private async Task <List <EwsItemIdentifier> > ApplyRemoteChanges(ExchangeChangeSet changeSet, EwsSyncServer server, List <ExchangeMapId> mapId, EwsFolderIdentifier folderIdentifier, EwsItemType ewsItemType)
{
// enumerate remote content
var remoteIdentifiers = await server.EnumerateFolderContentAsync(folderIdentifier, ewsItemType);
var editedItems = new List <EwsItemIdentifier>();
var newItems = new List <EwsItemIdentifier>();
// check for remote identifiers that have a new change key (ie. updated elements in Exchange)
foreach (var task in this.workbook.Tasks.Where(t => t.SyncId != null))
{
// check if we can find this task that exists in the workbook in the remote identifiers
var remoteId = remoteIdentifiers.FirstOrDefault(i => i.Id == task.SyncId.GetId());
// we find this task in the remote identifiers, check if the change key has changed since last sync
if (remoteId != null && remoteId.ChangeKey != task.SyncId.GetEwsItemIdentifier().ChangeKey)
{
// local item found on server with a different ChangeKey because it was updated => update
editedItems.Add(new EwsItemIdentifier(remoteId.Id, remoteId.ChangeKey));
}
}
// check for remote identifiers that we don't have in the workbook and that were not added during this sync operation
foreach (var identifier in remoteIdentifiers.Where(i => mapId.All(id => id.ExchangeId != null && id.ExchangeId.GetId() != i.Id)))
{
var task = this.workbook.Tasks.Where(t => t.SyncId != null).FirstOrDefault(t => t.SyncId.GetId() == identifier.Id);
if (task == null)
{
// item found on server but not locally => new item
newItems.Add(identifier);
}
}
var items = new List <EwsItemIdentifier>();
items.AddRange(editedItems);
items.AddRange(newItems);
var ewsTasks = await server.DownloadFolderContentAsync(items, ewsItemType);
foreach (var ewsTask in ewsTasks)
{
if (editedItems.Any(i => i.Id == ewsTask.Id))
{
changeSet.ModifiedTasks.Add(ewsTask.BuildExchangeTask());
}
else if (newItems.Any(i => i.Id == ewsTask.Id))
{
changeSet.AddedTasks.Add(ewsTask.BuildExchangeTask());
}
else
{
throw new NotSupportedException();
}
}
return(remoteIdentifiers);
}
