/*-
 * Copyright (c) 2005-2006 Benedikt Meurer <benny@xfce.org>
 *
 * This 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 3 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
 * Library 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301 USA
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#ifdef HAVE_MEMORY_H
#include <memory.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif

/* Taken from exo v0.10.2 (Debian package libexo-1-0), according to changelog
 * commit f455681554ca205ffe49bd616310b19f5f9f8ef1 Dec 27 13:50:21 2012 */

#include "exo-icon-chooser-model.h"
#include "exo-private.h"
#include "exo-string.h"

typedef struct _ExoIconChooserModelItem ExoIconChooserModelItem;



static void               exo_icon_chooser_model_tree_model_init    (GtkTreeModelIface         *iface);
static void               exo_icon_chooser_model_finalize           (GObject                   *object);
static GtkTreeModelFlags  exo_icon_chooser_model_get_flags          (GtkTreeModel              *tree_model);
static gint               exo_icon_chooser_model_get_n_columns      (GtkTreeModel              *tree_model);
static GType              exo_icon_chooser_model_get_column_type    (GtkTreeModel              *tree_model,
                                                                     gint                       idx);
static gboolean           exo_icon_chooser_model_get_iter           (GtkTreeModel              *tree_model,
                                                                     GtkTreeIter               *iter,
                                                                     GtkTreePath               *path);
static GtkTreePath       *exo_icon_chooser_model_get_path           (GtkTreeModel              *tree_model,
                                                                     GtkTreeIter               *iter);
static void               exo_icon_chooser_model_get_value          (GtkTreeModel              *tree_model,
                                                                     GtkTreeIter               *iter,
                                                                     gint                       column,
                                                                     GValue                    *value);
static gboolean           exo_icon_chooser_model_iter_next          (GtkTreeModel              *tree_model,
                                                                     GtkTreeIter               *iter);
static gboolean           exo_icon_chooser_model_iter_children      (GtkTreeModel              *tree_model,
                                                                     GtkTreeIter               *iter,
                                                                     GtkTreeIter               *parent);
static gboolean           exo_icon_chooser_model_iter_has_child     (GtkTreeModel              *tree_model,
                                                                     GtkTreeIter               *iter);
static gint               exo_icon_chooser_model_iter_n_children    (GtkTreeModel              *tree_model,
                                                                     GtkTreeIter               *iter);
static gboolean           exo_icon_chooser_model_iter_nth_child     (GtkTreeModel              *tree_model,
                                                                     GtkTreeIter               *iter,
                                                                     GtkTreeIter               *parent,
                                                                     gint                       n);
static gboolean           exo_icon_chooser_model_iter_parent        (GtkTreeModel              *tree_model,
                                                                     GtkTreeIter               *iter,
                                                                     GtkTreeIter               *child);
static void               exo_icon_chooser_model_icon_theme_changed (GtkIconTheme              *icon_theme,
                                                                     ExoIconChooserModel       *model);
static void               exo_icon_chooser_model_item_to_list       (gpointer                   key,
                                                                     gpointer                   value,
                                                                     gpointer                   data);
static void               exo_icon_chooser_model_item_free          (gpointer                   data);



struct _ExoIconChooserModelClass
{
    GObjectClass __parent__;
};

struct _ExoIconChooserModel
{
    GObject       __parent__;
    GtkIconTheme *icon_theme;
    GList        *items;
    gint          stamp;
};

struct _ExoIconChooserModelItem
{
    gchar                 *icon_name;
    ExoIconChooserContext  context;

    /* storage for symlink icons merge */
    GtkIconInfo           *icon_info;

    /* icon names of symlinks to this item */
    GPtrArray             *other_names;
};



static const gchar CONTEXT_NAMES[][14] =
{
    "Actions",        /* EXO_ICON_CHOOSER_CONTEXT_ACTIONS */
    "Animations",     /* EXO_ICON_CHOOSER_CONTEXT_ANIMATIONS */
    "Applications",   /* EXO_ICON_CHOOSER_CONTEXT_APPLICATIONS */
    "Categories",     /* EXO_ICON_CHOOSER_CONTEXT_CATEGORIES */
    "Devices",        /* EXO_ICON_CHOOSER_CONTEXT_DEVICES */
    "Emblems",        /* EXO_ICON_CHOOSER_CONTEXT_EMBLEMS */
    "Emotes",         /* EXO_ICON_CHOOSER_CONTEXT_EMOTES */
    "International",  /* EXO_ICON_CHOOSER_CONTEXT_INTERNATIONAL */
    "MimeTypes",      /* EXO_ICON_CHOOSER_CONTEXT_MIME_TYPES */
    "Places",         /* EXO_ICON_CHOOSER_CONTEXT_PLACES */
    "Status",         /* EXO_ICON_CHOOSER_CONTEXT_STATUS */
};



G_DEFINE_TYPE_WITH_CODE (ExoIconChooserModel, exo_icon_chooser_model, G_TYPE_OBJECT,
                         G_IMPLEMENT_INTERFACE (GTK_TYPE_TREE_MODEL, exo_icon_chooser_model_tree_model_init))



static void
exo_icon_chooser_model_class_init (ExoIconChooserModelClass *klass)
{
    GObjectClass *gobject_class;

    gobject_class = G_OBJECT_CLASS (klass);
    gobject_class->finalize = exo_icon_chooser_model_finalize;
}



static void
exo_icon_chooser_model_tree_model_init (GtkTreeModelIface *iface)
{
    iface->get_flags = exo_icon_chooser_model_get_flags;
    iface->get_n_columns = exo_icon_chooser_model_get_n_columns;
    iface->get_column_type = exo_icon_chooser_model_get_column_type;
    iface->get_iter = exo_icon_chooser_model_get_iter;
    iface->get_path = exo_icon_chooser_model_get_path;
    iface->get_value = exo_icon_chooser_model_get_value;
    iface->iter_next = exo_icon_chooser_model_iter_next;
    iface->iter_children = exo_icon_chooser_model_iter_children;
    iface->iter_has_child = exo_icon_chooser_model_iter_has_child;
    iface->iter_n_children = exo_icon_chooser_model_iter_n_children;
    iface->iter_nth_child = exo_icon_chooser_model_iter_nth_child;
    iface->iter_parent = exo_icon_chooser_model_iter_parent;
}



static void
exo_icon_chooser_model_init (ExoIconChooserModel *model)
{
    model->stamp = g_random_int ();
}



static void
exo_icon_chooser_model_finalize (GObject *object)
{
    ExoIconChooserModel *model = EXO_ICON_CHOOSER_MODEL (object);

    /* check if we're connected to an icon theme */
    if (G_LIKELY (model->icon_theme != NULL))
    {
        /* disconnect from the icon theme */
        g_signal_handlers_disconnect_by_func (G_OBJECT (model->icon_theme), exo_icon_chooser_model_icon_theme_changed, model);
        g_object_set_data (G_OBJECT (model->icon_theme), "exo-icon-chooser-default-model", NULL);
        g_object_unref (G_OBJECT (model->icon_theme));
    }

    /* release all items */
    g_list_foreach (model->items, (GFunc) exo_icon_chooser_model_item_free, NULL);
    g_list_free (model->items);

    (*G_OBJECT_CLASS (exo_icon_chooser_model_parent_class)->finalize) (object);
}



static GtkTreeModelFlags
exo_icon_chooser_model_get_flags (GtkTreeModel *tree_model)
{
    return GTK_TREE_MODEL_ITERS_PERSIST | GTK_TREE_MODEL_LIST_ONLY;
}



static gint
exo_icon_chooser_model_get_n_columns (GtkTreeModel *tree_model)
{
    return EXO_ICON_CHOOSER_MODEL_N_COLUMNS;
}



static GType
exo_icon_chooser_model_get_column_type (GtkTreeModel *tree_model,
                                        gint          idx)
{
    switch (idx)
    {
    case EXO_ICON_CHOOSER_MODEL_COLUMN_CONTEXT:
        return G_TYPE_UINT;

    case EXO_ICON_CHOOSER_MODEL_COLUMN_ICON_NAME:
        return G_TYPE_STRING;
    }

    _exo_assert_not_reached ();
    return G_TYPE_INVALID;
}



static gboolean
exo_icon_chooser_model_get_iter (GtkTreeModel *tree_model,
                                 GtkTreeIter  *iter,
                                 GtkTreePath  *path)
{
    ExoIconChooserModel *model = EXO_ICON_CHOOSER_MODEL (tree_model);
    GList               *lp;

    _exo_return_val_if_fail (EXO_IS_ICON_CHOOSER_MODEL (model), FALSE);
    _exo_return_val_if_fail (gtk_tree_path_get_depth (path) > 0, FALSE);

    /* determine the list item for the path */
    lp = g_list_nth (model->items, gtk_tree_path_get_indices (path)[0]);
    if (G_LIKELY (lp != NULL))
    {
        iter->stamp = model->stamp;
        iter->user_data = lp;
        return TRUE;
    }

    return FALSE;
}



static GtkTreePath*
exo_icon_chooser_model_get_path (GtkTreeModel *tree_model,
                                 GtkTreeIter  *iter)
{
    ExoIconChooserModel *model = EXO_ICON_CHOOSER_MODEL (tree_model);
    gint                 idx;

    _exo_return_val_if_fail (EXO_IS_ICON_CHOOSER_MODEL (model), NULL);
    _exo_return_val_if_fail (iter->stamp == model->stamp, NULL);

    /* lookup the list item in the icon list */
    idx = g_list_position (model->items, iter->user_data);
    if (G_LIKELY (idx >= 0))
        return gtk_tree_path_new_from_indices (idx, -1);

    return NULL;
}



static void
exo_icon_chooser_model_get_value (GtkTreeModel *tree_model,
                                  GtkTreeIter  *iter,
                                  gint          column,
                                  GValue       *value)
{
    ExoIconChooserModelItem *item;
    ExoIconChooserModel     *model = EXO_ICON_CHOOSER_MODEL (tree_model);

    _exo_return_if_fail (EXO_IS_ICON_CHOOSER_MODEL (model));
    _exo_return_if_fail (iter->stamp == model->stamp);

    /* determine the item for the list position */
    item = ((GList *) iter->user_data)->data;

    switch (column)
    {
    case EXO_ICON_CHOOSER_MODEL_COLUMN_CONTEXT:
        g_value_init (value, G_TYPE_UINT);
        g_value_set_uint (value, item->context);
        break;

    case EXO_ICON_CHOOSER_MODEL_COLUMN_ICON_NAME:
        g_value_init (value, G_TYPE_STRING);
        g_value_set_static_string (value, item->icon_name);
        break;

    default:
        _exo_assert_not_reached ();
        break;
    }
}



static gboolean
exo_icon_chooser_model_iter_next (GtkTreeModel *tree_model,
                                  GtkTreeIter  *iter)
{
    _exo_return_val_if_fail (iter->stamp == EXO_ICON_CHOOSER_MODEL (tree_model)->stamp, FALSE);
    _exo_return_val_if_fail (EXO_IS_ICON_CHOOSER_MODEL (tree_model), FALSE);

    iter->user_data = g_list_next (iter->user_data);
    return (iter->user_data != NULL);
}



static gboolean
exo_icon_chooser_model_iter_children (GtkTreeModel *tree_model,
                                      GtkTreeIter  *iter,
                                      GtkTreeIter  *parent)
{
    ExoIconChooserModel *model = EXO_ICON_CHOOSER_MODEL (tree_model);

    _exo_return_val_if_fail (EXO_IS_ICON_CHOOSER_MODEL (model), FALSE);

    if (G_LIKELY (parent == NULL && model->items != NULL))
    {
        iter->stamp = model->stamp;
        iter->user_data = model->items;
        return TRUE;
    }

    return FALSE;
}



static gboolean
exo_icon_chooser_model_iter_has_child (GtkTreeModel *tree_model,
                                       GtkTreeIter  *iter)
{
    return FALSE;
}



static gint
exo_icon_chooser_model_iter_n_children (GtkTreeModel *tree_model,
                                        GtkTreeIter  *iter)
{
    ExoIconChooserModel *model = EXO_ICON_CHOOSER_MODEL (tree_model);

    _exo_return_val_if_fail (EXO_IS_ICON_CHOOSER_MODEL (tree_model), 0);

    return (iter == NULL) ? g_list_length (model->items) : 0;
}



static gboolean
exo_icon_chooser_model_iter_nth_child (GtkTreeModel *tree_model,
                                       GtkTreeIter  *iter,
                                       GtkTreeIter  *parent,
                                       gint          n)
{
    ExoIconChooserModel *model = EXO_ICON_CHOOSER_MODEL (tree_model);

    _exo_return_val_if_fail (EXO_IS_ICON_CHOOSER_MODEL (tree_model), FALSE);

    if (G_LIKELY (parent == NULL))
    {
        iter->stamp = model->stamp;
        iter->user_data = g_list_nth (model->items, n);
        return (iter->user_data != NULL);
    }

    return FALSE;
}



static gboolean
exo_icon_chooser_model_iter_parent (GtkTreeModel *tree_model,
                                    GtkTreeIter  *iter,
                                    GtkTreeIter  *child)
{
    return FALSE;
}



static gboolean
exo_icon_chooser_model_merge_symlinks (gpointer key,
                                       gpointer value,
                                       gpointer data)
{
    GHashTable              *items = data;
    ExoIconChooserModelItem *sym_item = value;
    ExoIconChooserModelItem *item;
    gchar                   *target;
    const gchar             *filename;
    gchar                   *p, *name;
    gboolean                 merged = FALSE;

    /* get the location the symlink points to */
    filename = gtk_icon_info_get_filename (sym_item->icon_info);
    target = g_file_read_link (filename, NULL);
    if (G_UNLIKELY (target == NULL))
        return merged;

    /* we don't care about paths and relative names, so make sure we
   * have the basename of the symlink target */
    if (g_path_is_absolute (target)
            || g_str_has_prefix (target, "../"))
    {
        p = g_path_get_basename (target);
        g_free (target);
        target = p;
    }

    /* the icon names all have an extension */
    p = strrchr (target, '.');
    if (G_LIKELY (p != NULL))
    {
        /* lookup the target from the items table */
        name = g_strndup (target, p - target);
        item = g_hash_table_lookup (items, name);
        g_free (name);

        if (G_LIKELY (item != NULL))
        {
            /* allocate the array on demand */
            if (item->other_names == NULL)
                item->other_names = g_ptr_array_new_with_free_func ((GDestroyNotify) g_free);

            /* take the symlinks display name */
            g_ptr_array_add (item->other_names, sym_item->icon_name);
            sym_item->icon_name = NULL;

            /* set the symlinks context if the item has none */
            if (item->context == EXO_ICON_CHOOSER_CONTEXT_OTHER)
                item->context = sym_item->context;

            /* this item can be removed from the hash table,
           * remaining data will be freed by the destroy func */
            merged = TRUE;
        }
    }

    g_free (target);

    return merged;
}



static void
exo_icon_chooser_model_icon_theme_changed (GtkIconTheme        *icon_theme,
                                           ExoIconChooserModel *model)
{
    ExoIconChooserModelItem *item;
    GHashTable              *items;
    GHashTable              *symlink_items;
    GList                   *icons, *lp;
    const gchar             *filename;
    ExoIconChooserContext    context;
    GtkTreePath             *path;
    GtkTreeIter              iter;
    GtkIconInfo             *icon_info;

    /* allocate a path to the first model item */
    path = gtk_tree_path_new_from_indices (0, -1);

    /* release all previously loaded icons */
    while (model->items != NULL)
    {
        /* free the first item resources */
        exo_icon_chooser_model_item_free (model->items->data);

        /* remove the item from the list */
        model->items = g_list_delete_link (model->items, model->items);

        /* tell the view that the first item is gone for good */
        gtk_tree_model_row_deleted (GTK_TREE_MODEL (model), path);
    }

    /* separate tables for the symlink and non-symlink icons */
    items = g_hash_table_new (g_str_hash, g_str_equal);
    symlink_items = g_hash_table_new_full (g_str_hash, g_str_equal, NULL, exo_icon_chooser_model_item_free);

    /* insert the theme icons in the correct hash table */
    icons = gtk_icon_theme_list_icons (icon_theme, NULL);
    for (lp = icons; lp != NULL; lp = lp->next)
    {
        item = g_slice_new0 (ExoIconChooserModelItem);
        item->icon_name = lp->data;
        item->context = EXO_ICON_CHOOSER_CONTEXT_OTHER;

        icon_info = gtk_icon_theme_lookup_icon (icon_theme, item->icon_name, 48, 0);
        if (G_LIKELY (icon_info != NULL))
        {
            /* check if this icon points to a symlink */
            filename = gtk_icon_info_get_filename (icon_info);
            if (filename != NULL
                    && g_file_test (filename, G_FILE_TEST_IS_SYMLINK))
            {
                /* insert this item in the symlink table */
                item->icon_info = icon_info;
                g_hash_table_insert (symlink_items, item->icon_name, item);
                continue;
            }

            gtk_icon_info_free (icon_info);
        }

        /* real file or no info, store it in the hash table */
        g_hash_table_insert (items, item->icon_name, item);
    }
    g_list_free (icons);

    /* now determine the categories for all items in the model */
    for (context = 0; context < G_N_ELEMENTS (CONTEXT_NAMES); ++context)
    {
        icons = gtk_icon_theme_list_icons (icon_theme, CONTEXT_NAMES[context]);
        for (lp = icons; lp != NULL; lp = lp->next)
        {
            /* lookup the item in one of the hash tables */
            item = g_hash_table_lookup (items, lp->data);
            if (item == NULL)
                item = g_hash_table_lookup (symlink_items, lp->data);

            /* set the categories */
            if (item != NULL)
                item->context = context;

            g_free (lp->data);
        }
        g_list_free (icons);
    }

    /* merge the symlinks in the items */
    g_hash_table_foreach_remove (symlink_items, exo_icon_chooser_model_merge_symlinks, items);
    g_hash_table_destroy (symlink_items);

    /* create a sorted list of the resulting table */
    icons = NULL;
    g_hash_table_foreach (items, exo_icon_chooser_model_item_to_list, &icons);
    g_hash_table_destroy (items);

    /* insert the items into the model */
    iter.stamp = model->stamp;
    for (lp = g_list_last (icons); lp != NULL; lp = lp->prev)
    {
        /* prepend the item to the beginning of our list */
        model->items = g_list_prepend (model->items, lp->data);

        /* setup the iterator for the item */
        iter.user_data = model->items;

        /* tell the view about our new item */
        gtk_tree_model_row_inserted (GTK_TREE_MODEL (model), path, &iter);
    }
    g_list_free (icons);

    /* release the path */
    gtk_tree_path_free (path);
}



static gint
exo_icon_chooser_model_item_compare (gconstpointer data_a,
                                     gconstpointer data_b)
{
    const ExoIconChooserModelItem *item_a = data_a;
    const ExoIconChooserModelItem *item_b = data_b;

    /* the case is not much of a problem in icon themes, so
   * therefore we only use good utf-8 sorting */
    return g_utf8_collate (item_a->icon_name, item_b->icon_name);
}



static void
exo_icon_chooser_model_item_to_list (gpointer key,
                                     gpointer value,
                                     gpointer data)
{
    GList                   **list = data;
    ExoIconChooserModelItem  *item = value;

    *list = g_list_insert_sorted (*list, item, exo_icon_chooser_model_item_compare);
}



static void
exo_icon_chooser_model_item_free (gpointer data)
{
    ExoIconChooserModelItem *item = data;

    if (G_LIKELY (item->other_names != NULL))
        g_ptr_array_free (item->other_names, TRUE);

    if (G_LIKELY (item->icon_info != NULL))
        gtk_icon_info_free (item->icon_info);

    g_free (item->icon_name);
    g_slice_free (ExoIconChooserModelItem, item);
}



/**
 * _exo_icon_chooser_model_get_for_widget:
 * @widget : a #GtkWidget.
 *
 * Returns the #ExoIconChooserModel that should be used for the @widget. The
 * caller is responsible to free the returned object using g_object_unref()
 * when no longer needed.
 *
 * Returns: an #ExoIconChooserModel for the @widget.
 *
 * Since: 0.3.1.9
 **/
ExoIconChooserModel*
_exo_icon_chooser_model_get_for_widget (GtkWidget *widget)
{
    GtkIconTheme *icon_theme;

    _exo_return_val_if_fail (GTK_IS_WIDGET (widget), NULL);

    /* determine the icon theme for the widget... */
    icon_theme = gtk_icon_theme_get_for_screen (gtk_widget_get_screen (widget));

    /* ...and return the icon chooser model for the icon theme */
    return _exo_icon_chooser_model_get_for_icon_theme (icon_theme);
}



/**
 * _exo_icon_chooser_model_get_for_icon_theme:
 * @icon_theme : a #GtkIconTheme.
 *
 * Returns an #ExoIconChooserModel for the specified @icon_theme. The
 * caller is responsible to free the returned object using g_object_unref()
 * when no longer needed.
 *
 * Returns: an #ExoIconChooserModel for the @icon_theme.
 *
 * Since: 0.3.1.9
 **/
ExoIconChooserModel*
_exo_icon_chooser_model_get_for_icon_theme (GtkIconTheme *icon_theme)
{
    ExoIconChooserModel *model;

    _exo_return_val_if_fail (GTK_IS_ICON_THEME (icon_theme), NULL);

    /* check if the icon theme is already associated with a model */
    model = g_object_get_data (G_OBJECT (icon_theme), I_("exo-icon-chooser-default-model"));
    if (G_LIKELY (model == NULL))
    {
        /* allocate a new model for the icon theme */
        model = g_object_new (EXO_TYPE_ICON_CHOOSER_MODEL, NULL);
        g_object_set_data (G_OBJECT (icon_theme), "exo-icon-chooser-default-model", model);

        /* associated the model with the icon theme */
        model->icon_theme = g_object_ref (G_OBJECT (icon_theme));
        exo_icon_chooser_model_icon_theme_changed (icon_theme, model);
        g_signal_connect (G_OBJECT (icon_theme), "changed", G_CALLBACK (exo_icon_chooser_model_icon_theme_changed), model);
    }
    else
    {
        /* take a reference for the caller */
        g_object_ref (G_OBJECT (model));
    }

    return model;
}



/**
 * _exo_icon_chooser_model_get_iter_for_icon_name:
 * @model     : an #ExoIconChooserModel.
 * @iter      : return location for the resulting #GtkTreeIter.
 * @icon_name : the name of the icon for which to lookup the iterator in the @model.
 *
 * Looks up the #GtkTreeIter for the @icon_name in the @model and returns %TRUE if the
 * @icon_name was found, %FALSE otherwise.
 *
 * Returns: %TRUE if the iterator for @icon_name was found, %FALSE otherwise.
 *
 * Since: 0.3.1.9
 **/
gboolean
_exo_icon_chooser_model_get_iter_for_icon_name (ExoIconChooserModel *model,
                                                GtkTreeIter         *iter,
                                                const gchar         *icon_name)
{
    ExoIconChooserModelItem *item;
    GList                   *lp;
    guint                    i;
    gboolean                 found;
    const gchar             *other_name;

    _exo_return_val_if_fail (EXO_IS_ICON_CHOOSER_MODEL (model), FALSE);
    _exo_return_val_if_fail (icon_name != NULL, FALSE);
    _exo_return_val_if_fail (iter != NULL, FALSE);

    /* check all items in the model */
    for (lp = model->items; lp != NULL; lp = lp->next)
    {
        found = FALSE;

        /* compare this item's icon name */
        item = (ExoIconChooserModelItem *) lp->data;
        if (strcmp (icon_name, item->icon_name) == 0)
            found = TRUE;

        /* look in the alternative names */
        if (!found && item->other_names != NULL)
        {
            for (i = 0; !found && i < item->other_names->len; ++i)
            {
                other_name = g_ptr_array_index (item->other_names, i);
                if (strcmp (icon_name, other_name) == 0)
                    found = TRUE;
            }
        }

        if (found)
        {
            /* generate an iterator for this item */
            iter->stamp = model->stamp;
            iter->user_data = lp;
            return TRUE;
        }
    }

    return FALSE;
}


#define __EXO_ICON_CHOOSER_MODEL_C__
