import { run } from "@ludus/ludus-js-pure"
import { unlinkSync, readFileSync } from "node:fs"

export async function listen () {
  const port = Math.floor((Math.random() * 1000) + 50000)
  const session_token = crypto.randomUUID();
  const repl_file_path = ".lrepl"
  const repl_info = { port, session: session_token }
  const repl_file = Bun.file(repl_file_path)
  await Bun.write(repl_file, JSON.stringify(repl_info))

  console.log(`Ludus REPL listening on localhost:${port}`)
  console.log(`Session token: ${session_token}`)

  Bun.listen({
    hostname: "localhost",
    port,
    socket: {
      data: (_, data) => {
        const payload = data.toString("utf-8")
        let session, source
        try {
          const json_msg = JSON.parse(payload)
          session = json_msg.session
          source = json_msg.source
        } catch (e) {
          console.log("Received malformed message.")
          return
        }
        if (session !== session_token) {
          console.log("Received message not from this REPL session.")
          return
        }
        const result = run(source)
        if (!result.errors) console.log("=>", result.result)
        else {
          console.log("Ludus had some errors:")
          console.log(result.errors)
        }
      },
      error: (socket, error) => { console.log(error); socket.end() }
    }
  })


  process.on("exit", async function () {
    try { cleanup(repl_file_path, session_token) } catch (e) {}
    console.log("\nGoodbye.")
  })

  process.on("SIGINT", () => process.exit())

  // Below here, I'm trying to get ctrl-d to work to close the listener
  // the while (true) loop locks the listener
  // see: https://github.com/oven-sh/bun/issues/3255
  // this should be doable with process.stdin.on("close"...)
  //const mystdin = Bun.file("/dev/stdin").stream().getReader()

  // while (true) {
  //   const {done, value} = await mystdin.read()
  //   if (done) process.exit()
  //   console.log(value)
  // }

}

// Don't delete an .lrepl we don't own
function cleanup (path: string, session_token: string) {
  const repl_file = readFileSync(path).toString("utf-8")
  const {session} = JSON.parse(repl_file)
  if (session === session_token) unlinkSync(path)
}