import { releaseLock } from "./lock";
import { logUtil } from "./logger";

/**
 * Daemonize the current process: spawns a detached child and exits the parent.
 *
 * When __IS_DAEMON is already set this is a no-op (the child continues).
 * Otherwise the parent releases its lock, spawns the child via Bun.spawn,
 * unrefs it so the child outlives the parent, and exits once the child
 * process is confirmed running (polls PID existence, 1s max).
 */
export function daemonize(): void {
  if (process.env["__IS_DAEMON"]) return; // child — keep running

  releaseLock();

  const child = Bun.spawn({
    cmd: [process.execPath, ...process.argv.slice(1)],
    stdout: "ignore",
    stderr: "ignore",
    stdin: "ignore",
    env: { ...process.env, __IS_DAEMON: "1" },
    cwd: process.cwd(),
  });

  child.unref();

  logUtil.log(`Backgrounded with PID ${child.pid}`);

  // Poll until the child process actually exists, then exit the parent.
  // Falls back to a hard exit after 1 second in case the child fails to start.
  const start = Date.now();
  const poll = setInterval(() => {
    try {
      process.kill(child.pid, 0); // signal 0 = existence check only
      clearInterval(poll);
      process.exit(0);
    } catch {
      if (Date.now() - start > 1000) {
        clearInterval(poll);
        process.exit(0);
      }
    }
  }, 50);
}