->pluginspath . "$mod/classes")) {
-						elgg_register_classes($CONFIG->pluginspath . "$mod/classes");
-					}
-
-					if (is_dir($CONFIG->pluginspath . $mod . "/languages")) {
-						register_translations($CONFIG->pluginspath . $mod . "/languages/");
-					}
-				}
+	$return = true;
+	$plugins = elgg_get_plugins('active');
+	if ($plugins) {
+		foreach ($plugins as $plugin) {
+			// check if plugin can be started and try to start it.
+			// if anything is bad, disable it and emit a message.
+			if (!$plugin->isValid()) {
+				$plugin->deactivate();
+				$msg = elgg_echo('PluginException:MisconfiguredPlugin', array($plugin->getID(), $plugin->guid));
+				register_error($msg);
+				$return = false;
+
+				continue;
+			}
+
+			try {
+				$plugin->start($start_flags);
+			} catch (Exception $e) {
+				$plugin->deactivate();
+				$msg = elgg_echo('PluginException:CannotStart',
+								array($plugin->getID(), $plugin->guid, $e->getMessage()));
+				register_error($msg);
+				$return = false;
+
+				continue;
 			}
 		}
 	}
@@ -212,21 +306,257 @@ function load_plugins() {
 		elgg_filepath_cache_save('views', serialize($CONFIG->views));
 		elgg_filepath_cache_save('view_types', serialize($CONFIG->view_types));
 	}
+
+	return $return;
+}
+
+/**
+ * Returns an ordered list of plugins
+ *
+ * @param string $status          The status of the plugins. active, inactive, or all.
+ * @param bool   $include_deleted Include physically deleted (and so inactive and disabled) plugins?
+ * @param mixed  $site_guid       Optional site guid
+ * @return array
+ */
+function elgg_get_plugins($status = 'active', $include_deleted = false, $site_guid = NULL) {
+	$db_prefix = get_config('dbprefix');
+	$priority = elgg_namespace_plugin_private_setting('internal', 'priority');
+
+	if (!$site_guid) {
+		$site = get_config('site');
+		$site_guid = $site->guid;
+	}
+
+	// grab plugins
+	$options = array(
+		'type' => 'object',
+		'subtype' => 'plugin',
+		'limit' => ELGG_ENTITIES_NO_VALUE,
+		'joins' => array("JOIN {$db_prefix}private_settings ps on ps.entity_guid = e.guid"),
+		'wheres' => array("ps.name = '$priority'"),
+		'order_by' => "CAST(ps.value as unsigned), e.guid"
+	);
+
+	switch ($status) {
+		case 'active':
+			$options['relationship'] = 'active_plugin';
+			$options['relationship_guid'] = $site_guid;
+			$options['inverse_relationship'] = true;
+			break;
+
+		case 'inactive':
+			$options['wheres'][] = "NOT EXISTS (
+					SELECT 1 FROM {$db_prefix}entity_relationships active_er
+					WHERE active_er.guid_one = e.guid
+						AND active_er.relationship = 'active_plugin'
+						AND active_er.guid_two = $site_guid)";
+			break;
+
+		case 'all':
+		default:
+			break;
+	}
+
+	if ($include_deleted) {
+		$old_id = elgg_set_ignore_access(true);
+	}
+
+	$plugins = elgg_get_entities_from_relationship($options);
+
+	if ($include_deleted) {
+		elgg_set_ignore_access($old_ia);
+	}
+
+	return $plugins;
+}
+
+/**
+ * Reorder plugins to an order specified by the array.
+ * Plugins not included in this array will be appended to the end.
+ *
+ * @note This doesn't use the ElggPlugin->setPriority() method because
+ *       all plugins are being changed and we don't want it to automatically
+ *       reorder plugins.
+ *
+ * @param array $order An array of plugin ids in the order to set them
+ * @return bool
+ */
+function elgg_set_plugin_priorities(array $order) {
+	$name = elgg_namespace_plugin_private_setting('internal', 'priority');
+
+	$plugins = elgg_get_plugins('any', true);
+	if (!$plugins) {
+		return false;
+	}
+
+	$return = true;
+
+	// reindex to get standard counting. no need to increment by 10.
+	// though we do start with 1
+	$order = array_values($order);
+
+	foreach ($plugins as $plugin) {
+		$plugin_id = $plugin->getID();
+
+		if (!in_array($plugin_id, $order)) {
+			$missing_plugins[] = $plugin;
+			continue;
+		}
+
+		$priority = array_search($plugin_id, $order) + 1;
+
+		if (!$plugin->set($name, $priority)) {
+			$return = false;
+			break;
+		}
+	}
+
+	// set the missing plugins priorities
+	if ($return && $missing_plugins) {
+		if (!$priority) {
+			$priority = 0;
+		}
+		foreach ($missing_plugins as $plugin) {
+			$priority++;
+			if (!$plugin->set($name, $priority)) {
+				$return = false;
+				break;
+			}
+		}
+	}
+
+	return $return;
+}
+
+/**
+ * Reindexes all plugin priorities starting at 1.
+ *
+ * @todo Can this be done in a single sql command?
+ * @return bool
+ */
+function elgg_plugins_reindex_priorities() {
+	return elgg_set_plugin_priorities(array());
+}
+
+/**
+ * Returns a list of plugins to load, in the order that they should be loaded.
+ *
+ * @deprecated 1.8
+ *
+ * @return array List of plugins
+ */
+function get_plugin_list() {
+	elgg_deprecated_notice('get_plugin_list() is deprecated by elgg_get_plugin_ids_in_dir() or elgg_get_plugins()', 1.8);
+
+	$plugins = elgg_get_plugins('any');
+
+	$list = array();
+	if ($plugins) {
+		foreach ($plugins as $i => $plugin) {
+			// in <=1.7 this returned indexed by multiples of 10.
+			// uh...sure...why not.
+			$index = ($i + 1) * 10;
+			$list[$index] = $plugin->getID();
+		}
+	}
+
+	return $list;
+}
+
+/**
+ * Regenerates the list of known plugins and saves it to the current site
+ *
+ * Important: You should regenerate simplecache and the viewpath cache after executing this function
+ * otherwise you may experience view display artifacts. Do this with the following code:
+ *
+ * 		elgg_view_regenerate_simplecache();
+ *		elgg_filepath_cache_reset();
+ *
+ * @deprecated 1.8
+ *
+ * @param array $pluginorder Optionally, a list of existing plugins and their orders
+ *
+ * @return array The new list of plugins and their orders
+ */
+function regenerate_plugin_list($pluginorder = FALSE) {
+	$msg = 'regenerate_plugin_list() is (sorta) deprecated by elgg_generate_plugin_entities() and'
+			. ' elgg_set_plugin_priorities().';
+	elgg_deprecated_notice($msg, 1.8);
+
+	// they're probably trying to set it?
+	if ($pluginorder) {
+		if (elgg_generate_plugin_entities()) {
+			// sort the plugins by the index numerically since we used
+			// weird indexes in the old system.
+			ksort($pluginorder, SORT_NUMERIC);
+			return elgg_set_plugin_priorities($pluginorder);
+		}
+		return false;
+	} else {
+		// they're probably trying to regenerate from disk?
+		return elgg_generate_plugin_entities();
+	}
+}
+
+
+/**
+ * Loads plugins
+ *
+ * @deprecate 1.8
+ *
+ * @return bool
+ */
+function load_plugins() {
+	elgg_deprecated_notice('load_plugins() is deprecated by elgg_load_plugins()', 1.8);
+
+	return elgg_load_plugins();
+}
+
+
+/**
+ * Namespaces a string to be used as a private setting for a plugin.
+ *
+ * @param string $type The type of value: user_setting or internal.
+ * @param string $name The name to namespace.
+ * @param string $id   The plugin's ID to namespace with.  Required for user_setting.
+ * @return string
+ */
+function elgg_namespace_plugin_private_setting($type, $name, $id = null) {
+	switch ($type) {
+//		case 'setting':
+//			$name = ELGG_PLUGIN_SETTING_PREFIX . $name;
+//			break;
+
+		case 'user_setting':
+			if (!$id) {
+				$id = elgg_get_calling_plugin_id();
+			}
+			$name = ELGG_PLUGIN_USER_SETTING_PREFIX . "$id:$name";
+			break;
+
+		case 'internal':
+			$name = ELGG_PLUGIN_INTERNAL_PREFIX . $name;
+			break;
+	}
+
+	return $name;
 }
 
 /**
  * Get the name of the most recent plugin to be called in the
  * call stack (or the plugin that owns the current page, if any).
  *
- * i.e., if the last plugin was in /mod/foobar/, get_plugin_name would return foo_bar.
+ * i.e., if the last plugin was in /mod/foobar/, this would return foo_bar.
  *
  * @param boolean $mainfilename If set to true, this will instead determine the
  *                              context from the main script filename called by
  *                              the browser. Default = false.
  *
+ * @since 1.8
+ *
  * @return string|false Plugin name, or false if no plugin name was called
  */
-function get_plugin_name($mainfilename = false) {
+function elgg_get_calling_plugin_id($mainfilename = false) {
 	if (!$mainfilename) {
 		if ($backtrace = debug_backtrace()) {
 			foreach ($backtrace as $step) {
@@ -254,31 +584,38 @@ function get_plugin_name($mainfilename = false) {
 }
 
 /**
- * Load and parse a plugin manifest from a plugin XML file.
+ * Get the name of the most recent plugin to be called in the
+ * call stack (or the plugin that owns the current page, if any).
  *
- * Example file:
+ * i.e., if the last plugin was in /mod/foobar/, get_plugin_name would return foo_bar.
  *
- *	<plugin_manifest>
- *		<!-- Basic information -->
- *		<field key="name" value="My Plugin" />
- *		<field key="description" value="My Plugin's concise description" />
- *		<field key="version" value="1.0" />
- *		<field key="category" value="theme" />
- *		<field key="category" value="bundled" />
- *		<field key="screenshot" value="path/relative/to/my_plugin.jpg" />
- *		<field key="screenshot" value="path/relative/to/my_plugin_2.jpg" />
+ * @deprecated 1.8
  *
- *		<field key="author" value="Curverider Ltd" />
- *		<field key="website" value="http://www.elgg.org/" />
- *		<field key="copyright" value="(C) Curverider 2008-2010" />
- *		<field key="licence" value="GNU Public License version 2" />
- *	</plugin_manifest>
+ * @param boolean $mainfilename If set to true, this will instead determine the
+ *                              context from the main script filename called by
+ *                              the browser. Default = false.
  *
- * @param string $plugin Plugin name.
+ * @return string|false Plugin name, or false if no plugin name was called
+ */
+function get_plugin_name($mainfilename = false) {
+	elgg_deprecated_notice('get_plugin_name() is deprecated by elgg_get_calling_plugin_id()', 1.8);
+
+	return elgg_get_calling_plugin_id($mainfilename);
+}
+
+/**
+ * Load and parse a plugin manifest from a plugin XML file.
+ *
+ * @example plugins/manifest.xml Example 1.8-style manifest file.
+ *
+ * @deprecated 1.8
  *
+ * @param string $plugin Plugin name.
  * @return array of values
  */
 function load_plugin_manifest($plugin) {
+	elgg_deprecated_notice('load_plugin_manifest() is deprecated by ElggPlugin->getManifest()', 1.8);
+
 	$xml_file = elgg_get_plugin_path() . "$plugin/manifest.xml";
 
 	try {
@@ -294,11 +631,14 @@ function load_plugin_manifest($plugin) {
  * This function checks a plugin manifest 'elgg_version' value against the current install
  * returning TRUE if the elgg_version is >= the current install's version.
  *
- * @param string $manifest_elgg_version_string The build version (eg 2009010201).
+ * @deprecated 1.8
  *
+ * @param string $manifest_elgg_version_string The build version (eg 2009010201).
  * @return bool
  */
 function check_plugin_compatibility($manifest_elgg_version_string) {
+	elgg_deprecated_notice('check_plugin_compatibility() is deprecated by ElggPlugin->canActivate()', 1.8);
+
 	$version = get_version();
 
 	if (strpos($manifest_elgg_version_string, '.') === false) {
@@ -327,6 +667,7 @@ function check_plugin_compatibility($manifest_elgg_version_string) {
  * @param string $name A specific provided name to return. Requires $provide_type.
  *
  * @return array
+ * @since 1.8
  */
 function elgg_get_plugins_provides($type = null, $name = null) {
 	static $provides = null;
@@ -377,6 +718,7 @@ function elgg_get_plugins_provides($type = null, $name = null) {
  * @param string $comparison The comparison operator to use in version_compare()
  *
  * @return bool
+ * @since 1.8
  */
 function elgg_check_plugins_provides($type, $name, $version = null, $comparison = 'ge') {
 	if (!$provided = elgg_get_plugins_provides($type, $name)) {
@@ -395,25 +737,33 @@ function elgg_check_plugins_provides($type, $name, $version = null, $comparison
 /**
  * Shorthand function for finding the plugin settings.
  *
- * @param string $plugin_name Optional plugin name, if not specified
- *                            then it is detected from where you are calling from.
+ * @deprecated 1.8
+ *
+ * @param string $plugin_id Optional plugin id, if not specified
+ *                          then it is detected from where you are calling.
  *
  * @return mixed
  */
-function find_plugin_settings($plugin_name = "") {
-	$options = array('type' => 'object', 'subtype' => 'plugin', 'limit' => 9999);
-	$plugins = elgg_get_entities($options);
-	$plugin_name = sanitise_string($plugin_name);
-	if (!$plugin_name) {
-		$plugin_name = get_plugin_name();
+function find_plugin_settings($plugin_id = null) {
+	elgg_deprecated_notice('find_plugin_setting() is deprecated by elgg_get_calling_plugin_entity() or elgg_get_plugin_from_id()', 1.8);
+	if ($plugin_id) {
+		return elgg_get_plugin_from_id($plugin_id);
+	} else {
+		return elgg_get_calling_plugin_entity();
 	}
+}
 
-	if ($plugins) {
-		foreach ($plugins as $plugin) {
-			if (strcmp($plugin->title, $plugin_name) == 0) {
-				return $plugin;
-			}
-		}
+/**
+ * Returns the ElggPlugin entity of the last plugin called.
+ *
+ * @return mixed ElggPlugin or false
+ * @since 1.8
+ */
+function elgg_get_calling_plugin_entity() {
+	$plugin_id = elgg_get_calling_plugin_id();
+
+	if ($plugin_id) {
+		return elgg_get_plugin_from_id($plugin_id);
 	}
 
 	return false;
@@ -422,34 +772,41 @@ function find_plugin_settings($plugin_name = "") {
 /**
  * Find the plugin settings for a user.
  *
- * @param string $plugin_name Plugin name.
- * @param int    $user_guid   The guid who's settings to retrieve.
+ * @param string $plugin_id Plugin name.
+ * @param int    $user_guid The guid who's settings to retrieve.
  *
  * @return array of settings in an associative array minus prefix.
  */
-function find_plugin_usersettings($plugin_name = "", $user_guid = 0) {
-	$plugin_name = sanitise_string($plugin_name);
+function find_plugin_usersettings($plugin_id = null, $user_guid = 0) {
+	$plugin_id = sanitise_string($plugin_id);
 	$user_guid = (int)$user_guid;
+	$db_prefix = get_config('db_prefix');
+	$ps_prefix = elgg_namespace_plugin_private_setting('user_setting', "$plugin_id:");
+	$ps_prefix_len = strlen($ps_prefix);
 
-	if (!$plugin_name) {
-		$plugin_name = get_plugin_name();
+	if (!$plugin_id) {
+		$plugin_id = elgg_get_calling_plugin_id();
 	}
 
 	if ($user_guid == 0) {
 		$user_guid = get_loggedin_userid();
 	}
 
-	// Get metadata for user
-	$all_metadata = get_all_private_settings($user_guid); //get_metadata_for_entity($user_guid);
-	if ($all_metadata) {
-		$prefix = "plugin:settings:$plugin_name:";
+	// Get private settings for user
+	$q = "SELECT * FROM {$db_prefix}private_settings
+		WHERE entity_guid = $user_guid
+		AND name LIKE '$ps_prefix$plugin_id'";
+
+	$private_settings = get_data($q);
+	if ($private_settings) {
 		$return = new stdClass;
 
-		foreach ($all_metadata as $key => $meta) {
-			$name = substr($key, strlen($prefix));
-			$value = $meta;
+		foreach ($private_settings as $setting) {
+			$name = substr($setting->name, $ps_prefix_len);
+			$value = $setting->value;
 
-			if (strpos($key, $prefix) === 0) {
+			// @todo why?
+			if (strpos($key, $ps_prefix) === 0) {
 				$return->$name = $value;
 			}
 		}
@@ -463,21 +820,21 @@ function find_plugin_usersettings($plugin_name = "", $user_guid = 0) {
 /**
  * Set a user specific setting for a plugin.
  *
- * @param string $name        The name - note, can't be "title".
- * @param mixed  $value       The value.
- * @param int    $user_guid   Optional user.
- * @param string $plugin_name Optional plugin name, if not specified then it
- *                            is detected from where you are calling from.
+ * @param string $name      The name - note, can't be "title".
+ * @param mixed  $value     The value.
+ * @param int    $user_guid Optional user.
+ * @param string $plugin_id Optional plugin name, if not specified then it
+ *                          is detected from where you are calling from.
  *
  * @return bool
  */
-function set_plugin_usersetting($name, $value, $user_guid = 0, $plugin_name = "") {
-	$plugin_name = sanitise_string($plugin_name);
+function set_plugin_usersetting($name, $value, $user_guid = 0, $plugin_id = "") {
+	$plugin_id = sanitise_string($plugin_id);
 	$user_guid = (int)$user_guid;
 	$name = sanitise_string($name);
 
-	if (!$plugin_name) {
-		$plugin_name = get_plugin_name();
+	if (!$plugin_id) {
+		$plugin_id = elgg_get_calling_plugin_id();
 	}
 
 	$user = get_entity($user_guid);
@@ -486,19 +843,17 @@ function set_plugin_usersetting($name, $value, $user_guid = 0, $plugin_name = ""
 	}
 
 	if (($user) && ($user instanceof ElggUser)) {
-		$prefix = "plugin:settings:$plugin_name:$name";
-		//$user->$prefix = $value;
-		//$user->save();
+		$name = elgg_namespace_plugin_private_setting('user_setting', "$plugin_id:$name");
 
 		// Hook to validate setting
 		$value = elgg_trigger_plugin_hook('plugin:usersetting', 'user', array(
 			'user' => $user,
-			'plugin' => $plugin_name,
+			'plugin' => $plugin_id,
 			'name' => $name,
 			'value' => $value
 		), $value);
 
-		return set_private_setting($user->guid, $prefix, $value);
+		return set_private_setting($user->guid, $name, $value);
 	}
 
 	return false;
@@ -507,18 +862,18 @@ function set_plugin_usersetting($name, $value, $user_guid = 0, $plugin_name = ""
 /**
  * Clears a user-specific plugin setting
  *
- * @param str $name        Name of the plugin setting
- * @param int $user_guid   Defaults to logged in user
- * @param str $plugin_name Defaults to contextual plugin name
+ * @param str $name      Name of the plugin setting
+ * @param int $user_guid Defaults to logged in user
+ * @param str $plugin_id Defaults to contextual plugin name
  *
  * @return bool Success
  */
-function clear_plugin_usersetting($name, $user_guid = 0, $plugin_name = '') {
-	$plugin_name = sanitise_string($plugin_name);
+function clear_plugin_usersetting($name, $user_guid = 0, $plugin_id = '') {
+	$plugin_id = sanitise_string($plugin_id);
 	$name = sanitise_string($name);
 
-	if (!$plugin_name) {
-		$plugin_name = get_plugin_name();
+	if (!$plugin_id) {
+		$plugin_id = elgg_get_calling_plugin_id();
 	}
 
 	$user = get_entity((int) $user_guid);
@@ -527,7 +882,7 @@ function clear_plugin_usersetting($name, $user_guid = 0, $plugin_name = '') {
 	}
 
 	if (($user) && ($user instanceof ElggUser)) {
-		$prefix = "plugin:settings:$plugin_name:$name";
+		$prefix = elgg_namespace_plugin_private_setting('user_setting', "$plugin_id:$name");
 
 		return remove_private_setting($user->getGUID(), $prefix);
 	}
@@ -538,20 +893,20 @@ function clear_plugin_usersetting($name, $user_guid = 0, $plugin_name = '') {
 /**
  * Get a user specific setting for a plugin.
  *
- * @param string $name        The name.
- * @param int    $user_guid   Guid of owning user
- * @param string $plugin_name Optional plugin name, if not specified
+ * @param string $name      The name.
+ * @param int    $user_guid Guid of owning user
+ * @param string $plugin_id Optional plugin name, if not specified
  *                            then it is detected from where you are calling from.
  *
  * @return mixed
  */
-function get_plugin_usersetting($name, $user_guid = 0, $plugin_name = "") {
-	$plugin_name = sanitise_string($plugin_name);
+function get_plugin_usersetting($name, $user_guid = 0, $plugin_id = "") {
+	$plugin_id = sanitise_string($plugin_id);
 	$user_guid = (int)$user_guid;
 	$name = sanitise_string($name);
 
-	if (!$plugin_name) {
-		$plugin_name = get_plugin_name();
+	if (!$plugin_id) {
+		$plugin_id = elgg_get_calling_plugin_id();
 	}
 
 	$user = get_entity($user_guid);
@@ -560,8 +915,8 @@ function get_plugin_usersetting($name, $user_guid = 0, $plugin_name = "") {
 	}
 
 	if (($user) && ($user instanceof ElggUser)) {
-		$prefix = "plugin:settings:$plugin_name:$name";
-		return get_private_setting($user->guid, $prefix);
+		$name = elgg_namespace_plugin_private_setting('user_setting', "$plugin_id:$name");
+		return get_private_setting($user->guid, $name);
 	}
 
 	return false;
@@ -570,143 +925,126 @@ function get_plugin_usersetting($name, $user_guid = 0, $plugin_name = "") {
 /**
  * Set a setting for a plugin.
  *
- * @param string $name        The name - note, can't be "title".
- * @param mixed  $value       The value.
- * @param string $plugin_name Optional plugin name, if not specified
- *                            then it is detected from where you are calling from.
+ * @param string $name      The name - note, can't be "title".
+ * @param mixed  $value     The value.
+ * @param string $plugin_id Optional plugin name, if not specified
+ *                          then it is detected from where you are calling from.
  *
  * @return int|false
  */
-function set_plugin_setting($name, $value, $plugin_name = "") {
-	if (!$plugin_name) {
-		$plugin_name = get_plugin_name();
+function set_plugin_setting($name, $value, $plugin_id = null) {
+	if ($plugin_id) {
+		$plugin = elgg_get_plugin_from_id($plugin_id);
+	} else {
+		$plugin = elgg_get_calling_plugin_entity();
 	}
-	$plugin = find_plugin_settings($plugin_name);
 
 	if (!$plugin) {
-		$plugin = new ElggPlugin();
-	}
-
-	if ($name != 'title') {
-		// Hook to validate setting
-		$value = elgg_trigger_plugin_hook('plugin:setting', 'plugin', array(
-			'plugin' => $plugin_name,
-			'name' => $name,
-			'value' => $value
-		), $value);
-
-		$plugin->title = $plugin_name;
-		$plugin->access_id = ACCESS_PUBLIC;
-		$plugin->save();
-		$plugin->$name = $value;
-
-		return $plugin->getGUID();
+		return false;
 	}
 
-	return false;
+	return $plugin->setSetting($name, $value);
 }
 
 /**
  * Get setting for a plugin.
  *
- * @param string $name        The name.
- * @param string $plugin_name Optional plugin name, if not specified
- *                            then it is detected from where you are calling from.
+ * @param string $name      The name.
+ * @param string $plugin_id Optional plugin name, if not specified
+ *                          then it is detected from where you are calling from.
  *
  * @return mixed
  */
-function get_plugin_setting($name, $plugin_name = "") {
-	$plugin = find_plugin_settings($plugin_name);
+function get_plugin_setting($name, $plugin_id = "") {
+	if ($plugin_id) {
+		$plugin = elgg_get_plugin_from_id($plugin_id);
+	} else {
+		$plugin = elgg_get_calling_plugin_entity();
+	}
 
-	if ($plugin) {
-		return $plugin->$name;
+	if (!$plugin) {
+		return false;
 	}
 
-	return false;
+	return $plugin->getSetting($name);
 }
 
 /**
  * Clear a plugin setting.
  *
- * @param string $name        The name.
- * @param string $plugin_name Optional plugin name, if not specified
- *                            then it is detected from where you are calling from.
+ * @param string $name      The name.
+ * @param string $plugin_id Optional plugin name, if not specified
+ *                          then it is detected from where you are calling from.
  *
  * @return bool
  */
-function clear_plugin_setting($name, $plugin_name = "") {
-	$plugin = find_plugin_settings($plugin_name);
+function clear_plugin_setting($name, $plugin_id = "") {
+	if ($plugin_id) {
+		$plugin = elgg_get_plugin_from_id($plugin_id);
+	} else {
+		$plugin = elgg_get_calling_plugin_entity();
+	}
 
-	if ($plugin) {
-		return remove_private_setting($plugin->guid, $name);
+	if (!$plugin) {
+		return false;
 	}
 
-	return FALSE;
+	return $plugin->removeSetting($name);
 }
 
 /**
  * Clear all plugin settings.
  *
- * @param string $plugin_name Optional plugin name, if not specified
- *                            then it is detected from where you are calling from.
+ * @param string $plugin_id Optional plugin name, if not specified
+ *                          then it is detected from where you are calling from.
  *
  * @return bool
  * @since 1.7.0
  */
-function clear_all_plugin_settings($plugin_name = "") {
-	$plugin = find_plugin_settings($plugin_name);
+function clear_all_plugin_settings($plugin_id = "") {
+	if ($plugin_id) {
+		$plugin = elgg_get_plugin_from_id($plugin_id);
+	} else {
+		$plugin = elgg_get_calling_plugin_entity();
+	}
 
 	if ($plugin) {
-		return remove_all_private_settings($plugin->guid);
+		$plugin->removeAllSettings();
 	}
 
-	return FALSE;
+	return false;
 }
 
 /**
  * Return an array of installed plugins.
  *
+ * @deprecated 1.8
+ *
  * @param string $status any|enabled|disabled
  * @return array
  */
-function get_installed_plugins($status = 'any') {
+function get_installed_plugins($status = 'all') {
 	global $CONFIG;
 
-	$installed_plugins = array();
+	elgg_deprecated_notice('get_installed_plugins() was deprecated by elgg_get_plugins()', 1.8);
 
-	if (!empty($CONFIG->pluginspath)) {
-		$plugins = get_plugin_list();
+	$plugins = elgg_get_plugins($status);
 
-		foreach ($plugins as $mod) {
-			// require manifest.
-			if (!$manifest = load_plugin_manifest($mod)) {
-				continue;
-			}
-
-			$enabled = is_plugin_enabled($mod);
-
-			switch ($status) {
-				case 'enabled':
-					if ($enabled != true) {
-						continue 2;
-					}
-					break;
-
-				case 'disabled':
-					if ($enabled == true) {
-						continue 2;
-					}
-					break;
+	if (!$plugins) {
+		return array();
+	}
 
-				case 'any':
-				default:
-					break;
-			}
+	$installed_plugins = array();
 
-			$installed_plugins[$mod] = array();
-			$installed_plugins[$mod]['active'] = $enabled;
-			$installed_plugins[$mod]['manifest'] = $manifest;
+	foreach ($plugins as $plugin) {
+		if (!$plugin->isValid()) {
+			continue;
 		}
+
+		$installed_plugins[$plugin->getID()] = array(
+			'active' => $plugin->isActive(),
+			'manifest' => $plugin->manifest->getManifest()
+		);
 	}
 
 	return $installed_plugins;
@@ -721,82 +1059,36 @@ function get_installed_plugins($status = 'any') {
  * 		elgg_view_regenerate_simplecache();
  *		elgg_filepath_cache_reset();
  *
+ * @deprecated 1.8
+ *
  * @param string $plugin    The plugin name.
  * @param int    $site_guid The site id, if not specified then this is detected.
  *
  * @return array
  * @throws InvalidClassException
  */
-function enable_plugin($plugin, $site_guid = 0) {
-	global $CONFIG, $ENABLED_PLUGINS_CACHE;
+function enable_plugin($plugin, $site_guid = null) {
+	elgg_deprecated_notice('enable_plugin() was deprecated by ElggPlugin->activate()', 1.8);
 
 	$plugin = sanitise_string($plugin);
-	$site_guid = (int) $site_guid;
-	if ($site_guid == 0) {
-		$site_guid = $CONFIG->site_guid;
-	}
 
-	$site = get_entity($site_guid);
-	if (!($site instanceof ElggSite)) {
-		$msg = elgg_echo('InvalidClassException:NotValidElggStar', array($site_guid, "ElggSite"));
-		throw new InvalidClassException($msg);
-	}
-
-	if (!$plugin_info = load_plugin_manifest($plugin)) {
-		return FALSE;
+	$site_guid = (int) $site_guid;
+	if (!$site_guid) {
+		$site = get_config('site');
+		$site_guid = $site->guid;
 	}
 
-	// getMetadata() doesn't return an array if only one plugin is enabled
-	if ($enabled = $site->enabled_plugins) {
-		if (!is_array($enabled)) {
-			$enabled = array($enabled);
-		}
-	} else {
-		$enabled = array();
+	try {
+		$plugin = new ElggPlugin($plugin);
+	} catch(Exception $e) {
+		return false;
 	}
 
-	$enabled[] = $plugin;
-	$enabled = array_unique($enabled);
-
-	if ($return = $site->setMetaData('enabled_plugins', $enabled)) {
-
-		// for other plugins that want to hook into this.
-		$params = array('plugin' => $plugin, 'manifest' => $plugin_info);
-		if ($return && !elgg_trigger_event('enable', 'plugin', $params)) {
-			$return = FALSE;
-		}
-
-		// for this plugin's on_enable
-		if ($return && isset($plugin_info['on_enable'])) {
-			// pull in the actual plugin's start so the on_enable function is callable
-			// NB: this will not run re-run the init hooks!
-			$start = "{$CONFIG->pluginspath}$plugin/start.php";
-			if (!file_exists($start) || !include($start)) {
-				$return = FALSE;
-			}
-
-			// need language files for the messages
-			$translations = "{$CONFIG->pluginspath}$plugin/languages/";
-			register_translations($translations);
-			if (!is_callable($plugin_info['on_enable'])) {
-				$return = FALSE;
-			} else {
-				$on_enable = call_user_func($plugin_info['on_enable']);
-				// allow null to mean "I don't care" like other subsystems
-				$return = ($on_disable === FALSE) ? FALSE : TRUE;
-			}
-		}
-
-		// disable the plugin if the on_enable or trigger results failed
-		if (!$return) {
-			array_pop($enabled);
-			$site->setMetaData('enabled_plugins', $enabled);
-		}
-
-		$ENABLED_PLUGINS_CACHE = $enabled;
+	if (!$plugin->canActivate($site_guid)) {
+		return false;
 	}
 
-	return $return;
+	return $plugin->activate($site_guid);
 }
 
 /**
@@ -808,6 +1100,8 @@ function enable_plugin($plugin, $site_guid = 0) {
  * 		elgg_view_regenerate_simplecache();
  *		elgg_filepath_cache_reset();
  *
+ * @deprecated 1.8
+ *
  * @param string $plugin    The plugin name.
  * @param int    $site_guid The site id, if not specified then this is detected.
  *
@@ -815,118 +1109,53 @@ function enable_plugin($plugin, $site_guid = 0) {
  * @throws InvalidClassException
  */
 function disable_plugin($plugin, $site_guid = 0) {
-	global $CONFIG, $ENABLED_PLUGINS_CACHE;
+	elgg_deprecated_notice('disable_plugin() was deprecated by ElggPlugin->deactivate()', 1.8);
 
 	$plugin = sanitise_string($plugin);
-	$site_guid = (int) $site_guid;
-	if ($site_guid == 0) {
-		$site_guid = $CONFIG->site_guid;
-	}
-
-	$site = get_entity($site_guid);
-	if (!($site instanceof ElggSite)) {
-		$msg = elgg_echo('InvalidClassException:NotValidElggStar', array($site_guid, "ElggSite"));
-		throw new InvalidClassException();
-	}
 
-	if (!$plugin_info = load_plugin_manifest($plugin)) {
-		return FALSE;
-	}
-
-	// getMetadata() doesn't return an array if only one plugin is enabled
-	if ($enabled = $site->enabled_plugins) {
-		if (!is_array($enabled)) {
-			$enabled = array($enabled);
-		}
-	} else {
-		$enabled = array();
-	}
-
-	$old_enabled = $enabled;
-
-	// remove the disabled plugin from the array
-	if (FALSE !== $i = array_search($plugin, $enabled)) {
-		unset($enabled[$i]);
+	$site_guid = (int) $site_guid;
+	if (!$site_guid) {
+		$site = get_config('site');
+		$site_guid = $site->guid;
 	}
 
-	// if we're unsetting all the plugins, this will return an empty array.
-	// it will fail with FALSE, though.
-	$return = (FALSE === $site->enabled_plugins = $enabled) ? FALSE : TRUE;
-
-	if ($return) {
-		// for other plugins that want to hook into this.
-		$params = array('plugin' => $plugin, 'manifest' => $plugin_info);
-		if ($return && !elgg_trigger_event('disable', 'plugin', $params)) {
-			$return = FALSE;
-		}
-
-		// for this plugin's on_disable
-		if ($return && isset($plugin_info['on_disable'])) {
-			if (!is_callable($plugin_info['on_disable'])) {
-				$return = FALSE;
-			} else {
-				$on_disable = call_user_func($plugin_info['on_disable']);
-				// allow null to mean "I don't care" like other subsystems
-				$return = ($on_disable === FALSE) ? FALSE : TRUE;
-			}
-		}
-
-		// disable the plugin if the on_enable or trigger results failed
-		if (!$return) {
-			$site->enabled_plugins = $old_enabled;
-			$ENABLED_PLUGINS_CACHE = $old_enabled;
-		} else {
-			$ENABLED_PLUGINS_CACHE = $enabled;
-		}
+	try {
+		$plugin = new ElggPlugin($plugin);
+	} catch(Exception $e) {
+		return false;
 	}
 
-	return $return;
+	return $plugin->deactivate($site_guid);
 }
 
 /**
  * Return whether a plugin is enabled or not.
  *
+ * @deprecated 1.8
+ *
  * @param string $plugin    The plugin name.
  * @param int    $site_guid The site id, if not specified then this is detected.
  *
  * @return bool
- * @throws InvalidClassException
  */
 function is_plugin_enabled($plugin, $site_guid = 0) {
-	global $CONFIG, $ENABLED_PLUGINS_CACHE;
+	elgg_deprecated_notice('is_plugin_enabled() was deprecated by ElggPlugin->isActive()', 1.8);
 
-	if (!file_exists($CONFIG->pluginspath . $plugin)) {
-		return false;
-	}
+	$plugin = sanitise_string($plugin);
 
 	$site_guid = (int) $site_guid;
-	if ($site_guid == 0) {
-		$site_guid = $CONFIG->site_guid;
+	if (!$site_guid) {
+		$site = get_config('site');
+		$site_guid = $site->guid;
 	}
 
-	if (!$ENABLED_PLUGINS_CACHE) {
-		$site = get_entity($site_guid);
-		if (!($site instanceof ElggSite)) {
-			$msg = elgg_echo('InvalidClassException:NotValidElggStar', array($site_guid, "ElggSite"));
-			throw new InvalidClassException($msg);
-		}
-
-		$enabled_plugins = $site->enabled_plugins;
-		if ($enabled_plugins && !is_array($enabled_plugins)) {
-			$enabled_plugins = array($enabled_plugins);
-		}
-		$ENABLED_PLUGINS_CACHE = $enabled_plugins;
-	}
-
-	if (is_array($ENABLED_PLUGINS_CACHE)) {
-		foreach ($ENABLED_PLUGINS_CACHE as $e) {
-			if ($e == $plugin) {
-				return true;
-			}
-		}
+	try {
+		$plugin = new ElggPlugin($plugin);
+	} catch(Exception $e) {
+		return false;
 	}
 
-	return false;
+	return $plugin->isActive($site_guid);
 }
 
 /**
@@ -935,7 +1164,6 @@ function is_plugin_enabled($plugin, $site_guid = 0) {
  *  @return void
  */
 function plugin_run_once() {
-	// Register a class
 	add_subtype("object", "plugin", "ElggPlugin");
 }
 
@@ -978,4 +1206,4 @@ function plugin_init() {
 	elgg_register_action('admin/plugins/reorder', '', 'admin');
 }
 
-elgg_register_event_handler('init', 'system', 'plugin_init');
+elgg_register_event_handler('init', 'system', 'plugin_init');
\ No newline at end of file
diff --git a/engine/lib/upgrades/2011010101.php b/engine/lib/upgrades/2011010101.php
new file mode 100644
index 000000000..eac5810c4
--- /dev/null
+++ b/engine/lib/upgrades/2011010101.php
@@ -0,0 +1,75 @@
+<?php
+/**
+ * Migrate plugins to the new system using ElggPlugin and private settings
+ */
+
+$old_ia = elgg_set_ignore_access(true);
+
+$site = get_config('site');
+$old_plugin_order = unserialize($site->pluginorder);
+$old_enabled_plugins = $site->enabled_plugins;
+
+$db_prefix = get_config('dbprefix');
+$plugin_subtype_id = get_subtype_id('object', 'plugin');
+
+// easy one first: make sure the the site owns all plugin entities.
+$q = "UPDATE {$db_prefix}entities e
+	SET owner_guid = $site->guid, container_guid = $site->guid
+	WHERE e.type = 'object' AND e.subtype = $plugin_subtype_id";
+
+$r = update_data($q);
+
+// rewrite all plugin:setting:* to ELGG_PLUGIN_USER_SETTING_PREFIX . *
+$q = "UPDATE {$db_prefix}private_settings
+	SET name = replace(name, 'plugin:setting', '" . ELGG_PLUGIN_USER_SETTING_PREFIX . "')
+	WHERE name LIKE 'plugin:setting:%'";
+
+$r = update_data($q);
+
+// grab current plugin GUIDs to add a temp priority
+$q = "SELECT * FROM {$db_prefix}entities e
+	JOIN {$db_prefix}objects_entity oe ON e.guid = oe.guid
+	WHERE e.type = 'object' AND e.subtype = $plugin_subtype_id";
+
+$plugins = get_data($q);
+
+foreach ($plugins as $plugin) {
+	$priority = elgg_namespace_plugin_private_setting('internal', 'priority');
+	set_private_setting($plugin->guid, $priority, 0);
+}
+
+// force regenerating plugin entities
+elgg_generate_plugin_entities();
+
+// set the priorities for all plugins
+// this function rewrites it to a normal index so use the current one.
+elgg_set_plugin_priorities($old_plugin_order);
+
+// add relationships for enabled plugins
+if ($old_enabled_plugins) {
+	// they might only have one plugin enabled.
+	if (!is_array($old_enabled_plugins)) {
+		$old_enabled_plugins = array($old_enabled_plugins);
+	}
+
+	// sometimes there were problems and you'd get 1000s of enabled plugins.
+	$old_enabled_plugins = array_unique($old_enabled_plugins);
+
+	foreach ($old_enabled_plugins as $plugin_id) {
+		$plugin = elgg_get_plugin_from_id($plugin_id);
+
+		if ($plugin) {
+			$plugin->activate();
+		}
+	}
+}
+
+// invalidate caches
+elgg_invalidate_simplecache();
+elgg_filepath_cache_reset();
+
+// clean up.
+remove_metadata($site->guid, 'pluginorder');
+remove_metadata($site->guid, 'enabled_plugins');
+
+elgg_set_ignore_access($old_id);
\ No newline at end of file