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

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

// MQTT Broker Details
const char* mqtt_server = "broker.hivemq.com";
const int mqtt_port = 1883;

// MQTT Topics
const char* topic_temperature = "vit/iot/temp";
const char* topic_status = "vit/iot/status";

// Pin Definitions
const int potPin = 34;
const int ledPin = 23;

// Variables
WiFiClient espClient;
PubSubClient client(espClient);

float temperature = 0;
unsigned long lastMsg = 0;
const long interval = 5000;
int msgCount = 0;

// Function to Connect WiFi
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("\nWiFi Connected ✓");
  Serial.print("IP Address: ");
  Serial.println(WiFi.localIP());
}

// Function to Reconnect MQTT
void reconnect() {
  while (!client.connected()) {
    Serial.print("Connecting to MQTT...");

    String clientId = "ESP32_Publisher_";
    clientId += String(random(0xffff), HEX);

    if (client.connect(clientId.c_str())) {
      Serial.println(" connected ✓");
      Serial.print("Client ID: ");
      Serial.println(clientId);

      // Publish Online Status
      client.publish(topic_status, "{\"status\":\"online\",\"device\":\"publisher\"}");

      // Blink LED
      for (int i = 0; i < 3; i++) {
        digitalWrite(ledPin, HIGH);
        delay(100);
        digitalWrite(ledPin, LOW);
        delay(100);
      }

    } else {
      Serial.print(" failed, rc=");
      Serial.print(client.state());
      Serial.println(" retrying in 5 seconds...");
      delay(5000);
    }
  }
}

// Function to Publish Data
void publishData() {

  Serial.println("\n--- PUBLISHING ---");

  String payload = "{";
  payload += "\"temp\":" + String(temperature, 1) + ",";
  payload += "\"count\":" + String(msgCount) + ",";
  payload += "\"time\":" + String(millis());
  payload += "}";

  Serial.print("Topic: ");
  Serial.println(topic_temperature);
  Serial.print("Payload: ");
  Serial.println(payload);

  if (client.publish(topic_temperature, payload.c_str())) {
    Serial.println("Publish successful ✓");

    digitalWrite(ledPin, HIGH);
    delay(100);
    digitalWrite(ledPin, LOW);
  } else {
    Serial.println("Publish failed ✗");
  }

  Serial.println("------------------");
}

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

  setup_wifi();
  client.setServer(mqtt_server, mqtt_port);
}

void loop() {

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

  client.loop();

  int potValue = analogRead(potPin);

  // Map 0–4095 to 0–50°C
  temperature = map(potValue, 0, 4095, 0, 500) / 10.0;

  Serial.print("Temp: ");
  Serial.print(temperature);
  Serial.println(" °C");

  unsigned long now = millis();
  if (now - lastMsg > interval) {
    lastMsg = now;
    msgCount++;
    publishData();
  }

  delay(1000);
}