/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 2; tab-width: 8 -*- */

/* inotify-path.c - GVFS Directory Monitor based on inotify.

   Copyright (C) 2006 John McCutchan

   The Gnome Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The Gnome 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the Gnome Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.

   Authors:
		 John McCutchan <john@johnmccutchan.com>
*/

#include "config.h"

/* Don't put conflicting kernel types in the global namespace: */
#define __KERNEL_STRICT_NAMES

#include <sys/inotify.h>
#include <string.h>
#include <glib.h>
#include "inotify-kernel.h"
#include "inotify-path.h"
#include "inotify-missing.h"

#define IP_INOTIFY_MASK (IN_MODIFY|IN_ATTRIB|IN_MOVED_FROM|IN_MOVED_TO|IN_DELETE|IN_CREATE|IN_DELETE_SELF|IN_UNMOUNT|IN_MOVE_SELF|IN_CLOSE_WRITE)

typedef struct ip_watched_dir_s {
  char *path;
  /* TODO: We need to maintain a tree of watched directories
   * so that we can deliver move/delete events to sub folders.
   * Or the application could do it...
   */
  struct ip_watched_dir_s* parent;
  GList*	 children;

  /* Inotify state */
  gint32 wd;
  
  /* List of inotify subscriptions */
  GList *subs;
} ip_watched_dir_t;

static gboolean     ip_debug_enabled = FALSE;
#define IP_W if (ip_debug_enabled) g_warning

/* path -> ip_watched_dir */
static GHashTable * path_dir_hash = NULL;
/* inotify_sub * -> ip_watched_dir *
 *
 * Each subscription is attached to a watched directory or it is on
 * the missing list
 */
static GHashTable * sub_dir_hash = NULL;
/* This hash holds GLists of ip_watched_dir_t *'s
 * We need to hold a list because symbolic links can share
 * the same wd
 */
static GHashTable * wd_dir_hash = NULL;

static ip_watched_dir_t *ip_watched_dir_new  (const char       *path,
					      int               wd);
static void              ip_watched_dir_free (ip_watched_dir_t *dir);
static void              ip_event_callback   (ik_event_t       *event);


static void (*event_callback)(ik_event_t *event, inotify_sub *sub);

gboolean
_ip_startup (void (*cb)(ik_event_t *event, inotify_sub *sub))
{
  static gboolean initialized = FALSE;
  static gboolean result = FALSE;
  
  if (initialized == TRUE)
    return result;

  event_callback = cb;
  result = _ik_startup (ip_event_callback);

  if (!result)
    return FALSE;

  path_dir_hash = g_hash_table_new (g_str_hash, g_str_equal);
  sub_dir_hash = g_hash_table_new (g_direct_hash, g_direct_equal);
  wd_dir_hash = g_hash_table_new (g_direct_hash, g_direct_equal);
  
  initialized = TRUE;
  return TRUE;
}

static void
ip_map_path_dir (const char       *path, 
                 ip_watched_dir_t *dir)
{
  g_assert (path && dir);
  g_hash_table_insert (path_dir_hash, dir->path, dir);
}

static void
ip_map_sub_dir (inotify_sub      *sub, 
                ip_watched_dir_t *dir)
{
  /* Associate subscription and directory */
  g_assert (dir && sub);
  g_hash_table_insert (sub_dir_hash, sub, dir);
  dir->subs = g_list_prepend (dir->subs, sub);
}

static void
ip_map_wd_dir (gint32            wd, 
               ip_watched_dir_t *dir)
{
  GList *dir_list;
  
  g_assert (wd >= 0 && dir);
  dir_list = g_hash_table_lookup (wd_dir_hash, GINT_TO_POINTER (wd));
  dir_list = g_list_prepend (dir_list, dir);
  g_hash_table_replace (wd_dir_hash, GINT_TO_POINTER (dir->wd), dir_list);
}

gboolean
_ip_start_watching (inotify_sub *sub)
{
  gint32 wd;
  int err;
  ip_watched_dir_t *dir;
  
  g_assert (sub);
  g_assert (!sub->cancelled);
  g_assert (sub->dirname);
  
  IP_W ("Starting to watch %s\n", sub->dirname);
  dir = g_hash_table_lookup (path_dir_hash, sub->dirname);
  if (dir)
    {
      IP_W ("Already watching\n");
      goto out;
    }
	
  IP_W ("Trying to add inotify watch ");
  wd = _ik_watch (sub->dirname, IP_INOTIFY_MASK|IN_ONLYDIR, &err);
  if (wd < 0) 
    {
      IP_W ("Failed\n");
      return FALSE;
    }
  else
    {
      /* Create new watched directory and associate it with the 
       * wd hash and path hash
       */
      IP_W ("Success\n");
      dir = ip_watched_dir_new (sub->dirname, wd);
      ip_map_wd_dir (wd, dir);
      ip_map_path_dir (sub->dirname, dir);
    }
  
 out:
  ip_map_sub_dir (sub, dir);
  
  return TRUE;
}

static void
ip_unmap_path_dir (const char       *path, 
                   ip_watched_dir_t *dir)
{
  g_assert (path && dir);
  g_hash_table_remove (path_dir_hash, dir->path);
}

static void
ip_unmap_wd_dir (gint32            wd, 
                 ip_watched_dir_t *dir)
{
  GList *dir_list = g_hash_table_lookup (wd_dir_hash, GINT_TO_POINTER (wd));
  
  if (!dir_list)
    return;
  
  g_assert (wd >= 0 && dir);
  dir_list = g_list_remove (dir_list, dir);
  if (dir_list == NULL) 
    g_hash_table_remove (wd_dir_hash, GINT_TO_POINTER (dir->wd));
  else
    g_hash_table_replace (wd_dir_hash, GINT_TO_POINTER (dir->wd), dir_list);
}

static void
ip_unmap_wd (gint32 wd)
{
  GList *dir_list = g_hash_table_lookup (wd_dir_hash, GINT_TO_POINTER (wd));
  if (!dir_list)
    return;
  g_assert (wd >= 0);
  g_hash_table_remove (wd_dir_hash, GINT_TO_POINTER (wd));
  g_list_free (dir_list);
}

static void
ip_unmap_sub_dir (inotify_sub       *sub, 
                  ip_watched_dir_t *dir)
{
  g_assert (sub && dir);
  g_hash_table_remove (sub_dir_hash, sub);
  dir->subs = g_list_remove (dir->subs, sub);
}

static void
ip_unmap_all_subs (ip_watched_dir_t *dir)
{
  GList *l = NULL;
  
  for (l = dir->subs; l; l = l->next)
    {
      inotify_sub *sub = l->data;
      g_hash_table_remove (sub_dir_hash, sub);
    }
  g_list_free (dir->subs);
  dir->subs = NULL;
}

gboolean
_ip_stop_watching (inotify_sub *sub)
{
  ip_watched_dir_t *dir = NULL;
  
  dir = g_hash_table_lookup (sub_dir_hash, sub);
  if (!dir) 
    return TRUE;
  
  ip_unmap_sub_dir (sub, dir);
  
  /* No one is subscribing to this directory any more */
  if (dir->subs == NULL)
    {
      _ik_ignore (dir->path, dir->wd);
      ip_unmap_wd_dir (dir->wd, dir);
      ip_unmap_path_dir (dir->path, dir);
      ip_watched_dir_free (dir);
    }
  
  return TRUE;
}


static ip_watched_dir_t *
ip_watched_dir_new (const char *path, 
                    gint32      wd)
{
  ip_watched_dir_t *dir = g_new0 (ip_watched_dir_t, 1);
  
  dir->path = g_strdup (path);
  dir->wd = wd;
  
  return dir;
}

static void
ip_watched_dir_free (ip_watched_dir_t *dir)
{
  g_assert (dir->subs == NULL);
  g_free (dir->path);
  g_free (dir);
}

static void
ip_wd_delete (gpointer data, 
              gpointer user_data)
{
  ip_watched_dir_t *dir = data;
  GList *l = NULL;
  
  for (l = dir->subs; l; l = l->next)
    {
      inotify_sub *sub = l->data;
      /* Add subscription to missing list */
      _im_add (sub);
    }
  ip_unmap_all_subs (dir);
  /* Unassociate the path and the directory */
  ip_unmap_path_dir (dir->path, dir);
  ip_watched_dir_free (dir);
}

static void
ip_event_dispatch (GList      *dir_list, 
                   GList      *pair_dir_list, 
                   ik_event_t *event)
{
  GList *dirl;
  
  if (!event)
    return;

  for (dirl = dir_list; dirl; dirl = dirl->next)
    {
      GList *subl;
      ip_watched_dir_t *dir = dirl->data;
      
      for (subl = dir->subs; subl; subl = subl->next)
	{
	  inotify_sub *sub = subl->data;
	  
	  /* If the subscription and the event
	   * contain a filename and they don't
	   * match, we don't deliver this event.
	   */
	  if (sub->filename &&
	      event->name &&
	      strcmp (sub->filename, event->name))
	    continue;
	  
	  /* If the subscription has a filename
	   * but this event doesn't, we don't
	   * deliever this event.
	   */
	  if (sub->filename && !event->name)
	    continue;
	  
	  /* FIXME: We might need to synthesize
	   * DELETE/UNMOUNT events when
	   * the filename doesn't match
	   */
	  
	  event_callback (event, sub);
	}
    }
  
  if (!event->pair)
    return;
  
  for (dirl = pair_dir_list; dirl; dirl = dirl->next)
    {
      GList *subl;
      ip_watched_dir_t *dir = dirl->data;
      
      for (subl = dir->subs; subl; subl = subl->next)
	{
	  inotify_sub *sub = subl->data;
	  
	  /* If the subscription and the event
	   * contain a filename and they don't
	   * match, we don't deliver this event.
	   */
	  if (sub->filename &&
	      event->pair->name &&
	      strcmp (sub->filename, event->pair->name))
	    continue;
	  
	  /* If the subscription has a filename
	   * but this event doesn't, we don't
	   * deliever this event.
	   */
	  if (sub->filename && !event->pair->name)
	    continue;
	  
	  /* FIXME: We might need to synthesize
	   * DELETE/UNMOUNT events when
	   * the filename doesn't match
	   */
	  
	  event_callback (event->pair, sub);
	}
    }
}

static void
ip_event_callback (ik_event_t *event)
{
  GList* dir_list = NULL;
  GList* pair_dir_list = NULL;
  
  dir_list = g_hash_table_lookup (wd_dir_hash, GINT_TO_POINTER (event->wd));
  
  /* We can ignore the IGNORED events */
  if (event->mask & IN_IGNORED)
    {
      _ik_event_free (event);
      return;
    }

  if (event->pair)
    pair_dir_list = g_hash_table_lookup (wd_dir_hash, GINT_TO_POINTER (event->pair->wd));

  if (event->mask & IP_INOTIFY_MASK)
    ip_event_dispatch (dir_list, pair_dir_list, event);
  
  /* We have to manage the missing list
   * when we get an event that means the
   * file has been deleted/moved/unmounted.
   */
  if (event->mask & IN_DELETE_SELF ||
      event->mask & IN_MOVE_SELF ||
      event->mask & IN_UNMOUNT)
    {
      /* Add all subscriptions to missing list */
      g_list_foreach (dir_list, ip_wd_delete, NULL);
      /* Unmap all directories attached to this wd */
      ip_unmap_wd (event->wd);
    }
  
  _ik_event_free (event);
}
