import machine
import time
from utime import sleep

BUTTON_START_PIN = 16
BUTTON_COUNT = 3

LED_START_PIN = 7
LED_COUNT = 9

MUX4_IN_PIN = 26
MUX4_S0_PIN = 27
MUX4_S1_PIN = 28
MUX4_INPUT_COUNT = 4

DEBOUNCE_DELAY = 200

last_button_press_time_stamp = 0
button_pressed_count = 0

get_passcode_list = []

PASSCODE_ENTERING_INACTIVE_TIME = 3000

## Button Init
#
# A function to initialize connected buttons
# Returns list of connected buttons
def button_Init():
    button_init_list = []
    for btn_idx in range(BUTTON_COUNT):
        button_init_list.append(machine.Pin(BUTTON_START_PIN + btn_idx, machine.Pin.IN, machine.Pin.PULL_DOWN))
        button_init_list[btn_idx].irq(trigger=machine.Pin.IRQ_FALLING, handler=interrupt_callback)
    return button_init_list

## LED Init
#
# A function to initialize connected LEDs
# Returns list of connected LEDs
def led_Init():
    led_init_list = []
    for led_idx in range(LED_COUNT):
        led_init_list.append(machine.Pin(LED_START_PIN + led_idx, machine.Pin.OUT))
    return led_init_list

## MUX Init
#
# A function to initialize MUX input (to muc) and selections pins
# Returns mux s0, s1, in connected pins
def mux4_Init():
    mux4_s0 = machine.Pin(MUX4_S0_PIN, machine.Pin.OUT)
    mux4_s1 = machine.Pin(MUX4_S1_PIN, machine.Pin.OUT)
    mux4_in = machine.Pin(MUX4_IN_PIN, machine.Pin.IN, machine.Pin.PULL_DOWN)
    return mux4_s0, mux4_s1, mux4_in

## Reset password list, clear its elements
def clear_password_list():
    global get_passcode_list
    get_passcode_list = []


def get_button_index(pin):
    # pin class as >> Pin(GPIO18, mode=IN, pull=PULL_DOWN)
    x = str(pin).split(',')
    y = x[0].split('(')
    btn_idx = y[1][4:]
    return int(btn_idx)


## Pin interrupt handler
#
# A function to handle pin interrupts
# Expects a machine.Pin type parameter
def interrupt_callback(pin):
    global last_button_press_time_stamp
    global button_pressed_count

    current_button_press_time_stamp = time.ticks_ms()
    button_press_delta = current_button_press_time_stamp - last_button_press_time_stamp

    if button_press_delta > DEBOUNCE_DELAY:
        last_button_press_time_stamp = current_button_press_time_stamp
        get_passcode_list.append(pin)
        print(f'key press: {get_button_index(pin) - BUTTON_START_PIN}')
        button_pressed_count += 1

def main():
    # a tiny sleep to allow the first print to be displayed
    sleep(0.01)
    print('Program starting')
    print('')

    global last_button_press_time_stamp
    global button_pressed_count
    global get_passcode_list

    # HW Initialization
    buttons = button_Init();
    leds = led_Init();
    s0, s1, mux_in = mux4_Init();

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

    last_decimal_value = -1

    while True:

        decimal_value = 0

        # Convert binary representation of mux4 input lines to decimal value
        for selector_val in range(MUX4_INPUT_COUNT):
            s0.value(selector_val %  2)
            s1.value(selector_val // 2)
            decimal_value += (mux_in.value() * (pow(2, selector_val)))

        if decimal_value != last_decimal_value:
            last_decimal_value = decimal_value
            print(f'selected output: {decimal_value}')
        
        sleep(0.100)
        
        if len(get_passcode_list) >= PASSCODE_LENGTH:
            if get_passcode_list[:PASSCODE_LENGTH] == PASSCODE:
                print('correct passcode')

                if decimal_value < LED_COUNT:
                    print(f'Toggling led: {decimal_value}')
                    leds[decimal_value].toggle()
                else:
                    print(f'Invalid output: {decimal_value}. Valid range: 0-{len(leds) - 1}. Nothing to be done')
            else:
                print("wrong passcode")
            print('')
            get_passcode_list = get_passcode_list[PASSCODE_LENGTH:]

        # Reset button pressed count after the third press
        if button_pressed_count == PASSCODE_LENGTH:
            button_pressed_count = 0

        # Clear passcode list for after 3 seconds on inactivity while entering the passcode
        current_time_stamp = time.ticks_ms()
        buttons_press_delta = current_time_stamp - last_button_press_time_stamp

        if ((buttons_press_delta > PASSCODE_ENTERING_INACTIVE_TIME) and (button_pressed_count != 0) and (button_pressed_count < PASSCODE_LENGTH)):
            clear_password_list()
            button_pressed_count = 0
            print("Clearing Input, Reason: Inactive while entering passcode for more than 3 seconds")

if __name__ == "__main__":
    main()