<?php
/**
 *	PluginManager object
 *
 *	Provides an abstract way to handle plugins
 *
 * This file is copyright (c) Roland Mas <lolando@debian.org>, 2002
 *
 * @version   $Id: PluginManager.class 5541 2006-06-06 21:27:52Z lo-lan-do $
 *
 * This file is part of GForge.
 *
 * GForge is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * GForge is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GForge; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

class PluginManager extends Error {
	var $plugins_objects ;
	var $plugins_to_hooks ;
	var $hooks_to_plugins ;

	/**
	 * PluginManager() - constructor
	 *
	 */
	function PluginManager () {
		$this->Error() ;
		$this->plugins_objects = array () ;
		$this->plugins_to_hooks = array () ;
		$this->hooks_to_plugins = array () ;
	}

	/**
	 * GetPlugins() - get a list of installed plugins
	 *
	 * @return hash of plugin id => plugin names
	 */
	function GetPlugins () {
		if (!isset($this->plugins_data)) {
			$this->plugins_data = array () ;
			$sql = "SELECT plugin_id, plugin_name FROM plugins" ;
			$res = db_query($sql);
			$rows = db_numrows($res);
			for ($i=0; $i<$rows; $i++) {
				$plugin_id = db_result($res,$i,'plugin_id');
				$this->plugins_data[$plugin_id] = db_result($res,$i,'plugin_name');
			}
		}
		return $this->plugins_data ;
	}

	/**
	 * GetPluginObject() - get a particular plugin object
	 *
         * @param pluginname - name of plugin
	 * @return a plugin object
	 */
	function GetPluginObject ($pluginname) {
		return $this->plugins_objects [$pluginname] ;
	}

	/**
	 * PluginIsInstalled() - is a plugin installed?
	 *
	 * @param pluginname - name of plugin
	 * @return boolean, true if installed
	 */
	function PluginIsInstalled ($pluginname) {
		$plugins_data = $this->getPlugins() ;
		foreach ($plugins_data as $p_id => $p_name) {
			if ($p_name == $pluginname) {
				return true ;
			}
		}
		return false ;
	}

	/**
	 * LoadPlugins() - load available plugins
	 *
	 */
	function LoadPlugins () {
		$plugins_data = $this->GetPlugins() ;
		$include_path = $GLOBALS['sys_plugins_path'] ;
		foreach ($plugins_data as $p_id => $p_name) {
			$filename = $include_path . $p_name . "/include/".$p_name."-init.php" ;
			if (file_exists ($filename)) {
				require_once ($filename) ;
			} else {
				// we can't find the plugin so we remove it from the array
				unset($this->plugins_data[$p_id]);
			}
		}
		return true ;
	}

	/**
	 * SetupHooks() - setup all hooks for installed plugins
	 *
	 */
	function SetupHooks () {
		foreach ($this->plugins_to_hooks as $p_name => $hook_list) {
			foreach ($hook_list as $hook_name) {
				if (!isset ($this->hooks_to_plugins[$hook_name])) {
					$this->hooks_to_plugins[$hook_name] = array () ;
				}
				$this->hooks_to_plugins[$hook_name][] = $p_name ;
			}
		}
		return true ;
	}

	/**
	 * RegisterPlugin() - register a plugin
	 *
	 * @param pluginobject - an object of a subclass of the Plugin class
	 */
	function RegisterPlugin (&$pluginobject) {
		if (!$pluginobject->GetName ()) {
			exit_error ("Some plugin did not provide a name.  I'd gladly tell you which one, but obviously I can't.  Sorry.") ;
		}
		$p_name = $pluginobject->GetName () ;
		$this->plugins_objects [$p_name] =& $pluginobject ;
		$this->plugins_to_hooks [$p_name] = $pluginobject->GetHooks () ;
		return true ;
	}

	/**
	 * RunHooks() - call hooks from a particular point
	 *
	 * @param hookname - name of the hook
	 * @param params - array of extra parameters
	 */
	function RunHooks ($hookname, & $params) {
		if (isset($this->hooks_to_plugins[$hookname])) {
			$p_list = $this->hooks_to_plugins[$hookname];
			foreach ($p_list as $p_name) {
				$p_obj = $this->plugins_objects[$p_name] ;
				$p_obj->CallHook ($hookname, $params) ;
			}
		}
		return true ;
	}

	/**
	 * CountHookListeners() - number of listeners on a particular hook
	 *
	 * @param hookname - name of the hook
	 */
	function CountHookListeners ($hookname) {
		if (isset($this->hooks_to_plugins[$hookname])) {
			$p_list = $this->hooks_to_plugins[$hookname];
			return count ($p_list) ;
		} else {
			return 0 ;
		}
		
	}
}

/**
 * plugin_manager_get_object() - get the PluginManager object
 *
 * @return the PluginManager object
 */
function &plugin_manager_get_object() {
	global $PLUGINMANAGER_OBJ;
	if (!isset($PLUGINMANAGER_OBJ) || !$PLUGINMANAGER_OBJ) {
		$PLUGINMANAGER_OBJ = new PluginManager ;
	}
	return $PLUGINMANAGER_OBJ ;
}

/**
 * plugin_get_object() - get a particular Plugin object
 *
 * @param pluginname - a plugin name
 * @return the Plugin object
 */
function &plugin_get_object ($pluginname) {
	global $PLUGINMANAGER_OBJ;
	return $PLUGINMANAGER_OBJ->Getpluginobject ($pluginname) ;
}

/**
 * register_plugin () - register a plugin
 *
 * @param pluginobject - an object of a subclass of the Plugin class
 */
function register_plugin (&$pluginobject) {
	$pm =& plugin_manager_get_object () ;
	return $pm->RegisterPlugin ($pluginobject) ;
}

/**
 * plugin_hook () - run a set of hooks
 *
 * @param hookname - name of the hook
 * @param params - parameters for the hook
 */
function plugin_hook ($hookname, $params = false) {
	$pm =& plugin_manager_get_object () ;
	return $pm->RunHooks ($hookname, $params) ;
}

/**
 * plugin_hook_by_reference () - run a set of hooks with params passed by reference
 *
 * @param hookname - name of the hook
 * @param params - parameters for the hook
 */
function plugin_hook_by_reference ($hookname, & $params) {
	$pm =& plugin_manager_get_object () ;
	return $pm->RunHooks ($hookname, $params) ;
}

/**
 * plugin_hook_listeners () - count the number of listeners on a hook
 *
 * @param hookname - name of the hook
 */
function plugin_hook_listeners ($hookname, $params=false) {
	$pm =& plugin_manager_get_object () ;
	return $pm->CountHookListeners ($hookname) ;
}

/**
 * setup_plugin_manager () - initialise the plugin infrastructure
 *
 */
function setup_plugin_manager () {
	$pm =& plugin_manager_get_object() ;
	$pm->LoadPlugins () ;
	$pm->SetupHooks () ;
	return true ;
}

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// mode: php
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?>