***************************** Subroutines ************************************/
/**
 * Creating channel event and subscribing chat service
 */
function subscribeChatMessage(objectInstanceID: string, objectInstanceValue: string) {
  return eventChannel<Map<string, Enote>>((emmiter) => {
      const unsubscribe = enoteService.subscribeEnotesById(objectInstanceID, objectInstanceValue,
        (enotes: Map<string, Enote>) => {
          emmiter(enotes)
       })
       return () => {
           // unsubscribe()
       }
   })
}

/**
 * On database fetch
 */
function* dbFetchChatMessages(objectInstanceID: string, objectInstanceValue: string) {
   try {
       while (true) {
         const channelSubscription: Channel<Map<string, Enote>> =  yield call(subscribeChatMessage, objectInstanceID, objectInstanceValue)
          let messages: Map<string, Enote> = yield take(channelSubscription)
          yield put({ type: EnoteActionType.ENOTE_POLL_MESSAGES, payload: { messages: messages, objectInstanceId: objectInstanceValue} })
          yield delay(4000)
      }
    } catch (e) {
      console.error(e)
    }
}

/******************************************************************************/
/******************************* WATCHERS *************************************/
/******************************************************************************/
export default function* enoteSaga() {
  while (true) {
    const pollingAction = yield take(EnoteActionType.DB_SUBSCRIBE_ENOTE_MESSAGE)
    const {objectInstanceID, objectInstanceValue} = pollingAction.payload
    yield race([
      call(dbFetchChatMessages, objectInstanceID, objectInstanceValue),
      take(EnoteActionType.DB_UNSUBSCRIBE_ENOTE_MESSAGE)
    ])
  }
}