from machine import Pin, ADC, time_pulse_us
import time

# PIR sensor
pir = Pin(14, Pin.IN)

# Ultrasonic sensor
trig = Pin(5, Pin.OUT)
echo = Pin(18, Pin.IN)

# MQ-2 Gas sensor (Analog input)
mq2 = ADC(Pin(34))
mq2.atten(ADC.ATTN_11DB)  # full 0-3.3V range

# LED alarm
led = Pin(2, Pin.OUT)

# Buzzer alarm
buzzer = Pin(4, Pin.OUT)

# Function: get distance from ultrasonic
def get_distance():
    trig.off()
    time.sleep_us(2)
    trig.on()
    time.sleep_us(10)
    trig.off()
    
    duration = time_pulse_us(echo, 1, 30000)  # wait for echo
    distance = (duration / 2) / 29.1 if duration > 0 else 999
    return distance

# Main loop
while True:
    motion = pir.value()
    distance = get_distance()
    gas_value = mq2.read()

    print("PIR:", motion, " Distance:", distance, "cm  Gas:", gas_value)

    # Flags to track if any condition triggered
    alert_triggered = False

    # 🚶 Motion Alert
    if motion == 1:
        print("🚶 Motion Detected")
        led.on()
        buzzer.on()
        time.sleep(0.2)
        buzzer.off()
        led.off()
        alert_triggered = True

    # 🚪 Person Near Door Alert
    if distance < 30:
        print("🚪 Person Near Door (<30 cm)")
        led.on()
        buzzer.on()
        time.sleep(0.5)
        buzzer.off()
        led.off()
        alert_triggered = True

    # 🔥 Gas Leak Alert
    if gas_value > 2000:  # adjust threshold as needed
        print("🔥 Gas Leak Detected")
        for _ in range(3):       # beep 3 times
            led.on()
            buzzer.on()
            time.sleep(0.2)
            buzzer.off()
            led.off()
            time.sleep(0.2)
        alert_triggered = True

    # ⚠️ Combined DANGER Alert
    if motion == 1 and distance < 30 and gas_value > 2000:
        print("⚠️ DANGER: Motion + Person + Gas Detected!")
        for _ in range(10):      # continuous flashing + buzzer
            led.on()
            buzzer.on()
            time.sleep(0.3)
            buzzer.off()
            led.off()
            time.sleep(0.3)
        alert_triggered = True

    # ✅ System Normal
    if not alert_triggered:
        print("✅ System Normal")
        led.off()
        buzzer.off()

    time.sleep(1)