/* Eye Of Mate - EOM Plugin Manager
 *
 * Copyright (C) 2007 The Free Software Foundation
 *
 * Author: Lucas Rocha <lucasr@gnome.org>
 *
 * Based on gedit code (gedit/gedit-module.c) by:
 * 	- Paolo Maggi <paolo@gnome.org>
 *
 * 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <string.h>

#include "eom-plugin-engine.h"
#include "eom-plugin.h"
#include "eom-module.h"
#include "eom-debug.h"
#include "eom-application.h"
#include "eom-config-keys.h"
#include "eom-util.h"

#include <glib/gi18n.h>
#include <glib.h>
#include <gio/gio.h>

#define USER_EOM_PLUGINS_LOCATION "plugins/"

#define PLUGIN_EXT	".eom-plugin"

typedef enum {
	EOM_PLUGIN_LOADER_C,
} EomPluginLoader;

struct _EomPluginInfo
{
	gchar             *file;

	gchar             *location;
	EomPluginLoader    loader;
	GTypeModule       *module;

	gchar             *name;
	gchar             *desc;
	gchar             *icon_name;
	gchar            **authors;
	gchar             *copyright;
	gchar             *website;

	EomPlugin         *plugin;

	gint               active : 1;

	/* A plugin is unavailable if it is not possible to activate it
	   due to an error loading the plugin module */
	gint               available : 1;
};

static void	eom_plugin_engine_active_plugins_changed (GSettings *settings,
							  gchar *key,
							  gpointer user_data);

static GList *eom_plugins_list = NULL;

static GSettings *eom_plugin_engine_settings = NULL;

static GSList *active_plugins = NULL;

static void
eom_plugin_info_free (EomPluginInfo *info)
{
	if (info->plugin != NULL) {
	       	eom_debug_message (DEBUG_PLUGINS, "Unref plugin %s", info->name);

		g_object_unref (info->plugin);
	}

	g_free (info->file);
	g_free (info->location);
	g_free (info->name);
	g_free (info->desc);
	g_free (info->icon_name);
	g_free (info->website);
	g_free (info->copyright);
	g_strfreev (info->authors);

	g_free (info);
}

static EomPluginInfo *
eom_plugin_engine_load (const gchar *file)
{
	EomPluginInfo *info;
	GKeyFile *plugin_file = NULL;
	gchar *str;

	g_return_val_if_fail (file != NULL, NULL);

	eom_debug_message (DEBUG_PLUGINS, "Loading plugin: %s", file);

	info = g_new0 (EomPluginInfo, 1);
	info->file = g_strdup (file);

	plugin_file = g_key_file_new ();

	if (!g_key_file_load_from_file (plugin_file, file, G_KEY_FILE_NONE, NULL)) {
		g_warning ("Bad plugin file: %s", file);

		goto error;
	}

	if (!g_key_file_has_key (plugin_file,
			   	 "Eom Plugin",
				 "IAge",
				 NULL))	{
		eom_debug_message (DEBUG_PLUGINS,
				   "IAge key does not exist in file: %s", file);

		goto error;
	}

	/* Check IAge=2 */
	if (g_key_file_get_integer (plugin_file,
				    "Eom Plugin",
				    "IAge",
				    NULL) != 2) {
		eom_debug_message (DEBUG_PLUGINS,
				   "Wrong IAge in file: %s", file);

		goto error;
	}

	/* Get Location */
	str = g_key_file_get_string (plugin_file,
				     "Eom Plugin",
				     "Module",
				     NULL);

	if ((str != NULL) && (*str != '\0')) {
		info->location = str;
	} else {
		g_warning ("Could not find 'Module' in %s", file);

		goto error;
	}

	/* Get the loader for this plugin */
	str = g_key_file_get_string (plugin_file,
				     "Eom Plugin",
				     "Loader",
				     NULL);

	info->loader = EOM_PLUGIN_LOADER_C;

	g_free (str);

	/* Get Name */
	str = g_key_file_get_locale_string (plugin_file,
					    "Eom Plugin",
					    "Name",
					    NULL, NULL);
	if (str) {
		info->name = str;
	} else {
		g_warning ("Could not find 'Name' in %s", file);

		goto error;
	}

	/* Get Description */
	str = g_key_file_get_locale_string (plugin_file,
					    "Eom Plugin",
					    "Description",
					    NULL, NULL);
	if (str) {
		info->desc = str;
	} else {
		eom_debug_message (DEBUG_PLUGINS, "Could not find 'Description' in %s", file);
 	}

	/* Get Icon */
	str = g_key_file_get_locale_string (plugin_file,
					    "Eom Plugin",
					    "Icon",
					    NULL, NULL);
	if (str) {
		info->icon_name = str;
	} else {
		eom_debug_message (DEBUG_PLUGINS, "Could not find 'Icon' in %s, "
						  "using 'eom-plugin'", file);
	}

	/* Get Authors */
	info->authors = g_key_file_get_string_list (plugin_file,
						    "Eom Plugin",
						    "Authors",
						    NULL,
						    NULL);

	if (info->authors == NULL)
		eom_debug_message (DEBUG_PLUGINS, "Could not find 'Authors' in %s", file);


	/* Get Copyright */
	str = g_key_file_get_string (plugin_file,
				     "Eom Plugin",
				     "Copyright",
				     NULL);
	if (str) {
		info->copyright = str;
	} else {
		eom_debug_message (DEBUG_PLUGINS, "Could not find 'Copyright' in %s", file);
	}

	/* Get Website */
	str = g_key_file_get_string (plugin_file,
				     "Eom Plugin",
				     "Website",
				     NULL);
	if (str) {
		info->website = str;
	} else {
		eom_debug_message (DEBUG_PLUGINS, "Could not find 'Website' in %s", file);
	}

	g_key_file_free (plugin_file);

	/* If we know nothing about the availability of the plugin,
	   set it as available */
	info->available = TRUE;

	return info;

error:
	g_free (info->file);
	g_free (info->location);
	g_free (info->name);
	g_free (info);
	g_key_file_free (plugin_file);

	return NULL;
}

static gint
compare_plugin_info (EomPluginInfo *info1,
		     EomPluginInfo *info2)
{
	return strcmp (info1->location, info2->location);
}

static void
eom_plugin_engine_load_dir (const gchar *dir)
{
	GError *error = NULL;
	GDir *d;
	const gchar *dirent;

	if (!g_file_test (dir, G_FILE_TEST_IS_DIR)) {
		return;
	}

	g_return_if_fail (eom_plugin_engine_settings != NULL);

	eom_debug_message (DEBUG_PLUGINS, "DIR: %s", dir);

	d = g_dir_open (dir, 0, &error);

	if (!d)	{
		g_warning ("%s", error->message);
		g_error_free (error);

		return;
	}

	while ((dirent = g_dir_read_name (d))) {
		if (g_str_has_suffix (dirent, PLUGIN_EXT)) {
			gchar *plugin_file;
			EomPluginInfo *info;

			plugin_file = g_build_filename (dir, dirent, NULL);
			info = eom_plugin_engine_load (plugin_file);
			g_free (plugin_file);

			if (info == NULL)
				continue;

			/* If a plugin with this name has already been loaded
			 * drop this one (user plugins override system plugins) */
			if (g_list_find_custom (eom_plugins_list,
						info,
						(GCompareFunc)compare_plugin_info) != NULL) {
				g_warning ("Two or more plugins named '%s'. "
					   "Only the first will be considered.\n",
					   info->location);

				eom_plugin_info_free (info);

				continue;
			}

			/* Actually, the plugin will be activated when reactivate_all
			 * will be called for the first time. */
			info->active = (g_slist_find_custom (active_plugins,
							     info->location,
							     (GCompareFunc)strcmp) != NULL);

			eom_plugins_list = g_list_prepend (eom_plugins_list, info);

			eom_debug_message (DEBUG_PLUGINS, "Plugin %s loaded", info->name);
		}
	}

	eom_plugins_list = g_list_reverse (eom_plugins_list);

	g_dir_close (d);
}

static void
eom_plugin_engine_load_all (void)
{
	gchar *pdir;

	pdir = g_build_filename (eom_util_dot_dir (),
                                 USER_EOM_PLUGINS_LOCATION, NULL);

	/* Load user's plugins */
	eom_plugin_engine_load_dir (pdir);

	g_free (pdir);

	/* Load system plugins */
	eom_plugin_engine_load_dir (EOM_PLUGIN_DIR "/");
}

static void
eom_plugin_engine_get_active_plugins (void)
{
	gchar **array;
	gint i;

	active_plugins = NULL;
	array = g_settings_get_strv (eom_plugin_engine_settings, EOM_CONF_PLUGINS_ACTIVE_PLUGINS);
	if (array != NULL) {
		for (i = 0; array[i]; i++) {
			active_plugins = g_slist_append (active_plugins, g_strdup (array[i]));
		}
	}
	g_strfreev (array);
}

gboolean
eom_plugin_engine_init (void)
{
	eom_debug (DEBUG_PLUGINS);

	g_return_val_if_fail (eom_plugins_list == NULL, FALSE);

	if (!g_module_supported ()) {
		g_warning ("eom is not able to initialize the plugins engine.");

		return FALSE;
	}

	eom_plugin_engine_settings = g_settings_new (EOM_CONF_PLUGINS);

	g_signal_connect (eom_plugin_engine_settings,
			  "changed::" EOM_CONF_PLUGINS_ACTIVE_PLUGINS,
			  G_CALLBACK (eom_plugin_engine_active_plugins_changed),
			  NULL);

	eom_plugin_engine_get_active_plugins ();

	eom_plugin_engine_load_all ();

	return TRUE;
}

void
eom_plugin_engine_shutdown (void)
{
	GList *pl;

	eom_debug (DEBUG_PLUGINS);

	g_return_if_fail (eom_plugin_engine_settings != NULL);

	for (pl = eom_plugins_list; pl; pl = pl->next) {
		EomPluginInfo *info = (EomPluginInfo*) pl->data;

		eom_plugin_info_free (info);
	}

	g_slist_foreach (active_plugins, (GFunc)g_free, NULL);
	g_slist_free (active_plugins);

	active_plugins = NULL;

	g_list_free (eom_plugins_list);
	eom_plugins_list = NULL;

	g_object_unref (eom_plugin_engine_settings);
	eom_plugin_engine_settings = NULL;
}

const GList *
eom_plugin_engine_get_plugins_list (void)
{
	eom_debug (DEBUG_PLUGINS);

	return eom_plugins_list;
}

static gboolean
load_plugin_module (EomPluginInfo *info)
{
	gchar *path;
	gchar *dirname;

	eom_debug (DEBUG_PLUGINS);

	g_return_val_if_fail (info != NULL, FALSE);
	g_return_val_if_fail (info->file != NULL, FALSE);
	g_return_val_if_fail (info->location != NULL, FALSE);
	g_return_val_if_fail (info->plugin == NULL, FALSE);
	g_return_val_if_fail (info->available, FALSE);

	switch (info->loader) {
	case EOM_PLUGIN_LOADER_C:
		dirname = g_path_get_dirname (info->file);
		g_return_val_if_fail (dirname != NULL, FALSE);

		path = g_module_build_path (dirname, info->location);

		g_free (dirname);

		g_return_val_if_fail (path != NULL, FALSE);

		info->module = G_TYPE_MODULE (eom_module_new (path));

		g_free (path);

		break;

	default:
		g_return_val_if_reached (FALSE);
	}

	if (!g_type_module_use (info->module)) {
		switch (info->loader) {
		case EOM_PLUGIN_LOADER_C:
			g_warning ("Cannot load plugin '%s' since file '%s' cannot be read.",
				   info->name,
				   eom_module_get_path (EOM_MODULE (info->module)));
			break;

		default:
			g_return_val_if_reached (FALSE);
		}

		g_object_unref (G_OBJECT (info->module));

		info->module = NULL;

		/* Mark plugin as unavailable and fails */
		info->available = FALSE;

		return FALSE;
	}

	switch (info->loader) {
	case EOM_PLUGIN_LOADER_C:
		info->plugin =
			EOM_PLUGIN (eom_module_new_object (EOM_MODULE (info->module)));
		break;

	default:
		g_return_val_if_reached (FALSE);
	}

	g_type_module_unuse (info->module);

	eom_debug_message (DEBUG_PLUGINS, "End");

	return TRUE;
}

static gboolean
eom_plugin_engine_activate_plugin_real (EomPluginInfo *info)
{
	gboolean res = TRUE;

	/* Plugin is not available, don't try to activate/load it */
	if (!info->available) {
		return FALSE;
	}

	if (info->plugin == NULL)
		res = load_plugin_module (info);

	if (res) {
		const GList *wins = eom_application_get_windows (EOM_APP);

		while (wins != NULL) {
			eom_plugin_activate (info->plugin,
					     EOM_WINDOW (wins->data));

			wins = g_list_next (wins);
		}
	} else {
		g_warning ("Error activating plugin '%s'", info->name);
	}

	return res;
}

gboolean
eom_plugin_engine_activate_plugin (EomPluginInfo *info)
{
	eom_debug (DEBUG_PLUGINS);

	g_return_val_if_fail (info != NULL, FALSE);

	if (!info->available)
		return FALSE;

	if (info->active)
		return TRUE;

	if (eom_plugin_engine_activate_plugin_real (info)) {
		GSList *list;

		/* Update plugin state */
		info->active = TRUE;

		list = active_plugins;

		while (list != NULL) {
			if (strcmp (info->location, (gchar *)list->data) == 0) {
				g_warning ("Plugin '%s' is already active.", info->name);

				return TRUE;
			}

			list = g_slist_next (list);
		}

		active_plugins = g_slist_insert_sorted (active_plugins,
						        g_strdup (info->location),
						        (GCompareFunc)strcmp);

		GArray *array;
		GSList *l;
		array = g_array_new (TRUE, TRUE, sizeof (gchar *));
		for (l = active_plugins; l; l = l->next) {
			array = g_array_append_val (array, l->data);
		}
		g_settings_set_strv (eom_plugin_engine_settings, EOM_CONF_PLUGINS_ACTIVE_PLUGINS,
				(const gchar **) array->data);
		g_array_free (array, TRUE);

		return TRUE;
	}

	return FALSE;
}

static void
eom_plugin_engine_deactivate_plugin_real (EomPluginInfo *info)
{
	const GList *wins = eom_application_get_windows (EOM_APP);

	while (wins != NULL) {
		eom_plugin_deactivate (info->plugin,
				       EOM_WINDOW (wins->data));

		wins = g_list_next (wins);
	}
}

gboolean
eom_plugin_engine_deactivate_plugin (EomPluginInfo *info)
{
	gboolean res;
	GSList *list;

	eom_debug (DEBUG_PLUGINS);

	g_return_val_if_fail (info != NULL, FALSE);

	if (!info->active || !info->available)
		return TRUE;

	eom_plugin_engine_deactivate_plugin_real (info);

	/* Update plugin state */
	info->active = FALSE;

	list = active_plugins;
	res = (list == NULL);

	while (list != NULL) {
		if (strcmp (info->location, (gchar *)list->data) == 0) {
			g_free (list->data);
			active_plugins = g_slist_delete_link (active_plugins, list);
			list = NULL;
			res = TRUE;
		} else {
			list = g_slist_next (list);
		}
	}

	if (!res) {
		g_warning ("Plugin '%s' is already deactivated.", info->name);

		return TRUE;
	}

	GArray *array;
	GSList *l;
	array = g_array_new (TRUE, TRUE, sizeof (gchar *));
	for (l = active_plugins; l; l = l->next) {
		array = g_array_append_val (array, l->data);
	}
	g_settings_set_strv (eom_plugin_engine_settings, EOM_CONF_PLUGINS_ACTIVE_PLUGINS,
			(const gchar **) array->data);
	g_array_free (array, TRUE);

	return TRUE;
}

gboolean
eom_plugin_engine_plugin_is_active (EomPluginInfo *info)
{
	g_return_val_if_fail (info != NULL, FALSE);

	return (info->available && info->active);
}

gboolean
eom_plugin_engine_plugin_is_available (EomPluginInfo *info)
{
	g_return_val_if_fail (info != NULL, FALSE);

	return (info->available != FALSE);
}

static void
reactivate_all (EomWindow *window)
{
	GList *pl;

	eom_debug (DEBUG_PLUGINS);

	for (pl = eom_plugins_list; pl; pl = pl->next) {
		gboolean res = TRUE;

		EomPluginInfo *info = (EomPluginInfo*)pl->data;

		/* If plugin is not available, don't try to activate/load it */
		if (info->available && info->active) {
			if (info->plugin == NULL)
				res = load_plugin_module (info);

			if (res)
				eom_plugin_activate (info->plugin,
						     window);
		}
	}

	eom_debug_message (DEBUG_PLUGINS, "End");
}

void
eom_plugin_engine_update_plugins_ui (EomWindow *window,
				     gboolean   new_window)
{
	GList *pl;

	eom_debug (DEBUG_PLUGINS);

	g_return_if_fail (EOM_IS_WINDOW (window));

	if (new_window)
		reactivate_all (window);

	/* Updated ui of all the plugins that implement update_ui */
	for (pl = eom_plugins_list; pl; pl = pl->next) {
		EomPluginInfo *info = (EomPluginInfo*)pl->data;

		if (!info->available || !info->active)
			continue;

	       	eom_debug_message (DEBUG_PLUGINS, "Updating UI of %s", info->name);

		eom_plugin_update_ui (info->plugin, window);
	}
}

gboolean
eom_plugin_engine_plugin_is_configurable (EomPluginInfo *info) {
	eom_debug (DEBUG_PLUGINS);

	g_return_val_if_fail (info != NULL, FALSE);

	if ((info->plugin == NULL) || !info->active || !info->available)
		return FALSE;

	return eom_plugin_is_configurable (info->plugin);
}

void
eom_plugin_engine_configure_plugin (EomPluginInfo *info,
				    GtkWindow     *parent)
{
	GtkWidget *conf_dlg;

	GtkWindowGroup *wg;

	eom_debug (DEBUG_PLUGINS);

	g_return_if_fail (info != NULL);

	conf_dlg = eom_plugin_create_configure_dialog (info->plugin);

	g_return_if_fail (conf_dlg != NULL);

	gtk_window_set_transient_for (GTK_WINDOW (conf_dlg),
				      parent);

	// Will return a default group if no group is set
	wg = gtk_window_get_group (parent);

	// For now assign a dedicated window group if it is 
	// the default one until we know if this is really needed
	if (wg == gtk_window_get_group (NULL)) {
		wg = gtk_window_group_new ();
		gtk_window_group_add_window (wg, parent);
	}

	gtk_window_group_add_window (wg,
				     GTK_WINDOW (conf_dlg));

	gtk_window_set_modal (GTK_WINDOW (conf_dlg), TRUE);

	gtk_widget_show (conf_dlg);
}

static void
eom_plugin_engine_active_plugins_changed (GSettings *settings,
					  gchar *key,
					  gpointer user_data)
{
	GList *pl;
	gboolean to_activate;

	eom_debug (DEBUG_PLUGINS);

	g_return_if_fail (settings != NULL);
	g_return_if_fail (key != NULL);

	eom_plugin_engine_get_active_plugins ();

	for (pl = eom_plugins_list; pl; pl = pl->next) {
		EomPluginInfo *info = (EomPluginInfo*)pl->data;

		if (!info->available)
			continue;

		to_activate = (g_slist_find_custom (active_plugins,
						    info->location,
						    (GCompareFunc)strcmp) != NULL);

		if (!info->active && to_activate) {
			/* Activate plugin */
			if (eom_plugin_engine_activate_plugin_real (info))
				/* Update plugin state */
				info->active = TRUE;
		} else {
			if (info->active && !to_activate) {
				eom_plugin_engine_deactivate_plugin_real (info);

				/* Update plugin state */
				info->active = FALSE;
			}
		}
	}
}

const gchar *
eom_plugin_engine_get_plugin_name (EomPluginInfo *info)
{
	g_return_val_if_fail (info != NULL, NULL);

	return info->name;
}

const gchar *
eom_plugin_engine_get_plugin_description (EomPluginInfo *info)
{
	g_return_val_if_fail (info != NULL, NULL);

	return info->desc;
}

const gchar *
eom_plugin_engine_get_plugin_icon_name (EomPluginInfo *info)
{
	g_return_val_if_fail (info != NULL, NULL);

	/* Use the eom-plugin icon as a default if the plugin does not
	   have its own */
	if (info->icon_name != NULL &&
	    gtk_icon_theme_has_icon (gtk_icon_theme_get_default (),
	    			     info->icon_name))
		return info->icon_name;
	else
		return "eom-plugin";
}

const gchar **
eom_plugin_engine_get_plugin_authors (EomPluginInfo *info)
{
	g_return_val_if_fail (info != NULL, (const gchar **)NULL);

	return (const gchar **) info->authors;
}

const gchar *
eom_plugin_engine_get_plugin_website (EomPluginInfo *info)
{
	g_return_val_if_fail (info != NULL, NULL);

	return info->website;
}

const gchar *
eom_plugin_engine_get_plugin_copyright (EomPluginInfo *info)
{
	g_return_val_if_fail (info != NULL, NULL);

	return info->copyright;
}