import { execSync } from "child_process";

export function treeKillSync(pid: number, signal?: string | number): void {
  if (process.platform === "win32") {
    execSync("taskkill /pid " + pid + " /T /F");
    return;
  }

  const childs = getAllChilds(pid);
  childs.forEach(function (pid) {
    killPid(pid, signal);
  });

  killPid(pid, signal);
  return;
}

function getAllPid(): {
  pid: number;
  ppid: number;
}[] {
  const rows = execSync("ps -A -o pid,ppid")
    .toString()
    .trim()
    .split("\n")
    .slice(1);

  return rows
    .map(function (row) {
      const parts = row.match(/\s*(\d+)\s*(\d+)/);

      if (parts === null) {
        return null;
      }

      return {
        pid: Number(parts[1]),
        ppid: Number(parts[2]),
      };
    })
    .filter(<T>(input: null | undefined | T): input is T => {
      return input != null;
    });
}

function getAllChilds(pid: number) {
  const allpid = getAllPid();

  const ppidHash: {
    [key: number]: number[];
  } = {};

  const result: number[] = [];

  allpid.forEach(function (item) {
    ppidHash[item.ppid] = ppidHash[item.ppid] || [];
    ppidHash[item.ppid].push(item.pid);
  });

  const find = function (pid: number) {
    ppidHash[pid] = ppidHash[pid] || [];
    ppidHash[pid].forEach(function (childPid) {
      result.push(childPid);
      find(childPid);
    });
  };

  find(pid);
  return result;
}

function killPid(pid: number, signal?: string | number) {
  try {
    process.kill(pid, signal);
  } catch (err) {
    const error = err as any;
    if (error.code !== "ESRCH") {
      throw error;
    }
  }
}