from machine import Pin, PWM, I2C
from time import sleep
import utime
from dht import DHT22
from pico_i2c_lcd import I2cLcd
# RTC used
import ds3231   

# Buzzer control 
buzzer = None  

def buzzer_on(freq=1000, duty_value=5000):
    global buzzer
    if buzzer is None:
        buzzer = PWM(Pin(19))   
    buzzer.freq(freq)
    buzzer.duty_u16(duty_value)
def buzzer_off():
    global buzzer
    if buzzer is not None:
        buzzer.duty_u16(0)

# DHT22 Setup 
dht = DHT22(Pin(16))   

# I2C for LCD & RTC 
i2c = I2C(0, sda=Pin(4), scl=Pin(5), freq=400000)

# Get I2C address for LCD
I2C_ADDR = i2c.scan()[0]
# LCD object (16x2)
lcd = I2cLcd(i2c, I2C_ADDR, 2, 16)
# RTC object (DS3231)
rtc = ds3231.DS3231(i2c)

# LEDs 
red_led = Pin(27, Pin.OUT)     # Red LED GP27
green_led = Pin(26, Pin.OUT)   # Green LED GP26

# LDR Module 
ldr = Pin(20, Pin.IN)          

# Alert state tracking 
alert_active = False
buzzer_start_time = 0

print("Temperature & Humidity Monitor Started")

while True:
    try:
        # Get sensor readings 
        dht.measure()
        temp = dht.temperature()
        hum = dht.humidity()
        
        # Read LDR Module (Digital Output) -->no ADC so cannot get the analog output
        light_value = ldr.value()  
        light_status = "LOW" if light_value == 0 else "HIGH"
        
        # Get real time from RTC 
        year, month, day, weekday, hour, minute, second, _ = rtc.datetime()
        
        # LCD Display 
        lcd.clear()
        lcd.move_to(0, 0)
        lcd.putstr(f"{hour:02}:{minute:02}:{second:02} {day:02}/{month:02}")
        lcd.move_to(0, 1)
        lcd.putstr(f"T:{temp:.1f}C H:{hum:.1f}%")
        
        current_time = utime.ticks_ms()
        
        temp_high = temp > 30        # Temperature > 30°C
        humidity_low = hum < 30      # Humidity < 30%
        
        if temp_high or humidity_low:
            # ALERT CONDITIONS: Red LED + Buzzer
            red_led.value(0)
            green_led.value(1)
            
            if not alert_active:
                buzzer_on()
                buzzer_start_time = current_time
                alert_active = True
                print(f"ALERT, Temp: {temp:.1f}°C, Humidity: {hum:.1f}%")
                if temp_high:
                    print("- Temperature is HIGH (>30°C)")
                if humidity_low:
                    print("- Humidity is LOW (<30%)")
            #elif utime.ticks_diff(current_time, buzzer_start_time) > 1000:  # 1 second
                # Turn off buzzer after 1 second, but keep red LED on
                #buzzer_off()
                
        else:
            # NORMAL CONDITIONS: Green LED (no buzzer)
            green_led.value(0)
            red_led.value(1)
            buzzer_off()
            alert_active = False
            print(f"Normal conditions - Temp: {temp:.1f}°C, Humidity: {hum:.1f}%")
        
        
    except Exception as e:
        print(f"Sensor Error: {e}")
        # Turn off everything in case of error
        red_led.value(1)
        green_led.value(1)  
        buzzer_off()
        lcd.clear()
        lcd.putstr("SENSOR ERROR")
    
    sleep(2)   # Update every 2 seconds