#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd = LiquidCrystal_I2C(0x27, 16, 2);
const char on[4] = "7123";
const char off[4] = "4569";
const int numRows = 4; // number of rows in the keypad
const int numCols = 4; // number of columns
const int ledpin = 12;
const int debounceTime = 20; // number of milliseconds for switch to be stable
char pressedKeys[4]; // Array to store pressed keys
int keyIndex = 0; // Index for storing pressed keys

const char keymap[numRows][numCols] = {
  { '1', '2', '3', 'A' },
  { '4', '5', '6', 'B' },
  { '7', '8', '9', 'C' },
  { '*', '0', '#', 'D' }
};
const int rowPins[numRows] = { 2,3 ,4 ,5  }; // Rows 0 through 3
const int colPins[numCols] = { 6, 7, 8, 9 }; // Columns 0 through 3

void setup() {
  pinMode(ledpin, OUTPUT);

  for (int row = 0; row < numRows; row++) {
    pinMode(rowPins[row], INPUT); // Set row pins as input
    digitalWrite(rowPins[row], HIGH); // turn on Pull-ups
  }

  for (int column = 0; column < numCols; column++) {
    pinMode(colPins[column], OUTPUT); // Set column pins as outputs
    digitalWrite(colPins[column], HIGH); // Make all columns inactive
  }

  lcd.init();
  lcd.backlight();
  lcd.cursor();
  lcd.println("Got key:");




  
}

void loop() {
  char key = getKey();

  if (key != 0) {
    pressedKeys[keyIndex] = key; // Store the pressed key
    keyIndex++; // Increment the index
    lcd.print(key);

    if (keyIndex >= 3) {
      pressedKeys[keyIndex] = '\0'; // Add null terminator to make it a valid string
      int result = strcmp(on, pressedKeys);
      int result2 = strcmp(off, pressedKeys);

      if (result == 0) {
        digitalWrite(ledpin, HIGH);
        lcd.clear();
      } else if (result2 == 0) {
        digitalWrite(ledpin, LOW);
      }

      // Reset the array and index for the next set of pressed keys
      memset(pressedKeys, 0, sizeof(pressedKeys));
      keyIndex = 0;
    }
  }
}

// returns the key pressed, or 0 if no key is pressed
char getKey() {
  char key = 0; // 0 indicates no key pressed

  for (int column = 0; column < numCols; column++) {
    digitalWrite(colPins[column], LOW); // Activate the current column.

    for (int row = 0; row < numRows; row++) {
      // Scan all rows for a key press.
      if (digitalRead(rowPins[row]) == LOW) {
        delay(debounceTime); // debounce
        while (digitalRead(rowPins[row]) == LOW)
          ; // wait for key to be released
        key = keymap[row][column]; // Remember which key was pressed.
      }
    }

    digitalWrite(colPins[column], HIGH); // De-activate the current column.
  }

  return key; // returns the key pressed or 0 if none
}