interleave<T> method

Future<List<Message>> interleave<T>(List a, List b)

function to mix the incoming and outgoing messages by timestamp

Implementation

Future<List<Message>> interleave<T>(List a, List b) async {
  List result = [];
  final ita = a.iterator;
  final itb = b.iterator;
  bool hasa = ita.moveNext();
  bool hasb = itb.moveNext();
  Message valueA, valueB;
  while (hasa | hasb) {
    if (hasa && hasb) {
      valueA = Message.fromJson(ita.current);
      if (valueA.contentType == MessageContentType.image) {
        valueA.imageData = await getImage(valueA.message ?? '');
      }
      valueB = Message.fromJson(itb.current);
      valueB.type = MessageType.incoming;
      if (valueB.contentType == MessageContentType.image) {
        valueB.imageData = await getImage(valueB.message ?? '');
      }
      if ((valueA.time ?? 0) > (valueB.time ?? 0)) {
        result.add(valueA);
        hasa = ita.moveNext();
      } else {
        result.add(valueB);
        hasb = itb.moveNext();
      }
    } else if (hasa) {
      valueA = Message.fromJson(ita.current);
      if (valueA.contentType == MessageContentType.image) {
        valueA.imageData = await getImage(valueA.message ?? '');
      }
      result.add(valueA);
      while (hasa = ita.moveNext()) {
        valueA = Message.fromJson(ita.current);
        if (valueA.contentType == MessageContentType.image) {
          valueA.imageData = await getImage(valueA.message ?? '');
        }
        result.add(valueA);
      }
    } else if (hasb) {
      valueB = Message.fromJson(itb.current);
      valueB.type = MessageType.incoming;
      if (valueB.contentType == MessageContentType.image) {
        valueB.imageData = await getImage(valueB.message ?? '');
      }
      result.add(valueB);
      while (hasb = itb.moveNext()) {
        valueB = Message.fromJson(itb.current);
        valueB.type = MessageType.incoming;
        if (valueB.contentType == MessageContentType.image) {
          valueB.imageData = await getImage(valueB.message ?? '');
        }
        result.add(valueB);
      }
    }
  }
  List<Message> finalResult = List<Message>.from(result);
  return finalResult;
}