store.js

import { createStore, applyMiddleware, compose } from 'redux'
import withRedux from 'next-redux-wrapper'
import Immutable from 'seamless-immutable'
import nextReduxSaga from 'next-redux-saga'
import createSagaMiddleware from 'redux-saga'

import rootReducer from './reducers'
import rootSaga from './sagas'

const sagaMiddleware = createSagaMiddleware()
const dev = process.env.NODE_ENV !== 'production'
const windowExist = typeof window === 'object'

/* eslint-disable no-underscore-dangle */
const composeEnhancers =
  dev && windowExist && window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__
    ? window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__
    : compose

/* eslint-enable */

export function configureStore (initialState = {}) {
  /* eslint-disable no-param-reassign */
  if (!initialState.toJS) initialState = Immutable(initialState)

  const store = createStore(
    rootReducer(),
    initialState,
    composeEnhancers(applyMiddleware(sagaMiddleware))
  )

  store.sagaTask = sagaMiddleware.run(rootSaga)
  return store
}

export function withReduxSaga (BaseComponent) {
  return withRedux(configureStore)(nextReduxSaga(BaseComponent))
}