[gnome-control-center/gnome-3-8] search: fix moving unsorted applications

[Giovanni Campagna <gcampagna src gnome org>]

commit ad857bdada10aa2192636ffe52be9f92a5f147fc
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Sat Mar 2 02:11:52 2013 +0100

    search: fix moving unsorted applications
    
    Search providers can either have an explicitly configured sort order,
    or be in the default alphabetical order based on their name.
    Previously, when moving we would always assume that all providers had
    a sort order, so moving an unsorted provider would put at the top.
    The right thing to do, instead, is to walk the list in visual order
    and assign an appropriate sort order, that is then flushed to gsettings.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=694975

 panels/search/cc-search-panel.c |   89 +++++++++++++++++++++++++++++++++++----
 1 files changed, 80 insertions(+), 9 deletions(-)
---
diff --git a/panels/search/cc-search-panel.c b/panels/search/cc-search-panel.c
index 97dd8a5..b70184f 100644
--- a/panels/search/cc-search-panel.c
+++ b/panels/search/cc-search-panel.c
@@ -192,30 +192,101 @@ search_panel_move_selected (CcSearchPanel *self,
   GtkWidget *box, *other_box;
   GAppInfo *app_info, *other_app_info;
   const gchar *app_id, *other_app_id;
+  const gchar *last_good_app, *target_app;
   gint idx, other_idx;
-  GList *children, *l;
+  gpointer idx_ptr;
+  gboolean found;
+  GList *children, *l, *other;
 
   box = egg_list_box_get_selected_child (EGG_LIST_BOX (self->priv->list_box));
   app_info = g_object_get_data (G_OBJECT (box), "app-info");
   app_id = g_app_info_get_id (app_info);
 
-  other_app_id = NULL;
   children = gtk_container_get_children (GTK_CONTAINER (self->priv->list_box));
+
+  /* The assertions are valid only as long as we don't move the first
+     or the last item. */
+
   l = g_list_find (children, box);
+  g_assert (l != NULL);
+
+  other = down ? g_list_next(l) : g_list_previous(l);
+  g_assert (other != NULL);
+
+  other_box = other->data;
+  other_app_info = g_object_get_data (G_OBJECT (other_box), "app-info");
+  other_app_id = g_app_info_get_id (other_app_info);
+
+  g_assert (other_app_id != NULL);
+
+  /* Check if we're moving one of the unsorted providers at the end of
+     the list; in that case, the value we obtain from the sort order table
+     is garbage.
+     We need to find the last app with a valid sort order, and
+     then set the sort order on all intermediate apps until we find the
+     one we want to move, if moving up, or the neighbor, if moving down.
+  */
+  last_good_app = target_app = app_id;
+  found = g_hash_table_lookup_extended (self->priv->sort_order, last_good_app, NULL, &idx_ptr);
+  while (!found)
+    {
+      GAppInfo *tmp;
+      const char *tmp_id;
+
+      l = g_list_previous (l);
+      if (l == NULL)
+        {
+          last_good_app = NULL;
+          break;
+        }
+
+      tmp =  g_object_get_data (G_OBJECT (l->data), "app-info");
+      tmp_id = g_app_info_get_id (tmp);
+
+      last_good_app = tmp_id;
+      found = g_hash_table_lookup_extended (self->priv->sort_order, tmp_id, NULL, &idx_ptr);
+    }
 
-  if (l != NULL)
+  /* For simplicity's sake, set all sort orders to the previously visible state
+     first, and only then do the modification requested.
+
+     The loop actually sets the sort order on last_good_app even if we found a
+     valid one already, but I preferred to keep the logic simple, at the expense
+     of a small performance penalty.
+  */
+  if (found)
+    {
+      idx = GPOINTER_TO_INT (idx_ptr);
+    }
+  else
     {
-      other_box = down ? g_list_next (l)->data : g_list_previous (l)->data;
-      other_app_info = g_object_get_data (G_OBJECT (other_box), "app-info");
-      other_app_id = g_app_info_get_id (other_app_info);
+      /* If not found, there is no configured app that has a sort order, so we start
+         from the first position and walk the entire list.
+         Sort orders are 1 based, so that 0 (NULL) is not a valid value.
+      */
+      idx = 1;
+      l = children;
+    }
+
+  while (last_good_app != target_app)
+    {
+      GAppInfo *tmp;
+      const char *tmp_id;
+
+      tmp = g_object_get_data (G_OBJECT (l->data), "app-info");
+      tmp_id = g_app_info_get_id (tmp);
+
+      g_hash_table_replace (self->priv->sort_order, g_strdup (tmp_id), GINT_TO_POINTER (idx));
+
+      l = g_list_next (l);
+      idx++;
+      last_good_app = tmp_id;
     }
 
   other_idx = GPOINTER_TO_INT (g_hash_table_lookup (self->priv->sort_order, app_id));
   idx = down ? (other_idx + 1) : (other_idx - 1);
 
-  if (other_app_id != NULL)
-    g_hash_table_replace (self->priv->sort_order, g_strdup (other_app_id), GINT_TO_POINTER (other_idx));
-
+  g_hash_table_replace (self->priv->sort_order, g_strdup (other_app_id), GINT_TO_POINTER (other_idx));
   g_hash_table_replace (self->priv->sort_order, g_strdup (app_id), GINT_TO_POINTER (idx));
 
   search_panel_propagate_sort_order (self);