network.js

import {MainApi} from '../api'
// import * as postActions from '../actions/post'

// Similar to redux thunk
// type ReduxAction = {
//   dispatch: function
// , getState: function
// }
type StateFuncs = {
  getState: function
, setState: function
}
// It means you can just put this.props in and get a good outcome
async function getPosts(...params, {setState, getState}: StateFuncs){
  // first, we check posts
  if (getState().posts.isPostsLoading) {
    return
  }
  if (getState().posts.posts.length) {
    return // caching?
  }
  setState({isPostsLoading: true})
  const {token} = getState().user
  const api = new MainApi({token})
  try {
    const posts = await api.getPosts()
    setState({isPostsLoading: false, posts})
  } catch (err) {
    console.error('err', err.message, err)
    setState({isPostsLoading: false, errorText: 'Sorry, we failed to reach the server'})
  }
}