#!/usr/bin/env python3
# devtimer.py - Temperature Controlled Photographic Darkroom Timer
# Targeted for RaspberryPi
# Copyright (c) 2018 TundraWare Inc.
# Permission Hereby Granted For Unrestricted Personal Or Commercial Use

#####
# Imports
#####

# General Imports

from threading import Thread
from time import time, sleep

# Hardware Support

from ds18b20 import *
from tm1637 import *
from wiringpi import wiringPiSetupGpio

import globals


#####
# Constants
#####

# Display

BRIGHTNESS0 = 0x0a
CLK0 = 21
DIO0 = 20

# General Constants

DEBUG = True                  # Debugging switch

BEEP = 15                     # Beep interval
CALIBRATION_OFFSET = 0.003    # Compensate for program overhead in master loop


#####
# Lookup Table For Compensating Factors
#####

'''
  There are 3 tables in the list below.  In order:

      Realtime - never actually used, just there as a placeholder
      Paper
      Film

  Each contains entires for multiplicative corrections from 60F to 80F.

  The profile global above selects which of these tuples to index into
  - using the normalized temp global above as the index.  We don't
  want to use a dictionary here (with profile as the key) because of
  the overhead that incurs.  Straight tuple indexing should be much
  quicker.

  WARNING: It takes about 250ms to update the display on a Pi Zero.
           So, if the "virtual second" falls at or below this, the
           code will be attempting to do updates faster than the
           display can handle. So ... the total compensation cannot
           reduce the virtual second to less than about 0.300 to be on
           the safe side.
'''

compensate = (
              (1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000),
              (1.724, 1.611, 1.505, 1.406, 1.313, 1.227, 1.146, 1.070, 1.000, 0.934, 0.873, 0.815, 0.762, 0.711, 0.665, 0.621, 0.580, 0.542, 0.506, 0.473, 0.442),
              (1.445, 1.380, 1.318, 1.259, 1.202, 1.148, 1.096, 1.047, 1.000, 0.955, 0.912, 0.871, 0.832, 0.795, 0.759, 0.725, 0.692, 0.661, 0.631, 0.603, 0.576)
             )


# Beep at the user at fixed intervals

def beep():
    print("Beep!")


# Update the display with elapsed time

def show_elapsed(display0, elapsed):

    min = elapsed // 60
    sec = elapsed % 60
    d0 = display0.digit_to_segment[min // 10]
    d1 = display0.digit_to_segment[min % 10]
    d2 = display0.digit_to_segment[sec // 10]
    d3 = display0.digit_to_segment[sec % 10]
    display0.set_segments([d0, 0x80 + d1, d2, d3])

#####
# Program entry point
#####

'''
  We start a perpetual thread to read the current temperature
  and update the relevant global variable.

  Notice that the actual updating of the display gets run on its own
  thread as well.  That's because - on a Pi Zero, at least - it takes
  over 250ms to do this.  We don't want that time added to our timing
  loop, so we send it off on a parallel thread, and initiate timing
  for the next round in this thread.
'''

if __name__ == "__main__":

    # Setup the hardware

    wiringPiSetupGpio()
    display0 = TM1637(CLK0, DIO0, BRIGHTNESS0)

    # Start measuring temperature

    get_temps = Thread(name="Temperatures", target=read_temp_probe)
    get_temps.start()

    # Start timing, using the selected profile and measured temperature

    elapsed_time = 0
    compensation_factor = 1

    while True:

        # Beep periodically

        if not elapsed_time % BEEP:
            beep()

        if DEBUG:
            last = time()

        # Update the display on a separate thread

        update_thread = Thread(name="Timer", target=show_elapsed, args=(display0, elapsed_time))
        update_thread.start()

        # For temperatures in-range, look up the compensating factor

        current_temp = globals.CURRENT_TEMP
        if (globals.CURRENT_PROFILE == globals.REALTIME):
            compensation_factor = 1   # Realtime requires no compensation

        elif globals.TEMP_LOW <= globals.CURRENT_TEMP <= globals.TEMP_HIGH:
            compensation_factor = compensate[globals.CURRENT_PROFILE][current_temp-globals.TEMP_LOW]

        # Temperature is out of range for our correction table
        # This implictly uses the last known compensation factor so we can keep running

        else:
            print("Display Out-Of-Range Message Here")

        sleep(compensation_factor - CALIBRATION_OFFSET)
        elapsed_time += 1
        elapsed_time %= 6000

        if DEBUG:
           print("Current Temp: %s Factor: %s Inter-update Time: %s" % (current_temp, compensation_factor, str(time()-last)))