import machine
import time
from utime import sleep

BUTTON_COUNT = 3
LED_COUNT = 9
INPUT_COUNT = 4
BUTTON_START_ID = 16
LED_GPIO_START = 7

last_button_time_stamp = 0
key_presses = []

# Extract the numeric pin id from the passed in Pin instance
def PinId(pin):
    # Pin(GPIO17, mode=IN, pull=PULL_DOWN)
    # the pin value is in the format above
    # and the pin id, i.e. 7 or 17, can be single or double digit
    # So, we filter the characters 8-10, 
    # which would be '7,' or '17' depending on the pin,
    # then, we remove any ',' character at the end
    # and we are left with the numeric value of the pin, i.e. 7 or 17
    return int(str(pin)[8:10].rstrip(","))

def interrupt_callback(pin):
    global last_button_time_stamp

    cur_button_ts = time.ticks_ms()
    button_press_delta = cur_button_ts - last_button_time_stamp

    # Handle debouncing (ms)
    if button_press_delta > 200:
        last_button_time_stamp = cur_button_ts
        key_presses.append(pin)
        # Call the PinId method to get the numeric pin value (range 0-2)
        print(f'key press: {PinId(pin) - BUTTON_START_ID}')

def main():
    global key_presses
    global last_button_time_stamp
    PASSCODE_LENGTH = 0

# A tiny sleep to allow the first print to be displayed
    sleep(0.01)
    print('Program starting')

# Set pins controlling multiplexers' select lines
    s0 = machine.Pin(27, machine.Pin.OUT)
    s1 = machine.Pin(28, machine.Pin.OUT)

# Set pin reading multiplexers' input
    mux_in = machine.Pin(26, machine.Pin.IN, machine.Pin.PULL_DOWN)

# initialize and add buttons to buttons list
    buttons = []
    for btn_idx in range(0, BUTTON_COUNT):
        buttons.append(machine.Pin(BUTTON_START_ID + btn_idx, machine.Pin.IN, machine.Pin.PULL_DOWN))
        buttons[-1].irq(trigger=machine.Pin.IRQ_FALLING, handler=interrupt_callback)

    PASS_CODE = [buttons[0], buttons[2], buttons[1]]
    PASSCODE_LENGTH = len(PASS_CODE)

# initialize and add LEDs to out_pins list
    out_pins = []
    for out_id in range(0, LED_COUNT):
        out_pins.append(machine.Pin(LED_GPIO_START + out_id, machine.Pin.OUT))

    last_dev = -1
    while True:
        binary_code = 0
        for selector_val in range(INPUT_COUNT):
            s0.value(selector_val % 2)
            s1.value(selector_val // 2)
            sleep(0.02)
            binary_code += (pow(2, selector_val) * mux_in.value())

        if last_dev != binary_code:
            last_dev = binary_code
            print(f'selected output: {last_dev}')
        sleep(0.1)

        if len(key_presses) >= PASSCODE_LENGTH:
            if key_presses[:PASSCODE_LENGTH] == PASS_CODE:
                print('correct passcode')
                if binary_code < LED_COUNT:
                    print(f'toggling: {binary_code}')
                    out_pins[binary_code].toggle()
                else:
                    print(f'invalid output: {binary_code}, ' + \
                    f'valid range: 0-{len(out_pins) - 1}, doing nothing')
            else:
                print('wrong passcode')
            print('')
            key_presses = key_presses[PASSCODE_LENGTH:]

if __name__ == "__main__":
    main()