from machine import Pin, PWM, ADC, I2C
from time import sleep
from i2c_lcd import I2cLcd

# Hardware setup
i2c = I2C(0, sda=Pin(0), scl=Pin(1), freq=400000)
lcd = I2cLcd(i2c, 0x27, 2, 16)
gas_sensor = ADC(Pin(26))       
led_red = Pin(2, Pin.OUT)       
button = Pin(20, Pin.IN, Pin.PULL_UP)
buzzer = PWM(Pin(3))

# Servo configuration
servo = PWM(Pin(16))            
servo.freq(50)    

def set_servo_angle(angle):
    duty = int(1638 + (angle / 180) * (8192 - 1638))
    servo.duty_u16(duty)

def sound_alarm(enable):
    if enable:
        buzzer.freq(1000)
        buzzer.duty_u16(32768)
    else:
        buzzer.duty_u16(0)

# Initial states
set_servo_angle(0)
sound_alarm(False)
GAS_THRESHOLD = 40000

# Startup screen
lcd.clear()
lcd.putstr("System Ready\nStatus: Normal")
sleep(2)

while True:
    gas_value = gas_sensor.read_u16()
    # Gas alarm state
    if gas_value > GAS_THRESHOLD:
        led_red.value(1)
        sound_alarm(True)
        
        lcd.clear()
        lcd.putstr("WARNING: GAS!")
        lcd.move_to(0, 1)
        lcd.putstr("Press BTN to Open")
        
        # Open door on button press
        if button.value() == 0:
            lcd.clear()
            lcd.putstr("Door Opening...")
            set_servo_angle(90)  
            sound_alarm(False)
            
            sleep(5)
            
            lcd.clear()
            lcd.putstr("Door Closing...")
            set_servo_angle(0)   
            sleep(1)

    # Normal state
    else:
        led_red.value(0)
        sound_alarm(False)
        set_servo_angle(0)
        
        lcd.clear()
        lcd.putstr("Air: Safe")
        lcd.move_to(0, 1)
        lcd.putstr(f"Gas Level: {gas_value}")
    
    sleep(0.5)