const AlbumType = new GraphQLObjectType({
  name: "Album",
  fields: {
    id: {
      type: new GraphQLNonNull(GraphQLInt),
      description: "The id of the Album."
    },
    name: {
      type: new GraphQLNonNull(GraphQLString),
      description: "The name of the Album."
    },
    year: {
      type: GraphQLString,
      description: "The year of the Album."
    },
    artist_id: {
      type: GraphQLInt,
      description: "The artist_id of the Album."
    },
    artist: {
      type: ArtistType,
      resolve: (parent) => parent.getArtist()
    }
  }
})

const ArtistType = new GraphQLObjectType({
  name: "Artist",
  fields: {
    id: {
      type: new GraphQLNonNull(GraphQLInt),
      description: "The id of the Artist."
    },
    name: {
      type: new GraphQLNonNull(GraphQLString),
      description: "The name of the Artist."
    },
    url: {
      type: GraphQLString,
      description: "The url of the Artist."
    },
    albums: {
      type: new GraphQLList(AlbumType),
      resolve: (parent, args, context) => parent.getAlbums()
    }
  }
})