import { createLink } from './link';
import { ApolloClient, InMemoryCache } from '@apollo/client';
import { isServer } from 'tools/common';

/** @type {import('@apollo/client').ApolloClient<import('@apollo/client').NormalizedCacheObject>} */
let apolloClient;

function createApolloClient(headers) {
  return new ApolloClient({
    cache: new InMemoryCache(),
    link: createLink(headers),
    ssrMode: isServer(),
  });
}

export default function initializeApollo(initialState, headers) {
  if (isServer() && !headers) {
    throw new Error('initializeApollo: headers must be provided in server side');
  }

  const _apolloClient = apolloClient ?? createApolloClient(headers);

  // If your page has Next.js data fetching methods that use Apollo Client, the initial state
  // gets hydrated here
  if (initialState) {
    _apolloClient.cache.restore(initialState);
  }
  // For SSG and SSR always create a new Apollo Client
  if (isServer()) return _apolloClient;
  // Create the Apollo Client once in the client
  if (!apolloClient) apolloClient = _apolloClient;

  return _apolloClient;
}