import network
import time
import machine
import math
from umqtt.simple import MQTTClient

# WiFi & MQTT
SSID = "Wokwi-GUEST"
PASSWORD = ""
MQTT_BROKER ="broker.hivemq.com"

CLIENT_ID = "esp32-client"
TOPIC_TEMP = b"esp32/temp"
TOPIC_CMD = b"esp32/relay_cmd"
TOPIC_MODE = b"esp32/mode"
TOPIC_THRESHOLD = b"esp32/set_threshold"

# ADC & Relay setup
adc = machine.ADC(machine.Pin(34))
adc.atten(machine.ADC.ATTN_11DB)
adc.width(machine.ADC.WIDTH_10BIT)

relay = machine.Pin(25, machine.Pin.OUT)

# System state
mode = "manual"
threshold = 30.0  # default °C

# Connect Wi-Fi
def connect_wifi():
    print("Connecting to Wi-Fi...")
    wlan = network.WLAN(network.STA_IF)
    wlan.active(True)
    wlan.connect(SSID, PASSWORD)
    while not wlan.isconnected():
        time.sleep(0.1)
    print("Connected:", wlan.ifconfig())

# Read temperature using correct NTC equation
def read_temperature():
    analog_value = adc.read()
    if analog_value <= 0 or analog_value >= 1023:
        return -273.15  # Error or out of range
    try:
        celsius = 1 / (math.log(1 / (1023. / analog_value - 1)) / 3950 + 1.0 / 298.15) - 273.15
        return celsius
    except:
        return -273.15  # Catch any math error

# MQTT callback
def mqtt_callback(topic, msg):
    global mode, threshold
    print("Received:", topic, msg)
    
    if topic == TOPIC_CMD:
        if mode == "manual":
            if msg == b'on':
                relay.value(1)
            elif msg == b'off':
                relay.value(0)
    
    elif topic == TOPIC_MODE:
        if msg == b'auto':
            mode = "auto"
        elif msg == b'manual':
            mode = "manual"
        print("Mode changed to:", mode)
    
    elif topic == TOPIC_THRESHOLD:
        if mode == "auto":
            try:
                threshold = float(msg.decode())
                print("Threshold set to:", threshold)
            except:
                print("⚠️ Invalid threshold")

# Main loop
def main():
    connect_wifi()
    client = MQTTClient(CLIENT_ID, MQTT_BROKER)
    client.set_callback(mqtt_callback)
    client.connect()
    client.subscribe(TOPIC_CMD)
    client.subscribe(TOPIC_MODE)
    client.subscribe(TOPIC_THRESHOLD)
    print("MQTT connected and subscribed.")

    last_temp_publish = time.ticks_ms()

    while True:
        client.check_msg()

        temp = read_temperature()

        if mode == "auto":
            if temp > threshold:
                relay.value(1)
            else:
                relay.value(0)

        if mode == "manual" or time.ticks_diff(time.ticks_ms(), last_temp_publish) >= 2000:
            message = "Temperature is {:.2f}".format(temp)
            client.publish(TOPIC_TEMP, message.encode())
            last_temp_publish = time.ticks_ms()

        time.sleep(0.1)

main()