# LM: Touch-sensor keyer V2 - References
# https://learn.adafruit.com/processing-on-the-raspberry-pi-and-pitft/hardware-io
# http://raspi.tv/2014/rpi-gpio-update-and-detecting-both-rising-and-falling-edges

import os               # to adjust this script's priority
import sys              # for command-line parameters and exit
from time import sleep  # for Morse timing
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)

RIGHT = 23      # right touch sensor --> (Connector pin 16)
LEFT = 24       # left touch sensor <--  (Connector pin 18)
KEY = 25        # key down (output)      (Connector pin 22)

                        # inter-character and inter-word spaces are user timed
timeConstant = .85      # empirically determined - adjust as indicated
speed = 10.             # can be revalued from sys.argv (words per minute)
dotTime = .085          # recomputed in init()
dashTime = .255         # ditto

paddleOnRight = False   # True during press to right
paddleOnLeft = False    # True during press to left

# GPIO pin roles

GPIO.setup(RIGHT, GPIO.IN, pull_up_down = GPIO.PUD_DOWN)
GPIO.setup(LEFT, GPIO.IN, pull_up_down = GPIO.PUD_DOWN)
GPIO.setup(KEY, GPIO.OUT)

# Interrupt handlers

def dotEvent(channel):
  global paddleOnRight
  global paddleOnLeft
  if GPIO.input(RIGHT):         # Rising edge (start dots)
    paddleOnRight = True
    paddleOnLeft = False        # Disallow both paddles at the same time
  else:                         # Falling edge (stop dots)
    paddleOnRight = False

def dashEvent(channel):
  global paddleOnRight
  global paddleOnLeft
  if GPIO.input(LEFT):          # Rising edge (start dashes)
    paddleOnLeft = True
    paddleOnRight = False       # Disallow both paddles at the same time
  else:                         # Falling edge (stop dashes)
    paddleOnLeft = False

# Associate handlers to pins

GPIO.add_event_detect(RIGHT, GPIO.BOTH, callback=dotEvent)
GPIO.add_event_detect(LEFT, GPIO.BOTH, callback=dashEvent)

# Nuts and bolts

def init():
  # Initialize times, etc.
  global dotTime
  global dashTime
  dotTime = timeConstant / speed
  dashTime = dotTime + dotTime + dotTime
  GPIO.output(KEY, GPIO.LOW)    # Key up

def makeDot():
  dot()
  while paddleOnRight:
    dot()

def makeDash():
  dash()
  while paddleOnLeft:
    dash()

def dot():
  # Generate one dot + dot-length space
  GPIO.output(KEY, GPIO.HIGH)
  sleep(dotTime)
  GPIO.output(KEY, GPIO.LOW)
  sleep(dotTime)

def dash():
  # Generate one dash + dot-length space
  GPIO.output(KEY, GPIO.HIGH)
  sleep(dashTime)
  GPIO.output(KEY, GPIO.LOW)
  sleep(dotTime)

def waitForInterrupt():
  print("Type ctrl-c to exit.")
  while (True):
    if paddleOnRight:
      makeDot()
    if paddleOnLeft:
       makeDash()
    sleep(.0001)        # Release CPU

# Main
if (len(sys.argv) > 1):
  # get speed from command-line, else default to 10 WPM
  speed = float(sys.argv[1])
init()
if os.getuid() == 0:
  os.nice(-20)          # Requires root permissions
try:
  waitForInterrupt()
except KeyboardInterrupt:
  # GPIO.cleanup()      # Leaves KEY pin high
  print("\n")
except:
  sys.exit(0)