/// <summary>
/// Applies a document addition to the document tree. Returns the corresponding DocumentChange event.
/// </summary>
private DocumentChange AddDocument(DocumentSnapshot newDocument)
{
_documentSet = _documentSet.WithDocumentAdded(newDocument);
int newIndex = _documentSet.IndexOf(newDocument.Reference);
return(new DocumentChange(newDocument, DocumentChange.Type.Added, null, newIndex));
}
/// <summary>
/// Applies a document modification to the document tree. Returns the DocumentChange event for
/// successful modifications, or null if the old and new documents have the same update timestamp.
/// </summary>
private DocumentChange ModifyDocument(DocumentSnapshot newDocument)
{
var docRef = newDocument.Reference;
if (!_documentSet.TryGetDocument(docRef, out var oldDocument))
{
// TODO: Is this appropriate? Java throws an NPE here...
throw new InvalidOperationException("Attempt to create a document modification, but document wasn't in set.");
}
if (oldDocument.UpdateTime == newDocument.UpdateTime)
{
return(null);
}
int oldIndex = _documentSet.IndexOf(docRef);
_documentSet = _documentSet.WithDocumentRemoved(docRef);
_documentSet = _documentSet.WithDocumentAdded(newDocument);
int newIndex = _documentSet.IndexOf(docRef);
return(new DocumentChange(newDocument, DocumentChange.Type.Modified, oldIndex, newIndex));
}