initialize method

Implementation

Future<void> initialize() async {
  if (_isDisposed) return;
  if (_isInitialized) {
    throw InvalidInitializationException();
  }

  sbLog.i(StackTrace.current, 'initialize()');
  _isInitialized = true;

  _initializeParams.inclusive = true;

  final messages =
      await _chat.apiClient.send<List<BaseMessage>>(ChannelMessagesGetRequest(
    _chat,
    channelType: ChannelType.group,
    channelUrl: _channel.channelUrl,
    params: _initializeParams.toJson(),
    timestamp: _startingPoint,
  ));

  if (_isDisposed) return;

  if (messages.isNotEmpty) {
    final oldestMessage =
        _initializeParams.reverse ? messages.last : messages.first;
    final latestMessage =
        _initializeParams.reverse ? messages.first : messages.last;
    _oldestMessage = oldestMessage;
    _latestMessage = latestMessage;

    final maxCreatedAt = messages
        .reduce((current, next) =>
            current.createdAt > next.createdAt ? current : next)
        .createdAt;

    if (_startingPoint > maxCreatedAt) {
      _hasPrevious = messages.length == _initializeParams.previousResultSize;
      _hasNext = false;
    } else if (_startingPoint == 0) {
      _hasPrevious = false;
      _hasNext = messages.length == _initializeParams.nextResultSize;
    } else {
      final previousMessages =
          messages.where((e) => e.createdAt < _startingPoint).toList();
      final nextMessages =
          messages.where((e) => e.createdAt > _startingPoint).toList();

      _hasPrevious = previousMessages.length -
              _getExistedMessageCountInMessageList(previousMessages) ==
          _initializeParams.previousResultSize;
      _hasNext = nextMessages.length -
              _getExistedMessageCountInMessageList(nextMessages) ==
          _initializeParams.nextResultSize;
    }
  } else {
    _hasPrevious = false;
    _hasNext = false;
  }

  if (messages.isNotEmpty) {
    _chat.collectionManager.sendEventsToMessageCollection(
      messageCollection: this,
      groupChannel: _channel,
      eventSource: CollectionEventSource.messageInitialize,
      sendingStatus: SendingStatus.succeeded,
      addedMessages: messages,
      isReversedAddedMessages: _initializeParams.reverse,
    );
  }
}