/*

 * Copyright © 2010 Codethink Limited

 * Copyright © 2010 Novell, Inc.

 *

 * 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/>.

 *

 * Authors: Vincent Untz <vuntz@gnome.org>

 *          Ryan Lortie <desrt@desrt.ca>

 */

#include "config.h"

#include <stdio.h>

#include <string.h>

#include "gfile.h"

#include "gfileinfo.h"

#include "gfilemonitor.h"

#include "gsimplepermission.h"

#include "gsettingsbackend.h"

#define G_TYPE_KEYFILE_SETTINGS_BACKEND      (g_keyfile_settings_backend_get_type ())

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

                                              G_TYPE_KEYFILE_SETTINGS_BACKEND,         \

                                              GKeyfileSettingsBackend))

#define G_IS_KEYFILE_SETTINGS_BACKEND(inst)  (G_TYPE_CHECK_INSTANCE_TYPE ((inst),      \

                                              G_TYPE_KEYFILE_SETTINGS_BACKEND))

typedef GSettingsBackendClass GKeyfileSettingsBackendClass;

typedef struct

{

  GSettingsBackend   parent_instance;

  GKeyFile          *keyfile;

  GPermission       *permission;

  gboolean           writable;

  gchar             *prefix;

  gint               prefix_len;

  gchar             *root_group;

  gint               root_group_len;

  GFile             *file;

  GFileMonitor      *file_monitor;

  guint8             digest[32];

  GFile             *dir;

  GFileMonitor      *dir_monitor;

} GKeyfileSettingsBackend;

static GType g_keyfile_settings_backend_get_type (void);

G_DEFINE_TYPE (GKeyfileSettingsBackend,

               g_keyfile_settings_backend,

               G_TYPE_SETTINGS_BACKEND)

static void

compute_checksum (guint8        *digest,

                  gconstpointer  contents,

                  gsize          length)

{

  GChecksum *checksum;

  gsize len = 32;

  checksum = g_checksum_new (G_CHECKSUM_SHA256);

  g_checksum_update (checksum, contents, length);

  g_checksum_get_digest (checksum, digest, &len;;

  g_checksum_free (checksum);

  g_assert (len == 32);

}

static void

g_keyfile_settings_backend_keyfile_write (GKeyfileSettingsBackend *kfsb)

{

  gchar *contents;

  gsize length;

  contents = g_key_file_to_data (kfsb->keyfile, &length, NULL);

  g_file_replace_contents (kfsb->file, contents, length, NULL, FALSE,

                           G_FILE_CREATE_REPLACE_DESTINATION,

                           NULL, NULL, NULL);

  compute_checksum (kfsb->digest, contents, length);

  g_free (contents);

}

static gboolean

group_name_matches (const gchar *group_name,

                    const gchar *prefix)

{

  /* sort of like g_str_has_prefix() except that it must be an exact

   * match or the prefix followed by '/'.

   *

   * for example 'a' is a prefix of 'a' and 'a/b' but not 'ab'.

   */

  gint i;

  for (i = 0; prefix[i]; i++)

    if (prefix[i] != group_name[i])

      return FALSE;

  return group_name[i] == '\0' || group_name[i] == '/';

}

static gboolean

convert_path (GKeyfileSettingsBackend  *kfsb,

              const gchar              *key,

              gchar                   **group,

              gchar                   **basename)

{

  gint key_len = strlen (key);

  gint i;

  if (key_len < kfsb->prefix_len ||

      memcmp (key, kfsb->prefix, kfsb->prefix_len) != 0)

    return FALSE;

  key_len -= kfsb->prefix_len;

  key += kfsb->prefix_len;

  for (i = key_len; i >= 0; i--)

    if (key[i] == '/')

      break;

  if (kfsb->root_group)

    {

      /* if a root_group was specified, make sure the user hasn't given

       * a path that ghosts that group name

       */

      if (i == kfsb->root_group_len && memcmp (key, kfsb->root_group, i) == 0)

        return FALSE;

    }

  else

    {

      /* if no root_group was given, ensure that the user gave a path */

      if (i == -1)

        return FALSE;

    }

  if (group)

    {

      if (i >= 0)

        {

          *group = g_memdup (key, i + 1);

          (*group)[i] = '\0';

        }

      else

        *group = g_strdup (kfsb->root_group);

    }

  if (basename)

    *basename = g_memdup (key + i + 1, key_len - i);

  return TRUE;

}

static gboolean

path_is_valid (GKeyfileSettingsBackend *kfsb,

               const gchar             *path)

{

  return convert_path (kfsb, path, NULL, NULL);

}

static GVariant *

get_from_keyfile (GKeyfileSettingsBackend *kfsb,

                  const GVariantType      *type,

                  const gchar             *key)

{

  GVariant *return_value = NULL;

  gchar *group, *name;

  if (convert_path (kfsb, key, &group, &name))

    {

      gchar *str;

      g_assert (*name);

      str = g_key_file_get_value (kfsb->keyfile, group, name, NULL);

      if (str)

        {

          return_value = g_variant_parse (type, str, NULL, NULL, NULL);

          g_free (str);

        }

      g_free (group);

      g_free (name);

    }

  return return_value;

}

static gboolean

set_to_keyfile (GKeyfileSettingsBackend *kfsb,

                const gchar             *key,

                GVariant                *value)

{

  gchar *group, *name;

  if (convert_path (kfsb, key, &group, &name))

    {

      if (value)

        {

          gchar *str = g_variant_print (value, FALSE);

          g_key_file_set_value (kfsb->keyfile, group, name, str);

          g_variant_unref (g_variant_ref_sink (value));

          g_free (str);

        }

      else

        {

          if (*name == '\0')

            {

              gchar **groups;

              gint i;

              groups = g_key_file_get_groups (kfsb->keyfile, NULL);

              for (i = 0; groups[i]; i++)

                if (group_name_matches (groups[i], group))

                  g_key_file_remove_group (kfsb->keyfile, groups[i], NULL);

              g_strfreev (groups);

            }

          else

            g_key_file_remove_key (kfsb->keyfile, group, name, NULL);

        }

      g_free (group);

      g_free (name);

      return TRUE;

    }

  return FALSE;

}

static GVariant *

g_keyfile_settings_backend_read (GSettingsBackend   *backend,

                                 const gchar        *key,

                                 const GVariantType *expected_type,

                                 gboolean            default_value)

{

  GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);

  if (default_value)

    return NULL;

  return get_from_keyfile (kfsb, expected_type, key);

}

typedef struct

{

  GKeyfileSettingsBackend *kfsb;

  gboolean failed;

} WriteManyData;

static gboolean

g_keyfile_settings_backend_write_one (gpointer key,

                                      gpointer value,

                                      gpointer user_data)

{

  WriteManyData *data = user_data;

  gboolean success;

  success = set_to_keyfile (data->kfsb, key, value);

  g_assert (success);

  return FALSE;

}

static gboolean

g_keyfile_settings_backend_check_one (gpointer key,

                                      gpointer value,

                                      gpointer user_data)

{

  WriteManyData *data = user_data;

  return data->failed = !path_is_valid (data->kfsb, key);

}

static gboolean

g_keyfile_settings_backend_write_tree (GSettingsBackend *backend,

                                       GTree            *tree,

                                       gpointer          origin_tag)

{

  WriteManyData data = { G_KEYFILE_SETTINGS_BACKEND (backend) };

  if (!data.kfsb->writable)

    return FALSE;

  g_tree_foreach (tree, g_keyfile_settings_backend_check_one, &data);

  if (data.failed)

    return FALSE;

  g_tree_foreach (tree, g_keyfile_settings_backend_write_one, &data);

  g_keyfile_settings_backend_keyfile_write (data.kfsb);

  g_settings_backend_changed_tree (backend, tree, origin_tag);

  return TRUE;

}

static gboolean

g_keyfile_settings_backend_write (GSettingsBackend *backend,

                                  const gchar      *key,

                                  GVariant         *value,

                                  gpointer          origin_tag)

{

  GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);

  gboolean success;

  if (!kfsb->writable)

    return FALSE;

  success = set_to_keyfile (kfsb, key, value);

  if (success)

    {

      g_settings_backend_changed (backend, key, origin_tag);

      g_keyfile_settings_backend_keyfile_write (kfsb);

    }

  return success;

}

static void

g_keyfile_settings_backend_reset (GSettingsBackend *backend,

                                  const gchar      *key,

                                  gpointer          origin_tag)

{

  GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);

  if (set_to_keyfile (kfsb, key, NULL))

    g_keyfile_settings_backend_keyfile_write (kfsb);

  g_settings_backend_changed (backend, key, origin_tag);

}

static gboolean

g_keyfile_settings_backend_get_writable (GSettingsBackend *backend,

                                         const gchar      *name)

{

  GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);

  return kfsb->writable && path_is_valid (kfsb, name);

}

static GPermission *

g_keyfile_settings_backend_get_permission (GSettingsBackend *backend,

                                           const gchar      *path)

{

  GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);

  return g_object_ref (kfsb->permission);

}

static void

keyfile_to_tree (GKeyfileSettingsBackend *kfsb,

                 GTree                   *tree,

                 GKeyFile                *keyfile,

                 gboolean                 dup_check)

{

  gchar **groups;

  gint i;

  groups = g_key_file_get_groups (keyfile, NULL);

  for (i = 0; groups[i]; i++)

    {

      gboolean is_root_group;

      gchar **keys;

      gint j;

      is_root_group = g_strcmp0 (kfsb->root_group, groups[i]) == 0;

      /* reject group names that will form invalid key names */

      if (!is_root_group &&

          (g_str_has_prefix (groups[i], "/") ||

           g_str_has_suffix (groups[i], "/") || strstr (groups[i], "//")))

        continue;

      keys = g_key_file_get_keys (keyfile, groups[i], NULL, NULL);

      g_assert (keys != NULL);

      for (j = 0; keys[j]; j++)

        {

          gchar *path, *value;

          /* reject key names with slashes in them */

          if (strchr (keys[j], '/'))

            continue;

          if (is_root_group)

            path = g_strdup_printf ("%s%s", kfsb->prefix, keys[j]);

          else

            path = g_strdup_printf ("%s%s/%s", kfsb->prefix, groups[i], keys[j]);

          value = g_key_file_get_value (keyfile, groups[i], keys[j], NULL);

          if (dup_check && g_strcmp0 (g_tree_lookup (tree, path), value) == 0)

            {

              g_tree_remove (tree, path);

              g_free (value);

              g_free (path);

            }

          else

            g_tree_insert (tree, path, value);

        }

      g_strfreev (keys);

    }

  g_strfreev (groups);

}

static void

g_keyfile_settings_backend_keyfile_reload (GKeyfileSettingsBackend *kfsb)

{

  guint8 digest[32];

  gchar *contents;

  gsize length;

  contents = NULL;

  length = 0;

  g_file_load_contents (kfsb->file, NULL, &contents, &length, NULL, NULL);

  compute_checksum (digest, contents, length);

  if (memcmp (kfsb->digest, digest, sizeof digest) != 0)

    {

      GKeyFile *keyfiles[2];

      GTree *tree;

      tree = g_tree_new_full ((GCompareDataFunc) strcmp, NULL,

                              g_free, g_free);

      keyfiles[0] = kfsb->keyfile;

      keyfiles[1] = g_key_file_new ();

      if (length > 0)

        g_key_file_load_from_data (keyfiles[1], contents, length,

                                   G_KEY_FILE_KEEP_COMMENTS |

                                   G_KEY_FILE_KEEP_TRANSLATIONS, NULL);

      keyfile_to_tree (kfsb, tree, keyfiles[0], FALSE);

      keyfile_to_tree (kfsb, tree, keyfiles[1], TRUE);

      g_key_file_free (keyfiles[0]);

      kfsb->keyfile = keyfiles[1];

      if (g_tree_nnodes (tree) > 0)

        g_settings_backend_changed_tree (&kfsb->parent_instance, tree, NULL);

      g_tree_unref (tree);

      memcpy (kfsb->digest, digest, sizeof digest);

    }

  g_free (contents);

}

static void

g_keyfile_settings_backend_keyfile_writable (GKeyfileSettingsBackend *kfsb)

{

  GFileInfo *fileinfo;

  gboolean writable;

  fileinfo = g_file_query_info (kfsb->dir, "access::*", 0, NULL, NULL);

  if (fileinfo)

    {

      writable =

        g_file_info_get_attribute_boolean (fileinfo, G_FILE_ATTRIBUTE_ACCESS_CAN_WRITE) &&

        g_file_info_get_attribute_boolean (fileinfo, G_FILE_ATTRIBUTE_ACCESS_CAN_EXECUTE);

      g_object_unref (fileinfo);

    }

  else

    writable = FALSE;

  if (writable != kfsb->writable)

    {

      kfsb->writable = writable;

      g_settings_backend_path_writable_changed (&kfsb->parent_instance, "/");

    }

}

static void

g_keyfile_settings_backend_finalize (GObject *object)

{

  GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (object);

  g_key_file_free (kfsb->keyfile);

  g_object_unref (kfsb->permission);

  g_file_monitor_cancel (kfsb->file_monitor);

  g_object_unref (kfsb->file_monitor);

  g_object_unref (kfsb->file);

  g_file_monitor_cancel (kfsb->dir_monitor);

  g_object_unref (kfsb->dir_monitor);

  g_object_unref (kfsb->dir);

  g_free (kfsb->root_group);

  g_free (kfsb->prefix);

  G_OBJECT_CLASS (g_keyfile_settings_backend_parent_class)

    ->finalize (object);

}

static void

g_keyfile_settings_backend_init (GKeyfileSettingsBackend *kfsb)

{

}

static void

g_keyfile_settings_backend_class_init (GKeyfileSettingsBackendClass *class)

{

  GObjectClass *object_class = G_OBJECT_CLASS (class);

  object_class->finalize = g_keyfile_settings_backend_finalize;

  class->read = g_keyfile_settings_backend_read;

  class->write = g_keyfile_settings_backend_write;

  class->write_tree = g_keyfile_settings_backend_write_tree;

  class->reset = g_keyfile_settings_backend_reset;

  class->get_writable = g_keyfile_settings_backend_get_writable;

  class->get_permission = g_keyfile_settings_backend_get_permission;

  /* No need to implement subscribed/unsubscribe: the only point would be to

   * stop monitoring the file when there's no GSettings anymore, which is no

   * big win.

   */

}

static void

file_changed (GFileMonitor      *monitor,

              GFile             *file,

              GFile             *other_file,

              GFileMonitorEvent  event_type,

              gpointer           user_data)

{

  GKeyfileSettingsBackend *kfsb = user_data;

  /* Ignore file deletions, let the GKeyFile content remain in tact. */

  if (event_type != G_FILE_MONITOR_EVENT_DELETED)

    g_keyfile_settings_backend_keyfile_reload (kfsb);

}

static void

dir_changed (GFileMonitor       *monitor,

              GFile             *file,

              GFile             *other_file,

              GFileMonitorEvent  event_type,

              gpointer           user_data)

{

  GKeyfileSettingsBackend *kfsb = user_data;

  g_keyfile_settings_backend_keyfile_writable (kfsb);

}

/**

 * g_keyfile_settings_backend_new:

 * @filename: the filename of the keyfile

 * @root_path: the path under which all settings keys appear

 * @root_group: (nullable): the group name corresponding to

 *              @root_path, or %NULL

 *

 * Creates a keyfile-backed #GSettingsBackend.

 *

 * The filename of the keyfile to use is given by @filename.

 *

 * All settings read to or written from the backend must fall under the

 * path given in @root_path (which must start and end with a slash and

 * not contain two consecutive slashes).  @root_path may be "/".

 *

 * If @root_group is non-%NULL then it specifies the name of the keyfile

 * group used for keys that are written directly below @root_path.  For

 * example, if @root_path is "/apps/example/" and @root_group is

 * "toplevel", then settings the key "/apps/example/enabled" to a value

 * of %TRUE will cause the following to appear in the keyfile:

 *

 * |[

 *   [toplevel]

 *   enabled=true

 * ]|

 *

 * If @root_group is %NULL then it is not permitted to store keys

 * directly below the @root_path.

 *

 * For keys not stored directly below @root_path (ie: in a sub-path),

 * the name of the subpath (with the final slash stripped) is used as

 * the name of the keyfile group.  To continue the example, if

 * "/apps/example/profiles/default/font-size" were set to

 * 12 then the following would appear in the keyfile:

 *

 * |[

 *   [profiles/default]

 *   font-size=12

 * ]|

 *

 * The backend will refuse writes (and return writability as being

 * %FALSE) for keys outside of @root_path and, in the event that

 * @root_group is %NULL, also for keys directly under @root_path.

 * Writes will also be refused if the backend detects that it has the

 * inability to rewrite the keyfile (ie: the containing directory is not

 * writable).

 *

 * There is no checking done for your key namespace clashing with the

 * syntax of the key file format.  For example, if you have '[' or ']'

 * characters in your path names or '=' in your key names you may be in

 * trouble.

 *

 * Returns: (transfer full): a keyfile-backed #GSettingsBackend

 **/

GSettingsBackend *

g_keyfile_settings_backend_new (const gchar *filename,

                                const gchar *root_path,

                                const gchar *root_group)

{

  GKeyfileSettingsBackend *kfsb;

  g_return_val_if_fail (filename != NULL, NULL);

  g_return_val_if_fail (root_path != NULL, NULL);

  g_return_val_if_fail (g_str_has_prefix (root_path, "/"), NULL);

  g_return_val_if_fail (g_str_has_suffix (root_path, "/"), NULL);

  g_return_val_if_fail (strstr (root_path, "//") == NULL, NULL);

  kfsb = g_object_new (G_TYPE_KEYFILE_SETTINGS_BACKEND, NULL);

  kfsb->keyfile = g_key_file_new ();

  kfsb->permission = g_simple_permission_new (TRUE);

  kfsb->file = g_file_new_for_path (filename);

  kfsb->dir = g_file_get_parent (kfsb->file);

  g_file_make_directory_with_parents (kfsb->dir, NULL, NULL);

  kfsb->file_monitor = g_file_monitor (kfsb->file, 0, NULL, NULL);

  kfsb->dir_monitor = g_file_monitor (kfsb->dir, 0, NULL, NULL);

  kfsb->prefix_len = strlen (root_path);

  kfsb->prefix = g_strdup (root_path);

  if (root_group)

    {

      kfsb->root_group_len = strlen (root_group);

      kfsb->root_group = g_strdup (root_group);

    }

  compute_checksum (kfsb->digest, NULL, 0);

  g_signal_connect (kfsb->file_monitor, "changed",

                    G_CALLBACK (file_changed), kfsb);

  g_signal_connect (kfsb->dir_monitor, "changed",

                    G_CALLBACK (dir_changed), kfsb);

  g_keyfile_settings_backend_keyfile_writable (kfsb);

  g_keyfile_settings_backend_keyfile_reload (kfsb);

  return G_SETTINGS_BACKEND (kfsb);

}