#include <DHT.h>
#include <SoftwareSerial.h>
#include <LiquidCrystal_I2C.h>

// GSM Module connection
SoftwareSerial gsmSerial(9, 10); // RX, TX pins

// DHT Sensor setup
#define DHTPIN 2          // Pin connected to the DHT22 sensor
#define DHTTYPE DHT22     // Specify DHT22 type
DHT dht(DHTPIN, DHTTYPE);

// Initialize the LCD - adjust the I2C address if needed
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  Serial.begin(9600);          // Start Serial communication
  gsmSerial.begin(115200);       // Start GSM module communication
  dht.begin();                 // Initialize DHT sensor
  lcd.begin();                 // Initialize LCD
  lcd.backlight();             // Turn on LCD backlight

  // Display welcome message
  lcd.clear();
  lcd.setCursor(0, 0); // First line
  lcd.print("Sensor Data Mon."); 
  lcd.setCursor(0, 1); // Second line
  lcd.print("by technolab"); 
 delay(3000); // Keep the message for 3 seconds

  // After the welcome message, proceed with initialization
  lcd.clear();
  lcd.print("Initializing...");
  delay(2000); // Delay for GSM module to initialize

  // Setup GSM module for SMS
  sendATCommand("AT+CMGF=1", "OK", 2000); // Text mode
  sendATCommand("AT+CNMI=1,2,0,0,0", "OK", 2000); // New SMS indication

  lcd.clear();
  lcd.print("Getting Ready");
}

void loop() {
  static unsigned long lastUpdate = 0;
  unsigned long currentTime = millis();

  // Continuously display temperature and humidity every 10 seconds
  if (currentTime - lastUpdate > 10000) {
    lastUpdate = currentTime;
    float humidity = dht.readHumidity();
    float temperature = dht.readTemperature();
    lcd.clear();
    lcd.setCursor(0, 0); // First line
    lcd.print("Updating....");
    delay(500);
         

    lcd.clear();
    lcd.print("Temp: ");
    lcd.print(temperature);
    lcd.print(" C");
    lcd.setCursor(0, 1); // Move to second line
    lcd.print("Hum: ");
    lcd.print(humidity);
    lcd.print(" %");
  }

  // Check for incoming SMS
  if (gsmSerial.available()) {
    if (gsmSerial.find("+CMT:")) {
      String smsCommand = gsmSerial.readString();
        lcd.clear();
         lcd.setCursor(0, 0); // First line
         lcd.print("SMS Received");
         delay(500);
      smsCommand.toUpperCase(); // Convert command to uppercase

      if (smsCommand.indexOf("STATE") != -1) {
        float humidity = dht.readHumidity();
        float temperature = dht.readTemperature();
        String message = "Temp: " + String(temperature) + "C, Hum: " + String(humidity) + "%";

        sendSMS(message); // Respond with temperature and humidity via SMS
      }
    }
  }
}

void sendATCommand(String command, const char* expectedResponse, unsigned long timeout) {
  gsmSerial.println(command); // Send the AT command
  long int time = millis();
  while ((time + timeout) > millis()) {
    while (gsmSerial.available()) {
      if (gsmSerial.find(const_cast<char*>(expectedResponse))) {
        Serial.println(command + ": SUCCESS");
         return;
      }
    }
  }
  Serial.println(command + "FAILED");
  lcd.clear();
         lcd.setCursor(0, 0); // First line
         lcd.print(command + "FAILED"); 
         delay(1000);
  
}

void sendSMS(String message) {
  lcd.clear();
         lcd.setCursor(0, 0); // First line
         lcd.print("Sending......");
  String phoneNo = "+918543053029"; // Replace with the sender's phone number
  sendATCommand("AT+CMGS=\"" + phoneNo + "\"", ">", 2000); // Prepare to send SMS
  gsmSerial.println(message); // Send the message content
  delay(500);
  gsmSerial.write(26); // ASCII code for CTRL+Z to send the SMS
  Serial.println("SMS Sent: " + message);
  lcd.clear();
         lcd.setCursor(0, 0); // First line
         lcd.print("Data Send");
         delay(500);
}