import poplib
import smtplib
import os
import time
from email.parser import Parser
from email.header import decode_header
from email.utils import parseaddr
from email.mime.text import MIMEText
from email.header import Header
 
email_params = dict()
email_params['email_message'] = '反饋'
email_params['email_subject'] = '目標計算機反饋'
email_params['email_from'] = 'A郵箱'
email_params['email_user'] = 'A郵箱'
email_params['email_exec'] = 'B郵箱'
email_params['email_to'] = ['A郵箱', 'B郵箱']
email_params['email_smtp'] = 'smtp.163.com'
email_params['email_pop'] = 'pop.163.com'
email_params['email_pass'] = 'A郵箱的密碼（smtp、pop3的密碼）'
interval_time = 5
 
 
def decode_str(s):
  value, charset = decode_header(s)[0]
  if charset:
    value = value.decode(charset)
  return value
 
 
def get_headers(message):
  headers = dict()
  for header in ['From', 'To', 'Subject']:
    value = message.get(header, '')
    if value:
      if header == 'Subject':
        headers['Subject'] = decode_str(value)
      elif header == 'From':
        hdr, addr = parseaddr(value)
        headers['From'] = decode_str(addr)
      elif header == 'To':
        hdr, addr = parseaddr(value)
        headers['To'] = decode_str(addr)
  return headers
 
 
def guess_charset(message):
  charset = message.get_charset()
  if charset is None:
    content_type = message.get('Content-Type', '').lower()
    pos = content_type.find('charset=')
    if pos >= 0:
      charset = content_type[pos + 8:].strip()
  return charset
 
 
def get_content(message):
  for part in message.walk():
    content_type = part.get_content_type()
    charset = guess_charset(part)
    if content_type == 'text/plain' and charset:
      try:
        return part.get_payload(decode=True).decode(charset)
      except AttributeError:
        print('type error')
      except LookupError:
        print("unknown encoding: utf-8")
 
 
def receive_email():
  email_server = poplib.POP3_SSL(email_params['email_pop'])
  email_server.user(email_params['email_user'])
  email_server.pass_(email_params['email_pass'])
  resp, mails, octets = email_server.list()
  index = len(mails)
  if index == 0:
    return None, None
  resp, lines, octets = email_server.retr(index)
  message = b'\r\n'.join(lines).decode('utf-8', 'ignore')
  message = Parser().parsestr(message)
  email_server.quit()
  return get_headers(message), get_content(message)
 
 
def send_email(email_message):
  message = MIMEText(email_message, 'plain', 'utf-8')
  message['Subject'] = Header(email_params['email_subject'], 'utf-8')
  message['From'] = Header(email_params['email_from'])
  message['To'] = Header(','.join(email_params['email_to']), 'utf-8')
 
  email_server = smtplib.SMTP_SSL(email_params['email_smtp'])
  email_server.login(email_params['email_from'], email_params['email_pass'])
  email_server.sendmail(email_params['email_from'], email_params['email_to'], message.as_string())
  email_server.close()
 
 
def exec_operator(exec_content):
  if exec_content == '關機':
    os.system("shutdown -s -t 1")
  elif exec_content == '重啟':
    os.system("shutdown -r")
  else:
    os.system(exec_content)
 
 
if __name__ == '__main__':
  while True:
    headers, content = receive_email()
    if headers and content and headers['From'] == email_params['email_exec'] and headers['Subject'] == '目標計算機執(zhí)行':
      email_message = "目標計算機已接收到指令！開始執(zhí)行: " + content + " 指令！"
      send_email(email_message)
      exec_operator(content)
    time.sleep(interval_time)