/*

 * Copyright © 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 "gsimplepermission.h"

#include "gsettingsbackendinternal.h"

#include "giomodule.h"

#define G_TYPE_MEMORY_SETTINGS_BACKEND  (g_memory_settings_backend_get_type())

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

                                         G_TYPE_MEMORY_SETTINGS_BACKEND,     \

                                         GMemorySettingsBackend))

typedef GSettingsBackendClass GMemorySettingsBackendClass;

typedef struct

{

  GSettingsBackend parent_instance;

  GHashTable *table;

} GMemorySettingsBackend;

G_DEFINE_TYPE_WITH_CODE (GMemorySettingsBackend,

                         g_memory_settings_backend,

                         G_TYPE_SETTINGS_BACKEND,

                         g_io_extension_point_implement (G_SETTINGS_BACKEND_EXTENSION_POINT_NAME,

                                                         g_define_type_id, "memory", 10))

static GVariant *

g_memory_settings_backend_read (GSettingsBackend   *backend,

                                const gchar        *key,

                                const GVariantType *expected_type,

                                gboolean            default_value)

{

  GMemorySettingsBackend *memory = G_MEMORY_SETTINGS_BACKEND (backend);

  GVariant *value;

  if (default_value)

    return NULL;

  value = g_hash_table_lookup (memory->table, key);

  if (value != NULL)

    g_variant_ref (value);

  return value;

}

static gboolean

g_memory_settings_backend_write (GSettingsBackend *backend,

                                 const gchar      *key,

                                 GVariant         *value,

                                 gpointer          origin_tag)

{

  GMemorySettingsBackend *memory = G_MEMORY_SETTINGS_BACKEND (backend);

  GVariant *old_value;

  old_value = g_hash_table_lookup (memory->table, key);

  g_variant_ref_sink (value);

  if (old_value == NULL || !g_variant_equal (value, old_value))

    {

      g_hash_table_insert (memory->table, g_strdup (key), value);

      g_settings_backend_changed (backend, key, origin_tag);

    }

  else

    g_variant_unref (value);

  return TRUE;

}

static gboolean

g_memory_settings_backend_write_one (gpointer key,

                                     gpointer value,

                                     gpointer data)

{

  GMemorySettingsBackend *memory = data;

  if (value != NULL)

    g_hash_table_insert (memory->table, g_strdup (key), g_variant_ref (value));

  else

    g_hash_table_remove (memory->table, key);

  return FALSE;

}

static gboolean

g_memory_settings_backend_write_tree (GSettingsBackend *backend,

                                      GTree            *tree,

                                      gpointer          origin_tag)

{

  g_tree_foreach (tree, g_memory_settings_backend_write_one, backend);

  g_settings_backend_changed_tree (backend, tree, origin_tag);

  return TRUE;

}

static void

g_memory_settings_backend_reset (GSettingsBackend *backend,

                                 const gchar      *key,

                                 gpointer          origin_tag)

{

  GMemorySettingsBackend *memory = G_MEMORY_SETTINGS_BACKEND (backend);

  if (g_hash_table_lookup (memory->table, key))

    {

      g_hash_table_remove (memory->table, key);

      g_settings_backend_changed (backend, key, origin_tag);

    }

}

static gboolean

g_memory_settings_backend_get_writable (GSettingsBackend *backend,

                                        const gchar      *name)

{

  return TRUE;

}

static GPermission *

g_memory_settings_backend_get_permission (GSettingsBackend *backend,

                                          const gchar      *path)

{

  return g_simple_permission_new (TRUE);

}

static void

g_memory_settings_backend_finalize (GObject *object)

{

  GMemorySettingsBackend *memory = G_MEMORY_SETTINGS_BACKEND (object);

  g_hash_table_unref (memory->table);

  G_OBJECT_CLASS (g_memory_settings_backend_parent_class)

    ->finalize (object);

}

static void

g_memory_settings_backend_init (GMemorySettingsBackend *memory)

{

  memory->table = g_hash_table_new_full (g_str_hash, g_str_equal, g_free,

                                         (GDestroyNotify) g_variant_unref);

}

static void

g_memory_settings_backend_class_init (GMemorySettingsBackendClass *class)

{

  GSettingsBackendClass *backend_class = G_SETTINGS_BACKEND_CLASS (class);

  GObjectClass *object_class = G_OBJECT_CLASS (class);

  backend_class->read = g_memory_settings_backend_read;

  backend_class->write = g_memory_settings_backend_write;

  backend_class->write_tree = g_memory_settings_backend_write_tree;

  backend_class->reset = g_memory_settings_backend_reset;

  backend_class->get_writable = g_memory_settings_backend_get_writable;

  backend_class->get_permission = g_memory_settings_backend_get_permission;

  object_class->finalize = g_memory_settings_backend_finalize;

}

/**

 * g_memory_settings_backend_new:

 *

 * Creates a memory-backed #GSettingsBackend.

 *

 * This backend allows changes to settings, but does not write them

 * to any backing storage, so the next time you run your application,

 * the memory backend will start out with the default values again.

 *

 * Returns: (transfer full): a newly created #GSettingsBackend

 *

 * Since: 2.28

 */

GSettingsBackend *

g_memory_settings_backend_new (void)

{

  return g_object_new (G_TYPE_MEMORY_SETTINGS_BACKEND, NULL);

}