#include <Wire.h> // Include Wire library for I2C communication
#include <LiquidCrystal_I2C.h> // Include LCD library for I2C
#include <Keypad.h> // Include Keypad library

// Initialize LCD with I2C address (0x27 is common, change if needed)
LiquidCrystal_I2C lcd(0x27, 16, 2);

const byte row = 4;  // Define the number of rows in the keypad
const byte col = 4;  // Define the number of columns in the keypad

// Define the keypad layout (characters assigned to each button)
char keyarray[row][col] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

// Define column and row pin connections for the keypad
byte cpins[col] = {2, 3, 4, 5}; // Column pinouts (C4, C3, C2, C1)
byte rpins[row] = {6, 7, 8, 9}; // Row pinouts (R4, R3, R2, R1)

// Initialize the keypad object with the defined layout and pins
Keypad kpd = Keypad(makeKeymap(keyarray), rpins, cpins, row, col);

void setup() {
  lcd.init();  // Initialize LCD
  lcd.backlight(); // Turn on backlight
  lcd.clear();  // Clear the LCD screen
  lcd.setCursor(0, 0);  // Set cursor to the first row, first column
  lcd.print("Press 1-9");  // Display message
  lcd.setCursor(0, 1);  // Set cursor to the second row, first column
  lcd.print("For Multiplication");  // Display message
}

void loop() {
  char key = kpd.getKey(); // Read key press from the keypad

  if (key) { // Check if a key is pressed
    lcd.clear(); // Clear LCD screen before displaying new content

    if (key >= '1' && key <= '9') { // Check if the key pressed is between '1' and '9'
      int num = key - '0'; // Convert the character to an integer

      // Display multiplication table in pairs (x1 & x2, x3 & x4, etc.)
      lcd.setCursor(0, 0);
      lcd.print(num);
      lcd.print("x1=");
      lcd.print(num * 1);

      lcd.setCursor(0, 1);
      lcd.print(num);
      lcd.print("x2=");
      lcd.print(num * 2);
      delay(1500); // Pause before updating

      lcd.clear(); // Clear the screen for the next set of calculations
      lcd.setCursor(0, 0);
      lcd.print(num);
      lcd.print("x3=");
      lcd.print(num * 3);
      lcd.setCursor(0, 1);
      lcd.print(num);
      lcd.print("x4=");
      lcd.print(num * 4);
      delay(1500); // Pause before updating

      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print(num);
      lcd.print("x5=");
      lcd.print(num * 5);
      lcd.setCursor(0, 1);
      lcd.print(num);
      lcd.print("x6=");
      lcd.print(num * 6);
      delay(1500); // Pause before updating

      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print(num);
      lcd.print("x7=");
      lcd.print(num * 7);
      lcd.setCursor(0, 1);
      lcd.print(num);
      lcd.print("x8=");
      lcd.print(num * 8);
      delay(1500); // Pause before updating

      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print(num);
      lcd.print("x9=");
      lcd.print(num * 9);
      lcd.setCursor(0, 1);
      lcd.print(num);
      lcd.print("x10=");
      lcd.print(num * 10);
      delay(2000); // Pause before resetting the screen

      // Reset LCD screen to default message
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Press 1-9");
      lcd.setCursor(0, 1);
      lcd.print("For Multiplication");
    }
    else if (key == '0') { // If '0' is pressed
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Zero Selected"); // Display message
      delay(1000); // Wait before clearing the screen
      lcd.clear(); // Clear screen
    }
  }
}