//TODO: Cache newly created channel, and return if already exists
public async Task <SlackChatHub> JoinDirectMessageChannel(string user)
{
if (string.IsNullOrEmpty(user))
{
throw new ArgumentNullException(nameof(user));
}
IChannelMessenger client = _connectionFactory.CreateChannelMessenger();
Channel channel = await client.JoinDirectMessageChannel(SlackKey, user);
return(new SlackChatHub
{
Id = channel.Id,
Name = channel.Name,
Type = SlackChatHubType.DM
});
}