# This script is a sketch for a UV light sterilization project.
# It uses a display to show the time remaining, a relay module to turn on the
# LEDs, and a button to operate all the components.

# == IMPORTS ==
from machine import Pin, I2C
from ssd1306 import SSD1306_I2C
from time import sleep_ms
# Required imports for the script.

# == COMPONENTS DEFINITIONS ==
relay = Pin(19, Pin.OUT)  # Relay module setup
button = Pin(5, Pin.IN, Pin.PULL_DOWN)  # Button setup
screen = I2C(0, scl=Pin(1), sda=Pin(0), freq=200000)  # I2C screen interface setup

pix_res_x = 128
pix_res_y = 64
oled = SSD1306_I2C(pix_res_x, pix_res_y, screen)
# Screen resolution and OLED display initialization.

time_duration = 90

# == FUNCTION TO DISPLAY THE COUNTDOWN ==
def countdown_display(oled):
    for i in range(time_duration, -1, -1):
        oled.fill(0)          # Clear the screen.
        oled.text(str(i), 5, 5)  # Display the current time.
        oled.show()           # Update the display.
        sleep_ms(1000)        # Pause for 1 second.

    oled.fill(0)
    relay.value(0)            # Turn off the relay.
    oled.fill(0)
    oled.show()
    sleep_ms(500)
# Runs the countdown and updates the display.

current = new = button.value()

# Main loop that continuously monitors the button state,
# activates the relay and countdown when the button is pressed.
while True:
    new = button.value()

    if new != current:
        current = new
        if new == 1:
            relay.value(1)  # Relay turns on
            countdown_display(oled)  # Start countdown display

    sleep_ms(10)