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

LiquidCrystal_I2C lcd(0x27,20,4);

const byte ROWS = 4;
const byte COLS = 4;

char hexaKeys[ROWS][COLS] = {
  {'1','2','3','+'},
  {'4','5','6','-'},
  {'7','8','9','*'},
  {'.','0','=','/'}
};

byte rowPins[ROWS] = {9,8,7,6};
byte colPins[COLS] = {5,4,3,2};

Keypad customKeypad = Keypad(makeKeymap(hexaKeys),rowPins,colPins,ROWS,COLS);
char oper;
int No = 0;
int lcd_row = 0;
bool clear_lcd = 0;
float number1 = 0;
float number2 = 0;
String number;
void operated_number(int number1,int number2,char oper);
void setup() {
  lcd.init();
  Serial.begin(9600);
  lcd.backlight(); 
  number = String("\0");

}

void loop() {
  char customKey = customKeypad.getKey();
  if(customKey){
    Serial.println(customKey);
    switch(customKey){
      case'+':
        oper = '+';
        number1 = number.toFloat();
        No = 0;
        lcd_row = 1;
        lcd.setCursor(0,lcd_row);
        lcd_row = 2;
        lcd.print(oper);
        number = "";
        break;
      case'-':
        oper = '-';
        number1 = number.toFloat();
        No = 0;
        lcd_row = 1;
        lcd.setCursor(0,lcd_row);
        lcd_row = 2;
        lcd.print(oper);
        number = "";
        break;
      case'*':
        oper = '*';
        number1 = number.toFloat();
        No = 0;
        lcd_row = 1;
        lcd.setCursor(0,lcd_row);
        lcd_row = 2;
        lcd.print(oper);
        number = "";
        break;
      case'/':
        oper = '/';
        number1 = number.toFloat();
        No = 0;
        lcd_row = 1;
        lcd.setCursor(0,lcd_row);
        lcd_row = 2;
        lcd.print(oper);
        number = "";
        break;
      case'=':
        number2=number.toFloat();
        number = "";
        operated_number( number1, number2, oper);
        number1 = 0;
        number = String("\0");
        number2 = 0;
        break;
      default:
      if(clear_lcd == 1){
        Serial.println("clearing lcd");
        lcd.clear();
        clear_lcd = 0;
        lcd_row = 0;
        No = 0;
      }
      number += customKey;
      lcd.setCursor(0,lcd_row);
      lcd.print(number);
      
      break;
                        
    }
  }
}
void operated_number(float number1,float number2,char oper){
 Serial.println(number1);
 Serial.println(oper);
 Serial.println(number2);
 clear_lcd = 1;
  switch(oper){
      
    case '+':
      Serial.println("here");
      float plus=number1+number2;
      Serial.println(plus);
      lcd_row = 3;
      lcd.setCursor(0,lcd_row);
      lcd.print(plus);
      break;
    case '-':
      Serial.println("here");
      float subtract=number1-number2;
      Serial.println(subtract);
      lcd_row = 3;
      lcd.setCursor(0,lcd_row);
      lcd.print(subtract);
      break;
    case '*':
      Serial.println("here");
      float multiple=number1*number2;
      Serial.println(multiple);
      lcd_row = 3;
      lcd.setCursor(0,lcd_row);
      lcd.print(multiple);
      break;
    case '/':
      Serial.println("here");
      float divide=number1/number2;
      Serial.println(divide);
      lcd_row = 3;
      lcd.setCursor(0,lcd_row);
      lcd.print(divide);
      break;
    default:
      break;
  }
}