#define BLYNK_TEMPLATE_ID "TMPL4iwlB_40u"
#define BLYNK_TEMPLATE_NAME "MULTI GAS DETECTION SYSTEM SIMULATION"
#define BLYNK_AUTH_TOKEN "Sdpjkk52g8BeIzZ0UyckYwN7ebjOquU-"

#include <WiFi.h>
#include <BlynkSimpleEsp32.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <DHT.h>

// -------- WiFi --------
char ssid[] = "Wokwi-GUEST";
char pass[] = "";

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

// -------- Pins --------
#define MQ2_PIN 34
#define MQ7_PIN 35
#define MQ135_PIN 33
#define DHT_PIN 4

#define DHTTYPE DHT22
DHT dht(DHT_PIN, DHTTYPE);

// -------- Kalman Filter --------
class KalmanFilter {
  public:
    float Q, R, X, P, K;

    KalmanFilter(float q, float r, float initVal) {
      Q = q; R = r; X = initVal; P = 1;
    }

    float update(float m) {
      P += Q;
      K = P / (P + R);
      X = X + K * (m - X);
      P = (1 - K) * P;
      return X;
    }
};

// Filters
KalmanFilter mq2F(0.1, 10, 1000);
KalmanFilter mq7F(0.1, 10, 1000);
KalmanFilter mq135F(0.1, 10, 2000);

// -------- Alert Flags --------
bool smokeAlert = false;
bool coAlert = false;
bool co2Alert = false;

// -------- Timer --------
BlynkTimer timer;

// -------- Data Function --------
void sendData() {

  float mq2 = mq2F.update(analogRead(MQ2_PIN));
  float mq7 = mq7F.update(analogRead(MQ7_PIN));
  float mq135 = mq135F.update(analogRead(MQ135_PIN));

  float mq2P = (mq2 / 4095.0) * 100;
  float mq7P = (mq7 / 4095.0) * 100;
  float mq135P = (mq135 / 4095.0) * 100;

  float temp = dht.readTemperature();
  float hum = dht.readHumidity();

  if (isnan(temp) || isnan(hum)) return;

  // -------- Send to Blynk --------
  Blynk.virtualWrite(V0, mq2P);
  Blynk.virtualWrite(V1, mq7P);
  Blynk.virtualWrite(V2, mq135P);
  Blynk.virtualWrite(V3, temp);
  Blynk.virtualWrite(V4, hum);

  // -------- ALERTS --------
  if (mq2P > 50 && !smokeAlert) {
    Blynk.logEvent("gas_alert", "Smoke Detected");
    smokeAlert = true;
  }
  if (mq2P < 50) smokeAlert = false;

  if (mq7P > 60 && !coAlert) {
    Blynk.logEvent("gas_alert", "Carbon monoxide detected");
    coAlert = true;
  }
  if (mq7P < 60) coAlert = false;

  if (mq135P > 60 && !co2Alert) {
    Blynk.logEvent("gas_alert", "Carbon dioxide detected");
    co2Alert = true;
  }
  if (mq135P < 60) co2Alert = false;

  // -------- OLED --------
  display.clearDisplay();

  display.setCursor(0, 0);
  display.println("Gas Monitor");

  display.setCursor(0, 10);
  display.print("T:");
  display.print(temp, 1);
  display.print("C H:");
  display.print(hum, 0);
  display.println("%");

  display.setCursor(0, 25);
  display.print("MQ2:");
  display.print(mq2P, 1);

  display.setCursor(0, 35);
  display.print("MQ7:");
  display.print(mq7P, 1);

  display.setCursor(0, 45);
  display.print("MQ135:");
  display.print(mq135P, 1);

  display.display();

  // -------- SERIAL MONITOR OUTPUT --------
  Serial.println("------ GAS READINGS ------");
  Serial.print("MQ-2 (Smoke): "); Serial.print(mq2P); Serial.println(" %");
  Serial.print("MQ-7 (CO): "); Serial.print(mq7P); Serial.println(" %");
  Serial.print("MQ-135 (Air): "); Serial.print(mq135P); Serial.println(" %");
  Serial.print("Temperature: "); Serial.print(temp); Serial.println(" C");
  Serial.print("Humidity: "); Serial.print(hum); Serial.println(" %");
  Serial.println("---------------------------\n");
}

// -------- Setup --------
void setup() {
  Serial.begin(115200);

  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);

  dht.begin();

  // WiFi connect (only once)
  WiFi.begin(ssid, pass);
  while (WiFi.status() != WL_CONNECTED) {
    delay(300);
    Serial.print(".");
  }
  Serial.println("\nWiFi Connected");

  Blynk.config(BLYNK_AUTH_TOKEN);
  Blynk.connect();

  timer.setInterval(1000L, sendData);
}

// -------- Loop --------
void loop() {
  if (Blynk.connected()) {
    Blynk.run();
  }
  timer.run();
}