# [SCRAPEBOARD] is an arcade game in development by [@diskmem] & [@snakesandrews]
#
# It requires custom hardware to play but can be tested in keyboard mode without
# the hardware. For more information on setting up and running the game, see 
# README.md, or for the game in general, visit <https://scrape.nugget.fun/>.
#
# Full open source code is available at <https://git.nugget.fun/scrape/scrapeboard>.
#
# This is a utility script for testing if the GPIO interface of a Raspberry Pi is working
# with the four input wires, which correspond to the four metal floor pads in the standard
# Scrapeboard build.

import time, itertools
import RPi.GPIO as GPIO

# These represent the game pads and the GPIO pins they're connected to
LNW, LNE, LSE, LSW = range(4)
pins = {
    LNW: 17,
    LNE: 27,
    LSE: 22,
    LSW: 23
}

def connection2(pin_a, pin_b):
    """
    Set `pin_a` to output a low signal, and set every other pin to pullup. If `pin_b` reads a low signal even though
    it's set to pullup, that means `pin_a` is connected to it, so return `True`.

    @param pin_a   Pin which will be set to output LOW
    @param pin_b   Pin which will be read
    @return        `True` if a low signal is sent from `pin_a` to `pin_b`, `False` otherwise
    """
    for pin_id, pin in pins.items():
        if pin == pin_a:
            # Set pin_a to output LOW
            GPIO.setup(pin, GPIO.OUT)
            GPIO.output(pin, GPIO.LOW)
        else:
            # Set all other pins to input pullup
            GPIO.setup(pin, GPIO.IN, pull_up_down=GPIO.PUD_UP)

    # pin_b can now be tested to see if if reads the LOW signal from pin_a
    return GPIO.input(pin_b) == GPIO.LOW

def connection(pin_a, pin_b):
    """
    Tests low signals connect from both A to B and from B to A

    @param pin_a   Test if this pin is connected to `pin_b`
    @param pin_b   Test if this pin is connected to `pin_a`
    @return        `True` if `pin_a` and `pin_b` are connected, `False` otherwise
    """
    return connection2(pin_a, pin_b) and connection2(pin_b, pin_a)

def connections():
    """
    Look at all six possible connections between the four pins and print a message if one is found connected.
    """
    for pin_id_a, pin_id_b in itertools.combinations(pins, 2):
        if connection(pins[pin_id_a], pins[pin_id_b]):
            print(f"{pin_id_a} ({pins[pin_id_a]}) <-> {pin_id_b} ({pins[pin_id_b]})")

if __name__ == "__main__":
    # Use GPIO numbering
    GPIO.setmode(GPIO.BCM)

    # Set all pins to pullup
    for pin_id, pin in pins.items():
        GPIO.setup(pin, GPIO.IN, pull_up_down=GPIO.PUD_UP)

    while True:
        # Try all connections once each frame
        connections() 
        time.sleep(0.1)