const {
  GraphQLObjectType,
  GraphQLSchema,
  GraphQLList
} = require('graphql');
const songType = require('./queries/song');
const singerType = require('./queries/singer');
const songMutations = require('./mutations/song/');
const singerMutations = require('./mutations/singer/');



module.exports = new GraphQLSchema({
  query: new GraphQLObjectType({
    name: 'RootQueryType',
    fields: {
      song: songType,
      songs: {
        type: new GraphQLList(songType),
      },
      singer: singerType,
      singers: {
        type: new GraphQLList(singerType)
      }
    }
  }),
  mutation: new GraphQLObjectType({
    name: 'RootMutation',
    fields: {
      ...songMutations,
      ...singerMutations
    }
  })
});

type Singer {
    id: String!
    fullName: String!
    songs: [Song!]!
  }

{
  fields: () => ({ // <-------------- 😎
    id: ...
    singer: ...
  })
}