/*
 * glade-signal-model.c
 * Copyright (C) Johannes Schmid 2010 <jhs@gnome.org>
 * 
 * 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 program; 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

#include "glade-signal-model.h"
#include "glade-project.h"

#include <glib/gi18n-lib.h>
#include <string.h>

#define DETAIL_DEFAULT  _("<Type here>")
#define HANDLER_DEFAULT  _("<Type here>")
#define USERDATA_DEFAULT _("<Click here>")

struct _GladeSignalModelPrivate
{
  GladeWidget *widget;
  GList       *widgets; /* names of the widgets that this widgets derives from and that have signals */
  gint         stamp;

  GHashTable  *dummy_signals;
  GHashTable  *signals; /* signals of the widget */
};

enum
{
  PROP_0,
  PROP_WIDGET,
  PROP_SIGNALS
};

static void gtk_tree_model_iface_init (GtkTreeModelIface *iface);
static void gtk_tree_drag_source_iface_init (GtkTreeDragSourceIface *iface);
static void on_glade_signal_model_added (GladeWidget *widget, const GladeSignal *signal,
					 GladeSignalModel *model);
static void on_glade_signal_model_removed (GladeWidget *widget, const GladeSignal *signal,
					   GladeSignalModel *model);
static void on_glade_signal_model_changed (GladeWidget *widget, const GladeSignal *signal,
					   GladeSignalModel *model);	
static void on_glade_widget_support_changed (GladeWidget *widget, GladeSignalModel *model);

G_DEFINE_TYPE_WITH_CODE (GladeSignalModel, glade_signal_model, G_TYPE_OBJECT,
                         G_ADD_PRIVATE (GladeSignalModel)
                         G_IMPLEMENT_INTERFACE (GTK_TYPE_TREE_MODEL,
                                                gtk_tree_model_iface_init);
                         G_IMPLEMENT_INTERFACE (GTK_TYPE_TREE_DRAG_SOURCE,
                                                gtk_tree_drag_source_iface_init))

static void
glade_signal_model_init (GladeSignalModel *object)
{
  object->priv = glade_signal_model_get_instance_private (object);

  object->priv->dummy_signals = 
    g_hash_table_new_full (g_str_hash, g_str_equal, NULL, (GDestroyNotify) g_object_unref);
}

static void
glade_signal_model_create_widget_list (GladeSignalModel *sig_model)
{
  const GList *list;
  GladeWidget *widget = sig_model->priv->widget;
  GladeWidgetAdaptor *adaptor = glade_widget_get_adaptor (widget);

  for (list = glade_widget_adaptor_get_signals (adaptor);
       list != NULL; list = g_list_next (list))
    {
      GladeSignalClass *signal = (GladeSignalClass *) list->data;

      if (!g_list_find_custom (sig_model->priv->widgets, 
			       (gpointer) glade_signal_class_get_type (signal), (GCompareFunc) strcmp))
	{
	  sig_model->priv->widgets = 
	    g_list_prepend (sig_model->priv->widgets, (gpointer) glade_signal_class_get_type (signal));
	}
    }
  sig_model->priv->widgets = g_list_reverse (sig_model->priv->widgets);
}

static void
glade_signal_model_finalize (GObject *object)
{
  GladeSignalModel *sig_model = GLADE_SIGNAL_MODEL (object);

  g_list_free (sig_model->priv->widgets);
  g_hash_table_destroy (sig_model->priv->dummy_signals);
  G_OBJECT_CLASS (glade_signal_model_parent_class)->finalize (object);
}

static void
glade_signal_model_set_property (GObject *object,
                                 guint prop_id,
                                 const GValue *value,
                                 GParamSpec *pspec)
{
  GladeSignalModel *sig_model;

  g_return_if_fail (GLADE_IS_SIGNAL_MODEL (object));

  sig_model = GLADE_SIGNAL_MODEL (object);

  switch (prop_id)
    {
      case PROP_WIDGET:
        sig_model->priv->widget = g_value_get_object (value);
        glade_signal_model_create_widget_list (sig_model);
        g_signal_connect (sig_model->priv->widget, "add-signal-handler",
                          G_CALLBACK (on_glade_signal_model_added), sig_model);
        g_signal_connect (sig_model->priv->widget, "remove-signal-handler",
                          G_CALLBACK (on_glade_signal_model_removed), sig_model);
        g_signal_connect (sig_model->priv->widget, "change-signal-handler",
                          G_CALLBACK (on_glade_signal_model_changed), sig_model);
        g_signal_connect (sig_model->priv->widget, "support-changed",
                          G_CALLBACK (on_glade_widget_support_changed), sig_model);
      break;
      case PROP_SIGNALS:
        sig_model->priv->signals = g_value_get_pointer (value);
      break;
      default:
        G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
    }
}

static void
glade_signal_model_get_property (GObject *object,
                                 guint prop_id,
                                 GValue *value,
                                 GParamSpec *pspec)
{
  GladeSignalModel *sig_model;

  g_return_if_fail (GLADE_IS_SIGNAL_MODEL (object));

  sig_model = GLADE_SIGNAL_MODEL (object);

  switch (prop_id)
    {
      case PROP_WIDGET:
        g_value_set_object (value, sig_model->priv->widget);
      break;
      case PROP_SIGNALS:
        g_value_set_pointer (value, sig_model->priv->signals);
      break;
      default:
        G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
    }
}

static void
glade_signal_model_class_init (GladeSignalModelClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);

  object_class->finalize = glade_signal_model_finalize;
  object_class->set_property = glade_signal_model_set_property;
  object_class->get_property = glade_signal_model_get_property;

  g_object_class_install_property (object_class,
				   PROP_WIDGET,
				   g_param_spec_object ("widget",
							"A GladeWidget",
							"The GladeWidget used to query the signals",
							GLADE_TYPE_WIDGET,
							G_PARAM_CONSTRUCT_ONLY | G_PARAM_WRITABLE));
  g_object_class_install_property (object_class,
				   PROP_SIGNALS,
				   g_param_spec_pointer ("signals",
							 "A GHashTable containing the widget signals",
							 "Use to query signals",
							 G_PARAM_CONSTRUCT_ONLY | G_PARAM_WRITABLE));
}

/*
 * glade_signal_model_new:
 * @widget: The GladeWidget the signals belong to
 * @signals: The signals of the #GladeWidget
 *
 * Creates a new GladeSignalModel object to show and edit the
 * signals of a widgets in a GtkTreeView
 */

GtkTreeModel *
glade_signal_model_new (GladeWidget *widget, GHashTable *signals)
{
  GObject *object = g_object_new (GLADE_TYPE_SIGNAL_MODEL,
				  "widget", widget, 
				  "signals", signals, NULL);
  return GTK_TREE_MODEL (object);
}

static GtkTreeModelFlags
glade_signal_model_get_flags (GtkTreeModel *model)
{
  return 0;
}

static gint
glade_signal_model_get_n_columns (GtkTreeModel *model)
{
  return GLADE_SIGNAL_N_COLUMNS;
}

static GType
glade_signal_model_get_column_type (GtkTreeModel *model, gint column)
{
  switch (column)
    {
      case GLADE_SIGNAL_COLUMN_NAME:
        return G_TYPE_STRING;
      case GLADE_SIGNAL_COLUMN_SHOW_NAME:
        return G_TYPE_BOOLEAN;
      case GLADE_SIGNAL_COLUMN_HANDLER:
        return G_TYPE_STRING;
      case GLADE_SIGNAL_COLUMN_OBJECT:
        return G_TYPE_STRING;
      case GLADE_SIGNAL_COLUMN_SWAP:
        return G_TYPE_BOOLEAN;
      case GLADE_SIGNAL_COLUMN_AFTER:
        return G_TYPE_BOOLEAN;
      case GLADE_SIGNAL_COLUMN_TOOLTIP:
        return G_TYPE_STRING;
      case GLADE_SIGNAL_COLUMN_SIGNAL:
        return G_TYPE_OBJECT;
      case GLADE_SIGNAL_COLUMN_DETAIL:
        return G_TYPE_STRING;
      default:
        g_assert_not_reached();
        return G_TYPE_NONE;
    }
}

enum
{
  ITER_WIDGET = 0,
  ITER_SIGNAL = 1,
};

static inline gboolean
glade_signal_model_is_dummy_handler (GladeSignalModel *model,
                                     GladeSignal *signal)
{
  return glade_signal_get_handler (signal) == NULL;
}

static GladeSignal *
glade_signal_model_get_dummy_handler (GladeSignalModel *model, 
                                      const GladeSignalClass *sig_class)
{
  GladeSignal *signal;

  signal = g_hash_table_lookup (model->priv->dummy_signals, 
				glade_signal_class_get_name (sig_class));

  if (!signal)
    {
      signal = glade_signal_new (sig_class,
				 NULL,
				 NULL,
				 FALSE,
				 FALSE);
      g_hash_table_insert (model->priv->dummy_signals, 
			   (gpointer) glade_signal_class_get_name (sig_class), 
			   signal);

      glade_project_verify_signal (model->priv->widget, signal);
    }
  return signal;
}

static void
glade_signal_model_create_widget_iter (GladeSignalModel *sig_model,
                                       const gchar *widget,
                                       GtkTreeIter *iter)
{
  iter->stamp = sig_model->priv->stamp;
  iter->user_data = (gpointer) widget;
  iter->user_data2 = NULL;
  iter->user_data3 = NULL;
}

static void
glade_signal_model_create_signal_iter (GladeSignalModel *sig_model,
                                       const gchar *widget,
                                       const GladeSignal *signal,
                                       GtkTreeIter *iter)
{
	glade_signal_model_create_widget_iter (sig_model, widget, iter);
	iter->user_data2 = GLADE_SIGNAL (signal);
}

static GList *
glade_signal_model_create_signal_list (GladeSignalModel *sig_model,
				       const gchar *widget_type)
{
  GList *widget_signals = NULL;
  const GList *signals;
  GladeWidget *widget = sig_model->priv->widget;
  GladeWidgetAdaptor *adaptor = glade_widget_get_adaptor (widget);

  for (signals = glade_widget_adaptor_get_signals (adaptor);
       signals != NULL;
       signals = g_list_next (signals))
    {
      GladeSignalClass *sig_class = signals->data;
      if (g_str_equal (glade_signal_class_get_type (sig_class), widget_type))
	{
	  widget_signals = g_list_append (widget_signals, sig_class);
	}
    }
  return widget_signals;
}

static void
on_glade_signal_model_added (GladeWidget *widget,
                             const GladeSignal *signal,
                             GladeSignalModel* model)
{
  GtkTreeIter iter;	
  GtkTreePath *path;
  const GladeSignalClass *sig_class = glade_signal_get_class (signal);

  glade_signal_model_create_signal_iter (model,
					 glade_signal_class_get_type (sig_class),
					 signal, 
					 &iter);
  path = gtk_tree_model_get_path (GTK_TREE_MODEL (model), &iter);

  gtk_tree_model_row_inserted (GTK_TREE_MODEL (model), path, &iter);
  gtk_tree_path_free (path);
  model->priv->stamp++;
}

static void
on_glade_signal_model_removed (GladeWidget *widget,
                               const GladeSignal *signal,
                               GladeSignalModel *model)
{
  GtkTreeIter iter;
  GtkTreePath *path;
  const GladeSignalClass *sig_class = glade_signal_get_class (signal);
  
  glade_signal_model_create_signal_iter (model,
					 glade_signal_class_get_type (sig_class),
					 signal, 
					 &iter);
  path = gtk_tree_model_get_path (GTK_TREE_MODEL (model), &iter);
  gtk_tree_model_row_deleted (GTK_TREE_MODEL (model), path);
  gtk_tree_path_free (path);
  model->priv->stamp++;
}

static void
on_glade_signal_model_changed (GladeWidget *widget,
                               const GladeSignal *signal,
                               GladeSignalModel *model)
{
  GtkTreeIter iter;
  GtkTreePath *path;
  const GladeSignalClass *sig_class = glade_signal_get_class (signal);
  
  glade_signal_model_create_signal_iter (model,
					 glade_signal_class_get_type (sig_class),
					 signal, 
					 &iter);
  path = gtk_tree_model_get_path (GTK_TREE_MODEL (model), &iter);
  gtk_tree_model_row_changed (GTK_TREE_MODEL (model), path, &iter);
  gtk_tree_path_free (path);
  model->priv->stamp++;
}

static void
verify_dummies (const gchar *signal_name,
                GladeSignal *signal,
                GladeSignalModel *model)
{
  glade_project_verify_signal (model->priv->widget, signal);

  on_glade_signal_model_changed (model->priv->widget, signal, model);
}

static void
emit_changed (const gchar *signal_name,
	      GPtrArray *signals,
	      GladeSignalModel *model)
{
  gint i;
  GladeSignal *signal;

  for (i = 0; i < signals->len; i++)
    {
      signal = (GladeSignal *)signals->pdata[i];
      on_glade_signal_model_changed (model->priv->widget, signal, model);
    }
}

static void
on_glade_widget_support_changed (GladeWidget *widget, GladeSignalModel *model)
{
  /* Update support warning on dummy signals */
  g_hash_table_foreach (model->priv->dummy_signals, (GHFunc)verify_dummies, model);

  /* row changed on every row */
  g_hash_table_foreach (model->priv->signals, (GHFunc)emit_changed, model);
}

static gboolean
glade_signal_model_get_iter (GtkTreeModel *model,
                             GtkTreeIter *iter,
                             GtkTreePath *path)
{
  gint *indices;
  gint depth;
  GladeSignalModel *sig_model;

  g_return_val_if_fail (path != NULL, FALSE);
  g_return_val_if_fail (iter != NULL, FALSE);
  g_return_val_if_fail (GLADE_IS_SIGNAL_MODEL(model), FALSE);

  indices = gtk_tree_path_get_indices(path);
  depth = gtk_tree_path_get_depth (path);
  sig_model = GLADE_SIGNAL_MODEL (model);

  switch (depth)
    {
      case 1:
        /* Widget */
        {
          glade_signal_model_create_widget_iter (sig_model,
                                                 g_list_nth_data (sig_model->priv->widgets,
                                                                  indices[ITER_WIDGET]),
                                                 iter);
          return TRUE;
        }
      case 2:
        /* Signal */
        {
          gboolean retval;
          GtkTreePath *path =
            gtk_tree_path_new_from_indices (indices[ITER_WIDGET], -1);
          GtkTreeIter widget_iter;

          gtk_tree_model_get_iter (model, &widget_iter, path);
          retval = gtk_tree_model_iter_nth_child (model,
                                                  iter,
                                                  &widget_iter,
                                                  indices[ITER_SIGNAL]);
          gtk_tree_path_free (path);
          return retval;
        }
    }
  return FALSE;
}

static GtkTreePath*
glade_signal_model_get_path (GtkTreeModel *model, GtkTreeIter *iter)
{
  const gchar *widget;
  GladeSignal *handler;
  GladeSignalModel *sig_model;

  g_return_val_if_fail (iter != NULL, NULL);
  g_return_val_if_fail (GLADE_IS_SIGNAL_MODEL(model), NULL);

  widget = iter->user_data;
  handler = iter->user_data2;
  sig_model = GLADE_SIGNAL_MODEL (model);

  if (handler)
    {
      /* Signal */
      const GladeSignalClass *sig_class = glade_signal_get_class (handler);
      gint index0, index1 = 0;
      GList *signal;
      GList *signals = glade_signal_model_create_signal_list (sig_model,
							      widget);

      index0 = g_list_index (sig_model->priv->widgets,
			     widget);

      for (signal = signals; signal != NULL; signal = g_list_next (signal))
	{		
	  GPtrArray *handlers = g_hash_table_lookup (sig_model->priv->signals,
						     glade_signal_class_get_name (signal->data));

	  if (signal->data != sig_class)
	    {
	      if (handlers) 
                index1 += handlers->len;
	      index1++; /* dummy_handler */
	    }
	  else
	    {
	      if (handlers)
		{
		  guint handler_index;
		  if (g_ptr_array_find (handlers, handler, &handler_index))
		    index1 += handler_index;
		  else
		    index1 += handlers->len;
		}
	      break;
	    }
	}
      return gtk_tree_path_new_from_indices (index0, index1, -1);
    }
  else if (widget)
    {
      /* Widget */
      return gtk_tree_path_new_from_indices (g_list_index (sig_model->priv->widgets,
							   widget), -1);
    }
  g_assert_not_reached();
}

static void
glade_signal_model_get_value (GtkTreeModel *model,
                              GtkTreeIter *iter,
                              gint column,
                              GValue *value)
{	
  const gchar *widget;
  GladeSignal *signal;
  GladeSignalModel *sig_model;

  g_return_if_fail (iter != NULL);
  g_return_if_fail (GLADE_IS_SIGNAL_MODEL(model));

  widget = iter->user_data;
  signal = iter->user_data2;
  sig_model = GLADE_SIGNAL_MODEL (model);

  value = g_value_init (value, 
			glade_signal_model_get_column_type (model, column));

  switch (column)
    {
      case GLADE_SIGNAL_COLUMN_NAME:
        if (signal)
        {
          g_value_set_static_string (value, glade_signal_get_name (signal));
          break;
        }
        else
          g_value_set_static_string (value, widget);
      break;
      case GLADE_SIGNAL_COLUMN_SHOW_NAME:
        if (signal)
        {
          GPtrArray *handlers = g_hash_table_lookup (sig_model->priv->signals,
                                                     glade_signal_get_name (signal));
          guint index;
          if (!handlers || !handlers->len || (g_ptr_array_find (handlers, signal, &index) && index == 0))
            g_value_set_boolean (value, TRUE);
          else
            g_value_set_boolean (value, FALSE);
          break;
        }
        else if (widget)
          g_value_set_boolean (value, TRUE);
      break;	
      case GLADE_SIGNAL_COLUMN_HANDLER:
        if (signal)
          {
            const gchar *handler = glade_signal_get_handler (signal);
            g_value_set_static_string (value, handler ? handler : HANDLER_DEFAULT);
          }
        else 
          g_value_set_static_string (value, "");
      break;
      case GLADE_SIGNAL_COLUMN_OBJECT:
        if (signal)
        {
          const gchar *userdata = glade_signal_get_userdata (signal);
          if (userdata && strlen (userdata))
            g_value_set_static_string (value, userdata);
          else
            g_value_set_static_string (value, USERDATA_DEFAULT);
          break;
        }
        else 
          g_value_set_static_string (value, "");
      break;
      case GLADE_SIGNAL_COLUMN_SWAP:
        if (signal)
          g_value_set_boolean (value, glade_signal_get_swapped (signal));
        else 
          g_value_set_boolean (value, FALSE);
      break;
      case GLADE_SIGNAL_COLUMN_AFTER:
        if (signal)
          g_value_set_boolean (value, glade_signal_get_after (signal));
        else 
          g_value_set_boolean (value, FALSE);
        break;
      case GLADE_SIGNAL_COLUMN_TOOLTIP:
        if (signal)
          g_value_set_string (value, glade_signal_get_support_warning (signal));
        else
          g_value_set_static_string (value, NULL);
      break;
      case GLADE_SIGNAL_COLUMN_SIGNAL:
        g_value_set_object (value, signal);
      break;
      case GLADE_SIGNAL_COLUMN_DETAIL:
        if (signal)
          {
            const gchar *detail = glade_signal_get_detail (signal);
            g_value_set_static_string (value, detail ? detail : DETAIL_DEFAULT);
          }
        else 
          g_value_set_static_string (value, "");
      break;
      default:
        g_assert_not_reached();
    }
}

static gboolean
glade_signal_model_iter_next_signal (GladeSignalModel *sig_model,
                                     const gchar *widget,
                                     GtkTreeIter *iter,
                                     GList *signal)
{
  if (signal->next)
    {
      signal = signal->next;
      GladeSignal *next_handler;
      GPtrArray *next_handlers = 
	g_hash_table_lookup (sig_model->priv->signals,
			     glade_signal_class_get_name (signal->data));
      if (next_handlers && next_handlers->len)
	{
	  next_handler = g_ptr_array_index (next_handlers, 0);
	}
      else
	{
	  next_handler = 
	    glade_signal_model_get_dummy_handler (sig_model,
						  signal->data);
	}
      glade_signal_model_create_signal_iter (sig_model, widget,
					     next_handler,
					     iter);
      g_list_free (signal);
      return TRUE;
    }
  else
    {
      g_list_free (signal);
      return FALSE;
    }
}


static gboolean
glade_signal_model_iter_next (GtkTreeModel *model, GtkTreeIter *iter)
{
  const gchar *widget;
  GladeSignal *handler;
  GtkTreeIter parent;
  GladeSignalModel *sig_model;

  g_return_val_if_fail (iter != NULL, FALSE);
  g_return_val_if_fail (GLADE_IS_SIGNAL_MODEL(model), FALSE);

  widget = iter->user_data;
  handler = iter->user_data2;

  sig_model = GLADE_SIGNAL_MODEL (model);  

  gtk_tree_model_iter_parent (model, &parent, iter);		

  if (handler)
    {
      const GladeSignalClass *sig_class = glade_signal_get_class (handler);
      GList *signals = 
	glade_signal_model_create_signal_list (sig_model,
					       widget);
      GList* signal = g_list_find (signals, sig_class);
      GPtrArray* handlers = g_hash_table_lookup (sig_model->priv->signals,
						 glade_signal_class_get_name (sig_class));
      if (glade_signal_model_is_dummy_handler (sig_model, handler))
	{
	  return glade_signal_model_iter_next_signal (sig_model, widget, iter, signal);
	}
      else if (handlers)
	{
	  guint new_index = 0;
	  if (g_ptr_array_find (handlers, handler, &new_index))
	    new_index++;

	  if (new_index < handlers->len)
	    {
	      glade_signal_model_create_signal_iter (sig_model, widget,
						     g_ptr_array_index (handlers, new_index),
						     iter);
	      g_list_free (signals);
	      return TRUE;
	    }
	  else if (new_index == handlers->len)
	    {
	      glade_signal_model_create_signal_iter (sig_model, widget,
						     glade_signal_model_get_dummy_handler (sig_model,
											   sig_class),
						     iter);
	      g_list_free (signals);
	      return TRUE;
	    }
	  else
	    {
	      return glade_signal_model_iter_next_signal (sig_model, widget, iter, signal);
	    }
	}
      else
	{
	  g_list_free (signals);
	  return FALSE;
	}
    }
  else if (widget)
    {
      gint new_index = g_list_index (sig_model->priv->widgets, widget) + 1;
      
      return gtk_tree_model_iter_nth_child (model, iter, NULL, new_index);
    }
  iter->user_data = NULL;
  iter->user_data2 = NULL;
  iter->user_data3 = NULL;
  iter->stamp = 0;
  return FALSE;
}

static gint
glade_signal_model_iter_n_children (GtkTreeModel *model, GtkTreeIter *iter)
{
  GladeSignal *handler;
  GladeSignalModel *sig_model;
  const gchar *widget;

  g_return_val_if_fail (GLADE_IS_SIGNAL_MODEL(model), 0);

  /* FIXME: return the number of toplevels, if it makes sense in this context */
  if (iter == NULL) return 0;
  
  handler = iter->user_data2;
  sig_model = GLADE_SIGNAL_MODEL (model);
  widget = iter->user_data;

  if (handler)
    {
      return 0;
    }
  else if (widget)
    {
      GList *signals = glade_signal_model_create_signal_list (sig_model,
							      widget);
      GList *signal;
      gint retval = 0;

      for (signal = signals; signal != NULL; signal = g_list_next (signal))
	{
	  GPtrArray* handlers = g_hash_table_lookup (sig_model->priv->signals,
						     glade_signal_class_get_name (signal->data));
	  if (handlers)
	    retval += handlers->len;
	  retval++; 
	}
      g_list_free (signals);
      
      return retval;
    }
  g_assert_not_reached ();	
}

static gboolean
glade_signal_model_iter_has_child (GtkTreeModel *model, GtkTreeIter *iter)
{
  g_return_val_if_fail (iter != NULL, FALSE);
  g_return_val_if_fail (GLADE_IS_SIGNAL_MODEL(model), FALSE);

  return (glade_signal_model_iter_n_children (model, iter) != 0);
}

static gboolean
glade_signal_model_iter_nth_child (GtkTreeModel *model,
                                   GtkTreeIter *iter,
                                   GtkTreeIter *parent,
                                   gint n)
{
  GladeSignal *handler;
  GladeSignalModel *sig_model;
  const gchar *widget;

  g_return_val_if_fail (iter != NULL, 0);
  g_return_val_if_fail (GLADE_IS_SIGNAL_MODEL(model), 0);

  handler = parent ? parent->user_data2 : NULL;
  sig_model = GLADE_SIGNAL_MODEL (model);
  widget = parent ? parent->user_data : NULL;

  if (handler)
    {
      return FALSE;
    }
  else if (widget)
    {
      GList *signals = glade_signal_model_create_signal_list (sig_model,
							      widget);
      GList *signal;
      for (signal = signals; signal != NULL; signal = g_list_next (signal))
	{
	  GPtrArray *handlers = g_hash_table_lookup (sig_model->priv->signals,
						     glade_signal_class_get_name (signal->data));
	  if (handlers)
	    {
	      if (n >= handlers->len)
		n -= handlers->len;
	      else
		{
		  glade_signal_model_create_signal_iter (sig_model,
							 widget,
							 g_ptr_array_index (handlers, n),
							 iter);
		  g_list_free (signals);
		  return TRUE;
		}
	    }
	  if (n == 0)
	    {
	      GladeSignal *handler =
		glade_signal_model_get_dummy_handler (sig_model,
						      signal->data);
	      glade_signal_model_create_signal_iter (sig_model,
						     widget,
						     handler,
						     iter);
	      g_list_free (signals);
	      return TRUE;
	    }
	  n--;
	}
      return FALSE;
    }
  else
    {
      if (g_list_length (sig_model->priv->widgets) > n)
	{
	  glade_signal_model_create_widget_iter (sig_model,
						 g_list_nth_data (sig_model->priv->widgets, n),
						 iter);
	  return TRUE;
	}
    }
  return FALSE;
}

static gboolean
glade_signal_model_iter_children (GtkTreeModel *model,
                                  GtkTreeIter *iter,
                                  GtkTreeIter *parent)
{
  return glade_signal_model_iter_nth_child (model, iter, parent, 0);
}

static gboolean
glade_signal_model_iter_parent (GtkTreeModel *model,
                                GtkTreeIter *iter,
                                GtkTreeIter *child)
{
  GladeSignalModel *sig_model;
  GladeSignal *handler;
  const gchar *widget;

  g_return_val_if_fail (iter != NULL, FALSE);
  g_return_val_if_fail (child != NULL, FALSE);
  g_return_val_if_fail (GLADE_IS_SIGNAL_MODEL(model), FALSE);  

  sig_model = GLADE_SIGNAL_MODEL (model);
  handler = child->user_data2;
  widget = child->user_data;

  if (handler)
    {
      glade_signal_model_create_widget_iter (sig_model, widget, iter);
      return TRUE;
    }
  return FALSE;
}

static void
gtk_tree_model_iface_init (GtkTreeModelIface *iface)
{
  iface->get_flags = glade_signal_model_get_flags;
  iface->get_column_type = glade_signal_model_get_column_type;
  iface->get_n_columns = glade_signal_model_get_n_columns;
  iface->get_iter = glade_signal_model_get_iter;
  iface->get_path = glade_signal_model_get_path;
  iface->get_value = glade_signal_model_get_value;	
  iface->iter_next = glade_signal_model_iter_next;
  iface->iter_children = glade_signal_model_iter_children;
  iface->iter_has_child = glade_signal_model_iter_has_child;
  iface->iter_n_children = glade_signal_model_iter_n_children;
  iface->iter_nth_child = glade_signal_model_iter_nth_child;
  iface->iter_parent = glade_signal_model_iter_parent;
}

static gboolean
glade_signal_model_row_draggable (GtkTreeDragSource *model, GtkTreePath *path)
{
  GtkTreeIter iter;
  GladeSignal *signal;
  gboolean retval;
  gtk_tree_model_get_iter (GTK_TREE_MODEL (model), &iter, path);

  gtk_tree_model_get (GTK_TREE_MODEL (model), &iter,
		      GLADE_SIGNAL_COLUMN_SIGNAL, &signal,
		      -1);

  retval = signal && !glade_signal_model_is_dummy_handler (GLADE_SIGNAL_MODEL (model),
							   signal);

  g_object_unref (signal);
  return retval;
}

static gboolean
glade_signal_model_drag_data_get (GtkTreeDragSource *model, 
                                  GtkTreePath *path,
                                  GtkSelectionData *data)
{
  GtkTreeIter iter;

  if (gtk_tree_model_get_iter (GTK_TREE_MODEL (model), &iter, path))
    {
      GladeSignal *signal;
      const gchar *widget = iter.user_data;
      gchar *dnd_text;
      const gchar *user_data;

      gtk_tree_model_get (GTK_TREE_MODEL (model), &iter,
			  GLADE_SIGNAL_COLUMN_SIGNAL, &signal, -1);

      user_data = glade_signal_get_userdata (signal);
      
      dnd_text = g_strdup_printf ("%s:%s:%s:%s:%d:%d", widget, 
                                  glade_signal_get_name (signal),
                                  glade_signal_get_handler (signal),
                                  user_data && strlen (user_data) ? user_data : "(none)",
                                  glade_signal_get_swapped (signal),
                                  glade_signal_get_after (signal));
      gtk_selection_data_set (data,
			      gdk_atom_intern_static_string ("application/x-glade-signal"),
			      8,
			      (guchar*) dnd_text,
			      strlen (dnd_text));

      g_free (dnd_text);
      return TRUE;
    }
  else
    {
      return FALSE;
    }
}

static gboolean
glade_signal_model_drag_data_delete (GtkTreeDragSource *model, 
                                     GtkTreePath *path)
{
  /* We don't move rows... */
  return FALSE;
}

static void
gtk_tree_drag_source_iface_init (GtkTreeDragSourceIface *iface)
{
  iface->row_draggable = glade_signal_model_row_draggable;
  iface->drag_data_get = glade_signal_model_drag_data_get;
  iface->drag_data_delete = glade_signal_model_drag_data_delete;
}
