import os
import sys
import getpass
from uuid import uuid4


def build_config(user_name):
    """Generates a sudoers configuration to allow passwordless execution of sshuttle."""

    argv0 = os.path.abspath(sys.argv[0])
    is_python_script = argv0.endswith('.py')
    executable = f"{sys.executable} {argv0}" if is_python_script else argv0
    dist_packages = os.path.dirname(os.path.abspath(__file__))
    cmd_alias = f"SSHUTTLE{uuid4().hex[-3:].upper()}"

    template = f"""
# WARNING: If you intend to restrict a user to only running the
# sshuttle command as root, THIS CONFIGURATION IS INSECURE.
# When a user can run sshuttle as root (with or without a password),
# they can also run other commands as root because sshuttle itself
# can run a command specified by the user with the --ssh-cmd option.

# INSTRUCTIONS: Add this text to your sudo configuration to run
# sshuttle without needing to enter a sudo password. To use this
# configuration, run 'visudo /etc/sudoers.d/sshuttle_auto' as root and
# paste this text into the editor that it opens. If you want to give
# multiple users these privileges, you may wish to use different
# filenames for each one (i.e., /etc/sudoers.d/sshuttle_auto_john).

# This configuration was initially generated by the
# 'sshuttle --sudoers-no-modify' command.

Cmnd_Alias {cmd_alias} = /usr/bin/env PYTHONPATH={dist_packages} {executable} *

{user_name} ALL=NOPASSWD: {cmd_alias}
"""

    return template


def sudoers(user_name=None):
    user_name = user_name or getpass.getuser()
    content = build_config(user_name)
    sys.stdout.write(content)
    exit(0)