from machine import Pin, ADC
import time

# --- Pins ---
pir = Pin(14, Pin.IN)
led = Pin(27, Pin.OUT)
trig = Pin(18, Pin.OUT)
echo = Pin(5, Pin.IN)
mq2 = ADC(Pin(36))
mq2.atten(ADC.ATTN_11DB)  # For full range 0-3.3V

# --- Functions ---
def distance_cm():
    trig.off()
    time.sleep_us(2)
    trig.on()
    time.sleep_us(10)
    trig.off()
    
    pulse_time = 0
    # Wait for echo HIGH
    while echo.value() == 0:
        pass
    start = time.ticks_us()
    while echo.value() == 1:
        pass
    end = time.ticks_us()
    pulse_time = end - start
    
    distance = (pulse_time / 2) / 29.1  # cm
    return distance

def air_quality_ok():
    val = mq2.read()
    # Threshold (adjust after testing)
    if val < 3000:  # clean air
        return True
    else:
        return False

# --- Main Loop ---
while True:
    motion = pir.value()
    obj_distance = distance_cm()
    air_ok = air_quality_ok()
    
    print("Motion:", motion, "Distance:", obj_distance, "Air OK:", air_ok)
    
    if motion and obj_distance > 10 and air_ok:
        led.on()
    else:
        led.off()
    
    time.sleep(0.5)