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

LiquidCrystal_I2C screen(0x27, 16, 2);

// Keypad info
const byte cols = 4, rows = 4;
char keys[rows][cols] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowpins[4] = {9, 8, 7, 6}, colpins[4] = {5, 4, 3, 2};
Keypad inputkeypad = Keypad(makeKeymap(keys), rowpins, colpins, rows, cols);
// Price info
double total = 0;
// Input
String priceinput = "";
byte mode = 0;

void setup() {
  screen.init();
  screen.backlight();
  Serial.begin(9600);
}

void loop() {
  screen.clear();
  char inputkey = inputkeypad.getKey();
  if (inputkey) {
    if (inputkey == 'C') {mode = 2; screen.clear();}
    if (inputkey == 'D') {priceinput += ".";} 
    else if (inputkey == '*') {
      switch (mode) {
        case 1: total += priceinput.toDouble(); priceinput = ""; mode = 0;
        case 2: total = 0; mode = 0;
      }
    }
    else if (inputkey == '#') {
      if (mode == 1) {priceinput = "";}
    }
    else if (! (inputkey == 'A' || inputkey == 'B')) {mode = 1; priceinput += inputkey;}
  }
  switch (mode) {
    case 0:
      screen.home();
      screen.print("Type item price");
      screen.setCursor(0, 1);
      screen.print(String("Total: P") + String(total));
    case 1: 
      screen.print(priceinput);
      screen.setCursor(0, 1);
      screen.print("*:Entr #:Cancl");
    case 2:
      screen.print("Do you wanna");
      screen.setCursor(0,1);
      screen.print("start over?");
      delay(1000);
      screen.home();
      screen.print("*:Yes #:No");
  }
  delay(100);
}