#!/usr/bin/env python3
"""shellmcp: an MCP server with one tool, `run`, that runs a bash command. Stdlib only, stdio.

--mode readonly (default) runs every command in a bubblewrap sandbox: the filesystem is
read-only except a private /tmp, there is no network, no other process is visible, and the
--hide paths (always ~/.ssh and ~/.gnupg) look empty. --mode all runs commands with the
user's full permissions; let the MCP client ask before each call.
"""

import argparse
import getpass
import json
import os
import shutil
import signal
import socket
import subprocess
import sys

ENV = {"PAGER": "cat", "GIT_PAGER": "cat", "NO_COLOR": "1", "TERM": "dumb"}


def cut(text, limit):
    """text, or its head and tail around a note when it is longer than limit."""
    if len(text) <= limit:
        return text
    half = limit // 2
    return f"{text[:half]}\n[... {len(text) - 2 * half} characters cut ...]\n{text[-half:]}"


def run(command, cwd, timeout=60, limit=8000, prefix=()):
    """The exit code and combined stdout and stderr of `bash -c command`, as one text."""
    proc = subprocess.Popen([*prefix, "bash", "-c", command], cwd=cwd, stdin=subprocess.DEVNULL,
                            stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                            env={**os.environ, **ENV}, start_new_session=True)
    try:
        out, _ = proc.communicate(timeout=timeout)
        head = f"exit code {proc.returncode}"
    except subprocess.TimeoutExpired:
        os.killpg(proc.pid, signal.SIGKILL)
        try:
            out, _ = proc.communicate(timeout=5)
        except subprocess.TimeoutExpired:  # a process left the group and holds the pipe
            out = b""
        head = f"timed out after {timeout} s, killed"
    return f"{head}\n{cut(out.decode(errors='replace'), limit)}"