#include <LiquidCrystal_I2C.h> 
#include <EEPROM.h>

static const char NO_KEY = '\0';

class Keypad 
{
  public:
  Keypad(byte* rowPins, byte* colPins, char* custom_km, byte rows, byte cols) : numRows(rows), numCols(cols), rowPins(rowPins), colPins(colPins) 
  {
    keymap = new char[numRows * numCols];
    for (byte i = 0; i < numRows * numCols; i++) 
    {
      keymap[i] = custom_km[i];
    }
  }

  void begin() 
  {
     for (byte row = 0; row < numRows; ++row)
    {
      pinMode(rowPins[row], INPUT_PULLUP);
    }

    for (byte col = 0; col < numCols; ++col)
    {
      pinMode(colPins[col], OUTPUT);
      digitalWrite(colPins[col], LOW);
    }


  }

  char getKey() 
  {
    char key = NO_KEY;
    int numkey = -10;


    for (byte col = 0; col < numCols; ++col)
       digitalWrite(colPins[col], HIGH);
  
    for (byte col = 0; col < numCols; ++col)
    {
      digitalWrite(colPins[col], LOW);
      
        for (byte row = 0; row < numRows; ++row)
        {
          if (digitalRead(rowPins[row]) == LOW)
          {   
              //if (digitalRead(rowPins[row]) == LOW)
              numkey = row * numCols + col;
              key = keymap[numkey];
              //Serial.println(numkey);
              while(digitalRead(rowPins[row]) == LOW){};
              for (byte i = 0; i < 100; ++i);
          }
        }
      digitalWrite(colPins[col], HIGH);
    }
     for (byte col = 0; col < numCols; ++col)
      digitalWrite(colPins[col], LOW);
    return key;
   
  }


  private:
  unsigned long startTime = 0;
  unsigned int debounceTime = 10;
  byte numRows;
  byte numCols;
  int last_numkey = -1;
  char *keymap;
  byte* rowPins;
  byte* colPins;
};

struct Data
{
  int first_number = 0;
  int second_number = 0;
  int result = 0;
};

const byte ROWS = 4;
const byte COLS = 4;
const byte rowPins[ROWS] = {2, 3, 4, 5};
const byte colPins[COLS] = {9, 8, 7, 6};
const byte interruptPin = rowPins[0];
volatile bool Interrupt = false;
volatile char Pressed = NO_KEY;
volatile char key = NO_KEY;
int number_menu = -1;
int value = 0;
Data data;

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


LiquidCrystal_I2C display(0x27, 16, 2);
Keypad pad(rowPins, colPins, keys, ROWS, COLS);

void InitDisplay()
{
  display.clear();
  display.print("1,2,3 - menu");
  display.setCursor(0, 1);
  display.print("A - select");
}

void InitEPROM()
{
  EEPROM.get(0, value);
}

void UpdateEPROM()
{
  EEPROM.put(0, data.result);
  data.result = 0;
}

void DeleteEPROM()
{
  EEPROM.put(0, 0);
}

int inputNumber()
{
  key = NO_KEY;
  int result;
  value = 0;
  bool flag = true;
  while (flag)
  {
    noInterrupts();
    key = pad.getKey();
    interrupts();
    switch(key)
    {
        case '0'...'9':
          value = value * 10 + (key - '0');
          display.setCursor(0, 1);
          display.print(value);
          break;
        case 'A':
          result = value;
          flag = false;
          break;
        case 'B':
          result = 0;
          flag = false;
          break;
    }
  }
  return result;
}

void YesOrNo(void (*RunEPROM)())
{
  bool flag = true;
  while (flag)
  {
    noInterrupts();
    key = pad.getKey();
    interrupts();
    switch(key)
    {
      case 'A':
        RunEPROM();
      case 'B':
        flag = false;
    }
  }
}

void Menu1()
{
  display.clear();
  display.setCursor(0, 0);
  display.print("First number:");
  display.setCursor(0, 1);

  data.first_number = inputNumber();
  Serial.println(data.first_number);


  display.clear();
  display.setCursor(0, 0);
  display.print("Second number:");
  display.setCursor(0, 1);

  data.second_number = inputNumber();
  Serial.println(data.second_number);

  display.clear();
  display.setCursor(0, 0);
  display.print("Result:");

  data.result = data.first_number & data.second_number;
  display.print(data.result);

  display.setCursor(0, 1);
  display.print("Save result? A/B");

  data.first_number = 0;
  data.second_number = 0;

  YesOrNo(&UpdateEPROM);
}

void Menu3()
{
  display.setCursor(0, 0);
  display.print("Wanna reset?");
  display.setCursor(0, 1);
  display.print("A-Yes, B-No");

  YesOrNo(&DeleteEPROM);
}

void InitEnter(int number_menu)
{
  switch(number_menu)
  {
    case 1:
      Menu1();
      break;
    case 3:
      Menu3();
      break;
  }
  InitDisplay();
}

void MenuCalculate()
{
  display.clear();
  display.setCursor(0, 0);
  display.print("Menu Calculate:");
  display.setCursor(0, 1);
  display.print("A - enter");
}

void MenuMemory()
{
  display.clear();
  display.setCursor(0, 0);
  display.print("Menu Memory:");
  EEPROM.get(0, value);
  display.setCursor(0, 1);
  display.print("Save: " + String(value));
}

void MenuReset()
{
  display.clear();
  display.setCursor(0, 0);
  display.print("Menu Reset:");
  display.setCursor(0, 1);
  display.print("A - enter");
}

void Menu()
{
  if (Interrupt)
  {
  
  switch (key)
  {
    case '1':
      number_menu = 1;
      MenuCalculate();
      break;
    case '2':
      number_menu = 2;
      MenuMemory();
      break;
    case '3':
      number_menu = 3;
      MenuReset();
      break;
    case 'A':
      InitEnter(number_menu);
      number_menu = 4;
      break;
  }
    if (number_menu != -1)
      {
      
        //MenuCalculate();
        //display.print(number_menu);
        Serial.println(number_menu);
      }
    Interrupt = false;
  }
}

void handler()
{
  
  if (!Interrupt)
  {
    Interrupt = true;
    key = pad.getKey();
    // switch(k)
    // {
    //   case '1':
    //     key = '1';
    //     break;
    //   case '2':
    //     key = '2';
    //     break;
    //   case '3':
    //     key = '3';
    //     break;
    //   case 'A':
    //     key = 'A';
    //     break;
    //   default:
    //     key = NO_KEY;
    //}
  }
  Serial.println("I");
  
  //Interrupt = true;
  //Serial.println("Interrupted");
}

void setup() 
{
  Serial.begin(9600);
  pad.begin();
  display.init();
  display.backlight();

  InitEPROM();
  InitDisplay();

  attachInterrupt(digitalPinToInterrupt(interruptPin), handler, FALLING);

}

void loop() 
{
  Menu();
}