private static bool SyncPrivate(FlowObservableCollection <T> currentItems, FlowObservableCollection <T> updateItems, bool notify)
{
currentItems?.OnCollectionChangedSuspend();
var itemsAdded = notify ? new List <T>() : null;
var itemsRemoved = notify ? new List <T>() : null;
//var itemsMoved = notify ? new List<T>() : null;
//var itemsMovedIndexes = notify ? new List<Tuple<int, int>>() : null;
bool structureIsChanged = false;
bool forceReset = false;
var flowGroup = updateItems.FirstOrDefault() as FlowGroup;
if (flowGroup != null)
{
var result = updateItems
.Join(currentItems, k => ((FlowGroup)(object)k).Key, i => ((FlowGroup)(object)i).Key, (k, i) => i)
.ToList();
for (int i = 0; i < result.Count; i++)
{
var oldGroup = currentItems[i] as FlowGroup;
var newGroup = result[i] as FlowGroup;
if (oldGroup.Key != newGroup.Key)
{
forceReset = true;
currentItems[i] = (T)(object)newGroup;
}
}
}
for (int i = 0; i < updateItems.Count; i++)
{
var item = updateItems[i];
if (currentItems.Count <= i)
{
structureIsChanged = true;
currentItems.Add(item);
itemsAdded?.Add(item);
}
else
{
var itemList = item as FlowObservableCollection <object>;
var currentItem = currentItems[i];
var currentItemList = currentItem as FlowObservableCollection <object>;
if (itemList != null && currentItemList != null)
{
if (currentItemList.Sync(itemList, false))
{
structureIsChanged = true;
}
}
else if (structureIsChanged)
{
currentItems[i] = item;
}
else if ((object)item != (object)currentItem)
{
structureIsChanged = true;
currentItems[i] = item;
}
}
}
while (currentItems.Count > updateItems.Count)
{
structureIsChanged = true;
itemsRemoved?.Add(currentItems[currentItems.Count - 1]);
currentItems.RemoveAt(currentItems.Count - 1);
}
if (forceReset || structureIsChanged)
{
if (!forceReset && itemsAdded != null && itemsRemoved == null && itemsAdded.Count < 100)
{
currentItems?.OnCollectionChangedCancel();
currentItems?.NotifyCollectionChanged(
new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, itemsAdded));
}
else if (!forceReset && itemsRemoved != null && itemsAdded == null && itemsRemoved.Count < 100)
{
currentItems?.NotifyCollectionChanged(
new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, itemsRemoved));
}
else
{
currentItems?.OnCollectionChangedResume();
}
}
else
{
currentItems?.OnCollectionChangedCancel();
}
return(structureIsChanged);
}
internal bool Sync(FlowObservableCollection <T> newItems, bool notify = true)
{
return(SyncPrivate(this, newItems, notify));
}