from machine import Pin, PWM, time_pulse_us
import time

# =========================
# Pins
# =========================

TRIG = Pin(5, Pin.OUT)
ECHO = Pin(18, Pin.IN)

SERVO = PWM(Pin(19), freq=50)

GREEN_LED = Pin(25, Pin.OUT)
YELLOW_LED = Pin(26, Pin.OUT)
RED_LED = Pin(27, Pin.OUT)

ENTRY_BUTTON = Pin(21, Pin.IN, Pin.PULL_UP)
EXIT_BUTTON = Pin(22, Pin.IN, Pin.PULL_UP)

# =========================
# Parking settings
# =========================

MAX_CAPACITY = 15
cars = 0

# =========================
# Servo function
# =========================

def gate_open():
    SERVO.duty(77)
    time.sleep(1)

def gate_close():
    SERVO.duty(40)
    time.sleep(1)

# =========================
# Ultrasonic function
# =========================

def get_distance():
    TRIG.value(0)
    time.sleep_us(2)

    TRIG.value(1)
    time.sleep_us(10)
    TRIG.value(0)

    duration = time_pulse_us(ECHO, 1, 30000)

    if duration < 0:
        return 999

    distance = (duration * 0.0343) / 2
    return distance

# =========================
# Parking LEDs
# =========================

def update_leds():
    GREEN_LED.value(0)
    YELLOW_LED.value(0)
    RED_LED.value(0)

    if cars >= MAX_CAPACITY:
        RED_LED.value(1)

    elif cars >= 10:
        YELLOW_LED.value(1)

    else:
        GREEN_LED.value(1)

# =========================
# Start system
# =========================

update_leds()
gate_close()

print("Smart Parking System Started")
print("Capacity:", MAX_CAPACITY)

# =========================
# Main loop
# =========================

while True:

    distance = get_distance()

    print("Cars:", cars, "| Distance:", distance, "cm")

    # Entry button
    if ENTRY_BUTTON.value() == 0:

        if cars < MAX_CAPACITY:
            cars += 1

            print("Car entered!")
            print("Cars:", cars)

            gate_open()
            time.sleep(1)
            gate_close()

            update_leds()

            time.sleep(0.5)

        else:
            print("Parking FULL!")
            RED_LED.value(1)
            time.sleep(0.5)

    # Exit button
    if EXIT_BUTTON.value() == 0:

        if cars > 0:
            cars -= 1

            print("Car exited!")
            print("Cars:", cars)

            gate_open()
            time.sleep(1)
            gate_close()

            update_leds()

            time.sleep(0.5)

    time.sleep(0.1)