/*
 * Copyright (C) 2005 Red Hat, Inc.
 * Copyright (C) 2006 Mark McLoughlin
 * Copyright (C) 2007 Sebastian Dröge
 * Copyright (C) 2008 Vincent Untz
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include <config.h>

#include "menu-monitor.h"

#include <gio/gio.h>

#include "menu-util.h"

struct MenuMonitor {
	char* path;
	guint refcount;

	GSList* notifies;

	GFileMonitor* monitor;

	guint is_directory: 1;
};

typedef struct {
	MenuMonitor* monitor;
	MenuMonitorEvent event;
	char* path;
} MenuMonitorEventInfo;

typedef struct {
	MenuMonitorNotifyFunc notify_func;
	gpointer user_data;
	guint refcount;
} MenuMonitorNotify;

static MenuMonitorNotify* mate_menu_monitor_notify_ref(MenuMonitorNotify* notify);
static void mate_menu_monitor_notify_unref(MenuMonitorNotify* notify);

static GHashTable* monitors_registry = NULL;
static guint events_idle_handler = 0;
static GSList* pending_events = NULL;

static void invoke_notifies(MenuMonitor* monitor, MenuMonitorEvent  event, const char* path)
{
  GSList *copy;
  GSList *tmp;

  copy = g_slist_copy (monitor->notifies);
  g_slist_foreach (copy,
		   (GFunc) mate_menu_monitor_notify_ref,
		   NULL);

  tmp = copy;
  while (tmp != NULL)
    {
      MenuMonitorNotify *notify = tmp->data;
      GSList            *next   = tmp->next;

      if (notify->notify_func)
	{
	  notify->notify_func (monitor, event, path, notify->user_data);
	}

      mate_menu_monitor_notify_unref(notify);

      tmp = next;
    }

  g_slist_free (copy);
}

static gboolean emit_events_in_idle(void)
{
  GSList *events_to_emit;
  GSList *tmp;

  events_to_emit = pending_events;

  pending_events = NULL;
  events_idle_handler = 0;

  tmp = events_to_emit;
  while (tmp != NULL)
    {
      MenuMonitorEventInfo *event_info = tmp->data;

      mate_menu_monitor_ref(event_info->monitor);

      tmp = tmp->next;
    }

  tmp = events_to_emit;
  while (tmp != NULL)
    {
      MenuMonitorEventInfo *event_info = tmp->data;

      invoke_notifies (event_info->monitor,
		       event_info->event,
		       event_info->path);

      menu_monitor_unref (event_info->monitor);
      event_info->monitor = NULL;

      g_free (event_info->path);
      event_info->path = NULL;

      event_info->event = MENU_MONITOR_EVENT_INVALID;

      g_free (event_info);

      tmp = tmp->next;
    }

  g_slist_free (events_to_emit);

  return FALSE;
}

static void menu_monitor_queue_event(MenuMonitorEventInfo* event_info)
{
  pending_events = g_slist_append (pending_events, event_info);

  if (events_idle_handler == 0)
    {
      events_idle_handler = g_idle_add ((GSourceFunc) emit_events_in_idle, NULL);
    }
}

static inline char* get_registry_key(const char* path, gboolean is_directory)
{
  return g_strdup_printf ("%s:%s",
			  path,
			  is_directory ? "<dir>" : "<file>");
}

static gboolean monitor_callback (GFileMonitor* monitor, GFile* child, GFile* other_file, GFileMonitorEvent eflags, gpointer user_data)
{
  MenuMonitorEventInfo *event_info;
  MenuMonitorEvent      event;
  MenuMonitor          *menu_monitor = (MenuMonitor *) user_data;

  event = MENU_MONITOR_EVENT_INVALID;
  switch (eflags)
    {
    case G_FILE_MONITOR_EVENT_CHANGED:
      event = MENU_MONITOR_EVENT_CHANGED;
      break;
    case G_FILE_MONITOR_EVENT_CREATED:
      event = MENU_MONITOR_EVENT_CREATED;
      break;
    case G_FILE_MONITOR_EVENT_DELETED:
      event = MENU_MONITOR_EVENT_DELETED;
      break;
    default:
      return TRUE;
    }

  event_info = g_new0 (MenuMonitorEventInfo, 1);

  event_info->path    = g_file_get_path (child);
  event_info->event   = event;
  event_info->monitor = menu_monitor;

  menu_monitor_queue_event (event_info);

  return TRUE;
}

static MenuMonitor* register_monitor(const char* path, gboolean is_directory)
{
#if !GLIB_CHECK_VERSION (2, 36, 0)
  static gboolean  initted = FALSE;
#endif
  MenuMonitor     *retval;
  GFile           *file;

#if !GLIB_CHECK_VERSION (2, 36, 0)
  if (!initted)
    {
      /* This is the only place where we're using GObject and the app can't
       * know we're using it, so we need to init the type system ourselves. */
      g_type_init ();
      initted = TRUE;
    }
#endif

  retval = g_new0 (MenuMonitor, 1);

  retval->path         = g_strdup (path);
  retval->refcount     = 1;
  retval->is_directory = is_directory != FALSE;

  file = g_file_new_for_path (retval->path);

  if (file == NULL)
    {
      menu_verbose ("Not adding monitor on '%s', failed to create GFile\n",
                    retval->path);
      return retval;
    }

  if (retval->is_directory)
      retval->monitor = g_file_monitor_directory (file, G_FILE_MONITOR_NONE,
                                                  NULL, NULL);
  else
      retval->monitor = g_file_monitor_file (file, G_FILE_MONITOR_NONE,
                                             NULL, NULL);

  g_object_unref (G_OBJECT (file));

  if (retval->monitor == NULL)
    {
      menu_verbose ("Not adding monitor on '%s', failed to create monitor\n",
                    retval->path);
      return retval;
    }

  g_signal_connect (retval->monitor, "changed",
                    G_CALLBACK (monitor_callback), retval);

  return retval;
}

static MenuMonitor* lookup_monitor(const char* path, gboolean is_directory)
{
  MenuMonitor *retval;
  char        *registry_key;

  retval = NULL;

  registry_key = get_registry_key (path, is_directory);

  if (monitors_registry == NULL)
    {
      monitors_registry = g_hash_table_new_full (g_str_hash,
						 g_str_equal,
						 g_free,
						 NULL);
    }
  else
    {
      retval = g_hash_table_lookup (monitors_registry, registry_key);
    }

  if (retval == NULL)
    {
      retval = register_monitor (path, is_directory);
      g_hash_table_insert (monitors_registry, registry_key, retval);

      return retval;
    }
  else
    {
      g_free (registry_key);

      return mate_menu_monitor_ref(retval);
    }
}

MenuMonitor* mate_menu_monitor_file_get(const char* path)
{
	g_return_val_if_fail(path != NULL, NULL);

	return lookup_monitor(path, FALSE);
}

MenuMonitor* menu_get_directory_monitor(const char* path)
{
  g_return_val_if_fail (path != NULL, NULL);

  return lookup_monitor (path, TRUE);
}

MenuMonitor* mate_menu_monitor_ref(MenuMonitor* monitor)
{
	g_return_val_if_fail(monitor != NULL, NULL);
	g_return_val_if_fail(monitor->refcount > 0, NULL);

	monitor->refcount++;

	return monitor;
}

static void menu_monitor_clear_pending_events(MenuMonitor* monitor)
{
  GSList *tmp;

  tmp = pending_events;
  while (tmp != NULL)
    {
      MenuMonitorEventInfo *event_info = tmp->data;
      GSList               *next = tmp->next;

      if (event_info->monitor == monitor)
	{
	  pending_events = g_slist_delete_link (pending_events, tmp);

	  g_free (event_info->path);
	  event_info->path = NULL;

	  event_info->monitor = NULL;
	  event_info->event   = MENU_MONITOR_EVENT_INVALID;

	  g_free (event_info);
	}

      tmp = next;
    }
}

void menu_monitor_unref(MenuMonitor* monitor)
{
  char *registry_key;

  g_return_if_fail (monitor != NULL);
  g_return_if_fail (monitor->refcount > 0);

  if (--monitor->refcount > 0)
    return;

  registry_key = get_registry_key (monitor->path, monitor->is_directory);
  g_hash_table_remove (monitors_registry, registry_key);
  g_free (registry_key);

  if (g_hash_table_size (monitors_registry) == 0)
    {
      g_hash_table_destroy (monitors_registry);
      monitors_registry = NULL;
    }

  if (monitor->monitor)
    {
      g_file_monitor_cancel (monitor->monitor);
      g_object_unref (monitor->monitor);
      monitor->monitor = NULL;
    }

  g_slist_foreach (monitor->notifies, (GFunc) mate_menu_monitor_notify_unref, NULL);
  g_slist_free (monitor->notifies);
  monitor->notifies = NULL;

  menu_monitor_clear_pending_events (monitor);

  g_free (monitor->path);
  monitor->path = NULL;

  g_free (monitor);
}

static MenuMonitorNotify* mate_menu_monitor_notify_ref(MenuMonitorNotify* notify)
{
	g_return_val_if_fail(notify != NULL, NULL);
	g_return_val_if_fail(notify->refcount > 0, NULL);

	notify->refcount++;

	return notify;
}

static void mate_menu_monitor_notify_unref(MenuMonitorNotify* notify)
{
	g_return_if_fail(notify != NULL);
	g_return_if_fail(notify->refcount > 0);

	if (--notify->refcount > 0)
	{
		return;
	}

	g_free(notify);
}

void menu_monitor_add_notify(MenuMonitor* monitor, MenuMonitorNotifyFunc notify_func, gpointer user_data)
{
	MenuMonitorNotify* notify;

	g_return_if_fail(monitor != NULL);
	g_return_if_fail(notify_func != NULL);

	GSList* tmp = monitor->notifies;

	while (tmp != NULL)
	{
		notify = tmp->data;

		if (notify->notify_func == notify_func && notify->user_data == user_data)
		{
			break;
		}

		tmp = tmp->next;
	}

	if (tmp == NULL)
	{
		notify = g_new0(MenuMonitorNotify, 1);
		notify->notify_func = notify_func;
		notify->user_data = user_data;
		notify->refcount = 1;

		monitor->notifies = g_slist_append(monitor->notifies, notify);
	}
}

void mate_menu_monitor_notify_remove(MenuMonitor* monitor, MenuMonitorNotifyFunc notify_func, gpointer user_data)
{
	GSList* tmp = monitor->notifies;

	while (tmp != NULL)
	{
		MenuMonitorNotify* notify = tmp->data;
		GSList* next = tmp->next;

		if (notify->notify_func == notify_func && notify->user_data == user_data)
		{
			notify->notify_func = NULL;
			notify->user_data = NULL;

			mate_menu_monitor_notify_unref(notify);

			monitor->notifies = g_slist_delete_link(monitor->notifies, tmp);
		}

		tmp = next;
	}
}
