client.js

import {
  ApolloClient,
  ApolloLink,
  from,
  HttpLink,
  InMemoryCache,
} from '@apollo/client'
import { onError } from 'apollo-link-error'
import fetch from 'isomorphic-fetch'
import possibleTypes from './possibleTypes.json'

const httpLink = new HttpLink({
  uri: process.env.GATSBY_GRAPHQL_URL,
  fetch,
  credentials: 'include',
})

const middleware = new ApolloLink((operation, forward) => {
  const session = process.browser && localStorage.getItem('woo-session')

  if (session) {
    operation.setContext(() => ({
      headers: {
        'woocommerce-session': `Session ${session}`,
      },
    }))
  }
  return forward(operation)
})

const onErrorLink = onError(({ graphQLErrors, networkError }) => {
  if (graphQLErrors) {
    graphQLErrors.forEach(({ message, locations, path, extensions }) => {
      console.log(`[GraphQL error]:`, {
        Message: message,
        Location: locations,
        Path: path,
        Extension: extensions,
      })
    })
  }

  if (networkError) {
    console.log(`[Network error]: ${networkError}`)
  }
})

/**
 * Afterware operation.
 *
 * This catches the incoming session token and stores it in localStorage, for future GraphQL requests.
 */
export const afterware = new ApolloLink((operation, forward) =>
  forward(operation).map(response => {
    /**
     * Check for session header and update session in local storage accordingly.
     */
    const context = operation.getContext()
    const {
      response: { headers },
    } = context

    console.log('Headers: ')
    console.log(headers.get('woocommerce-session'))

    const session = headers.get('woocommerce-session')

    if (session) {
      // Remove session data if session destroyed.
      if (session === 'false') {
        localStorage.removeItem('woo-session')

        // Update session new data if changed.
      } else if (localStorage.getItem('woo-session') !== session) {
        localStorage.setItem('woo-session', headers.get('woocommerce-session'))
      }
    }
    return response
  })
)

export const client = new ApolloClient({
  link: from([middleware, onErrorLink, afterware, httpLink]),
  cache: new InMemoryCache({ possibleTypes }),
})