from machine import Pin, PWM, Timer, time_pulse_us
import time

# ======================
# Settings
# ======================
DISTANCE_THRESHOLD = 20  # cm

ANGLE_OPEN = 90
ANGLE_CLOSED = 0

DEBOUNCE_MS = 200

TRIG_PIN = 5
ECHO_PIN = 18
SERVO_PIN = 27

# ======================
# Hardware
# ======================
trig = Pin(TRIG_PIN, Pin.OUT)
echo = Pin(ECHO_PIN, Pin.IN)

servo = PWM(Pin(SERVO_PIN), freq=50, duty=0)

# ======================
# State (Interrupt style)
# ======================
last_irq_time = 0

request_open = False
request_close = False

door_is_open = False

# ======================
# Servo control
# ======================
def servo_angle(deg):
    duty = int((((deg) / 180.0) * 2.0 + 0.5) / 20.0 * 1023)
    servo.duty(duty)

# ======================
# Ultrasonic read
# ======================
def get_distance():
    trig.off()
    time.sleep_us(2)

    trig.on()
    time.sleep_us(10)

    trig.off()

    duration = time_pulse_us(echo, 1, 30000)

    if duration < 0:
        return 999

    return (duration * 0.0343) / 2
# ------------------1---------------------
# ======================
# "Interrupt" handler (edge trigger simulation)
# ======================
def Ultrasonic_irq_open():
    global last_irq_time, request_open
    now = time.ticks_ms()
    if time.ticks_diff(now, last_irq_time) > DEBOUNCE_MS:
        request_open = True
        last_irq_time = now

    
def Ultrasonic_irq_close():
    global last_irq_time, request_close
    now = time.ticks_ms()
    if time.ticks_diff(now, last_irq_time) > DEBOUNCE_MS:
        request_close = True
        last_irq_time = now
        
# ------------------2---------------------

# ======================
# Actions
# ======================
def open_water():
    global door_is_open
    servo_angle(ANGLE_OPEN)
    door_is_open = True
    print("Water is on")

def close_water():
    global door_is_open
    servo_angle(ANGLE_CLOSED)
    door_is_open = False
    print("Water is off")


# ======================
# Init
# ======================
servo_angle(ANGLE_CLOSED)
print("System Ready 🚰")

# ======================
# Previous state (IMPORTANT for edge detection)
# ======================
was_close = False


# ------------------3---------------------
# ======================
# Main loop
# ======================
while True:
    distance = get_distance()
    print("Distance = ", distance)
    # ======================
    # EDGE DETECTION (this is the key idea)
    # ======================
    # Entering range → OPEN interrupt
    if distance < DISTANCE_THRESHOLD and not was_close :
        Ultrasonic_irq_open()
        was_close = True

    # Leaving range → CLOSE interrupt
    elif distance >= DISTANCE_THRESHOLD and was_close:
        Ultrasonic_irq_close()
        was_close = False

    # ======================
    # Handle interrupts (like button IRQ)
    # ======================
    if request_open:
        request_open = False
        if not door_is_open:
            open_water()
    if request_close:
        request_close = False
        if door_is_open:
            close_water()



    time.sleep_ms(20)