import network
import time
from machine import Pin, ADC
from umqtt.simple import MQTTClient
import math


ssid = "Wokwi-GUEST"
password = ""
mqtt_server = "broker.hivemq.com"
client_id = "esp32-client"
topic_temp = b"esp32/temp"
topic_relay = b"esp32/relay/control"

relay_pin = Pin(19, Pin.OUT)
temp_sensor = ADC(Pin(34))
temp_sensor.atten(ADC.ATTN_11DB)  # full range (0 - 3.3V)
temp_sensor.width(ADC.WIDTH_12BIT)  # 0-4095

#  Connect to Wi-Fi
def connect_wifi():
    wlan = network.WLAN(network.STA_IF)
    wlan.active(True)
    wlan.connect(ssid, password)
    print("Connecting to Wi-Fi", end="")
    while not wlan.isconnected():
        print(".", end="")
        time.sleep(0.5)
    print("\nConnected to Wi-Fi")

#  Read temperature using BETA formula
def read_temp():
    BETA = 3950
    analog = temp_sensor.read()
    celsius = 1 / (math.log(1 / (4095 / analog - 1)) / BETA + 1 / 298.15) - 273.15
    return round(celsius, 2)

#  MQTT message handler
def mqtt_callback(topic, msg):
    print("Received:", topic, msg)
    if topic == topic_relay:
        if msg == b"on":
            relay_pin.on()
        elif msg == b"off":
            relay_pin.off()

# Connect and loop
connect_wifi()

client = MQTTClient(client_id, mqtt_server)
client.set_callback(mqtt_callback)
client.connect()
client.subscribe(topic_relay)
print("Connected to MQTT broker and subscribed to relay control.")

try:
    while True:
        temp = read_temp()
        print("Temperature:", temp, "°C")
        client.publish(topic_temp, str(temp))
        if temp >= 30:  
            relay_pin.on() 
            print("Relay ON due to high temp")
        else:
            relay_pin.off()   # 
            print("Relay OFF due to low temp")
        client.check_msg()  
        time.sleep(10)

except KeyboardInterrupt:
    print("Disconnected")
    client.disconnect()