plugins: first prototype version

git-svn-id: http://piwigo.org/svn/trunk@1578 68402e56-0260-453c-a942-63ccdbb3a9ee

include/functions_plugins.inc.php

@@ -0,0 +1,155 @@
+<?php
+// +-----------------------------------------------------------------------+
+// | PhpWebGallery - a PHP based picture gallery                           |
+// | Copyright (C) 2003-2006 PhpWebGallery Team - http://phpwebgallery.net |
+// +-----------------------------------------------------------------------+
+// | branch        : BSF (Best So Far)
+// | file          : $Id$
+// | last update   : $Date$
+// | last modifier : $Author$
+// | revision      : $Revision$
+// +-----------------------------------------------------------------------+
+// | This program 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                                          |
+// |                                                                       |
+// | This program 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 this program; if not, write to the Free Software           |
+// | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, |
+// | USA.                                                                  |
+// +-----------------------------------------------------------------------+
+
+/*
+Events and event handlers are the core of PhpWebGallery plugin management.
+Plugins are addons that are found in plugins subdirectory. If activated, PWG
+will include the index.php of each plugin.
+Events are triggered by PWG core code. Plugins (or even PWG itself) can
+register their functions to handle these events. An event is identified by a
+string.
+*/
+
+define('PHPWG_PLUGINS_PATH',PHPWG_ROOT_PATH.'plugins/');
+
+/* Register a event handler.
+ * @param string $event the name of the event to listen to
+ * @param mixed $func the function that will handle the event
+*/
+function add_event_handler($event, $func, $priority=50, $accepted_args=1)
+{
+  global $pwg_event_handlers;
+
+  if ( isset($pwg_event_handlers[$event]["$priority"]) )
+  {
+    foreach($pwg_event_handlers[$event]["$priority"] as $handler)
+    {
+      if ( $handler['function'] == $func )
+      {
+        return true;
+      }
+    }
+  }
+
+  trigger_event('add_event_handler',
+      array('event'=>$event, 'function'=>$func)
+    );
+
+  $pwg_event_handlers[$event]["$priority"][] =
+    array(
+      'function'=>$func,
+      'accepted_args'=>$accepted_args);
+
+  return true;
+}
+
+
+function trigger_event($event, $data=null)
+{
+  global $pwg_event_handlers;
+  if ($event!='pre_trigger_event' and $event!='post_trigger_event')
+  {// special case
+    trigger_event('pre_trigger_event',
+        array('event'=>$event, 'data'=>$data) );
+    if ( !isset($pwg_event_handlers[$event]) )
+    {
+      trigger_event('post_trigger_event',
+          array('event'=>$event, 'data'=>$data) );
+    }
+  }
+
+  if ( !isset($pwg_event_handlers[$event]) )
+  {
+    return $data;
+  }
+  $args = array_slice(func_get_args(), 2);
+
+  foreach ($pwg_event_handlers[$event] as $priority => $handlers)
+  {
+    if ( !is_null($handlers) )
+    {
+      foreach($handlers as $handler)
+      {
+        $all_args = array_merge( array($data), $args);
+        $function_name = $handler['function'];
+        $accepted_args = $handler['accepted_args'];
+
+        if ( $accepted_args == 1 )
+          $the_args = array($data);
+        elseif ( $accepted_args > 1 )
+          $the_args = array_slice($all_args, 0, $accepted_args);
+        elseif ( $accepted_args == 0 )
+          $the_args = NULL;
+        else
+          $the_args = $all_args;
+
+        $data = call_user_func_array($function_name, $the_args);
+      }
+    }
+  }
+
+  if ($event!='pre_trigger_event' and $event!='post_trigger_event')
+  {
+    trigger_event('post_trigger_event',
+        array('event'=>$event, 'data'=>$data) );
+  }
+
+  return $data;
+}
+
+
+
+
+
+function get_active_plugins($runtime = true)
+{
+  global $conf;
+  if ($conf['disable_plugins'] and $runtime)
+  {
+    return array();
+  }
+  if (empty($conf['active_plugins']))
+  {
+    return array();
+  }
+  return explode(',', $conf['active_plugins']);
+
+}
+
+
+function load_plugins()
+{
+  $plugins = get_active_plugins();
+  foreach( $plugins as $plugin)
+  {
+    if (!empty($plugin))
+    {
+      include_once( PHPWG_PLUGINS_PATH.$plugin.'/index.php' );
+    }
+  }
+  trigger_event('plugins_loaded');
+}
+?>