#include <WiFi.h>
#include <HTTPClient.h>

// WiFi credentials
const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";

// Telegram bot token and chat ID
const char* telegramBotToken = "your_TELEGRAM_BOT_TOKEN";
const char* chat_id = "your_CHAT_ID";

// ThingsBoard credentials
const char* thingsboardServer = "http://YOUR_THINGSBOARD_SERVER_URL";
const char* accessToken = "YOUR_ACCESS_TOKEN";

// Hardware pin definitions
const int trigPin = 18;   // GPIO pin for ultrasonic sensor trigger
const int echoPin = 19;   // GPIO pin for ultrasonic sensor echo
const int relayPin = 21;  // GPIO pin for relay
const int buzzerPin = 22; // GPIO pin for buzzer
const int ledBluePin = 23;   // GPIO pin for blue LED
const int ledRedPin = 25;    // GPIO pin for red LED
const int ledGreenPin = 26;  // GPIO pin for green LED

// Variables for averaging the gas sensor readings
const int numReadings = 10;
int readings[numReadings];      // the readings from the analog input
int readIndex = 0;              // the index of the current reading
int total = 0;                  // the running total
int average = 0;                // the average
int analogValue = 0;            // raw analog value from sensor

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

  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(relayPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(ledBluePin, OUTPUT);
  pinMode(ledRedPin, OUTPUT);
  pinMode(ledGreenPin, OUTPUT);

  digitalWrite(relayPin, LOW);
  digitalWrite(buzzerPin, LOW);
  digitalWrite(ledBluePin, HIGH); // System ON
  digitalWrite(ledRedPin, LOW);
  digitalWrite(ledGreenPin, LOW);

  connectToWiFi();
}

void loop() {
    MQ135 gasSensor = MQ135(0);
    float air_quality = gasSensor.getPPM();
    Serial.print("Air Quality: ");  
    Serial.print(air_quality);
    Serial.println("  PPM");   
    Serial.println();

  Serial.print("Gas Level (Analog): ");
  Serial.print(analogValue);
  Serial.print("\t Gas Level (ppm CO2): ");
  Serial.println(ppmCO2);

if (ppmCO2 > 0 && ppmCO2 <= 1000) {
    // Normal operating range, system is normal
    digitalWrite(relayPin, LOW);
    digitalWrite(buzzerPin, LOW);
    digitalWrite(ledRedPin, LOW);
    digitalWrite(ledGreenPin, HIGH);
} else if (ppmCO2 > 1000) {
    // Hazardous gas detected
    digitalWrite(relayPin, HIGH);
    digitalWrite(buzzerPin, HIGH);
    digitalWrite(ledRedPin, HIGH);
    digitalWrite(ledGreenPin, LOW);
    sendTelegramAlert(ppmCO2);
} else {
    // Handle cases where ppmCO2 is 0 or negative (sensor not connected or error)
    digitalWrite(relayPin, LOW);
    digitalWrite(buzzerPin, LOW);
    digitalWrite(ledRedPin, LOW);
    digitalWrite(ledGreenPin, LOW); // Indicate error state
}

  long duration = getUltrasonicReading();
  float distance = duration * 0.034 / 2; // Calculate distance in cm
  Serial.print("Water Level: ");
  Serial.print(distance);
  Serial.println(" cm");

  sendToThingsBoard(ppmCO2, distance);

  delay(5000); // Delay 5 seconds before the next reading
}

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

long getUltrasonicReading() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  return pulseIn(echoPin, HIGH);
}

void sendTelegramAlert(float gasLevel) {
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    String message = "Warning! Hazardous gas detected. Gas level: " + String(gasLevel) + " ppm CO2";
    String url = "https://api.telegram.org/bot" + String(telegramBotToken) + "/sendMessage?chat_id=" + String(chat_id) + "&text=" + message;

    http.begin(url);
    int httpResponseCode = http.GET();

    if (httpResponseCode > 0) {
      String response = http.getString();
      Serial.println(httpResponseCode);
      Serial.println(response);
    } else {
      Serial.print("Error on sending POST: ");
      Serial.println(httpResponseCode);
    }
    http.end();
  }
}

void sendToThingsBoard(float gasLevel, float waterLevel) {
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    String url = String(thingsboardServer) + "/api/v1/" + String(accessToken) + "/telemetry";

    http.begin(url);
    http.addHeader("Content-Type", "application/json");

    String payload = "{\"gasLevel\":" + String(gasLevel) + ",\"waterLevel\":" + String(waterLevel) + "}";
    int httpResponseCode = http.POST(payload);

    if (httpResponseCode > 0) {
      String response = http.getString();
      Serial.println(httpResponseCode);
      Serial.println(response);
    } else {
      Serial.print("Error on sending POST: ");
      Serial.println(httpResponseCode);
    }
    http.end();
  }
}