import http from "http";
import { createHandler } from "graphql-sse/lib/use/http";
import { makeExecutableSchema } from "@graphql-tools/schema";
import { Repeater } from "@repeaterjs/repeater";

(async () => {
  const schema = makeExecutableSchema({
    typeDefs: `
      type Query {
        hello: String
      }
      type Subscription {
        wait: Boolean
      }
    `,
    resolvers: {
      Query: {
        hello() {
          return "Hello.";
        },
      },
      Subscription: {
        wait: {
          subscribe() {
            return new Repeater((push) => {
              push({ wait: true });
            });
          },
        },
      },
    },
  });

  const handler = createHandler({ schema, context: (req) => ({ req }) });

  const server = http.createServer(async (req, res) => {
    try {
      await handler(req, res);
    } catch (err) {
      console.error(err);
      res.writeHead(500).end();
    }
  });

  server.listen(8000);
  console.log("Listening to port 8000");
})();

...
Subscription: {
  wait: {
    subscribe(root, args, { req }, info) {
      const res = req.context.res;
      return new Repeater((push, stop) => {
        const interval = setInterval(() => {
          res.write(":\n\n");
        }, 5_000);
        stop.then(() => {
          clearInterval(interval);
        });
        push({ wait: true });
      });
    },
  },
},
...