export interface IFlexChildShutdownOptions {
  dispose: () => Promise<void>;
  closeDescriptors: () => void;
  getExitCode: () => number | undefined;
  setExitCode: (exitCodeArg: number) => void;
  forceExit: (exitCodeArg: number) => void;
  timeoutMs: number;
}

export const createFlexChildShutdown = (
  optionsArg: IFlexChildShutdownOptions,
): ((fatalArg: boolean) => void) => {
  let shutdownTask: Promise<void> | undefined;
  let watchdog: ReturnType<typeof setTimeout> | undefined;
  let descriptorsClosed = false;
  const closeDescriptors = (): void => {
    if (descriptorsClosed) return;
    optionsArg.closeDescriptors();
    descriptorsClosed = true;
  };
  return (fatalArg: boolean): void => {
    if (fatalArg) optionsArg.setExitCode(1);
    else if (optionsArg.getExitCode() === undefined) optionsArg.setExitCode(0);
    if (!watchdog) {
      watchdog = setTimeout(() => {
        watchdog = undefined;
        try {
          closeDescriptors();
        } finally {
          optionsArg.forceExit(optionsArg.getExitCode() ?? 1);
        }
      }, optionsArg.timeoutMs);
    }
    if (shutdownTask) return;
    shutdownTask = optionsArg.dispose().then(() => {
      closeDescriptors();
      if (watchdog) {
        clearTimeout(watchdog);
        watchdog = undefined;
      }
    }).catch(() => {
      optionsArg.setExitCode(1);
      try {
        closeDescriptors();
      } catch {
        // The armed watchdog retries descriptor closure before forcing process exit.
      }
    });
  };
};