/*
 * SwamiPlugin.c - Swami plugin system
 *
 * Swami
 * Copyright (C) 1999-2003 Josh Green <jgreen@users.sourceforge.net>
 *
 * Code borrowed and modified from:
 * GStreamer (gst/gstplugin.c)
 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
 *                    2000 Wim Taymans <wtay@chello.be>
 *
 * 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; either version 2
 * of the License, or (at your option) any later version.
 *
 * 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 or point your web browser to http://www.gnu.org.
 *
 * To contact the author of this program:
 * Email: Josh Green <jgreen@users.sourceforge.net>
 * Swami homepage: http://swami.sourceforge.net
 */

#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <unistd.h>

#include "SwamiPlugin.h"
#include "SwamiLog.h"
#include "SwamiObject.h"	/* FIXME: SWAMI_OK */
#include "version.h"
#include "config.h"
#include "i18n.h"

static GModule *main_module;

GList *_swami_plugin_static = NULL;

/* global list of plugins and its sequence number */
GList *_swami_plugins = NULL;
int _swami_plugins_seqno = 0;
/* list of paths to check for plugins */
GList *_swami_plugin_paths = NULL;

GList *_swami_libraries = NULL;
gint _swami_libraries_seqno = 0;

/* whether or not to spew library load issues */
gboolean _swami_plugin_spew = FALSE;

static void swami_plugin_register_statics (GModule *module);
static SwamiPlugin *swami_plugin_register_func (SwamiPluginDesc *desc,
						SwamiPlugin *plugin, 
						GModule *module);
void
_swami_plugin_initialize (void)
{
  GList *paths = NULL;

  main_module =  g_module_open (NULL, G_MODULE_BIND_LAZY);
  swami_plugin_register_statics (main_module);

#ifdef PLUGINS_USE_BUILDDIR
  paths = g_list_prepend (paths, PLUGINS_BUILDDIR "/src/plugins");
#else  /* add the main (installed) library path */
  paths = g_list_prepend (paths, PLUGINS_DIR);
#endif

  _swami_plugin_paths = g_list_concat (_swami_plugin_paths, paths);
}

void
_swami_plugin_register_static (SwamiPluginDesc *desc)
{
  _swami_plugin_static = g_list_prepend (_swami_plugin_static, desc);
}

static void
swami_plugin_register_statics (GModule *module)
{
  GList *walk = _swami_plugin_static;

  while (walk)
    {
      SwamiPluginDesc *desc = (SwamiPluginDesc *) walk->data;
      SwamiPlugin *plugin;

      plugin = g_new0 (SwamiPlugin, 1);
      plugin->filename = NULL;
      plugin->module = NULL;
      plugin = swami_plugin_register_func (desc, plugin, module);

      if (plugin)
	{
	  _swami_plugins = g_list_prepend (_swami_plugins, plugin);
	  _swami_plugins_seqno++;
	  plugin->module = module;
	}

      walk = g_list_next (walk);
    }
}

/**
 * swami_plugin_add_path:
 * @path: the directory to add to the search path
 *
 * Add a directory to the path searched for plugins.
 */
void
swami_plugin_add_path (const gchar *path)
{
  _swami_plugin_paths = g_list_prepend (_swami_plugin_paths, g_strdup (path));
}

static gboolean
swami_plugin_load_recurse (gchar *directory, gchar *name)
{
  DIR *dir;
  struct dirent *dirent;
  gboolean loaded = FALSE;
  gchar *dirname;

  dir = opendir(directory);
  if (dir)
    {
      while ((dirent = readdir(dir)))
	{
	  /* don't want to recurse in place or backwards */
	  if (strcmp(dirent->d_name,".") && strcmp(dirent->d_name,".."))
	    {
	      dirname = g_strjoin("/",directory,dirent->d_name,NULL);
	      loaded = swami_plugin_load_recurse(dirname,name);
	      g_free(dirname);
	      if (loaded && name)
		{
		  closedir(dir);
		  return TRUE;
		}
	    }
	}
      closedir(dir);
    }
  else
    {
      if (strstr(directory,".so"))
	{
	  gchar *temp;
	  if (name)
	    {
	      if ((temp = strstr(directory,name)) && (!strcmp(temp,name)))
		loaded = swami_plugin_load_absolute(directory);
	    }
	  else if ((temp = strstr(directory,".so")) && (!strcmp(temp,".so")))
	    loaded = swami_plugin_load_absolute(directory);
	}
    }
  return loaded;
}

/**
 * swami_plugin_load_all:
 *
 * Load all plugins in the path (in the global GList* _swami_plugin_paths).
 */
void
swami_plugin_load_all (void)
{
  GList *path;

  path = _swami_plugin_paths;
  if (path == NULL)
    g_warning ("swami_plugin_load_all: path is NULL !");

  while (path != NULL)
    {
      g_message ("Loading plugins from %s", (gchar *)path->data);
      swami_plugin_load_recurse(path->data,NULL);
      path = g_list_next(path);
    }
  g_message (_("Loaded %d plugins"), _swami_plugins_seqno);
}

/**
 * swami_plugin_unload_all:
 *
 * Unload all plugins in memory.
 */
void
swami_plugin_unload_all (void)
{
  GList *walk = _swami_plugins;

  while (walk)
    {
      SwamiPlugin *plugin = (SwamiPlugin *) walk->data;

      SWAMI_INFO ("unloading plugin %s", plugin->name);
      if (plugin->module)
	{

	  /* FIXME - Plugin cleanup? */

	  if (g_module_close (plugin->module))
	    plugin->module = NULL;
	  else g_warning ("error closing module");
	}

      walk = g_list_next (walk);
    }
}

/**
 * swami_plugin_load:
 * @name: name of plugin to load
 *
 * Load the named plugin.  Name should be the file name of the plugin without
 * a path component.
 *
 * Returns: whether the plugin was loaded or not
 */
gboolean
swami_plugin_load (const gchar *name)
{
  GList *path;
  gchar *libspath;
  gchar *pluginname;
  SwamiPlugin *plugin;
  
  g_return_val_if_fail (name != NULL, FALSE);

  plugin = swami_plugin_find (name);
  
  if (plugin && plugin->module) 
    return TRUE;

  path = _swami_plugin_paths;
  while (path != NULL)
    {
      pluginname = g_module_build_path(path->data,name);
      if (swami_plugin_load_absolute(pluginname))
	{
	  g_free(pluginname);
	  return TRUE;
	}
      g_free(pluginname);
      libspath = g_strconcat(path->data,"/.libs",NULL);
      pluginname = g_module_build_path(libspath,name);
      g_free(libspath);
      if (swami_plugin_load_absolute(pluginname))
	{
	  g_free(pluginname);
	  return TRUE;
	}
      g_free(pluginname);
      pluginname = g_module_build_path("",name);
      if (swami_plugin_load_recurse(path->data,pluginname))
	{
	  g_free(pluginname);
	  return TRUE;
	}
      g_free(pluginname);
      path = g_list_next(path);
    }
  return FALSE;
}

/**
 * swami_plugin_load_absolute:
 * @name: name of plugin to load
 *
 * Load the named plugin.  Name should be given as
 * &quot;/path/to/plugin/plugin.so&quot;.
 *
 * Returns: whether the plugin was loaded or not
 */
gboolean
swami_plugin_load_absolute (const gchar *filename)
{
  SwamiPlugin *plugin = NULL;
  GList *plugins = _swami_plugins;

  g_return_val_if_fail (filename != NULL, FALSE);

  while (plugins)
    {
      SwamiPlugin *testplugin = (SwamiPlugin *)plugins->data;

      if (testplugin->filename)
	{
	  if (!strcmp (testplugin->filename, filename))
	    {
	      plugin = testplugin;
	      break;
	    }
	}
      plugins = g_list_next (plugins);
    }
  if (!plugin)
    {
      plugin = g_new0 (SwamiPlugin, 1);
      plugin->filename = g_strdup (filename);
      _swami_plugins = g_list_prepend (_swami_plugins, plugin);
      _swami_plugins_seqno++;
    }

  return swami_plugin_load_plugin (plugin);
}

static gboolean
swami_plugin_check_version (gint major, gint minor)
{
  /* return NULL if the major and minor version numbers are not compatible */
  /* with ours. */
  if (major != SWAMI_VERSION_MAJOR || minor != SWAMI_VERSION_MINOR) 
    return FALSE;

  return TRUE;
}

static SwamiPlugin*
swami_plugin_register_func (SwamiPluginDesc *desc, SwamiPlugin *plugin,
			    GModule *module)
{
  if (!swami_plugin_check_version (desc->major_version, desc->minor_version))
    {
      g_warning (_("Plugin \"%s\" has incompatible version, not loading"),
		 plugin->filename);
      return NULL;
    }

  plugin->name = g_strdup(desc->name);
  plugin->descr = g_strdup (desc->descr);
  plugin->author = g_strdup (desc->author);
  plugin->copyright = g_strdup (desc->copyright);

  if ((desc->plugin_init) (module, plugin) != SWAMI_OK)
    {
      g_warning (_("Plugin \"%s\" failed to initialize"), plugin->filename);
      return NULL;
    }

  return plugin;
}

/**
 * swami_plugin_load_plugin:
 * @plugin: The plugin to load
 *
 * Load the given plugin.
 *
 * Returns: whether or not the plugin loaded
 */
gboolean
swami_plugin_load_plugin (SwamiPlugin *plugin)
{
  GModule *module;
  SwamiPluginDesc *desc;
  struct stat file_status;
  gchar *filename;

  g_return_val_if_fail (plugin != NULL, FALSE);

  if (plugin->module) 
    return TRUE;

  filename = plugin->filename;

  if (g_module_supported () == FALSE)
    {
      g_critical ("SwamiPlugin: wow, you built this on a platform without dynamic loading???");
      return FALSE;
    }

  if (stat (filename, &file_status)) return FALSE;

  module = g_module_open (filename, G_MODULE_BIND_LAZY);

  if (module != NULL)
    {
      if (g_module_symbol (module, "swami_plugin_desc", (gpointer *)&desc))
	{
	  g_message (_("Loading plugin \"%s\"..."), filename);

	  plugin->filename = g_strdup (filename);
	  plugin = swami_plugin_register_func (desc, plugin, module);

	  if (plugin != NULL)
	    {
	      g_message (_("Plugin \"%s\" loaded"), plugin->filename);
	      plugin->module = module;
	      return TRUE;
	    }
	}
    } else g_warning (_("Error loading plugin %s, reason: %s\n"), filename,
		      g_module_error());

  return FALSE;
}

/**
 * swami_plugin_is_loaded:
 * @plugin: plugin to query
 *
 * queries if the plugin is loaded into memory
 *
 * Returns: TRUE is loaded, FALSE otherwise
 */
gboolean
swami_plugin_is_loaded (SwamiPlugin *plugin)
{
  g_return_val_if_fail (plugin != NULL, FALSE);

  return (plugin->module != NULL);
}

/**
 * swami_plugin_find:
 * @name: name of plugin to find
 *
 * Search the list of registered plugins for one of the given name
 *
 * Returns: pointer to the #SwamiPlugin if found, NULL otherwise
 */
SwamiPlugin*
swami_plugin_find (const gchar *name)
{
  GList *plugins = _swami_plugins;

  g_return_val_if_fail (name != NULL, NULL);

  while (plugins)
    {
      SwamiPlugin *plugin = (SwamiPlugin *)plugins->data;

      if (plugin->name && !strcmp (plugin->name, name))
	return plugin;

      plugins = g_list_next (plugins);
    }
  return NULL;
}

/**
 * swami_plugin_get_list:
 *
 * get the currently loaded plugins
 *
 * Returns: a GList of SwamiPlugin elements which should be freed with
 *   g_list_free when finished with.
 */
GList*
swami_plugin_get_list (void)
{
  return g_list_copy (_swami_plugins);
}