import time
import board
import digitalio
import usb_hid

from adafruit_hid.keyboard import Keyboard
from adafruit_hid.keycode import Keycode


# Prepare the PIN for input
def setup_pin(pin):
    key_pin = digitalio.DigitalInOut(pin)
    key_pin.direction = digitalio.Direction.INPUT
    key_pin.pull = digitalio.Pull.UP
    return key_pin


# A helper that returns true if the keypress is down
def io_pin_down(pin) -> bool:
    return not pin.value


# Setup the DIT variables
dit_pin = setup_pin(board.D1)
dit_keycode = Keycode.LEFT_BRACKET

# Setup the DAH variables
dah_pin = setup_pin(board.D2)
dah_keycode = Keycode.RIGHT_BRACKET

# Setup the Keyboard object
keyboard = Keyboard(usb_hid.devices)


# PressAction is returned when handle_pin decides that the keycode for
# the pin should be pressed
class PressAction:
    pass


# ReleaseAction is returned when handle_pin decides that the keycode
# for the pin should be pressed
class ReleaseAction:
    pass


# A state handler that compares the previous state of the pin with its
# current state
#
# The return value is the current state of the pin, and one of three
# possible actions to perform:
#
# 1. PressAction - Press the key
# 2. ReleaseAction - Release the key
# 3. None - Do nothing
def handle_pin(
    previous_state, current_state
) -> (bool, PressAction | ReleaseAction | None):
    if previous_state == current_state:
        return current_state, None
    elif current_state:
        return current_state, PressAction
    else:
        return current_state, ReleaseAction


# The effects handler. This performs the action if an action is needed
#
def io_act_on_pin(
    keyboard, keycode, action: PressAction | ReleaseAction | None
):
    if action == PressAction:
        keyboard.press(keycode)
    elif action == ReleaseAction:
        keyboard.release(keycode)


# Initialize the pin states
dit_state = False
dah_state = False


#
# This code follows the "Functional Core, Imperative Shell" pattern
# Made famous by Gary Bernhardt's Boundaries talk <https://www.youtube.com/watch?v=eOYal8elnZk>
#
# All the IO occurs in this loop, with the pure handle_pin function
# providing the logic that decides what action to perform.
#
while True:
    # Read the current states and determine what actions to perform
    dit_state, dit_action = handle_pin(dit_state, io_pin_down(dit_pin))
    dah_state, dah_action = handle_pin(dah_state, io_pin_down(dah_pin))

    # Perform the actions for each pin
    io_act_on_pin(keyboard, dit_keycode, dit_action)
    io_act_on_pin(keyboard, dah_keycode, dah_action)

    # Sleep a little
    time.sleep(0.001)