#!/usr/bin/python2.7


import signal
import sys
import time
import serial
import io
import getopt
import threading

interval = '0.1'



class SerialDevice():
  def __init__(self, device, interval):
    self.interval = interval
    self.data = (0,None,None)
    self.dataLock = threading.Lock()
    self._threadStopFlag = threading.Event()
    try:
      self.port=serial.Serial(port=device,
                         baudrate=2400,
                         bytesize=serial.EIGHTBITS,
                         stopbits=serial.STOPBITS_ONE,
                         parity=serial.PARITY_NONE,
                         timeout=None)

      if not self.port.isOpen():
        self.port.open()

    except IOError,err:
      print '\nError:' + str(err) + '\n'
      sys.exit(1)

    ## starting event loop

    self.t = threading.Thread(target=self._eventLoop)
    self.t.start()

  def __enter__(self):
    return self

  def __exit__(self, type, value, traceback):
    self._threadStopFlag.set()
    self.t.join()
    self.port.flushInput()
    self.port.close()

  def _eventLoop(self):
    while not self._threadStopFlag.isSet():
      substr = self._getPacket()
      data = self._decodeStream(substr)

      self.dataLock.acquire()
      self.data = data
      self.dataLock.release()

      time.sleep(float(self.interval))

      self.port.flushInput()

  def _getPacket(self):
    i = 0
    substr = ''
    while i<14:
      byte = self.port.read(1)
      # converting every byte to binary format keeping the low nibble.
      substr += '{0:08b}'.format(ord(byte))[4:]
      i += 1
    return substr

  def _decodeStream(self, substr):
    ac       = int(substr[0:1])
    dc       = int(substr[1:2])
    auto     = int(substr[2:3])
    pclink   = substr[3:4]
    minus    = int(substr[4:5])

    digit1   = substr[5:12]
    dot1     = int(substr[12:13])
    digit2   = substr[13:20]
    dot2     = int(substr[20:21])
    digit3   = substr[21:28]
    dot3     = int(substr[28:29])
    digit4   = substr[29:36]

    micro    = int(substr[36:37])
    nano     = int(substr[37:38])
    kilo     = int(substr[38:39])
    diotst   = int(substr[39:40])
    mili     = int(substr[40:41])
    percent  = int(substr[41:42])
    mega     = int(substr[42:43])
    contst   = int(substr[43:44])
    cap      = int(substr[44:45])
    ohm      = int(substr[45:46])
    rel      = int(substr[46:47])
    hold     = int(substr[47:48])
    amp      = int(substr[48:49])
    volts    = int(substr[49:50])
    hertz    = int(substr[50:51])
    lowbat   = int(substr[51:52])
    minm     = int(substr[52:53])
    fahrenh  = substr[53:54]
    celcius  = int(substr[54:55])
    maxm     = int(substr[55:56])

    digit = {"1111101":"0",
             "0000101":"1",
             "1011011":"2",
             "0011111":"3",
             "0100111":"4",
             "0111110":"5",
             "1111110":"6",
             "0010101":"7",
             "1111111":"8",
             "0111111":"9",
             "0000000":"",
             "1101000":"L"}

    valueStr = ("-" if minus else " ") +\
            digit.get(digit1,"") + ("." if dot1 else "") +\
            digit.get(digit2,"") + ("." if dot2 else "") +\
            digit.get(digit3,"") + ("." if dot3 else "") +\
            digit.get(digit4,"")
    try:
      valueNum = float(valueStr)
    except ValueError:
      valueNum = None

    flags = ",".join(["AC"         if ac     else "",
                      "DC"         if dc     else "",
                      "Auto"       if auto   else "",
                      "Diode test" if diotst else "",
                      "Conti test" if contst else "",
                      "Capacity"   if cap    else "",
                      "Rel"        if rel    else "",
                      "Hold"       if hold   else "",
                      "Min"        if minm   else "",
                      "Max"        if maxm   else "",
                      "LowBat"     if lowbat else ""])

    if valueNum == None:
      pass
    elif nano:
      valueNum *= 10e-9
    elif micro:
      valueNum *= 10e-6
    elif mili:
      valueNum *= 10e-3
    elif kilo:
      valueNum *= 10e3
    elif mega:
      valueNum *= 10e6


    units = ("%"    if percent else "") +\
            ("Ohm"  if ohm     else "") +\
            ("Amp"  if amp     else "") +\
            ("Volt" if volts   else "") +\
            ("Hz"   if hertz   else "") +\
            ("C"    if celcius else "")

    return (valueNum, units, flags)

  def _getAllValues(self):
    self.dataLock.acquire()
    data = self.data
    self.dataLock.release()
    return data

  def getValue(self):
    return self._getAllValues()[0]

  def getUnit(self):
    return self._getAllValues()[1]

  def getFlags(self):
    return self._getAllValues()[2]