/*

 * Copyright © 2015 Canonical Limited

 *

 * 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 2.1 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, see <http://www.gnu.org/licenses/>.

 *

 * Author: Ryan Lortie <desrt@desrt.ca>

 */

#include "config.h"

#include <gio/glocalfilemonitor.h>

#include <gio/giomodule.h>

#include "glib-private.h"

#include <glib-unix.h>

#include <fam.h>

static GMutex         fam_lock;

static gboolean       fam_initialised;

static FAMConnection  fam_connection;

static GSource       *fam_source;

#define G_TYPE_FAM_FILE_MONITOR      (g_fam_file_monitor_get_type ())

#define G_FAM_FILE_MONITOR(inst)     (G_TYPE_CHECK_INSTANCE_CAST ((inst), \

                                      G_TYPE_FAM_FILE_MONITOR, GFamFileMonitor))

typedef GLocalFileMonitorClass GFamFileMonitorClass;

typedef struct

{

  GLocalFileMonitor parent_instance;

  FAMRequest request;

} GFamFileMonitor;

static GType g_fam_file_monitor_get_type (void);

G_DEFINE_DYNAMIC_TYPE (GFamFileMonitor, g_fam_file_monitor, G_TYPE_LOCAL_FILE_MONITOR)

static gboolean

g_fam_file_monitor_callback (gint         fd,

                             GIOCondition condition,

                             gpointer     user_data)

{

  gint64 now = g_source_get_time (fam_source);

  g_mutex_lock (&fam_lock);

  while (FAMPending (&fam_connection))

    {

      const gchar *child;

      FAMEvent ev;

      if (FAMNextEvent (&fam_connection, &ev) != 1)

        {

          /* The daemon died.  We're in a really bad situation now

           * because we potentially have a bunch of request structures

           * outstanding which no longer make any sense to anyone.

           *

           * The best thing that we can do is do nothing.  Notification

           * won't work anymore for this process.

           */

          g_mutex_unlock (&fam_lock);

          g_warning ("Lost connection to FAM (file monitoring) service.  Expect no further file monitor events.");

          return FALSE;

        }

      /* We expect ev.filename to be a relative path for children in a

       * monitored directory, and an absolute path for a monitored file

       * or the directory itself.

       */

      if (ev.filename[0] != '/')

        child = ev.filename;

      else

        child = NULL;

      switch (ev.code)

        {

        case FAMAcknowledge:

          g_source_unref (ev.userdata);

          break;

        case FAMChanged:

          g_file_monitor_source_handle_event (ev.userdata, G_FILE_MONITOR_EVENT_CHANGED, child, NULL, NULL, now);

          break;

        case FAMDeleted:

          g_file_monitor_source_handle_event (ev.userdata, G_FILE_MONITOR_EVENT_DELETED, child, NULL, NULL, now);

          break;

        case FAMCreated:

          g_file_monitor_source_handle_event (ev.userdata, G_FILE_MONITOR_EVENT_CREATED, child, NULL, NULL, now);

          break;

        default:

          /* unknown type */

          break;

        }

    }

  g_mutex_unlock (&fam_lock);

  return TRUE;

}

static gboolean

g_fam_file_monitor_is_supported (void)

{

  g_mutex_lock (&fam_lock);

  if (!fam_initialised)

    {

      fam_initialised = FAMOpen2 (&fam_connection, "GLib GIO") == 0;

      if (fam_initialised)

        {

#ifdef HAVE_FAM_NO_EXISTS

          /* This is a gamin extension that avoids sending all the

           * Exists event for dir monitors

           */

          FAMNoExists (&fam_connection);

#endif

          fam_source = g_unix_fd_source_new (FAMCONNECTION_GETFD (&fam_connection), G_IO_IN);

          g_source_set_callback (fam_source, (GSourceFunc) g_fam_file_monitor_callback, NULL, NULL);

          g_source_attach (fam_source, GLIB_PRIVATE_CALL(g_get_worker_context) ());

        }

    }

  g_mutex_unlock (&fam_lock);

  return fam_initialised;

}

static gboolean

g_fam_file_monitor_cancel (GFileMonitor *monitor)

{

  GFamFileMonitor *gffm = G_FAM_FILE_MONITOR (monitor);

  g_mutex_lock (&fam_lock);

  g_assert (fam_initialised);

  FAMCancelMonitor (&fam_connection, &gffm->request);

  g_mutex_unlock (&fam_lock);

  return TRUE;

}

static void

g_fam_file_monitor_start (GLocalFileMonitor  *local_monitor,

                          const gchar        *dirname,

                          const gchar        *basename,

                          const gchar        *filename,

                          GFileMonitorSource *source)

{

  GFamFileMonitor *gffm = G_FAM_FILE_MONITOR (local_monitor);

  g_mutex_lock (&fam_lock);

  g_assert (fam_initialised);

  g_source_ref ((GSource *) source);

  if (dirname)

    FAMMonitorDirectory (&fam_connection, dirname, &gffm->request, source);

  else

    FAMMonitorFile (&fam_connection, filename, &gffm->request, source);

  g_mutex_unlock (&fam_lock);

}

static void

g_fam_file_monitor_init (GFamFileMonitor* monitor)

{

}

static void

g_fam_file_monitor_class_init (GFamFileMonitorClass *class)

{

  GFileMonitorClass *file_monitor_class = G_FILE_MONITOR_CLASS (class);

  class->is_supported = g_fam_file_monitor_is_supported;

  class->start = g_fam_file_monitor_start;

  file_monitor_class->cancel = g_fam_file_monitor_cancel;

}

static void

g_fam_file_monitor_class_finalize (GFamFileMonitorClass *class)

{

}

void

g_io_module_load (GIOModule *module)

{

  g_type_module_use (G_TYPE_MODULE (module));

  g_fam_file_monitor_register_type (G_TYPE_MODULE (module));

  g_io_extension_point_implement (G_LOCAL_FILE_MONITOR_EXTENSION_POINT_NAME,

                                 G_TYPE_FAM_FILE_MONITOR, "fam", 10);

  g_io_extension_point_implement (G_NFS_FILE_MONITOR_EXTENSION_POINT_NAME,

                                 G_TYPE_FAM_FILE_MONITOR, "fam", 10);

}

void

g_io_module_unload (GIOModule *module)

{

  g_assert_not_reached ();

}

char **

g_io_module_query (void)

{

  char *eps[] = {

    G_LOCAL_FILE_MONITOR_EXTENSION_POINT_NAME,

    G_NFS_FILE_MONITOR_EXTENSION_POINT_NAME,

    NULL

  };

  return g_strdupv (eps);

}