#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);
#include <Keypad.h>
const int ROW_NUM = 4; //four rows
const int COLUMN_NUM = 4; //four columns
char keys[ROW_NUM][COLUMN_NUM] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

int R1 = 1;
int C1 = 1;

int count;

byte pin_rows[ROW_NUM] = {A15, A14, A13, A12}; //connect to the row pinouts of the keypad
byte pin_column[COLUMN_NUM] = {A11, A10, A9, A8}; //connect to the column pinouts of the keypad
Keypad kpd = Keypad( makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM );

// #define Single_long_click_duration 10000

const byte numChars = 32;
char receivedChars[numChars];   // an array to store the received data

boolean newData = false;

int dataNumber = 0;             // new for this version

char Export[4];
byte a = 0;

unsigned long startTime;
bool holding = false;
bool longPress = false;
bool repeating = false;
int keyHeld;
String msg;

unsigned long startHold = 0;
uint16_t intervalLongPress = 1000;
unsigned long startRepeat = 0;
uint16_t intervalRepeat = 250;


void setup() {
  Serial.begin(115200);
  lcd.init(); // display initialization
  lcd.clear(); // clear the screen fully
  lcd.backlight(); // activate the backlight
  // Export[0] = 0x0; // Set "Export" buffer string to an empty string
}

void loop()
{
  lcd.setCursor(C1, R1);




  char key = checkKeys();
  if (key)
  {

    switch (key)
    {

      case '0'...'9':
        if (!longPress && !repeating) {
          if (C1 < 4)
          {
            Export[a++] = key;
            Export[a] = 0x0;
            if (atoi(Export) > 444)
            {
              Export[--a] = 0x0;
              break;
            }
            lcd.print(key);
            C1++;
            // count = atoi(Export);
          }
        }
        break;

      case 'B':
        if (!longPress) {
          if (C1 > 1)
          {
            C1--;
            if (C1 < 1)
              C1 = 1;
            Export[--a] = 0x0;
            count = atoi(Export);
            lcd.setCursor(C1, R1);
            lcd.print(' ');
          }
        } else {
          //all clear
          lcd.setCursor(11, 1);
          lcd.print("   ");
          count = 0;
          memset(Export, 0, sizeof(Export));
          a = 0;
          C1 = 1;
          lcd.setCursor(C1, R1);
          lcd.print("   ");
        }
        break;

      case '#':
        if (!longPress) {
          lcd.setCursor(11, 1);
          lcd.print("   ");
          lcd.setCursor(11, 1);
          lcd.print(Export);
          count = atoi(Export); //Converting 'chart to int' VIP
          a = 0;
          C1 = 1;
          lcd.setCursor(C1, R1);
          lcd.print("   ");
        }

        break;


      case 'C':
        if (!longPress) {

          if (count < 444)
          {
            count = count + 1;
          }
          else
          {
            count = 1;
          }
          lcd.setCursor(11, 1);
          lcd.print("   ");
          lcd.setCursor(11, 1);
          lcd.print(count);
        }
        break;


      case 'D':
        if (!longPress) {
          if (count > 1)
          {
            count = count - 1;
          }
          else
          {
            count = 444;
          }
          lcd.setCursor(11, 1);
          lcd.print("   ");
          lcd.setCursor(11, 1);
          lcd.print(count);
        }
        break;


    } //end switch key
    //crop the long press
    longPress = false;
  } // end if key


}


char checkKeys() {
  char result = 0;
  repeating = false;
  if (kpd.getKeys())
  {
    for (int i = 0; i < LIST_MAX; i++) // Scan the whole key list.
    {
      if ( kpd.key[i].stateChanged )   // Only find keys that have changed state.
      {
        switch (kpd.key[i].kstate) {  // Report active key state : IDLE, PRESSED, HOLD, or RELEASED
          case PRESSED:
            msg = " PRESSED. ";
            break;
          case HOLD:
            msg = " HOLD.    ";
            startHold = millis();
            holding = true;
            keyHeld = i;
            break;
          case RELEASED:
            msg = " RELEASED.";
            holding = false;
            result = kpd.key[i].kchar;
            break;
          case IDLE:
            msg = " IDLE.    ";
            break;
        }
        Serial.print("Key ");
        Serial.print(kpd.key[i].kchar);
        Serial.println(msg);
        // lcd.setCursor(0, 1);
        // lcd.print(kpd.key[i].kchar);
        //  lcd.print(msg);

      } // End if ( kpd.key[i].stateChanged )

    } // End for (int i=0; i<LIST_MAX; i++)

  } // End kpd.getKeys()
  if (holding) {
    if (millis() - startHold >= intervalLongPress)
    { //holding = false;
      result = kpd.key[keyHeld].kchar;
      startHold = millis();
      msg = " LONG PRESS.    ";
      Serial.print("Key ");
      Serial.print(kpd.key[keyHeld].kchar);
      Serial.println(msg);
      longPress = true;
      //  lcd.setCursor(0, 1);
      //   lcd.print(kpd.key[keyHeld].kchar);
      //   lcd.print(msg);
    } else if (millis() - startRepeat >= intervalRepeat) {
      startRepeat = millis();
      result = kpd.key[keyHeld].kchar;
      repeating = true;
      Serial.print("Repeating Key ");
      Serial.print(kpd.key[keyHeld].kchar);
    }
  }

  return result;
}