#!/usr/bin/env python
# -*- coding:utf-8 -*-

###################
# P26 ----> r_ch1 #
# P20 ----> r_ch2 #
# P21 ----> r_ch3 #
###################

import RPi.GPIO as GPIO
import argparse
import time

# Channels
r_ch1 = 26
r_ch2 = 20
r_ch3 = 21

# time constants in seconds
# single tap
t_large_beer = 6
t_small_beer = 2

# double tap
t_left_tap = 6
t_right_tap = 6

t_flush = 20


# Syntax suger because of negative logic
S_ON = GPIO.LOW
S_OFF = GPIO.HIGH

def cli_args_parser():
    """ 
        Argument parser configuration 
    """
    parser = argparse.ArgumentParser(
            description='Lightning beer tap cli',
            formatter_class=argparse.ArgumentDefaultsHelpFormatter
    )

    parser.add_argument(
            '-p',
            '--products',
            action='store',
            dest='products',
            help="Product description, beer size [small, large]"
    )

    parser.add_argument(
            '-t',
            '--test',
            action='store_true',
            help="Test mode which tests all available channels"
    )

    parser.add_argument(
            '-f1',
            '--flush1',
            action='store_true',
            help="Flush tap 1 for 20s!"
    )

    parser.add_argument(
            '-f2',
            '--flush2',
            action='store_true',
            help="Flush tap 2 for 20s!"
    )

    parser.add_argument(
            '-f3',
            '--flush3',
            action='store_true',
            help="Flush tap 3 for 20s!"
    )

    return parser.parse_args()

def __setup_GPIO(channel=r_ch1):
    """ 
        Setup all GPIOs, set output mode, and set gpio mode to bcm
    """
    GPIO.setwarnings(False)
    GPIO.setmode(GPIO.BCM)

    print("setting up gpio_{}".format(channel))
    GPIO.setup(channel, GPIO.OUT)
    __set_gpio(channel, S_OFF)

def __set_gpio(channel=r_ch1, value=S_OFF):
    """ 
        Try to safely change the value of a gpio, catch exception if it fails
        TODO: Exception Handling
    """
    try:
        GPIO.output(channel, value)
    except:
        print("GPIO Error")
        GPIO.cleanup()

def gpio_test():
    """ 
        Test all channels
    """
    for i, gpio in enumerate([r_ch1, r_ch2, r_ch3], start=1):
        # Setup gpio pin
        __setup_GPIO(gpio)

        __set_gpio(gpio, S_ON)
        print("Channel_{}: gpio_{} on".format(i, gpio))
        time.sleep(0.1)
        __set_gpio(gpio, S_OFF)
        print("Channel_{}: gpio_{} off".format(i, gpio))
        time.sleep(0.1)

def draw_beer(channel=r_ch1, wait=t_large_beer):
    """ 
        Draw a delicious beer, keep the tap on for n_wait seconds 
    """
    # Setup gpio pin
    __setup_GPIO(channel)

    __set_gpio(channel, S_ON)
    time.sleep(wait)
    __set_gpio(channel, S_OFF)

if __name__ == "__main__":
    """
        Main if not loaded as module
    """
    # parse arguments
    args = cli_args_parser()

    print(args.products)

    # call functions according to the given arguments
    if args.test:
        print("Test mode enabled")
        gpio_test()
    elif args.flush1:
        print("Choice: Flush tap1")
        draw_beer(r_ch1, t_flush)
    elif args.flush2:
        print("Choice: Flush tap2")
        draw_beer(r_ch2, t_flush)
    elif args.flush3:
        print("Choice: Flush tap3")
        draw_beer(r_ch3, t_flush)
    elif args.products == "LARGE":
        print("Choice: Large beer")
        draw_beer(r_ch1, t_large_beer)
    elif args.products == "SMALL":
        print("Choice: Small beer")
        draw_beer(r_ch1, t_small_beer)
    elif args.products == "LEFT_TAP":
        print("Choice: left tap")
        draw_beer(r_ch1, t_left_tap)
    elif args.products == "RIGHT_TAP":
        print("Choice: right tap")
        draw_beer(r_ch2, t_right_tap)
    else:
        print("RTFM!")