Prototype reader for MyWay card dumps.

myway_reader.py

#!/usr/bin/env python
# -*- mode: python; indent-tabs-mode: nil; tab-width: 2 -*-
"""
myway_reader.py
Prototype reader for MyWay (ACT) card dumps.
See https://github.com/micolous/metrodroid/wiki/MyWay for format details.

Copyright 2016 Michael Farrell <[email protected]>

Note: This loads the entire file into memory blindly.  Do not use on large file
sizes, as the memory usage of this file is extremely inefficient.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
"""

from __future__ import print_function
from argparse import ArgumentParser, FileType
from struct import unpack
from datetime import datetime, timedelta

EPOCH = datetime(2000,1,1,0,0)

def parse_myway(input_data):
  if len(input_data) != 1024:
    raise Exception, 'mfc data must be exactly 1024 bytes'

  # don't know how to check header yet

  # Read balance (sector 2&3, block 2)
  for off in (0xa0, 0xe0):
    # TODO: figure out balance priorities
    balance = unpack('<7xH7x', input_data[off:off+16])[0]
    balance /= 100.
    print('Balance: $%.2f' % balance)
  
  # Read trips (sector 10-12, blocks 0-2)
  trips = []
  for off in (0x280, 0x290, 0x2a0, 0x2c0, 0x2d0, 0x2e0, 0x300, 0x310, 0x320):
    ts, tap_on, route, cost = unpack('<3xLB4s1xH1x', input_data[off:off+16])

    ts = EPOCH + timedelta(seconds=ts)
    tag_on = (tap_on & 0x10 == 0x10)
    route = route.rstrip('\0')
    cost /= 100.
    
    trips.append((ts.isoformat(), cost, route, 'on' if tag_on else 'off'))
  
  # Place trips in chronological order to make things nicer.
  trips.sort(key=lambda x: x[0])
  for trip in trips:
    print('%s: $%.2f %s Tag %s' % trip)
  

def main():
  parser = ArgumentParser()
  parser.add_argument('input', type=FileType('rb'), nargs=1)
  options = parser.parse_args()
  parse_myway(options.input[0].read())

if __name__ == '__main__':
  main()