import network
import time
from machine import Pin, ADC
from umqtt import MQTTClient
import ubinascii
import machine

# ---------------- WiFi ----------------
SSID = "Wokwi-GUEST"
PASSWORD = ""

# ---------------- MQTT ----------------
BROKER = "broker.hivemq.com"
PORT = 1883
TOPIC = b"factory/gas/mq2/alert"

CLIENT_ID = b"pico-" + ubinascii.hexlify(machine.unique_id())

# ---------------- Hardware ----------------
mq2 = ADC(26)
led = Pin(15, Pin.OUT)
buzzer = Pin(14, Pin.OUT)

GAS_THRESHOLD = 35000
led_state = False   # for blinking

# ---------------- WiFi Connect ----------------
print("Connecting to WiFi...")
wifi = network.WLAN(network.STA_IF)
wifi.active(True)
wifi.connect(SSID, PASSWORD)

while not wifi.isconnected():
    time.sleep(0.2)

print("WiFi Connected")
time.sleep(2)

# ---------------- MQTT Connect ----------------
print("Connecting to MQTT...")
client = MQTTClient(
    client_id=CLIENT_ID,
    server=BROKER,
    port=PORT,
    keepalive=60
)

client.connect()
print("MQTT Connected")

# ---------------- Main Loop ----------------
while True:
    gas_value = mq2.read_u16()
    print("Gas Level:", gas_value)

    if gas_value > GAS_THRESHOLD:
        # ---- ALARM ACTIONS ----
        buzzer.on()

        # LED BLINK
        led_state = not led_state
        led.value(led_state)

        # ---- ALERT + TELEMETRY ----
        msg = "ALERT: HARMFUL GAS | Level={}".format(gas_value)
        client.publish(TOPIC, msg)
        print("🚨 ALERT SENT")

    else:
        # ---- SAFE STATE ----
        led.off()
        buzzer.off()

    time.sleep(1)