"""
Listen to serial, return most recent numeric values
Lots of help from here:
http://stackoverflow.com/questions/1093598/pyserial-how-to-read-last-line-sent-from-serial-device
"""
from threading import Thread
import time
import serial
import struct

last_received = ''
profile = []

PI_TS_MIN = 0
PI_TS_MAX = 1
PI_TL = 2
PI_TP = 3
PI_TIME_MAX = 4

PI_RAMP_UP_MIN = 5
PI_RAMP_UP_MAX = 6
PI_RAMP_DOWN_MIN = 7
PI_RAMP_DOWN_MAX = 8

PI_TS_DURATION_MIN = 9
PI_TS_DURATION_MAX = 10
PI_TL_DURATION_MIN = 11
PI_TL_DURATION_MAX = 12
PI_TP_DURATION_MIN = 13
PI_TP_DURATION_MAX = 14

def receiving(ser):
    global last_received
    buffer = ''
    ser.write(chr(255))
    ser.flush()
    profile = struct.unpack("hhhhhhhhhhhhhhh", ser.read(30))
    ser.flushInput()
    while 1:
        ser.write(chr(254))
        ser.flush()
        last_received = ser.read(11)
        print repr(last_received)
        ser.flushInput()


class SerialData(object):
    def __init__(self, init=50):
        try:
            self.ser = ser = serial.Serial(
                port='/dev/ttyUSB0',
                baudrate=9600, timeout=2)
        except serial.serialutil.SerialException:
            #no serial connection
            self.ser = None
        else:
            Thread(target=receiving, args=(self.ser,)).start()

    def next(self):
        if not self.ser:
            return 100 #return anything so we can test when Arduino isn't connected

        try:
          return int(struct.unpack("hhhhhb", last_received)[1])
        except Exception, e:
          print e
          return 0


    def __del__(self):
        if self.ser:
            self.ser.close()

if __name__=='__main__':
    s = SerialData()
    for i in range(500):
        time.sleep(1)
        print s.next()