#include <WiFi.h>
#include <PubSubClient.h>

#define WIFI_SSID = "Wokwi-GUEST"
#define WIFI_PASSWORD = ""
#define MQTT_BROKER = "mqtt.eclipseprojects.io"
#define MQTT_PORT = 1883
#define BUZZER_PIN = 5

// MQTT Topics
const char* tempTopic = "sensors/esp32";
const char* alertTopic = "project/alerts";

// Global clients
WiFiClient espClient;
PubSubClient mqttClient(espClient);

// Threshold for temperature alert
float tempThreshold = 30.0;

void connectToWiFi() {
  Serial.print("Connecting to WiFi...");
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nWiFi connected. IP: " + WiFi.localIP().toString());
}

void connectToMQTT() {
  while (!mqttClient.connected()) {
    Serial.print("Connecting to MQTT...");
    if (mqttClient.connect("ESP32_Client")) {
      Serial.println("connected!");
      mqttClient.subscribe(tempTopic);
    } else {
      Serial.print("failed. State=");
      Serial.print(mqttClient.state());
      Serial.println(" Retrying in 5s...");
      delay(5000);
    }
  }
}

void mqttCallback(char* topic, byte* payload, unsigned int length) {
  String message;
  for (int i = 0; i < length; i++) {
    message += (char)payload[i];
  }

  float tempValue = message.toFloat();
  Serial.println("Temp Received: " + String(tempValue));

  if (tempValue > tempThreshold) {
    digitalWrite(BUZZER_PIN, HIGH);
    mqttClient.publish(alertTopic, "Alert: High temperature!");
  } else {
    digitalWrite(BUZZER_PIN, LOW);
  }
}

void setup() {
  Serial.begin(115200);
  pinMode(BUZZER_PIN, OUTPUT);
  digitalWrite(BUZZER_PIN, LOW);

  connectToWiFi();
  mqttClient.setServer(MQTT_BROKER, MQTT_PORT);
  mqttClient.setCallback(mqttCallback);
}

void loop() {
  if (!mqttClient.connected()) {
    connectToMQTT();
  }
  mqttClient.loop();
}