/* nautilus-dnd.c - Common Drag & drop handling code shared by the icon container
 *  and the list view.
 *
 *  Copyright (C) 2000, 2001 Eazel, Inc.
 *
 *  The Gnome 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.
 *
 *  The Gnome 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 the Gnome Library; see the file COPYING.LIB.  If not,
 *  see <http://www.gnu.org/licenses/>.
 *
 *  Authors: Pavel Cisler <pavel@eazel.com>,
 *           Ettore Perazzoli <ettore@gnu.org>
 */

#include <config.h>
#include "nautilus-dnd.h"

#include "nautilus-program-choosing.h"
#include "nautilus-link.h"
#include <eel/eel-glib-extensions.h>
#include <eel/eel-gtk-extensions.h>
#include <eel/eel-string.h>
#include <eel/eel-vfs-extensions.h>
#include <gtk/gtk.h>
#include <glib/gi18n.h>
#include "nautilus-file-utilities.h"
#include "nautilus-canvas-dnd.h"
#include <src/nautilus-list-view-dnd.h>
#include <stdio.h>
#include <string.h>

/* a set of defines stolen from the eel-icon-dnd.c file.
 * These are in microseconds.
 */
#define AUTOSCROLL_TIMEOUT_INTERVAL 100
#define AUTOSCROLL_INITIAL_DELAY 100000

/* drag this close to the view edge to start auto scroll*/
#define AUTO_SCROLL_MARGIN 30

/* the smallest amount of auto scroll used when we just enter the autoscroll
 * margin
 */
#define MIN_AUTOSCROLL_DELTA 5

/* the largest amount of auto scroll used when we are right over the view
 * edge
 */
#define MAX_AUTOSCROLL_DELTA 50

void
nautilus_drag_init (NautilusDragInfo     *drag_info,
                    const GtkTargetEntry *drag_types,
                    int                   drag_type_count,
                    gboolean              add_text_targets)
{
    drag_info->target_list = gtk_target_list_new (drag_types,
                                                  drag_type_count);

    if (add_text_targets)
    {
        gtk_target_list_add_text_targets (drag_info->target_list,
                                          NAUTILUS_ICON_DND_TEXT);
    }

    drag_info->drop_occured = FALSE;
    drag_info->need_to_destroy = FALSE;
}

void
nautilus_drag_finalize (NautilusDragInfo *drag_info)
{
    gtk_target_list_unref (drag_info->target_list);
    nautilus_drag_destroy_selection_list (drag_info->selection_list);
    nautilus_drag_destroy_selection_list (drag_info->selection_cache);

    g_free (drag_info);
}


/* Functions to deal with NautilusDragSelectionItems.  */

NautilusDragSelectionItem *
nautilus_drag_selection_item_new (void)
{
    return g_new0 (NautilusDragSelectionItem, 1);
}

static void
drag_selection_item_destroy (NautilusDragSelectionItem *item)
{
    g_clear_object (&item->file);
    g_free (item->uri);
    g_free (item);
}

void
nautilus_drag_destroy_selection_list (GList *list)
{
    GList *p;

    if (list == NULL)
    {
        return;
    }

    for (p = list; p != NULL; p = p->next)
    {
        drag_selection_item_destroy (p->data);
    }

    g_list_free (list);
}

GList *
nautilus_drag_uri_list_from_selection_list (const GList *selection_list)
{
    NautilusDragSelectionItem *selection_item;
    GList *uri_list;
    const GList *l;

    uri_list = NULL;
    for (l = selection_list; l != NULL; l = l->next)
    {
        selection_item = (NautilusDragSelectionItem *) l->data;
        if (selection_item->uri != NULL)
        {
            uri_list = g_list_prepend (uri_list, g_strdup (selection_item->uri));
        }
    }

    return g_list_reverse (uri_list);
}

/*
 * Transfer: Full. Free with g_list_free_full (list, g_object_unref);
 */
GList *
nautilus_drag_file_list_from_selection_list (const GList *selection_list)
{
    NautilusDragSelectionItem *selection_item;
    GList *file_list;
    const GList *l;

    file_list = NULL;
    for (l = selection_list; l != NULL; l = l->next)
    {
        selection_item = (NautilusDragSelectionItem *) l->data;
        if (selection_item->file != NULL)
        {
            file_list = g_list_prepend (file_list, g_object_ref (selection_item->file));
        }
    }

    return g_list_reverse (file_list);
}

GList *
nautilus_drag_uri_list_from_array (const char **uris)
{
    GList *uri_list;
    int i;

    if (uris == NULL)
    {
        return NULL;
    }

    uri_list = NULL;

    for (i = 0; uris[i] != NULL; i++)
    {
        uri_list = g_list_prepend (uri_list, g_strdup (uris[i]));
    }

    return g_list_reverse (uri_list);
}

GList *
nautilus_drag_build_selection_list (GtkSelectionData *data)
{
    GList *result;
    const guchar *p, *oldp;
    int size;

    result = NULL;
    oldp = gtk_selection_data_get_data (data);
    size = gtk_selection_data_get_length (data);

    while (size > 0)
    {
        NautilusDragSelectionItem *item;
        guint len;

        /* The list is in the form:
         *
         *  name\rx:y:width:height\r\n
         *
         *  The geometry information after the first \r is optional.  */

        /* 1: Decode name. */

        p = memchr (oldp, '\r', size);
        if (p == NULL)
        {
            break;
        }

        item = nautilus_drag_selection_item_new ();

        len = p - oldp;

        item->uri = g_malloc (len + 1);
        memcpy (item->uri, oldp, len);
        item->uri[len] = 0;
        item->file = nautilus_file_get_by_uri (item->uri);

        p++;
        if (*p == '\n' || *p == '\0')
        {
            result = g_list_prepend (result, item);
            if (p == 0)
            {
                g_warning ("Invalid x-special/gnome-icon-list data received: "
                           "missing newline character.");
                break;
            }
            else
            {
                oldp = p + 1;
                continue;
            }
        }

        size -= p - oldp;
        oldp = p;

        /* 2: Decode geometry information.  */

        item->got_icon_position = sscanf ((const gchar *) p, "%d:%d:%d:%d%*s",
                                          &item->icon_x, &item->icon_y,
                                          &item->icon_width, &item->icon_height) == 4;
        if (!item->got_icon_position)
        {
            g_warning ("Invalid x-special/gnome-icon-list data received: "
                       "invalid icon position specification.");
        }

        result = g_list_prepend (result, item);

        p = memchr (p, '\r', size);
        if (p == NULL || p[1] != '\n')
        {
            g_warning ("Invalid x-special/gnome-icon-list data received: "
                       "missing newline character.");
            if (p == NULL)
            {
                break;
            }
        }
        else
        {
            p += 2;
        }

        size -= p - oldp;
        oldp = p;
    }

    return g_list_reverse (result);
}

static gboolean
nautilus_drag_file_local_internal (const char *target_uri_string,
                                   const char *first_source_uri)
{
    /* check if the first item on the list has target_uri_string as a parent
     * FIXME:
     * we should really test each item but that would be slow for large selections
     * and currently dropped items can only be from the same container
     */
    GFile *target, *item, *parent;
    gboolean result;

    result = FALSE;

    target = g_file_new_for_uri (target_uri_string);

    /* get the parent URI of the first item in the selection */
    item = g_file_new_for_uri (first_source_uri);
    parent = g_file_get_parent (item);
    g_object_unref (item);

    if (parent != NULL)
    {
        result = g_file_equal (parent, target);
        g_object_unref (parent);
    }

    g_object_unref (target);

    return result;
}

gboolean
nautilus_drag_uris_local (const char  *target_uri,
                          const GList *source_uri_list)
{
    /* must have at least one item */
    g_assert (source_uri_list);

    return nautilus_drag_file_local_internal (target_uri, source_uri_list->data);
}

gboolean
nautilus_drag_items_local (const char  *target_uri_string,
                           const GList *selection_list)
{
    /* must have at least one item */
    g_assert (selection_list);

    return nautilus_drag_file_local_internal (target_uri_string,
                                              ((NautilusDragSelectionItem *) selection_list->data)->uri);
}

gboolean
nautilus_drag_items_on_desktop (const GList *selection_list)
{
    char *uri;
    GFile *desktop, *item, *parent;
    gboolean result;

    /* check if the first item on the list is in trash.
     * FIXME:
     * we should really test each item but that would be slow for large selections
     * and currently dropped items can only be from the same container
     */
    uri = ((NautilusDragSelectionItem *) selection_list->data)->uri;
    if (eel_uri_is_desktop (uri))
    {
        return TRUE;
    }

    desktop = nautilus_get_desktop_location ();

    item = g_file_new_for_uri (uri);
    parent = g_file_get_parent (item);
    g_object_unref (item);

    result = FALSE;

    if (parent)
    {
        result = g_file_equal (desktop, parent);
        g_object_unref (parent);
    }
    g_object_unref (desktop);

    return result;
}

GdkDragAction
nautilus_drag_default_drop_action_for_netscape_url (GdkDragContext *context)
{
    /* Mozilla defaults to copy, but unless thats the
     *  only allowed thing (enforced by ctrl) we want to LINK */
    if (gdk_drag_context_get_suggested_action (context) == GDK_ACTION_COPY &&
        gdk_drag_context_get_actions (context) != GDK_ACTION_COPY)
    {
        return GDK_ACTION_LINK;
    }
    else if (gdk_drag_context_get_suggested_action (context) == GDK_ACTION_MOVE)
    {
        /* Don't support move */
        return GDK_ACTION_COPY;
    }

    return gdk_drag_context_get_suggested_action (context);
}

static gboolean
check_same_fs (NautilusFile *file1,
               NautilusFile *file2)
{
    char *id1, *id2;
    gboolean result;

    result = FALSE;

    if (file1 != NULL && file2 != NULL)
    {
        id1 = nautilus_file_get_filesystem_id (file1);
        id2 = nautilus_file_get_filesystem_id (file2);

        if (id1 != NULL && id2 != NULL)
        {
            result = (strcmp (id1, id2) == 0);
        }

        g_free (id1);
        g_free (id2);
    }

    return result;
}

static gboolean
source_is_deletable (GFile *file)
{
    NautilusFile *naut_file;
    gboolean ret;

    /* if there's no a cached NautilusFile, it returns NULL */
    naut_file = nautilus_file_get (file);
    if (naut_file == NULL)
    {
        return FALSE;
    }

    ret = nautilus_file_can_delete (naut_file);
    nautilus_file_unref (naut_file);

    return ret;
}

NautilusDragInfo *
nautilus_drag_get_source_data (GdkDragContext *context)
{
    GtkWidget *source_widget;
    NautilusDragInfo *source_data;

    source_widget = gtk_drag_get_source_widget (context);
    if (source_widget == NULL)
    {
        return NULL;
    }

    if (NAUTILUS_IS_CANVAS_CONTAINER (source_widget))
    {
        source_data = nautilus_canvas_dnd_get_drag_source_data (NAUTILUS_CANVAS_CONTAINER (source_widget),
                                                                context);
    }
    else if (GTK_IS_TREE_VIEW (source_widget))
    {
        NautilusWindow *window;
        NautilusWindowSlot *active_slot;
        NautilusView *view;

        window = NAUTILUS_WINDOW (gtk_widget_get_toplevel (source_widget));
        active_slot = nautilus_window_get_active_slot (window);
        view = nautilus_window_slot_get_current_view (active_slot);
        if (NAUTILUS_IS_LIST_VIEW (view))
        {
            source_data = nautilus_list_view_dnd_get_drag_source_data (NAUTILUS_LIST_VIEW (view),
                                                                       context);
        }
        else
        {
            g_warning ("Got a drag context with a tree view source widget, but current view is not list view");
            source_data = NULL;
        }
    }
    else
    {
        /* it's a slot or something else */
        g_warning ("Requested drag source data from a widget that doesn't support it");
        source_data = NULL;
    }

    return source_data;
}

void
nautilus_drag_default_drop_action_for_icons (GdkDragContext *context,
                                             const char     *target_uri_string,
                                             const GList    *items,
                                             guint32         source_actions,
                                             int            *action)
{
    gboolean same_fs;
    gboolean target_is_source_parent;
    gboolean source_deletable;
    const char *dropped_uri;
    GFile *target, *dropped, *dropped_directory;
    GdkDragAction actions;
    NautilusFile *dropped_file, *target_file;

    if (target_uri_string == NULL)
    {
        *action = 0;
        return;
    }

    /* this is needed because of how dnd works. The actions at the time drag-begin
     * is done are not set, because they are first set on drag-motion. However,
     * for our use case, which is validation with the sidebar for dnd feedback
     * when the dnd doesn't have as a destination the sidebar itself, we need
     * a way to know the actions at drag-begin time. Either canvas view or
     * list view know them when starting the drag, but asking for them here
     * would be breaking the current model too much. So instead we rely on the
     * caller, which will ask if appropiate to those objects about the actions
     * available, instead of relying solely on the context here. */
    if (source_actions)
    {
        actions = source_actions & (GDK_ACTION_MOVE | GDK_ACTION_COPY);
    }
    else
    {
        actions = gdk_drag_context_get_actions (context) & (GDK_ACTION_MOVE | GDK_ACTION_COPY);
    }
    if (actions == 0)
    {
        /* We can't use copy or move, just go with the suggested action. */
        *action = gdk_drag_context_get_suggested_action (context);
        return;
    }

    if (gdk_drag_context_get_suggested_action (context) == GDK_ACTION_ASK)
    {
        /* Don't override ask */
        *action = gdk_drag_context_get_suggested_action (context);
        return;
    }

    dropped_uri = ((NautilusDragSelectionItem *) items->data)->uri;
    dropped_file = ((NautilusDragSelectionItem *) items->data)->file;
    target_file = nautilus_file_get_by_uri (target_uri_string);

    if (eel_uri_is_desktop (dropped_uri) &&
        !eel_uri_is_desktop (target_uri_string))
    {
        /* Desktop items only move on the desktop */
        *action = 0;
        return;
    }

    /*
     * Check for trash URI.  We do a find_directory for any Trash directory.
     * Passing 0 permissions as gnome-vfs would override the permissions
     * passed with 700 while creating .Trash directory
     */
    if (eel_uri_is_trash (target_uri_string))
    {
        /* Only move to Trash */
        if (actions & GDK_ACTION_MOVE)
        {
            *action = GDK_ACTION_MOVE;
        }
        nautilus_file_unref (target_file);
        return;
    }
    else if (dropped_file != NULL && nautilus_file_is_launcher (dropped_file))
    {
        if (actions & GDK_ACTION_MOVE)
        {
            *action = GDK_ACTION_MOVE;
        }
        nautilus_file_unref (target_file);
        return;
    }
    else if (eel_uri_is_desktop (target_uri_string))
    {
        target = nautilus_get_desktop_location ();

        nautilus_file_unref (target_file);
        target_file = nautilus_file_get (target);

        if (eel_uri_is_desktop (dropped_uri))
        {
            /* Only move to Desktop icons */
            if (actions & GDK_ACTION_MOVE)
            {
                *action = GDK_ACTION_MOVE;
            }

            g_object_unref (target);
            nautilus_file_unref (target_file);
            return;
        }
    }
    else if (target_file != NULL && nautilus_file_is_archive (target_file))
    {
        *action = GDK_ACTION_COPY;

        nautilus_file_unref (target_file);
        return;
    }
    else
    {
        target = g_file_new_for_uri (target_uri_string);
    }

    same_fs = check_same_fs (target_file, dropped_file);

    nautilus_file_unref (target_file);

    /* Compare the first dropped uri with the target uri for same fs match. */
    dropped = g_file_new_for_uri (dropped_uri);
    dropped_directory = g_file_get_parent (dropped);
    target_is_source_parent = FALSE;
    if (dropped_directory != NULL)
    {
        /* If the dropped file is already in the same directory but
         *  is in another filesystem we still want to move, not copy
         *  as this is then just a move of a mountpoint to another
         *  position in the dir */
        target_is_source_parent = g_file_equal (dropped_directory, target);
        g_object_unref (dropped_directory);
    }
    source_deletable = source_is_deletable (dropped);

    if ((same_fs && source_deletable) || target_is_source_parent ||
        g_file_has_uri_scheme (dropped, "trash"))
    {
        if (actions & GDK_ACTION_MOVE)
        {
            *action = GDK_ACTION_MOVE;
        }
        else
        {
            *action = gdk_drag_context_get_suggested_action (context);
        }
    }
    else
    {
        if (actions & GDK_ACTION_COPY)
        {
            *action = GDK_ACTION_COPY;
        }
        else
        {
            *action = gdk_drag_context_get_suggested_action (context);
        }
    }

    g_object_unref (target);
    g_object_unref (dropped);
}

GdkDragAction
nautilus_drag_default_drop_action_for_uri_list (GdkDragContext *context,
                                                const char     *target_uri_string)
{
    if (eel_uri_is_trash (target_uri_string) && (gdk_drag_context_get_actions (context) & GDK_ACTION_MOVE))
    {
        /* Only move to Trash */
        return GDK_ACTION_MOVE;
    }
    else
    {
        return gdk_drag_context_get_suggested_action (context);
    }
}

/* Encode a "x-special/gnome-icon-list" selection.
 *  Along with the URIs of the dragged files, this encodes
 *  the location and size of each icon relative to the cursor.
 */
static void
add_one_gnome_icon (const char *uri,
                    int         x,
                    int         y,
                    int         w,
                    int         h,
                    gpointer    data)
{
    GString *result;

    result = (GString *) data;

    g_string_append_printf (result, "%s\r%d:%d:%hu:%hu\r\n",
                            uri, x, y, w, h);
}

static void
add_one_uri (const char *uri,
             int         x,
             int         y,
             int         w,
             int         h,
             gpointer    data)
{
    GString *result;

    result = (GString *) data;

    g_string_append (result, uri);
    g_string_append (result, "\r\n");
}

static void
cache_one_item (const char *uri,
                int         x,
                int         y,
                int         w,
                int         h,
                gpointer    data)
{
    GList **cache = data;
    NautilusDragSelectionItem *item;

    item = nautilus_drag_selection_item_new ();
    item->uri = g_strdup (uri);
    item->file = nautilus_file_get_by_uri (uri);
    item->icon_x = x;
    item->icon_y = y;
    item->icon_width = w;
    item->icon_height = h;
    *cache = g_list_prepend (*cache, item);
}

GList *
nautilus_drag_create_selection_cache (gpointer                             container_context,
                                      NautilusDragEachSelectedItemIterator each_selected_item_iterator)
{
    GList *cache = NULL;

    (*each_selected_item_iterator)(cache_one_item, container_context, &cache);
    cache = g_list_reverse (cache);

    return cache;
}

/* Common function for drag_data_get_callback calls.
 * Returns FALSE if it doesn't handle drag data */
gboolean
nautilus_drag_drag_data_get_from_cache (GList            *cache,
                                        GdkDragContext   *context,
                                        GtkSelectionData *selection_data,
                                        guint             info,
                                        guint32           time)
{
    GList *l;
    GString *result;
    NautilusDragEachSelectedItemDataGet func;

    if (cache == NULL)
    {
        return FALSE;
    }

    switch (info)
    {
        case NAUTILUS_ICON_DND_GNOME_ICON_LIST:
        {
            func = add_one_gnome_icon;
        }
        break;

        case NAUTILUS_ICON_DND_URI_LIST:
        case NAUTILUS_ICON_DND_TEXT:
        {
            func = add_one_uri;
        }
        break;

        default:
            return FALSE;
    }

    result = g_string_new (NULL);

    for (l = cache; l != NULL; l = l->next)
    {
        NautilusDragSelectionItem *item = l->data;
        (*func)(item->uri, item->icon_x, item->icon_y, item->icon_width, item->icon_height, result);
    }

    gtk_selection_data_set (selection_data,
                            gtk_selection_data_get_target (selection_data),
                            8, (guchar *) result->str, result->len);
    g_string_free (result, TRUE);

    return TRUE;
}

typedef struct
{
    GMainLoop *loop;
    GdkDragAction chosen;
} DropActionMenuData;

static void
menu_deactivate_callback (GtkWidget *menu,
                          gpointer   data)
{
    DropActionMenuData *damd;

    damd = data;

    if (g_main_loop_is_running (damd->loop))
    {
        g_main_loop_quit (damd->loop);
    }
}

static void
drop_action_activated_callback (GtkWidget *menu_item,
                                gpointer   data)
{
    DropActionMenuData *damd;

    damd = data;

    damd->chosen = GPOINTER_TO_INT (g_object_get_data (G_OBJECT (menu_item),
                                                       "action"));

    if (g_main_loop_is_running (damd->loop))
    {
        g_main_loop_quit (damd->loop);
    }
}

static void
append_drop_action_menu_item (GtkWidget          *menu,
                              const char         *text,
                              GdkDragAction       action,
                              gboolean            sensitive,
                              DropActionMenuData *damd)
{
    GtkWidget *menu_item;

    menu_item = gtk_menu_item_new_with_mnemonic (text);
    gtk_widget_set_sensitive (menu_item, sensitive);
    gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_item);

    g_object_set_data (G_OBJECT (menu_item),
                       "action",
                       GINT_TO_POINTER (action));

    g_signal_connect (menu_item, "activate",
                      G_CALLBACK (drop_action_activated_callback),
                      damd);

    gtk_widget_show (menu_item);
}

/* Pops up a menu of actions to perform on dropped files */
GdkDragAction
nautilus_drag_drop_action_ask (GtkWidget     *widget,
                               GdkDragAction  actions)
{
    GtkWidget *menu;
    GtkWidget *menu_item;
    DropActionMenuData damd;

    /* Create the menu and set the sensitivity of the items based on the
     * allowed actions.
     */
    menu = gtk_menu_new ();
    gtk_menu_set_screen (GTK_MENU (menu), gtk_widget_get_screen (widget));

    append_drop_action_menu_item (menu, _("_Move Here"),
                                  GDK_ACTION_MOVE,
                                  (actions & GDK_ACTION_MOVE) != 0,
                                  &damd);

    append_drop_action_menu_item (menu, _("_Copy Here"),
                                  GDK_ACTION_COPY,
                                  (actions & GDK_ACTION_COPY) != 0,
                                  &damd);

    append_drop_action_menu_item (menu, _("_Link Here"),
                                  GDK_ACTION_LINK,
                                  (actions & GDK_ACTION_LINK) != 0,
                                  &damd);

    eel_gtk_menu_append_separator (GTK_MENU (menu));

    menu_item = gtk_menu_item_new_with_mnemonic (_("Cancel"));
    gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_item);
    gtk_widget_show (menu_item);

    damd.chosen = 0;
    damd.loop = g_main_loop_new (NULL, FALSE);

    g_signal_connect (menu, "deactivate",
                      G_CALLBACK (menu_deactivate_callback),
                      &damd);

    gtk_grab_add (menu);

    gtk_menu_popup (GTK_MENU (menu), NULL, NULL,
                    NULL, NULL, 0, GDK_CURRENT_TIME);

    g_main_loop_run (damd.loop);

    gtk_grab_remove (menu);

    g_main_loop_unref (damd.loop);

    g_object_ref_sink (menu);
    g_object_unref (menu);

    return damd.chosen;
}

gboolean
nautilus_drag_autoscroll_in_scroll_region (GtkWidget *widget)
{
    float x_scroll_delta, y_scroll_delta;

    nautilus_drag_autoscroll_calculate_delta (widget, &x_scroll_delta, &y_scroll_delta);

    return x_scroll_delta != 0 || y_scroll_delta != 0;
}


void
nautilus_drag_autoscroll_calculate_delta (GtkWidget *widget,
                                          float     *x_scroll_delta,
                                          float     *y_scroll_delta)
{
    GtkAllocation allocation;
    GdkDisplay *display;
    GdkSeat *seat;
    GdkDevice *pointer;
    int x, y;

    g_assert (GTK_IS_WIDGET (widget));

    display = gtk_widget_get_display (widget);
    seat = gdk_display_get_default_seat (display);
    pointer = gdk_seat_get_pointer (seat);
    gdk_window_get_device_position (gtk_widget_get_window (widget), pointer,
                                    &x, &y, NULL);

    /* Find out if we are anywhere close to the tree view edges
     * to see if we need to autoscroll.
     */
    *x_scroll_delta = 0;
    *y_scroll_delta = 0;

    if (x < AUTO_SCROLL_MARGIN)
    {
        *x_scroll_delta = (float) (x - AUTO_SCROLL_MARGIN);
    }

    gtk_widget_get_allocation (widget, &allocation);
    if (x > allocation.width - AUTO_SCROLL_MARGIN)
    {
        if (*x_scroll_delta != 0)
        {
            /* Already trying to scroll because of being too close to
             * the top edge -- must be the window is really short,
             * don't autoscroll.
             */
            return;
        }
        *x_scroll_delta = (float) (x - (allocation.width - AUTO_SCROLL_MARGIN));
    }

    if (y < AUTO_SCROLL_MARGIN)
    {
        *y_scroll_delta = (float) (y - AUTO_SCROLL_MARGIN);
    }

    if (y > allocation.height - AUTO_SCROLL_MARGIN)
    {
        if (*y_scroll_delta != 0)
        {
            /* Already trying to scroll because of being too close to
             * the top edge -- must be the window is really narrow,
             * don't autoscroll.
             */
            return;
        }
        *y_scroll_delta = (float) (y - (allocation.height - AUTO_SCROLL_MARGIN));
    }

    if (*x_scroll_delta == 0 && *y_scroll_delta == 0)
    {
        /* no work */
        return;
    }

    /* Adjust the scroll delta to the proper acceleration values depending on how far
     * into the sroll margins we are.
     * FIXME bugzilla.eazel.com 2486:
     * we could use an exponential acceleration factor here for better feel
     */
    if (*x_scroll_delta != 0)
    {
        *x_scroll_delta /= AUTO_SCROLL_MARGIN;
        *x_scroll_delta *= (MAX_AUTOSCROLL_DELTA - MIN_AUTOSCROLL_DELTA);
        *x_scroll_delta += MIN_AUTOSCROLL_DELTA;
    }

    if (*y_scroll_delta != 0)
    {
        *y_scroll_delta /= AUTO_SCROLL_MARGIN;
        *y_scroll_delta *= (MAX_AUTOSCROLL_DELTA - MIN_AUTOSCROLL_DELTA);
        *y_scroll_delta += MIN_AUTOSCROLL_DELTA;
    }
}



void
nautilus_drag_autoscroll_start (NautilusDragInfo *drag_info,
                                GtkWidget        *widget,
                                GSourceFunc       callback,
                                gpointer          user_data)
{
    if (nautilus_drag_autoscroll_in_scroll_region (widget))
    {
        if (drag_info->auto_scroll_timeout_id == 0)
        {
            drag_info->waiting_to_autoscroll = TRUE;
            drag_info->start_auto_scroll_in = g_get_monotonic_time ()
                                              + AUTOSCROLL_INITIAL_DELAY;

            drag_info->auto_scroll_timeout_id = g_timeout_add
                                                    (AUTOSCROLL_TIMEOUT_INTERVAL,
                                                    callback,
                                                    user_data);
        }
    }
    else
    {
        if (drag_info->auto_scroll_timeout_id != 0)
        {
            g_source_remove (drag_info->auto_scroll_timeout_id);
            drag_info->auto_scroll_timeout_id = 0;
        }
    }
}

void
nautilus_drag_autoscroll_stop (NautilusDragInfo *drag_info)
{
    if (drag_info->auto_scroll_timeout_id != 0)
    {
        g_source_remove (drag_info->auto_scroll_timeout_id);
        drag_info->auto_scroll_timeout_id = 0;
    }
}

gboolean
nautilus_drag_selection_includes_special_link (GList *selection_list)
{
    GList *node;
    char *uri;

    for (node = selection_list; node != NULL; node = node->next)
    {
        uri = ((NautilusDragSelectionItem *) node->data)->uri;

        if (eel_uri_is_desktop (uri))
        {
            return TRUE;
        }
    }

    return FALSE;
}
