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

#WiFi
WIFI_SSID = "Wokwi-GUEST"
WIFI_PASSWORD = ""

#MQTT
MQTT_BROKER = "broker.hivemq.com"
MQTT_PORT = 1883
MQTT_CLIENT_ID = "ESP32_MicroPython_Mousa"
MQTT_TOPIC_RELAY = b"relay/status"
MQTT_TOPIC_CURRENT = b"current/status"
MQTT_TOPIC_ALERT = b"alert/status"

#Pins
RELAY_PIN = Pin(26, Pin.OUT)
LED_PIN = Pin(27, Pin.OUT)
ALERT_LED_PIN = Pin(12, Pin.OUT)
CURRENT_SENSOR = ADC(Pin(34))
CURRENT_SENSOR.width(ADC.WIDTH_12BIT)
BUTTON_PIN = Pin(25, Pin.IN, Pin.PULL_UP)
RESET_BUTTON_PIN = Pin(33, Pin.IN, Pin.PULL_UP)

#Relay & Control State
relay_state = False
manual_control = False  
OVER_CURRENT_THRESHOLD_A = 15
VREF = 1.65  
SENSITIVITY = 0.103
ADC_MAX = 4095
ADC_VOLTAGE = 3.3

# ==== Functions ====
def connect_wifi():
    wifi = network.WLAN(network.STA_IF)
    wifi.active(True)
    wifi.connect(WIFI_SSID, WIFI_PASSWORD)
    print("Connecting to WiFi...", end="")
    while not wifi.isconnected():
        print(".", end="")
        time.sleep(0.5)
    print("\nWiFi connected:", wifi.ifconfig()[0])

def set_relay(state):
    global relay_state
    relay_state = state
    RELAY_PIN.value(0 if state else 1)  # Active LOW relay
    LED_PIN.value(1 if state else 0)    # LED ON when relay ON
    print("Relay", "ON" if state else "OFF")

def read_current():
    if not relay_state:
        return 0  # Relay OFF →
    adc_val = CURRENT_SENSOR.read()
    voltage = adc_val * ADC_VOLTAGE / ADC_MAX
    current = (voltage - VREF) / SENSITIVITY  
    return max(current, 0)

def check_alert(current):
    if current > OVER_CURRENT_THRESHOLD_A:
        ALERT_LED_PIN.value(1)
        client.publish(MQTT_TOPIC_ALERT, b"Overcurrent")
        set_relay(False)
    else:
        ALERT_LED_PIN.value(0)

def mqtt_callback(topic, msg):
    global manual_control
    print("Message:", msg)
    if msg == b"ON":
        manual_control = True
        set_relay(True)
    elif msg == b"OFF":
        manual_control = True
        set_relay(False)
    elif msg == b"AUTO":
        manual_control = False  

# ==== Main Program ====
connect_wifi()

client = MQTTClient(MQTT_CLIENT_ID, MQTT_BROKER, port=MQTT_PORT)
client.set_callback(mqtt_callback)
client.connect()
client.subscribe(MQTT_TOPIC_RELAY)
print("Connected_MQTT_broker_&_subscribed_relay topic")

# Start with relay OFF
set_relay(False)

while True:
    client.check_msg()

    # ==== Read Current from ACS712 ====
    current_reading = read_current()
    formatted_current = "{:.2f}".format(current_reading)  
    print(f"Current: {formatted_current}A")
    client.publish(MQTT_TOPIC_CURRENT, formatted_current)

    #Check Overcurrent Alert
    check_alert(current_reading)

    #control by current sensor
    if not manual_control:
        if current_reading > 0.5 and not relay_state:  # Load detected
            set_relay(True)
            client.publish(MQTT_TOPIC_RELAY, b"ON")
        elif current_reading <= 0.5 and relay_state:  # No load
            set_relay(False)
            client.publish(MQTT_TOPIC_RELAY, b"OFF")

    # ==== Toggle button (manual override) ====
    if BUTTON_PIN.value() == 0:
        time.sleep(0.2)
        set_relay(not relay_state)
        manual_control = True  # manual button press overrides auto
        client.publish(MQTT_TOPIC_RELAY, b"ON" if relay_state else b"OFF")
        while BUTTON_PIN.value() == 0:
            pass

    # ==== Reset button ====
    if RESET_BUTTON_PIN.value() == 0:
        time.sleep(0.2)
        manual_control = False  # back to auto
        set_relay(False)
        client.publish(MQTT_TOPIC_RELAY, b"OFF")
        while RESET_BUTTON_PIN.value() == 0:
            pass

    time.sleep(1)