import { Observable, Observer } from 'rxjs'
import { combineEpics, ActionsObservable } from 'redux-observable'
import { Store } from 'redux'

import * as api from './api'
import * as actions from './actions'
import * as selectors from './selectors'
import * as AuthSelectors from '../auth/selectors'
import * as PopupActions from '../popup/actions'
import * as PopupSelectors from '../popup/selectors'
import {
  SocketCluster,
  SocketChannel,
} from '../socket/constants'
import {
  makeJoinChannelPendingEpic,
  makeJoinChannelSuccessEpic,
} from '../socket/epic'

const socketPendingEpic = makeJoinChannelPendingEpic(SocketCluster.MESSAGES, SocketChannel.USER)
const socketSuccessEpic = makeJoinChannelSuccessEpic(SocketCluster.MESSAGES, SocketChannel.USER)

export const triggerFetchActivitiesEpic = (action$: ActionsObservable<any>, store: Store<any>) => {
  return socketSuccessEpic(action$)
    .switchMap(() => {
      // delay on reconnect to avoid herding
      if (selectors.isLoaded(store.getState())) {
        const delayMs = Math.random() * 60000
        return Observable.timer(delayMs)
          .first()
          .map(() => actions.fetchActivities())
      } else {
        return Observable.of(actions.fetchActivities())
      }
    })
}

export const fetchActivities = (action$: ActionsObservable<any>, store: Store<any>) => {
  return action$.ofType(actions.fetchActivities.toString())
    .pluck('payload')
    .map(() => ({ accessToken: AuthSelectors.accessToken(store.getState()) }))
    .mergeMap((options) => {
      return api.fetchActivities(options)
        .map(activities => actions.fetchActivitiesSuccess(activities))
        .startWith(actions.fetchActivitiesPending())
        .catch(() => Observable.of(actions.fetchActivitiesFailure()))
    })
}

export const fetchActivitiesByEmail = (action$: ActionsObservable<any>, store: Store<any>) => {
  return action$.ofType(PopupActions.updateSearchQuery.toString())
    .pluck('payload')
    .filter(query => !!query)
    .map((query: string) => ({ email: query, accessToken: AuthSelectors.accessToken(store.getState()) }))
    .switchMap((options) => {
      return api.fetchActivities(options)
        .map(activities => actions.fetchActivitiesByEmailSuccess(activities))
        .startWith(actions.fetchActivitiesPending())
        .catch(() => Observable.of(actions.fetchActivitiesFailure()))
    })
}

interface ChannelPayload {
  body: any
}

export const joinUserChannelPendingEpic = (action$: ActionsObservable<any>, store: Store<any>) => {
  return socketPendingEpic(action$)
    .switchMap(({ channel }) => {
      return Observable.create((observer: Observer<any>) => {
        channel.on('outbound', ({ body }: ChannelPayload) => {
          observer.next(actions.receiveActivities([body]))

          const searchQuery = PopupSelectors.searchQuery(store.getState())
          if (searchQuery && body.email.indexOf(searchQuery) !== -1) {
            observer.next(actions.receiveActivitiesByEmail([body]))
          }
        })
      })
    })
}

export const epic = combineEpics(
  triggerFetchActivitiesEpic,
  fetchActivities,
  fetchActivitiesByEmail,
  joinUserChannelPendingEpic,
)