sql-edition/servers/VendingMachine.py

   1 # vim:ts=4
   2 import re
   3 from CRC import do_crc
   4 from select import select
   5 import socket, logging
   6
   7 asynchronous_responses = [      '400', '401', # door open/closed
   8                                 '610',        # switches changed
   9                                 '200', '201', '202', '203', '204', '205', '206',
  10                                 '207', '208', '209', '211', # key presses
  11                          ]
  12 DOOR = 1
  13 SWITCH = 2
  14 KEY = 3
  15
  16 class VendingException(Exception): pass
  17
  18 class VendingMachine:
  19         def __init__(self, rfh, wfh):
  20                 self.events = []
  21                 self.secret = 'AAAAAAAAAAAAAAAA'
  22                 self.rfh = rfh
  23                 self.wfh = wfh
  24                 self.challenge = None
  25                 # Initialise ourselves into a known state
  26                 self.wfh.write('\n')
  27                 self.await_prompt()
  28                 self.wfh.write('echo off\n')
  29                 self.await_prompt()
  30                 self.wfh.write('PING\n')
  31                 code = ''
  32                 while code != '000':
  33                         code = self.get_response()[0]
  34                 self.get_switches()
  35
  36         def await_prompt(self):
  37                 self.wfh.flush()
  38                 state = 1
  39                 prefix = ''
  40                 s = ''
  41                 while True:
  42                         try:
  43                                 s = self.rfh.read(1)
  44                         except socket.error:
  45                                 raise VendingException('failed to read input from vending machine')
  46                         if s == '': raise VendingException('nothing read!')
  47                         if (s != '#' and s != '%') and state == 1: prefix += s
  48                         if s == '\n' or s == '\r':
  49                                 state = 1
  50                                 prefix = ''
  51                         if (s == '#' or s == '%') and state == 1: state = 2
  52                         if s == ' ' and state == 2:
  53                                 if prefix == '':
  54                                         self.challenge = None
  55                                         return
  56                                 if re.search('^[0-9a-fA-F]{4}$', prefix):
  57                                         self.challenge = int(prefix, 16)
  58                                         return
  59
  60         def get_response(self, async = False):
  61                 self.wfh.flush()
  62                 while True:
  63                         s = ''
  64                         while s == '':
  65                                 s = self.rfh.readline()
  66                                 if s == '':
  67                                         raise VendingException('Input socket has closed!')
  68                                 s = s.strip('\r\n')
  69                         code = s[0:3]
  70                         text = s[4:]
  71                         if code in asynchronous_responses:
  72                                 self.handle_event(code, text)
  73                                 if async: return None
  74                         else:
  75                                 self.await_prompt()
  76                                 return (code, text)
  77
  78         def get_switches(self):
  79                 self.wfh.write('S\n')
  80                 (code, text) = self.get_response()
  81                 if code != '600':
  82                         return (False, code, text)
  83                 self.interpret_switches(text)
  84                 return (True, code, text)
  85
  86         def interpret_switches(self, text):
  87                 self.switches = (int(text[0:2], 16) << 8) | int(text[3:5], 16)
  88
  89         def handle_event(self, code, text):
  90                 if code == '400':
  91                         self.events.append((DOOR, 1))
  92                 elif code == '401':
  93                         self.events.append((DOOR, 0))
  94                 elif code == '610':
  95                         self.events.append((SWITCH, None))
  96                         self.interpret_switches(text)
  97                 elif code[0] == '2':
  98                         self.events.append((KEY, int(code[1:3])))
  99                 else:
 100                         logging.warning('Unhandled event! (%s %s)\n'%(code,text))
 101
 102         def authed_message(self, message):
 103                 if self.challenge == None:
 104                         return message
 105                 crc = do_crc('%c%c'%(self.challenge >> 8, self.challenge & 0xff))
 106                 crc = do_crc(self.secret, crc)
 107                 crc = do_crc(message, crc)
 108                 return message+'|'+('%04x'%crc)
 109
 110         def ping(self):
 111                 self.wfh.write('PING\n')
 112                 (code, string) = self.get_response()
 113                 return (code == '000', code, string)
 114
 115         def vend(self, item):
 116                 if not re.search('^[0-9][0-9]$', item):
 117                         return (False, 'Invalid item requested (%s)'%item)
 118                 self.wfh.write(self.authed_message(('V%s'%item))+'\n')
 119                 (code, string) = self.get_response()
 120                 return (code == '100', code, string)
 121
 122         def beep(self, duration = None, synchronous = True):
 123                 msg = 'B'
 124                 if synchronous: msg += 'S'
 125                 if duration != None:
 126                         if duration > 255: duration = 255
 127                         if duration < 1: duration = 1
 128                         msg += '%02x'%duration
 129                 self.wfh.write(msg+'\n')
 130                 (code, string) = self.get_response()
 131                 return (code == '500', code, string)
 132
 133         def silence(self, duration = None, synchronous = True):
 134                 msg = 'C'
 135                 if synchronous: msg += 'S'
 136                 if duration != None:
 137                         if duration > 255: duration = 255
 138                         if duration < 1: duration = 1
 139                         msg += '%02x'%duration
 140                 self.wfh.write(msg+'\n')
 141                 (code, string) = self.get_response()
 142                 return (code == '501', code, string)
 143
 144         def display(self, string):
 145                 if len(string) > 10:
 146                         string = string[0:10]
 147                 self.wfh.write('D'+string+'\n')
 148                 (code, string) = self.get_response()
 149                 return (code == '300', code, string)
 150
 151         def next_event(self, timeout = None):
 152                 # we don't want to buffer in the serial port, so we get all the events
 153                 # we can ASAP.
 154                 if len(self.events) > 0: timeout = 0
 155                 while True:
 156                         (r, _, _) = select([self.rfh], [], [], timeout)
 157                         if r:
 158                                 self.get_response(async = True)
 159                                 timeout = 0
 160                         else:
 161                                 break
 162                 if len(self.events) == 0: return None
 163                 ret = self.events[0]
 164                 del self.events[0]
 165                 return ret