"""
hello.light.44.py

receive and display light level
hello.light.44.py serial_port


Orignal author:  Neil Gershenfeld (CBA MIT)
Modified by Alex Berke

(c) Massachusetts Institute of Technology 2009
Permission granted for experimental and personal use;
license for commercial sale available from MIT
"""


from tkinter import *
import serial

GUI_WIDTH = 650
GUI_HEIGHT = .25*GUI_WIDTH
# The light measurement is shown in a rectangular bar.
MEASUREMENT_RECT_X0 = 0.2*GUI_WIDTH
MEASUREMENT_RECT_X1 = 0.9*GUI_WIDTH
MEASUREMENT_RECT_Y0 = 0.45*GUI_HEIGHT
MEASUREMENT_RECT_Y1 = 0.75*GUI_HEIGHT
EPS = 0.5  # FILTER time constant
FILTER = 0.0  # FILTERed value


def idle(parent, canvas):
    """ Handles receiving serial messages from the microcontroller
        which sends information about light intensity read from the
        phototransistor.
        The message sent is framed by a prefix sequence: 1, 2, 3, 4
        The message that follows is the ADC low byte
        and then the ADC high byte.
    """
    global FILTER, EPS
    #
    # idle routine
    #
    byte2 = 0
    byte3 = 0
    byte4 = 0
    ser.flush()
    while 1:
        #
        # find framing
        #
        byte1 = byte2
        byte2 = byte3
        byte3 = byte4
        byte4 = ord(ser.read())
        if ((byte1 == 1) & (byte2 == 2) & (byte3 == 3) & (byte4 == 4)):
            break
    low = ord(ser.read())
    high = ord(ser.read())
    value = 256*high + low
    FILTER = (1-EPS)*FILTER + EPS*value
    x = int(MEASUREMENT_RECT_X0 + (MEASUREMENT_RECT_X1 - MEASUREMENT_RECT_X0)*FILTER/1024.0)
    canvas.itemconfigure('measurement', text='%.1f' % FILTER)
    canvas.coords('rect1', MEASUREMENT_RECT_X0, MEASUREMENT_RECT_Y0, x, MEASUREMENT_RECT_Y1)
    canvas.coords('rect2', x, MEASUREMENT_RECT_Y0, MEASUREMENT_RECT_X1, MEASUREMENT_RECT_Y1)
    canvas.update()
    parent.after_idle(idle, parent, canvas)

#
#  check command line arguments
#
if (len(sys.argv) != 2):
    print('command line: hello.light.44.py serial_port')
    sys.exit()
port = sys.argv[1]
#
# open serial port
#
ser = serial.Serial(port, 9600)
ser.setDTR()

#
# set up GUI
#
root = Tk()
root.title('hello.light.44.py (q to exit)')
root.bind('q', 'exit')
canvas = Canvas(root, width=GUI_WIDTH, height=GUI_HEIGHT, background='black')
canvas.create_text(.55*GUI_WIDTH, .2*GUI_HEIGHT,
                   text='LIGHT MEASUREMENT', font=('Helvetica', 18),
                   tags='title', fill='white')
canvas.create_text(.1*GUI_WIDTH, MEASUREMENT_RECT_Y0 + (MEASUREMENT_RECT_Y1 - MEASUREMENT_RECT_Y0)/2,
                   text='.33', font=('Helvetica', 18),
                   tags='measurement', fill='white')
# start x
x = MEASUREMENT_RECT_X0 + 0.1*GUI_WIDTH
canvas.create_rectangle(MEASUREMENT_RECT_X0, MEASUREMENT_RECT_Y0, x, MEASUREMENT_RECT_Y1, tags='rect1', fill='black', outline='white')
canvas.create_rectangle(x, MEASUREMENT_RECT_Y0, MEASUREMENT_RECT_X1, MEASUREMENT_RECT_Y1, tags='rect2', fill='white', outline='white')
canvas.pack()
#
# start idle loop
#
root.after(100, idle, root, canvas)
print('HELLO LIGHT')
root.mainloop()