How to get message from method - scala

Question

I want to rewrite console IO application (sum counting) to messenger-bot. The StdIn.readLine() let me get the next input number in recursion.
object HelloCountBot extends TelegramBot with Polling with Commands {
def go(number: Long, chatId: Long): IO[Long] =
for {
input <- ??? /*here I need get the next number*/
acc <- input.toLong match {
case 0L => sendMessageMethodIO(chatId, "The sum is:") *> IO(0L)
case _ => go(number + 1, chatId)
}
acc <- IO(acc + input.toLong)
} yield acc
/*input point for every new message*/
override def onMessage(message: Message) = message.text match {
case Some(text) if text == "start" => go(1, message.chat.id)
.unsafeRunSync
}
def main(args: Array[String]): Unit = HelloCountBot.run()
}
How to organize code to get the next message inside recursion from method onMessage with Unit return.

Answer 1

I didn't find in https://github.com/bot4s/telegram any methods for receiving messages in the way that you want. So I think the best option is to create stateful bot as shown in this example: https://github.com/bot4s/telegram/blob/master/examples/src/StatefulBot.scala.
So if I understand your code correctly, it can be reorganized in the following way (trait PerChatState is taken from the link above):
object HelloCountBot
extends TelegramBot
with Polling
with Commands
with PerChatState[Long] {
override def onMessage(message: Message): Future[Unit] = {
implicit val msg = message
message.text match {
case Some(text) if text == "start" =>
Future {
setChatState(0L)
}
case Some(value) if value == "0" =>
withChatState {
sum =>
reply(s"The sum is ${sum.getOrElse(0L)}")
.map(_ => clearChatState)
}
case Some(value) =>
withChatState {
mayBeSum =>
Future {
mayBeSum.foreach(
sum => setChatState(sum + value.toLong)
)
}
}
}
}
def main(args: Array[String]): Unit = HelloCountBot.run()
}
It uses Futures, but you can rewrite it to IO, if you prefer.