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

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

// ESP32 GPIO pins connected to keypad
byte rowPins[ROWS] = {19, 18, 5, 17};  // Connect to the row pinouts of the keypad
byte colPins[COLS] = {16, 4, 0, 2};    // Connect to the column pinouts of the keypad

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

// LCD Configuration
#define LCD_ADDR 0x27  // I2C address (common for most I2C LCD adapters)
#define LCD_COLS 16    // Number of columns
#define LCD_ROWS 2     // Number of rows

// I2C pins for LCD
#define SDA_PIN 21
#define SCL_PIN 22

// Initialize LCD
LiquidCrystal_I2C lcd(LCD_ADDR, LCD_COLS, LCD_ROWS);

// Variables for input handling
String inputBuffer = "";
unsigned long lastKeyPressTime = 0;
const unsigned long keyTimeout = 3000; // Clear input after 3 seconds of no activity

void setup() {
  // Initialize Serial for debugging
  Serial.begin(115200);
  Serial.println("ESP32 Keypad and LCD Example");
  
  // Initialize I2C for LCD
  Wire.begin(SDA_PIN, SCL_PIN);
  
  // Initialize LCD
  lcd.init();
  lcd.backlight();
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("4x4 Keypad Demo");
  lcd.setCursor(0, 1);
  lcd.print("Press a key...");
  
  Serial.println("Setup completed");
}

void loop() {
  // Check for keypress
  char key = keypad.getKey();
  
  if (key) {
    // Update the last keypress time
    lastKeyPressTime = millis();
    
    Serial.print("Key pressed: ");
    Serial.println(key);
    
    // Add key to input buffer
    if (inputBuffer.length() < 16) { // Prevent buffer overflow
      inputBuffer += key;
    }
    
    // Update LCD
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Key pressed: ");
    lcd.print(key);
    lcd.setCursor(0, 1);
    lcd.print("Input: ");
    lcd.print(inputBuffer);
    
    // Special handling for certain keys
    if (key == '#') {
      // Clear input buffer when # is pressed
      delay(500); // Brief delay for visual feedback
      inputBuffer = "";
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Input cleared");
      lcd.setCursor(0, 1);
      lcd.print("Press a key...");
      delay(1000);
    }
    else if (key == '*') {
      // Delete last character when * is pressed
      if (inputBuffer.length() > 0) {
        inputBuffer.remove(inputBuffer.length() - 2, 1); // Remove the character before *
        inputBuffer.remove(inputBuffer.length() - 1, 1); // Remove the *
        
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Deleted last");
        lcd.setCursor(0, 1);
        lcd.print("Input: ");
        lcd.print(inputBuffer);
        delay(500);
      }
    }
  }
  
  // Check for timeout to clear input
  if (inputBuffer.length() > 0 && (millis() - lastKeyPressTime > keyTimeout)) {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Timeout - Reset");
    lcd.setCursor(0, 1);
    lcd.print("Press a key...");
    inputBuffer = "";
    delay(1000);
  }
}