/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 8; tab-width: 8 -*- */

/* CajaUndoManager - Undo/Redo transaction manager.
 *
 * Copyright (C) 2000 Eazel, Inc.
 *
 * Author: Gene Z. Ragan <gzr@eazel.com>
 *
 * 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 2 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 Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <config.h>
#include <libcaja-private/caja-undo-manager.h>
#include <libcaja-private/caja-undo-transaction.h>

#include <eel/eel-gtk-macros.h>
#include <eel/eel-gtk-extensions.h>
#include <gtk/gtk.h>
#include "caja-undo-private.h"

struct CajaUndoManagerDetails
{
    CajaUndoTransaction *transaction;

    /* These are used to tell undo from redo. */
    gboolean current_transaction_is_redo;
    gboolean new_transaction_is_redo;

    /* These are used only so that we can complain if we get more
     * than one transaction inside undo.
     */
    gboolean undo_in_progress;
    int num_transactions_during_undo;
};

enum
{
    CHANGED,
    LAST_SIGNAL
};
static guint signals[LAST_SIGNAL];

typedef struct
{
#ifdef UIH
    MateComponentUIHandler *handler;
#endif /* UIH */
    char *path;
    char *no_undo_menu_item_label;
    char *no_undo_menu_item_hint;
} UndoMenuHandlerConnection;

G_DEFINE_TYPE (CajaUndoManager,
               caja_undo_manager,
               G_TYPE_OBJECT)

static void
release_transaction (CajaUndoManager *manager)
{
    CajaUndoTransaction *transaction;

    transaction = manager->details->transaction;
    manager->details->transaction = NULL;
    if (transaction != NULL)
    {
        g_object_unref (transaction);
    }
}

void
caja_undo_manager_append (CajaUndoManager *manager,
                          CajaUndoTransaction *transaction)
{
    CajaUndoTransaction *duplicate_transaction;

    /* Check, complain, and ignore the passed-in transaction if we
     * get more than one within a single undo operation. The single
     * transaction we get during the undo operation is supposed to
     * be the one for redoing the undo (or re-undoing the redo).
     */
    if (manager->details->undo_in_progress)
    {
        manager->details->num_transactions_during_undo += 1;
        g_return_if_fail (manager->details->num_transactions_during_undo == 1);
    }

    g_return_if_fail (transaction != NULL);

    /* Keep a copy of this transaction (dump the old one). */
    duplicate_transaction = g_object_ref (transaction);
    release_transaction (manager);
    manager->details->transaction = duplicate_transaction;
    manager->details->current_transaction_is_redo =
        manager->details->new_transaction_is_redo;

    /* Fire off signal indicating that the undo state has changed. */
    g_signal_emit (manager, signals[CHANGED], 0);
}

void
caja_undo_manager_forget (CajaUndoManager *manager,
                          CajaUndoTransaction *transaction)
{
    /* Nothing to forget unless the item we are passed is the
     * transaction we are currently holding.
     */
    if (transaction != manager->details->transaction)
    {
        return;
    }

    /* Get rid of the transaction we are holding on to. */
    release_transaction (manager);

    /* Fire off signal indicating that the undo state has changed. */
    g_signal_emit (manager, signals[CHANGED], 0);
}

CajaUndoManager *
caja_undo_manager_new (void)
{
    return CAJA_UNDO_MANAGER (g_object_new (caja_undo_manager_get_type (), NULL));
}

static void
caja_undo_manager_init (CajaUndoManager *manager)
{
    manager->details = g_new0 (CajaUndoManagerDetails, 1);
}

void
caja_undo_manager_undo (CajaUndoManager *manager)
{
    CajaUndoTransaction *transaction;

    g_return_if_fail (CAJA_IS_UNDO_MANAGER (manager));

    transaction = manager->details->transaction;
    manager->details->transaction = NULL;
    if (transaction != NULL)
    {
        /* Perform the undo. New transactions that come in
         * during an undo are redo transactions. New
         * transactions that come in during a redo are undo
         * transactions. Transactions that come in outside
         * are always undo and never redo.
         */
        manager->details->new_transaction_is_redo =
            !manager->details->current_transaction_is_redo;
        manager->details->undo_in_progress = TRUE;
        manager->details->num_transactions_during_undo = 0;
        caja_undo_transaction_undo (transaction);
        manager->details->undo_in_progress = FALSE;
        manager->details->new_transaction_is_redo = FALSE;

        /* Let go of the transaction. */
        g_object_unref (transaction);

        /* Fire off signal indicating the undo state has changed. */
        g_signal_emit (manager, signals[CHANGED], 0);
    }
}

static void
finalize (GObject *object)
{
    CajaUndoManager *manager;

    manager = CAJA_UNDO_MANAGER (object);

    release_transaction (manager);

    g_free (manager->details);

    if (G_OBJECT_CLASS (caja_undo_manager_parent_class)->finalize)
    {
        (* G_OBJECT_CLASS (caja_undo_manager_parent_class)->finalize) (object);
    }
}

void
caja_undo_manager_attach (CajaUndoManager *manager, GObject *target)
{
    g_return_if_fail (CAJA_IS_UNDO_MANAGER (manager));
    g_return_if_fail (G_IS_OBJECT (target));

    caja_undo_attach_undo_manager (G_OBJECT (target), manager);
}

#ifdef UIH
static void
update_undo_menu_item (CajaUndoManager *manager,
                       UndoMenuHandlerConnection *connection)
{
    CORBA_Environment ev;
    Caja_Undo_MenuItem *menu_item;

    g_assert (CAJA_IS_UNDO_MANAGER (manager));
    g_assert (connection != NULL);
    g_assert (MATECOMPONENT_IS_UI_HANDLER (connection->handler));
    g_assert (connection->path != NULL);
    g_assert (connection->no_undo_menu_item_label != NULL);
    g_assert (connection->no_undo_menu_item_hint != NULL);

    CORBA_exception_init (&ev);

    if (CORBA_Object_is_nil (manager->details->transaction, &ev))
    {
        menu_item = NULL;
    }
    else
    {
        if (manager->details->current_transaction_is_redo)
        {
            menu_item = Caja_Undo_Transaction__get_redo_menu_item
                        (manager->details->transaction, &ev);
        }
        else
        {
            menu_item = Caja_Undo_Transaction__get_undo_menu_item
                        (manager->details->transaction, &ev);
        }
    }

    matecomponent_ui_handler_menu_set_sensitivity
    (connection->handler, connection->path,
     menu_item != NULL);
    matecomponent_ui_handler_menu_set_label
    (connection->handler, connection->path,
     menu_item == NULL
     ? connection->no_undo_menu_item_label
     : menu_item->label);
    matecomponent_ui_handler_menu_set_hint
    (connection->handler, connection->path,
     menu_item == NULL
     ? connection->no_undo_menu_item_hint
     : menu_item->hint);

    CORBA_free (menu_item);

    CORBA_exception_free (&ev);
}

static void
undo_menu_handler_connection_free (UndoMenuHandlerConnection *connection)
{
    g_assert (connection != NULL);
    g_assert (MATECOMPONENT_IS_UI_HANDLER (connection->handler));
    g_assert (connection->path != NULL);
    g_assert (connection->no_undo_menu_item_label != NULL);
    g_assert (connection->no_undo_menu_item_hint != NULL);

    g_free (connection->path);
    g_free (connection->no_undo_menu_item_label);
    g_free (connection->no_undo_menu_item_hint);
    g_free (connection);
}

static void
undo_menu_handler_connection_free_cover (gpointer data)
{
    undo_menu_handler_connection_free (data);
}

void
caja_undo_manager_set_up_matecomponent_ui_handler_undo_item (CajaUndoManager *manager,
        MateComponentUIHandler *handler,
        const char *path,
        const char *no_undo_menu_item_label,
        const char *no_undo_menu_item_hint)
{
    UndoMenuHandlerConnection *connection;

    connection = g_new (UndoMenuHandlerConnection, 1);
    connection->handler = handler;
    connection->path = g_strdup (path);
    connection->no_undo_menu_item_label = g_strdup (no_undo_menu_item_label);
    connection->no_undo_menu_item_hint = g_strdup (no_undo_menu_item_hint);

    /* Set initial state of menu item. */
    update_undo_menu_item (manager, connection);

    /* Update it again whenever the changed signal is emitted. */
    eel_gtk_signal_connect_full_while_alive
    (GTK_OBJECT (manager), "changed",
     G_CALLBACK (update_undo_menu_item), NULL,
     connection, undo_menu_handler_connection_free_cover,
     FALSE, FALSE,
     GTK_OBJECT (handler));
}
#endif /* UIH */

static void
caja_undo_manager_class_init (CajaUndoManagerClass *class)
{
    G_OBJECT_CLASS (class)->finalize = finalize;

    signals[CHANGED] = g_signal_new
                       ("changed",
                        G_TYPE_FROM_CLASS (class),
                        G_SIGNAL_RUN_LAST,
                        G_STRUCT_OFFSET (CajaUndoManagerClass,
                                         changed),
                        NULL, NULL,
                        g_cclosure_marshal_VOID__VOID,
                        G_TYPE_NONE, 0);
}
