#include <LiquidCrystal_I2C.h>
#include <Keypad.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);

const uint8_t ROWS = 4;
const uint8_t COLS = 4;

char keys[ROWS][COLS] = {
  { '1', '2', '3', 'A' },
  { '4', '5', '6', 'B' },
  { '7', '8', '9', 'C' },
  { '*', '0', '#', 'D' }
};

uint8_t colPins[COLS] = { 25, 33, 32, 35}; // Pins connected to C1, C2, C3, C4
uint8_t rowPins[ROWS] = { 12, 14, 27, 26 }; // Pins connected to R1, R2, R3, R4

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// SIM800L Setup
SoftwareSerial sim800lSerial(10, 11); // RX, TX

char key;
String phoneNumber = "";


// SIM MODULE INITALIZE
bool initializeSIM800L() {
  sim800lSerial.begin(9600);
  delay(1000);
  
  sim800lSerial.println("AT"); // Test AT command
  delay(1000);
  
  if (sim800lSerial.find("OK")) {
    sim800lSerial.println("AT+CREG?"); // Check network registration
    delay(1000);

    if (sim800lSerial.find("+CREG: 0,1")) {
      return true;
    }
  }
   return false;
}

void setup() {
  Wire.begin(21, 22);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(1, 0);
  lcd.print("SYSTEM STARTING");
  lcd.setCursor(1, 1);
  lcd.print("PLEASE WAIT...");
  delay(2000);
  lcd.clear();
    lcd.setCursor(0, 0);
  
  if (initializeSIM800L()) {
    lcd.print("SIM800L initialized");
  } else {
    lcd.print("Initialization failed");
    while (1); // Halt if initialization fails
  }

  delay(2000);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Enter number:");
}

void loop() {
  key = keypad.getKey();
  if (key != NO_KEY) {
    lcd.setCursor(0, 0);
    lcd.print("Dialing: ");
    lcd.print(key);

    String phoneNumber;
    phoneNumber += key;

    while (true) {
      char nextKey = keypad.getKey();

      if (nextKey != NO_KEY) {
        lcd.setCursor(0, 1);
        lcd.print(phoneNumber);
        lcd.print(nextKey);

        phoneNumber += nextKey;
      }

      if (nextKey == '#') {
        break;
      }

      delay(100);
    }

    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Calling...");
    delay(1000);

    dialNumber(phoneNumber);
  }
}

void dialNumber(String number) {
  sim800lSerial.print("ATD");
  sim800lSerial.print(number);
  sim800lSerial.println(";");
  
  delay(1000);
  
  while (sim800lSerial.available()) {
    char c = sim800lSerial.read();
    Serial.write(c);
  }
  
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Call ended");
  
  delay(2000);
  lcd.clear();
}