/*
 * Copyright (C) 2007 OpenedHand Ltd
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program 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 General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <config.h>

#include <glib/gi18n.h>
#include <gtk/gtk.h>

#include "koto-undo-action.h"

/* this is defined in glib 2.14 */
#ifndef G_PARAM_STATIC_STRINGS
#define G_PARAM_STATIC_STRINGS (G_PARAM_STATIC_NAME | G_PARAM_STATIC_NICK | G_PARAM_STATIC_BLURB)
#endif

G_DEFINE_TYPE (KotoUndoAction, koto_undo_action, GTK_TYPE_ACTION);

#define GET_PRIVATE(obj)      \
        (G_TYPE_INSTANCE_GET_PRIVATE ((obj),    \
         KOTO_TYPE_UNDO_ACTION,                \
         KotoUndoActionPrivate))

typedef void (*ChangedHandler) (KotoUndoManager *manager, gpointer user_data);

typedef struct {
  gboolean undo; /* TRUE for undo, FALSE for redo */
  ChangedHandler handler; /* Handler to invoke on manager state change */
  KotoUndoManager *manager;
  guint changed_id;
} KotoUndoActionPrivate;

enum {
  PROP_0,
  PROP_UNDO,
  PROP_MANAGER,
};

static void
on_manager_changed_undo (KotoUndoManager *manager, gpointer user_data)
{
  GtkAction *action = GTK_ACTION (user_data);
  char *label;

  if (koto_undo_manager_can_undo (manager)) {
    label = g_strdup_printf (_("Undo %s"),
                             koto_undo_manager_get_undo_name (manager));
    
    g_object_set (action,
                  "sensitive", TRUE,
                  "label", label,
                  NULL);
    
    g_free (label);
  } else {
    g_object_set (action,
                  "sensitive", FALSE,
                  "label", _("Undo"),
                  NULL);
  }
}

static void
on_manager_changed_redo (KotoUndoManager *manager, gpointer user_data)
{
  GtkAction *action = GTK_ACTION (user_data);
  char *label;

  if (koto_undo_manager_can_redo (manager)) {
    label = g_strdup_printf (_("Redo %s"),
                             koto_undo_manager_get_redo_name (manager));
    
    g_object_set (action,
                  "sensitive", TRUE,
                  "label", label,
                  NULL);
    
    g_free (label);
  } else {
    g_object_set (action,
                  "sensitive", FALSE,
                  "label", _("Redo"),
                  NULL);
  }
}

static void
koto_undo_action_activate (GtkAction *action)
{
  KotoUndoActionPrivate *priv = GET_PRIVATE (action);

  if (priv->undo) {
    koto_undo_manager_undo (priv->manager);
  } else {
    koto_undo_manager_redo (priv->manager);
  }
}

static void
koto_undo_action_set_property (GObject *gobject, guint prop_id,
                               const GValue *value, GParamSpec *pspec)
{
  KotoUndoActionPrivate *priv = GET_PRIVATE (gobject);

  switch (prop_id) {
  case PROP_UNDO:
    priv->undo = g_value_get_boolean (value);
    priv->handler = priv->undo ?
      on_manager_changed_undo : on_manager_changed_redo;
    break;
  case PROP_MANAGER:
    if (priv->manager) {
      g_signal_handler_disconnect (priv->manager, priv->changed_id);
      g_object_unref (priv->manager);
    }
    priv->manager = g_value_dup_object (value);
    priv->changed_id = g_signal_connect (priv->manager, "changed",
                                         G_CALLBACK (priv->handler), gobject);
    /* Update the state */
    priv->handler (priv->manager, gobject);
    break;
  default:
    G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
    return;
  }
}

static void
koto_undo_action_get_property (GObject *gobject, guint prop_id,
                               GValue *value, GParamSpec *pspec)
{
  KotoUndoActionPrivate *priv = GET_PRIVATE (gobject);

  switch (prop_id) {
  case PROP_UNDO:
    g_value_set_boolean (value, priv->undo);
    break;
  case PROP_MANAGER:
    g_value_set_object (value, priv->manager);
    break;
  default:
    G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
    return;
  }
}

static void
koto_undo_action_dispose (GObject *gobject)
{
  KotoUndoActionPrivate *priv = GET_PRIVATE (gobject);

  if (priv->manager) {
    g_signal_handler_disconnect (priv->manager, priv->changed_id);
    g_object_unref (priv->manager);
    priv->manager = NULL;
  }

  G_OBJECT_CLASS (koto_undo_action_parent_class)->dispose (gobject);
}

static void
koto_undo_action_class_init (KotoUndoActionClass *klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
  GtkActionClass *action_class = GTK_ACTION_CLASS (klass);

  g_type_class_add_private (klass, sizeof (KotoUndoActionPrivate));

  gobject_class->dispose = koto_undo_action_dispose;
  gobject_class->set_property = koto_undo_action_set_property;
  gobject_class->get_property = koto_undo_action_get_property;

  action_class->activate = koto_undo_action_activate;
  
  g_object_class_install_property (gobject_class, PROP_UNDO,
                                   g_param_spec_boolean ("undo", "undo", "TRUE for undo, FALSE for redo",
                                                         TRUE,
                                                         G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_MANAGER,
                                   g_param_spec_object ("manager", "manager", "Undo manager",
                                                        KOTO_TYPE_UNDO_MANAGER,
                                                        G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
}

static void
koto_undo_action_init (KotoUndoAction *action)
{
  /* TODO: set stock-id in a constructor */
}

GtkAction *
koto_undo_action_new (const char *name, KotoUndoManager *undo_manager)
{
  g_return_val_if_fail (KOTO_IS_UNDO_MANAGER (undo_manager), NULL);

  return g_object_new (KOTO_TYPE_UNDO_ACTION,
                       "name", name,
                       "manager", undo_manager,
                       "undo", TRUE,
                       "stock-id", GTK_STOCK_UNDO,
                       NULL);
}

GtkAction *
koto_undo_action_new_redo (const char *name, KotoUndoManager *undo_manager)
{
  g_return_val_if_fail (KOTO_IS_UNDO_MANAGER (undo_manager), NULL);

  return g_object_new (KOTO_TYPE_UNDO_ACTION,
                       "name", name,
                       "manager", undo_manager,
                       "undo", FALSE,
                       "stock-id", GTK_STOCK_REDO,
                       NULL);
}