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

// ---------- Pin Definitions ----------
#define DHTPIN 15
#define DHTTYPE DHT22
#define LM35_PIN 34
#define BUZZER_PIN 12

// ---------- Wi-Fi Credentials ----------
const char* ssid = "Wokwi-GUEST";
const char* password = "";

// ---------- MQTT Broker ----------
const char* mqtt_server = "mqtt.eclipseprojects.io";
const char* topic_sub = "activate/buzzer";
const char* topic_pub = "alert/status";

WiFiClient espClient;
PubSubClient client(espClient);
DHT dht(DHTPIN, DHTTYPE);

// ---------- Threshold ----------
const float TEMP_THRESHOLD = 40.0;

void setup_wifi() {
  delay(10);
  Serial.println("Connecting to WiFi...");
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("WiFi connected");
}

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

  Serial.printf("Message arrived [%s]: %s\n", topic, msg.c_str());

  if (String(topic) == topic_sub && msg == "HIGH") {
    tone(BUZZER_PIN, 1000);
    Serial.println("Activating Buzzer Tone (1000 Hz)");
  } else {
    noTone(BUZZER_PIN);
    Serial.println("Buzzer OFF");
  }
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (client.connect("ESP32Client")) {
      Serial.println("connected");
      client.subscribe(topic_sub);
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" retrying in 5 sec");
      delay(5000);
    }
  }
}

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

  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  // Read LM35 analog temperature
  int analogValue = analogRead(LM35_PIN);
  float voltage = analogValue * (3.3 / 4095.0); // 12-bit ADC
  float tempC_LM35 = voltage * 100.0;

  // Read DHT22
  float tempC_DHT = dht.readTemperature();

  Serial.printf("LM35 Temp: %.2f°C\n", tempC_LM35);
  Serial.printf("DHT22 Temp: %.2f°C\n", tempC_DHT);

  // Check threshold
  if (tempC_LM35 > TEMP_THRESHOLD || tempC_DHT > TEMP_THRESHOLD) {
    tone(BUZZER_PIN, 1000);
    Serial.println("ALERT: Temperature Exceeded!");
    client.publish(topic_pub, "Temperature Alert Triggered!");
  } else {
    noTone(BUZZER_PIN);
  }

  delay(3000);
}