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

// WiFi credentials
const char* ssid = "Airtel_77";
const char* password = "380565750";

// MQTT Broker settings
const char* mqtt_server = "192.168.1.6";
const int mqtt_port = 1883;
const char* mqtt_topic = "home/sensors";

// Pin Definitions
#define TRIG_PIN 5
#define ECHO_PIN 18
#define DHT_PIN 4
#define LED_PIN 2
#define BUTTON_PIN 15
#define DHTTYPE DHT22

// Initialize objects
DHT dht(DHT_PIN, DHTTYPE);
WiFiClient espClient;
PubSubClient client(espClient);

// Variables
float temperature;
float humidity;
long duration;
float distance;
bool alertMode = false;
unsigned long lastReadingTime = 0;
const int readingInterval = 2000;

void setup_wifi() {
  delay(10);
  Serial.println("Connecting to WiFi");
  WiFi.begin(ssid, password);

  int retries = 0;
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    retries++;

    if (retries >= 10) {
      Serial.println("\nWiFi connection failed. Retrying in 10 seconds.");
      delay(10000);
      retries = 0;
      WiFi.begin(ssid, password);
    }
  }
  Serial.println("\nWiFi connected");
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    String clientId = "ESP32Client-";
    clientId += String(random(0xffff), HEX);

    if (client.connect(clientId.c_str())) {
      Serial.println("connected");
      client.subscribe("home/control"); // Subscribe to control messages
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" retrying in 5 seconds");
      delay(5000);
    }
  }
}

void callback(char* topic, byte* payload, unsigned int length) {
  // Handle incoming MQTT messages
  if (String(topic) == "home/control") {
    DynamicJsonDocument doc(1024);
    deserializeJson(doc, payload, length);

    if (doc.containsKey("alertMode")) {
      alertMode = doc["alertMode"].as<bool>();
    }
  }
}

void setup() {
  Serial.begin(115200);

  // Initialize sensors
  dht.begin();
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);

  setup_wifi();
  client.setServer(mqtt_server, mqtt_port);
  client.setCallback(callback);

  Serial.println("Smart Space Monitor Initialized!");
}

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

  // Check button state for alert mode toggle
  if (digitalRead(BUTTON_PIN) == LOW) {
    alertMode = !alertMode;

    // Publish alert mode change
    DynamicJsonDocument doc(1024);
    doc["alertMode"] = alertMode;
    char buffer[256];
    serializeJson(doc, buffer);
    client.publish("home/status", buffer);

    delay(500); // Debounce
  }

  // Read sensors every 2 seconds
  if (millis() - lastReadingTime >= readingInterval) {
    // Read DHT sensor
    temperature = dht.readTemperature();
    humidity = dht.readHumidity();

    // Read Ultrasonic sensor
    digitalWrite(TRIG_PIN, LOW);
    delayMicroseconds(2);
    digitalWrite(TRIG_PIN, HIGH);
    delayMicroseconds(10);
    digitalWrite(TRIG_PIN, LOW);

    duration = pulseIn(ECHO_PIN, HIGH);
    distance = duration * 0.034 / 2;

    // Prepare JSON payload
    DynamicJsonDocument doc(1024);
    doc["temperature"] = temperature;
    doc["humidity"] = humidity;
    doc["distance"] = distance;
    doc["alertMode"] = alertMode;

    char buffer[256];
    serializeJson(doc, buffer);
    client.publish(mqtt_topic, buffer);

    // LED Logic
    if (alertMode) {
      if (distance < 50) {
        digitalWrite(LED_PIN, HIGH);
        delay(100);
        digitalWrite(LED_PIN, LOW);
      }
    } else {
      int brightness = map(temperature, 20, 40, 0, 255);
      analogWrite(LED_PIN, brightness);
    }

    lastReadingTime = millis();
  }
}