/*

 * Copyright © 2009, 2010 Codethink 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 "gdelayedsettingsbackend.h"

#include "gsettingsbackendinternal.h"

#include <string.h>

struct _GDelayedSettingsBackendPrivate

{

  GSettingsBackend *backend;

  GMutex lock;

  GTree *delayed;

  GMainContext *owner_context;

  gpointer owner;

};

G_DEFINE_TYPE_WITH_PRIVATE (GDelayedSettingsBackend,

                            g_delayed_settings_backend,

                            G_TYPE_SETTINGS_BACKEND)

static gboolean

invoke_notify_unapplied (gpointer data)

{

  g_object_notify (data, "has-unapplied");

  g_object_unref (data);

  return FALSE;

}

static void

g_delayed_settings_backend_notify_unapplied (GDelayedSettingsBackend *delayed)

{

  GMainContext *target_context;

  GObject *target;

  g_mutex_lock (&delayed->priv->lock);

  if (delayed->priv->owner)

    {

      target_context = delayed->priv->owner_context;

      target = g_object_ref (delayed->priv->owner);

    }

  else

    {

      target_context = NULL;

      target = NULL;

    }

  g_mutex_unlock (&delayed->priv->lock);

  if (target != NULL)

    g_main_context_invoke (target_context, invoke_notify_unapplied, target);

}

static GVariant *

g_delayed_settings_backend_read (GSettingsBackend   *backend,

                                 const gchar        *key,

                                 const GVariantType *expected_type,

                                 gboolean            default_value)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);

  gpointer result = NULL;

  if (!default_value)

    {

      g_mutex_lock (&delayed->priv->lock);

      if (g_tree_lookup_extended (delayed->priv->delayed, key, NULL, &result))

        {

          /* NULL in the tree means we should consult the default value */

          if (result != NULL)

            g_variant_ref (result);

          else

            default_value = TRUE;

        }

      g_mutex_unlock (&delayed->priv->lock);

    }

  if (result == NULL)

    result = g_settings_backend_read (delayed->priv->backend, key,

                                      expected_type, default_value);

  return result;

}

static GVariant *

g_delayed_settings_backend_read_user_value (GSettingsBackend   *backend,

                                            const gchar        *key,

                                            const GVariantType *expected_type)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);

  gboolean value_found = FALSE;

  gpointer result = NULL;

  /* If we find an explicit NULL in our changeset then we want to return

   * NULL (because the user value has been reset).

   *

   * Otherwise, chain up.

   */

  g_mutex_lock (&delayed->priv->lock);

  value_found = g_tree_lookup_extended (delayed->priv->delayed, key, NULL, &result);

  if (result)

    g_variant_ref (result);

  g_mutex_unlock (&delayed->priv->lock);

  if (value_found)

    return result;

  return g_settings_backend_read_user_value (delayed->priv->backend, key, expected_type);

}

static gboolean

g_delayed_settings_backend_write (GSettingsBackend *backend,

                                  const gchar      *key,

                                  GVariant         *value,

                                  gpointer          origin_tag)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);

  gboolean was_empty;

  g_mutex_lock (&delayed->priv->lock);

  was_empty = g_tree_nnodes (delayed->priv->delayed) == 0;

  g_tree_insert (delayed->priv->delayed, g_strdup (key),

                 g_variant_ref_sink (value));

  g_mutex_unlock (&delayed->priv->lock);

  g_settings_backend_changed (backend, key, origin_tag);

  if (was_empty)

    g_delayed_settings_backend_notify_unapplied (delayed);

  return TRUE;

}

static gboolean

add_to_tree (gpointer key,

             gpointer value,

             gpointer user_data)

{

  g_tree_insert (user_data, g_strdup (key), g_variant_ref (value));

  return FALSE;

}

static gboolean

g_delayed_settings_backend_write_tree (GSettingsBackend *backend,

                                       GTree            *tree,

                                       gpointer          origin_tag)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);

  gboolean was_empty;

  g_mutex_lock (&delayed->priv->lock);

  was_empty = g_tree_nnodes (delayed->priv->delayed) == 0;

  g_tree_foreach (tree, add_to_tree, delayed->priv->delayed);

  g_mutex_unlock (&delayed->priv->lock);

  g_settings_backend_changed_tree (backend, tree, origin_tag);

  if (was_empty)

    g_delayed_settings_backend_notify_unapplied (delayed);

  return TRUE;

}

static gboolean

g_delayed_settings_backend_get_writable (GSettingsBackend *backend,

                                         const gchar      *name)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);

  return g_settings_backend_get_writable (delayed->priv->backend, name);

}

static void

g_delayed_settings_backend_reset (GSettingsBackend *backend,

                                  const gchar      *key,

                                  gpointer          origin_tag)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);

  gboolean was_empty;

  g_mutex_lock (&delayed->priv->lock);

  was_empty = g_tree_nnodes (delayed->priv->delayed) == 0;

  g_tree_insert (delayed->priv->delayed, g_strdup (key), NULL);

  g_mutex_unlock (&delayed->priv->lock);

  if (was_empty)

    g_delayed_settings_backend_notify_unapplied (delayed);

}

static void

g_delayed_settings_backend_subscribe (GSettingsBackend *backend,

                                      const char       *name)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);

  g_settings_backend_subscribe (delayed->priv->backend, name);

}

static void

g_delayed_settings_backend_unsubscribe (GSettingsBackend *backend,

                                        const char       *name)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);

  g_settings_backend_unsubscribe (delayed->priv->backend, name);

}

static GPermission *

g_delayed_settings_backend_get_permission (GSettingsBackend *backend,

                                           const gchar      *path)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);

  return g_settings_backend_get_permission (delayed->priv->backend, path);

}

/* method calls */

gboolean

g_delayed_settings_backend_get_has_unapplied (GDelayedSettingsBackend *delayed)

{

  /* we don't need to lock for this... */

  return g_tree_nnodes (delayed->priv->delayed) > 0;

}

void

g_delayed_settings_backend_apply (GDelayedSettingsBackend *delayed)

{

  if (g_tree_nnodes (delayed->priv->delayed) > 0)

    {

      gboolean success;

      GTree *tmp;

      g_mutex_lock (&delayed->priv->lock);

      tmp = delayed->priv->delayed;

      delayed->priv->delayed = g_settings_backend_create_tree ();

      success = g_settings_backend_write_tree (delayed->priv->backend,

                                               tmp, delayed->priv);

      g_mutex_unlock (&delayed->priv->lock);

      if (!success)

        g_settings_backend_changed_tree (G_SETTINGS_BACKEND (delayed),

                                         tmp, NULL);

      g_tree_unref (tmp);

      g_delayed_settings_backend_notify_unapplied (delayed);

    }

}

void

g_delayed_settings_backend_revert (GDelayedSettingsBackend *delayed)

{

  if (g_tree_nnodes (delayed->priv->delayed) > 0)

    {

      GTree *tmp;

      g_mutex_lock (&delayed->priv->lock);

      tmp = delayed->priv->delayed;

      delayed->priv->delayed = g_settings_backend_create_tree ();

      g_mutex_unlock (&delayed->priv->lock);

      g_settings_backend_changed_tree (G_SETTINGS_BACKEND (delayed), tmp, NULL);

      g_tree_unref (tmp);

      g_delayed_settings_backend_notify_unapplied (delayed);

    }

}

/* change notification */

static void

delayed_backend_changed (GObject          *target,

                         GSettingsBackend *backend,

                         const gchar      *key,

                         gpointer          origin_tag)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (target);

  if (origin_tag != delayed->priv)

    g_settings_backend_changed (G_SETTINGS_BACKEND (delayed),

                                key, origin_tag);

}

static void

delayed_backend_keys_changed (GObject             *target,

                              GSettingsBackend    *backend,

                              const gchar         *path,

                              gpointer             origin_tag,

                              const gchar * const *items)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (target);

  if (origin_tag != delayed->priv)

    g_settings_backend_keys_changed (G_SETTINGS_BACKEND (delayed),

                                     path, items, origin_tag);

}

static void

delayed_backend_path_changed (GObject          *target,

                              GSettingsBackend *backend,

                              const gchar      *path,

                              gpointer          origin_tag)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (target);

  if (origin_tag != delayed->priv)

    g_settings_backend_path_changed (G_SETTINGS_BACKEND (delayed),

                                     path, origin_tag);

}

static void

delayed_backend_writable_changed (GObject          *target,

                                  GSettingsBackend *backend,

                                  const gchar      *key)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (target);

  gboolean last_one = FALSE;

  g_mutex_lock (&delayed->priv->lock);

  if (g_tree_lookup (delayed->priv->delayed, key) != NULL &&

      !g_settings_backend_get_writable (delayed->priv->backend, key))

    {

      /* drop the key from our changeset if it just became read-only.

       * no need to signal since the writable change below implies it.

       *

       * note that the item in the tree may very well be set to NULL in

       * the case that the user stored a reset.  we intentionally don't

       * drop the key in this case since a reset will always succeed

       * (even against a non-writable key).

       */

      g_tree_remove (delayed->priv->delayed, key);

      /* if that was the only key... */

      last_one = g_tree_nnodes (delayed->priv->delayed) == 0;

    }

  g_mutex_unlock (&delayed->priv->lock);

  if (last_one)

    g_delayed_settings_backend_notify_unapplied (delayed);

  g_settings_backend_writable_changed (G_SETTINGS_BACKEND (delayed), key);

}

/* slow method until we get foreach-with-remove in GTree

 */

typedef struct

{

  const gchar *path;

  const gchar **keys;

  gsize index;

} CheckPrefixState;

static gboolean

check_prefix (gpointer key,

              gpointer value,

              gpointer data)

{

  CheckPrefixState *state = data;

  if (g_str_has_prefix (key, state->path))

    state->keys[state->index++] = key;

  return FALSE;

}

static void

delayed_backend_path_writable_changed (GObject          *target,

                                       GSettingsBackend *backend,

                                       const gchar      *path)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (target);

  gboolean last_one = FALSE;

  gsize n_keys;

  g_mutex_lock (&delayed->priv->lock);

  n_keys = g_tree_nnodes (delayed->priv->delayed);

  if (n_keys > 0)

    {

      CheckPrefixState state = { path, g_new (const gchar *, n_keys) };

      gsize i;

      /* collect a list of possibly-affected keys (ie: matching the path) */

      g_tree_foreach (delayed->priv->delayed, check_prefix, &state);

      /* drop the keys that have been affected.

       *

       * don't drop 'reset' keys (see above) */

      for (i = 0; i < state.index; i++)

        if (g_tree_lookup (delayed->priv->delayed, state.keys[i]) != NULL &&

            !g_settings_backend_get_writable (delayed->priv->backend,

                                              state.keys[i]))

          g_tree_remove (delayed->priv->delayed, state.keys[i]);

      g_free (state.keys);

      last_one = g_tree_nnodes (delayed->priv->delayed) == 0;

    }

  g_mutex_unlock (&delayed->priv->lock);

  if (last_one)

    g_delayed_settings_backend_notify_unapplied (delayed);

  g_settings_backend_path_writable_changed (G_SETTINGS_BACKEND (delayed),

                                            path);

}

static void

g_delayed_settings_backend_finalize (GObject *object)

{

  GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (object);

  g_mutex_clear (&delayed->priv->lock);

  g_object_unref (delayed->priv->backend);

  g_tree_unref (delayed->priv->delayed);

  /* if our owner is still alive, why are we finalizing? */

  g_assert (delayed->priv->owner == NULL);

  G_OBJECT_CLASS (g_delayed_settings_backend_parent_class)

    ->finalize (object);

}

static void

g_delayed_settings_backend_class_init (GDelayedSettingsBackendClass *class)

{

  GSettingsBackendClass *backend_class = G_SETTINGS_BACKEND_CLASS (class);

  GObjectClass *object_class = G_OBJECT_CLASS (class);

  backend_class->read = g_delayed_settings_backend_read;

  backend_class->read_user_value = g_delayed_settings_backend_read_user_value;

  backend_class->write = g_delayed_settings_backend_write;

  backend_class->write_tree = g_delayed_settings_backend_write_tree;

  backend_class->reset = g_delayed_settings_backend_reset;

  backend_class->get_writable = g_delayed_settings_backend_get_writable;

  backend_class->subscribe = g_delayed_settings_backend_subscribe;

  backend_class->unsubscribe = g_delayed_settings_backend_unsubscribe;

  backend_class->get_permission = g_delayed_settings_backend_get_permission;

  object_class->finalize = g_delayed_settings_backend_finalize;

}

static void

g_delayed_settings_backend_init (GDelayedSettingsBackend *delayed)

{

  delayed->priv = g_delayed_settings_backend_get_instance_private (delayed);

  delayed->priv->delayed = g_settings_backend_create_tree ();

  g_mutex_init (&delayed->priv->lock);

}

static void

g_delayed_settings_backend_disown (gpointer  data,

                                   GObject  *where_the_object_was)

{

  GDelayedSettingsBackend *delayed = data;

  g_mutex_lock (&delayed->priv->lock);

  delayed->priv->owner_context = NULL;

  delayed->priv->owner = NULL;

  g_mutex_unlock (&delayed->priv->lock);

}

GDelayedSettingsBackend *

g_delayed_settings_backend_new (GSettingsBackend *backend,

                                gpointer          owner,

                                GMainContext     *owner_context)

{

  static GSettingsListenerVTable vtable = {

    delayed_backend_changed,

    delayed_backend_path_changed,

    delayed_backend_keys_changed,

    delayed_backend_writable_changed,

    delayed_backend_path_writable_changed

  };

  GDelayedSettingsBackend *delayed;

  delayed = g_object_new (G_TYPE_DELAYED_SETTINGS_BACKEND, NULL);

  delayed->priv->backend = g_object_ref (backend);

  delayed->priv->owner_context = owner_context;

  delayed->priv->owner = owner;

  g_object_weak_ref (owner, g_delayed_settings_backend_disown, delayed);

  g_settings_backend_watch (delayed->priv->backend,

                            &vtable, G_OBJECT (delayed), NULL);

  return delayed;

}