import { createSubgraph } from "../../subgraph.js";
import { books } from "./data.js";

export default createSubgraph("a", {
  typeDefs: /* GraphQL */ `
    extend schema
      @link(url: "https://specs.apollo.dev/federation/v2.3", import: ["@key"])

    type Query {
      bookContainers: [BookContainer]
    }
    type BookContainer {
      book: Book
    }
    type Book @key(fields: "upc") {
      upc: ID!
    }
  `,
  resolvers: {
    Query: {
      bookContainers() {
        return books.map((book) => ({ book: { upc: book.upc } }));
      },
    },
    Book: {
      __resolveReference(reference: { upc: String }) {
        if (reference != null) {
          let book = books.find((book) => book.upc === reference.upc);
          if (book != null && book.upc !== null) {
            return {
              __typename: "Book",
              upc: book.upc,
            };
          }
        }
        throw new Error("Invalid reference");
      },
    },
  },
});