import * as plugins from './smartexit.plugins.js';
import type { TProcessSignal } from './smartexit.types.js';

export interface IProcessTreeSignalResult {
  status: 'signalled' | 'notFound' | 'failed';
  error?: unknown;
}

export interface IProcessGroupProbeResult {
  status: 'exists' | 'notFound' | 'failed';
  error?: unknown;
}

const errorCodeFor = (errorArg: unknown): string | undefined => {
  if (typeof errorArg !== 'object' || errorArg === null || !('code' in errorArg)) {
    return undefined;
  }
  const { code } = errorArg;
  return typeof code === 'string' ? code : undefined;
};

const probeExactProcessByPid = (pidArg: number): IProcessGroupProbeResult => {
  try {
    process.kill(pidArg, 0);
    return { status: 'exists' };
  } catch (error) {
    const errorCode = errorCodeFor(error);
    if (errorCode === 'ESRCH') {
      return { status: 'notFound' };
    }
    if (errorCode === 'EPERM') {
      return { status: 'exists' };
    }
    return { status: 'failed', error };
  }
};

/**
 * Signal one owned process tree synchronously so shutdown and the final exit
 * safety net use the same OS contract.
 */
export const signalProcessTreeByPid = (
  pidArg: number,
  signalArg: TProcessSignal,
): IProcessTreeSignalResult => {
  if (process.platform === 'win32') {
    if (probeExactProcessByPid(pidArg).status === 'notFound') {
      return { status: 'notFound' };
    }
    try {
      plugins.childProcess.execFileSync(
        'taskkill',
        ['/T', '/F', '/PID', String(pidArg)],
        { stdio: 'ignore' },
      );
      return { status: 'signalled' };
    } catch (error) {
      if (probeExactProcessByPid(pidArg).status === 'notFound') {
        return { status: 'notFound' };
      }
      return { status: 'failed', error };
    }
  }

  try {
    process.kill(-pidArg, signalArg);
    return { status: 'signalled' };
  } catch (error) {
    if (errorCodeFor(error) === 'ESRCH') {
      return { status: 'notFound' };
    }
    return { status: 'failed', error };
  }
};

/** Probe the exact POSIX process group owned by a detached group leader. */
export const probeProcessGroupByPid = (pidArg: number): IProcessGroupProbeResult => {
  try {
    process.kill(-pidArg, 0);
    return { status: 'exists' };
  } catch (error) {
    const errorCode = errorCodeFor(error);
    if (errorCode === 'ESRCH') {
      return { status: 'notFound' };
    }
    if (errorCode === 'EPERM') {
      return { status: 'exists' };
    }
    return { status: 'failed', error };
  }
};