from machine import Pin, I2C
import ssd1306
import time

CAPACITY = 20

btn_in = Pin(14, Pin.IN, Pin.PULL_UP)
btn_out = Pin(27, Pin.IN, Pin.PULL_UP)

led_green = Pin(2, Pin.OUT)
led_yellow = Pin(5, Pin.OUT)
led_red = Pin(4, Pin.OUT)
led_blue = Pin(18, Pin.OUT)

# OLED I2C: SDA = GPIO21, SCL = GPIO22-
i2c = I2C(0, scl=Pin(22), sda=Pin(21), freq=400000)
oled = ssd1306.SSD1306_I2C(128, 64, i2c)

count = 0

# Variables for the non-blocking blue LED blink
blink_start_time = 0
is_blinking = False


def update_display():
    oled.fill(0)
    oled.text("PARKING GARAGE", 0, 0)
    oled.text("Cars: " + str(count), 0, 20)
    oled.text("Free: " + str(CAPACITY - count), 0, 35)

    if count >= CAPACITY:
        oled.text("FULL", 0, 50)
    elif count >= CAPACITY - 2:
        oled.text("NEARLY FULL", 0, 50)
    else:
        oled.text("AVAILABLE", 0, 50)

    oled.show()


def update_status_leds():
    if count >= CAPACITY:
        # Garage is Full
        led_green.value(0)
        led_yellow.value(0)
        led_red.value(1)
    elif count >= CAPACITY - 2:
        # Garage is Nearly Full (18 or 19 cars)
        led_green.value(0)
        led_yellow.value(1)
        led_red.value(0)
    else:
        # Garage has plenty of space
        led_green.value(1)
        led_yellow.value(0)
        led_red.value(0)

    update_display()


# Start-up state
update_status_leds()
led_blue.value(0)

prev_in = 1
prev_out = 1

while True:
    cur_in = btn_in.value()
    cur_out = btn_out.value()
    current_time = time.ticks_ms()

    # 1. Handle non-blocking blue LED blink
    if is_blinking and time.ticks_diff(current_time, blink_start_time) >= 300:
        led_blue.value(0)
        is_blinking = False

    # 2. A car enters
    if prev_in == 1 and cur_in == 0:
        if count < CAPACITY:
            count += 1
            print("Car entered. Count =", count)
            update_status_leds()
        else:
            print("Garage FULL. Entry ignored. Count =", count)
        time.sleep_ms(50) # Debounce delay

    # 3. A car exits
    if prev_out == 1 and cur_out == 0:
        if count > 0:
            count -= 1
            print("Car exited. Count =", count)
            
            # Trigger the non-blocking blink instead of pausing the script
            led_blue.value(1)
            blink_start_time = time.ticks_ms()
            is_blinking = True
            
            update_status_leds()
        else:
            print("Garage EMPTY. Exit ignored. Count =", count)
        time.sleep_ms(50) # Debounce delay

    prev_in = cur_in
    prev_out = cur_out
    time.sleep_ms(10)