epics.js

import Rx from 'rxjs'
import { loginUser, retrieveCurrentUser } from '../api/users'
import { combineEpics } from 'redux-observable'
import { 
    LOGIN_USER, LOGIN_USER_CANCELLED, LOGIN_USER_SUCCESS,
    RETRIEVE_CURRENT_USER, RETRIEVE_CURRENT_USER_CANCELLED
 } from '../constants/UserActionTypes'
import { 
    loginUserSuccess, loginUserError,
    retrieveCurrentUser as retrieveCurrentUserAction, retrieveCurrentUserSuccess, retrieveCurrentUserError
} from '../actions/users'

const loginUserEpic = action$ => 
    action$.ofType(LOGIN_USER) //When users are logging in
        .mergeMap(action =>
            loginUser(action.email, action.password) //Send login POST request
                .map(payload => loginUserSuccess(payload.data)) // Notify store/reducer of request being fulfilled
                .takeUntil(action$.ofType(LOGIN_USER_CANCELLED)) // Cancel request if AUTHENTICATE_CANCELLED is dispatched
                .catch(error => Rx.Observable.of(loginUserError(error))) // dispatch authentication error if request fails
        )

const loginUserSuccessEpic = action$ => 
    action$.ofType(LOGIN_USER_SUCCESS)
        .map(() => retrieveCurrentUserAction())

const retrieveCurrentUserEpic = action$ => 
    action$.ofType(RETRIEVE_CURRENT_USER)
        .mergeMap(action => 
            retrieveCurrentUser()
                .map(payload => {console.log(payload); return retrieveCurrentUserSuccess(payload.data)})
                .takeUntil(action$.ofType(RETRIEVE_CURRENT_USER_CANCELLED))
                .catch(error => Rx.Observable.of(retrieveCurrentUserError(error)))
        )

const users = combineEpics(
    loginUserEpic,
    loginUserSuccessEpic,
    retrieveCurrentUserEpic
)

export default users