React Native Apollo client setup

apollo.js

import { createHttpLink } from 'apollo-link-http'
import { ApolloLink, split, concat } from 'apollo-link'
import { ApolloClient } from 'apollo-client'
import { WebSocketLink } from 'apollo-link-ws'
import { getMainDefinition } from 'apollo-utilities'
import { InMemoryCache } from 'apollo-cache-inmemory'
import { onError } from 'apollo-link-error'
import { withClientState } from 'apollo-link-state'

import env from '../env.json'
import { defaults, resolvers } from './local-state'

function hasSubscriptionOperation({ query }) {
  const { kind, operation } = getMainDefinition(query)
  return kind === 'OperationDefinition' && operation === 'subscription'
}

export function createClient(token) {

  const httpLink = createHttpLink({ uri: env.API_ENDPOINT })

  const wsLink = new WebSocketLink({
    uri: env.API_SUBSCRIPTION_ENDPOINT,
    options: {
      reconnect: true,
      connectionParams: {
        authorization: token ? `Bearer ${token}` : ''
      }
    }
  })

  const link = split(
    hasSubscriptionOperation,
    wsLink,
    httpLink
  )

  const stateLink = withClientState({ resolvers, cache, defaults })

  const cache = new InMemoryCache()

  const authMiddleware = new ApolloLink((operation, forward) => {
    operation.setContext(context => ({
      ... context,
      headers: {
        ...context.headers,
        authorization: token ? `Bearer ${token}` : ''
      }
    }))
    return forward(operation)
  })

  const client = new ApolloClient({
    link: ApolloLink.from([
      onError(({ graphQLErrors, networkError }) => {
        if (graphQLErrors)
          graphQLErrors.map(({ message, locations, path }) =>
            console.log(
              `[GraphQL error]: Message: ${message}, Location: ${JSON.stringify(locations)}, Path: ${path}`,
            ),
          )
        if (networkError) console.log(`[Network error]: ${networkError}`)
      }),
      stateLink,
      concat(authMiddleware, link)
    ]),
    cache
  })

  return client
}