#include <WiFi.h>
#include <PubSubClient.h>
#include <DHT.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// --- Definitions ---
#define DHTPIN 15        // Cyan wire in your diagram
#define DHTTYPE DHT22    // White DHT22 sensor
#define MQ2_PIN 34       // Gas sensor pin

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// --- Network & ThingsBoard ---
const char* ssid = "Wokwi-GUEST"; 
const char* password = "";        
const char* mqtt_server = "thingsboard.cloud";
const char* token = "rs4g3t698mx0rsp7od4i"; // <--- MAKE SURE YOUR TOKEN IS HERE

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

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

  // 1. Initialize OLED
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { 
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  display.clearDisplay();
  display.setTextColor(WHITE);
  display.setTextSize(1);
  display.setCursor(0, 10);
  display.println("Connecting WiFi...");
  display.display();

  // 2. Initialize WiFi
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  
  display.clearDisplay();
  display.setCursor(0, 10);
  display.println("WiFi Connected!");
  display.display();

  // 3. Initialize MQTT & DHT
  client.setServer(mqtt_server, 1883);
  dht.begin();
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect("ESP32_Client", token, NULL)) {
      Serial.println("connected");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}
void loop() {
  // 1. Read and Display sensors FIRST (Local display works even without internet)
  float temp = dht.readTemperature();
  float hum = dht.readHumidity();
  int gas = analogRead(MQ2_PIN);
  

  display.clearDisplay();
  display.setCursor(0, 0);
  display.println("--- SENSOR DATA ---");
  display.setCursor(0, 20);
  display.print("Temp: "); display.print(temp); display.println(" C");
  display.setCursor(0, 35);
  display.print("Hum:  "); display.print(hum); display.println(" %");
  display.setCursor(0, 50);
  display.print("Gas:  "); display.println(gas);display.println(" ppm");
  display.display();

  // 2. Now try to talk to ThingsBoard in the background
  if (!client.connected()) {
    Serial.println("MQTT Connecting...");
    if (client.connect("ESP32_Client", token, NULL)) {
      Serial.println("Connected to ThingsBoard!");
    } else {
      Serial.print("Auth Failed, rc=");
      Serial.println(client.state());
    }
  }

  if (client.connected()) {
    client.loop();
    String payload = "{\"temperature\":" + String(temp) + ",\"humidity\":" + String(hum) + ",\"gas\":" + String(ppm) + "}";
    client.publish("v1/devices/me/telemetry", payload.c_str());
  }

  delay(2000); 
}