#!/usr/bin/env python3

from base64 import b32decode
from os import environ, listdir, path, uname
from pathlib import Path
from sshync import get_profile
from sshyp import decrypt, shm_gen, whitelist_verify
from subprocess import PIPE, Popen, run
from sys import argv, exit as s_exit
from time import sleep, strftime, time


def totp(_secret, _algo, _digits, _period):  # uses provided information to generate a standard totp key
    from hmac import new as new_mac
    from struct import pack, unpack
    _secret = b32decode(_secret.upper() + '=' * ((8 - len(_secret)) % 8))
    _counter = pack('>Q', int(time() / _period))
    _mac = new_mac(_secret, _counter, _algo).digest()
    _offset = _mac[-1] & 0x0f
    _binary = unpack('>L', _mac[_offset:_offset + 4])[0] & 0x7fffffff
    return str(_binary)[-_digits:].zfill(_digits)


def mfa_read_shortcut():  # extracts MFA info from the user-specified sshyp entry
    from shutil import rmtree
    if not Path(f"{directory}{arguments[0]}.gpg").exists():
        print(f"\n\u001b[38;5;9merror: entry ({arguments[0]}) does not exist\u001b[0m\n")
        s_exit(1)
    _shm_folder, _shm_entry = shm_gen()
    if quick_unlock_enabled == 'y':
        decrypt(directory + arguments[0], _shm_folder, _shm_entry, whitelist_verify(port, username_ssh, ip, device_id))
    else:
        decrypt(directory + arguments[0], _shm_folder, _shm_entry, False)
    try:
        _mfa_data = open(f"{path.expanduser('~/.config/sshyp/tmp/')}{_shm_folder}/{_shm_entry}", 'r').readlines()
        _type = _mfa_data[4].split('otpauth://')[1].split('/')[0]
        _secret = _mfa_data[4].split('?secret=')[1].split('&issuer=')[0]
        _algo = _mfa_data[4].split('&algorithm=')[1].split('&digits=')[0]
        _digits = int(_mfa_data[4].split('&digits=')[1].split('&period=')[0])
        _period = int(_mfa_data[4].split('&period=')[1])
        rmtree(f"{path.expanduser('~/.config/sshyp/tmp/')}{_shm_folder}")
        return _type, _secret, _algo, _digits, _period
    except IndexError:
        print(f"\n\u001b[38;5;9merror: entry ({arguments[0]}) does not contain valid mfa data\u001b[0m\n")
        rmtree(f"{path.expanduser('~/.config/sshyp/tmp/')}{_shm_folder}")
        s_exit(1)


if __name__ == '__main__':
    # argument fetcher
    arguments = argv[1:]
    if len(arguments) < 1 or not arguments[0].startswith('/'):
        print("\nsshyp-mfa extension usage: sshyp </entry name> copy -m\n\nrun 'man sshyp-mfa' for more information\n")
        s_exit(1)

    # user data fetcher
    device_id = listdir(path.expanduser('~/.config/sshyp/devices'))[0]
    quick_unlock_enabled = open(path.expanduser('~/.config/sshyp/sshyp-data')).readlines()[3].rstrip()
    ssh_info = get_profile(path.expanduser('~/.config/sshyp/sshyp.sshync'))
    username_ssh = str(ssh_info[0].rstrip())
    ip = str(ssh_info[1].rstrip())
    port = str(ssh_info[2].rstrip())
    directory = str(ssh_info[3].rstrip())

    # main process: runs functions to generate MFA key, then continuously copies up-to-date MFA key to clipboard
    try:
        mfa_data, copied = mfa_read_shortcut(), None
        print('\nmfa key copied to clipboard\n\nuntil this process is closed, your clipboard will be automatically '
              'updated with the newest mfa key')
        while True:
            if str(int(strftime('%S'))/mfa_data[4]).endswith('.0') or copied is None:
                if copied is None:
                    copied = 1
                if mfa_data[0] == 'steam':
                    from steam.guard import generate_twofactor_code as steam_totp
                    _mfa_key = steam_totp(b32decode(mfa_data[1]))
                else:
                    _mfa_key = totp(mfa_data[1], mfa_data[2], mfa_data[3], mfa_data[4])
                if 'WSL_DISTRO_NAME' in environ:  # WSL clipboard detection
                        run(('powershell.exe', '-c', 'Set-Clipboard', _mfa_key))
                elif 'WAYLAND_DISPLAY' in environ:  # Wayland clipboard detection
                    run(('wl-copy', _mfa_key))
                elif uname()[0] == 'Haiku':  # Haiku clipboard detection
                    run(('clipboard', '-c', _mfa_key))
                elif Path("/data/data/com.termux").exists():  # Termux (Android) clipboard detection
                    run(('termux-clipboard-set', _mfa_key))
                else:  # X11 clipboard detection
                    run(('xclip', '-sel', 'c'), stdin=Popen(('echo', '-n', _mfa_key), stdout=PIPE).stdout)
            sleep(1)
    except KeyboardInterrupt:
        print('\n')
        s_exit(0)