#!/usr/bin/python3
import tty
import termios
import sys
import subprocess
out = subprocess.check_output('loginctl').decode('utf8')
users = {}
for line in out.splitlines():
    session = line[8:13].strip()
    user = line[22:30].strip()
    seat = line[39:].strip()
    if not user in users:
        users[user] = []
    users[user].append({'session':session, 'seat':seat})
session = None
for row in users['username']:
    if row['seat']: session = row['session']
def getchar():
   #Returns a single character from standard input
   fd = sys.stdin.fileno()
   old_settings = termios.tcgetattr(fd)
   try:
      tty.setraw(sys.stdin.fileno())
      ch = sys.stdin.read(1)
   finally:
      termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
   return ch

print("UNLOCK <=== SWIPE ===> LOCK")
while 1:
    c = getchar()
    if c == "\x01":
        ctrla = True
    elif ctrla and c == "p":
        subprocess.check_call("loginctl unlock-session "+session, shell=True)
        ctrla = False
    elif ctrla and c == "n":
        print(session)
        subprocess.check_call("loginctl lock-session "+session, shell=True)
        ctrla = False
    elif ctrla and c == "q":
        sys.exit()
    else:
        ctrla = False