import { makeExecutableSchema } from 'graphql-tools';
import { SchemaLink } from 'apollo-link-schema';
import { InMemoryCache } from 'apollo-cache-inmemory';
import ApolloClient from 'apollo-client';

const typeDefs = `
  type Hello {
    message: String
  }
`;

const resolvers = {
  Query: {
    message: (root, args, context, info) => "hello-world"
  }
};

const schema = makeExecutableSchema({
  typeDefs,
  resolvers
});

const client = new ApolloClient({
  link: new SchemaLink({ schema }),
  cache: new InMemoryCache()
})

// You can use this client in your app and it will work like any other GraphQL server

import { makeRemoteExecutableSchema, introspectSchema, mergeSchemas } from 'graphql-tools';
import { SchemaLink } from 'apollo-link-schema';
import ApolloClient from 'apollo-client';

const uri1 = 'https://server1.com/graphql';
const uri2 = 'https://server2.com/graphql';

const getRemoteExecutableSchema = async (uri) => {
  const httpLink = new HttpLink({ uri });
  const remoteSchema = await introspectSchema(httpLink);
  return makeRemoteExecutableSchema({ schema: remoteSchema, link: httpLink });
}

const executableSchema1 = await getRemoteExecutableSchema(uri1);
const executableSchema2 = await getRemoteExecutableSchema(uri2);

const newSchema = mergeSchemas({
  schemas: [
    executableSchema1,
    executableSchema2
  ]
});

const client = new ApolloClient({
  link: new SchemaLink({ schema: newSchema }),
  cache: new InMemoryCache()
});

// You can use this client in your app and it will work like any other GraphQL server

const resolvers = {
  Query: {
    ...
  },
  Mutation: {
    ...
  }
}

const newSchema = mergeSchemas({
  schemas: [
    executableSchema1,
    executableSchema2
  ],
  resolvers: resolvers
});