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

int num_colunas = 16;
int num_linhas = 2;

LiquidCrystal_I2C lcd(0x27, num_colunas, num_linhas);

const byte KEYPAD_ROWS = 4;
const byte KEYPAD_COLS = 4;
byte rowPins[KEYPAD_ROWS] = {18, 17, 16, 15};
byte colPins[KEYPAD_COLS] = {7, 6, 5, 4};
char keys[KEYPAD_ROWS][KEYPAD_COLS] = {
  {'1', '2', '3', '+'},
  {'4', '5', '6', '-'},
  {'7', '8', '9', '*'},
  {'.', '0', '=', '/'}
};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, KEYPAD_ROWS, KEYPAD_COLS);

uint64_t value = 0;

void setup(){
   
  Serial.begin(115200);
  print_inicial();
  
}



char operation = 0;
String memory = "";
String current = "";
uint64_t currentDecimal;
bool decimalPoint = false;

double calculate(char operation, double left, double right) {
  switch (operation) {
    case '+': return left + right;
    case '-': return left - right;
    case '*': return left * right;
    case '/': return left / right;
  }
}

void processInput(char key) {

       if ('-' == key && current == "") {
          current = "-";
          lcd.print("-");
          return;
        }

      switch (key) {
          case '+':
          case '-':
          case '*':
          case '/':
          if (!operation) {
              memory = current;
              current = "";
          }
         operation = key;
         lcd.setCursor(0, 1);
         lcd.print(key);
         lcd.setCursor(current.length() + 1, 1);
        return;

        case '=':
        if(current == "2456"){
        print_inicial();
        
        }
        float leftNum = memory.toDouble();
        float rightNum = current.toDouble();
        memory = String(calculate(operation, leftNum, rightNum));
        current = "";
        lcd.clear();
        lcd.setCursor(1, 0);
        lcd.print(memory);
        lcd.setCursor(0, 1);
        lcd.print(operation);
        return;

      }

      if ('.' == key && current.indexOf('.') >= 0) {
        return;
      }

      if ('.' != key && current == "0") {
        current = String(key);
      } else if (key) {
      current += String(key);
      }

      lcd.print(key);

  

 
}


void loop(){
 //print_inicial();

 updateCursor();
   char key = keypad.getKey();
  if (key) {
    processInput(key);

} 
}



void print_inicial(){
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0,0);
  lcd.print("Sist Embarcados");
  lcd.setCursor(2,1);
  lcd.print("Calculadora");
  delay(2000);
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Alunos:");
  lcd.setCursor(2,1);
  lcd.print("Andrew");
  delay(2000);
  lcd.clear();
  
}

void showSpalshScreen() {
  lcd.print("SistemasEmbarcados");
  lcd.setCursor(3, 1);
  String message = "Calculadora";
  for (byte i = 0; i < message.length(); i++) {
    lcd.print(message[i]);
    delay(50);
  }
  delay(500);
}

void updateCursor() {
  if (millis() / 250 % 2 == 0 ) {
    lcd.cursor();
  } else {
    lcd.noCursor();
  }
}