#include <Keypad.h>

const byte rows= 4;     // Number of rows on the keypad
const byte columns= 3;  // Number of columns on the keypad

// The 2-dimensional array keymap uses the same layout as the keypad
char keymap[rows][columns]=
  {
    {'1', '2', '3'},
    {'4', '5', '6'},
    {'7', '8', '9'},
    {'*', '0', '#'}
  };

// These arrays map rows and columns to the Arduino pins
byte rowPins[rows]       = {13,12,11,10}; //Rows 0 to 3
byte columnPins[columns] = {9,8,7}; //Columns 0 to 2

// Initialises an instance of the Keypad class
Keypad keypad = Keypad(makeKeymap(keymap), rowPins, columnPins, rows, columns);

// initialise code as 'xx'
String code = "xx\0";

// arrays to store product info
String products[] = {"Twix", "Mars Bar", "Squares", "Bueno", "Quavers", "Wotsits", "Mini Cheddars", "Freddo", "KitKat"};
int prodCode[] = {1, 2, 3, 4, 5, 6, 7, 8, 9};
float prodCost[] = {0.80, 1, 0.50, 0.50, 0.60, 0.40, 0.35, 0.20, 0.60};
const int numberOfProds = 9;



int checkPosition(String codeStr)
{
  // if first or 2nd position are x, they are empty so can have a value inserted
  if (codeStr[0] == 'x')
    return 0;
  else if (codeStr[1] == 'x')
    return 1;
  else
  // otherwise return 666 to signify full code selection
    return 666;
}


// get name of item from given code; return error message if invalid
String getItem(String codeStr)
{
  int codeInt = codeStr.toInt();
  for (int i = 0; i <= (numberOfProds - 1); i++)
  {
    if (codeInt == prodCode[i])
    {
      return products[i];
    }
  }
  return "Invalid item code.";
}



void setup()
{
  // put your setup code here, to run once:
  Serial.begin(9600);
}


void loop()
{
  // Set key equal to the key pressed
  char key = keypad.getKey();

  // If a key was pressed (ie not NO_KEY)
  if (key != NO_KEY)
  {
    Serial.println(key);
    int position = 666;

    switch (key)
    {
      case '1':
        position = checkPosition(code);
        if (position == 666)
        {
          // print invalid choice to LCD
          Serial.println("Invalid choice.");
        }
        else
        {
          code[position] = '1';
        }
      break;
      case '2':
        position = checkPosition(code);
        if (position == 666)
        {
          // print invalid choice to LCD
          Serial.println("Invalid choice.");
        }
        else
        {
          code[position] = '2';
        }
      break;
      case '3':
        position = checkPosition(code);
        if (position == 666)
        {
          // print invalid choice to LCD
          Serial.println("Invalid choice.");
        }
        else
        {
          code[position] = '3';
        }
      break;
      case '4':
        position = checkPosition(code);
        if (position == 666)
        {
          // print invalid choice to LCD
          Serial.println("Invalid choice.");
        }
        else
        {
          code[position] = '4';
        }
      break;
      case '5':
        position = checkPosition(code);
        if (position == 666)
        {
          // print invalid choice to LCD
          Serial.println("Invalid choice.");
        }
        else
        {
          code[position] = '5';
        }
      break;
      case '6':
        position = checkPosition(code);
        if (position == 666)
        {
          // print invalid choice to LCD
          Serial.println("Invalid choice.");
        }
        else
        {
          code[position] = '6';
        }
      break;
      case '7':
        position = checkPosition(code);
        if (position == 666)
        {
          // print invalid choice to LCD
          Serial.println("Invalid choice.");
        }
        else
        {
          code[position] = '7';
        }
      break;
      case '8':
        position = checkPosition(code);
        if (position == 666)
        {
          // print invalid choice to LCD
          Serial.println("Invalid choice.");
        }
        else
        {
          code[position] = '8';
        }
      break;
      case '9':
        position = checkPosition(code);
        if (position == 666)
        {
          // print invalid choice to LCD
          Serial.println("Invalid choice.");
        }
        else
        {
          code[position] = '9';
        }
      break;
      case '0':
        position = checkPosition(code);
        if (position == 666)
        {
          // print invalid choice to LCD
          Serial.println("Invalid choice.");
        }
        else
        {
          code[position] = '0';
        }
      break;
      case '*':
        //reset array to xx
        code = "xx\0";
      break;
      case '#':
        Serial.println("Code is:" + code);
        String itemName = getItem(code);
        Serial.println(itemName);
      break;
    }
  }
}