// vending machine

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

LiquidCrystal_I2C lcd (0x27, 16, 2);

// ---------------------------------------------------------
// Keypad Pins
const byte ROWS = 4;
const byte COLS = 4;
char hexaKeys[ROWS][COLS] = {
  {'D', '#', '0', '*'},
  {'C', '9', '8', '7'},
  {'B', '6', '5', '4'},
  {'A', '3', '2', '1'}
};

#if 0
byte rowPins[ROWS] = {22, 24, 26, 28};
byte colPins[COLS] = {30, 32, 34, 36};
#else
byte colPins[ROWS] = {22, 24, 26, 28};
byte rowPins[COLS] = {30, 32, 34, 36};
#endif

Keypad customKeypad = Keypad (makeKeymap (hexaKeys), rowPins, colPins, ROWS, COLS);

// ---------------------------------------------------------
struct Item {
  const byte  PinServo;
  const char  Row;
  const char  Col;
  float       price;
  const char *label;

  Servo       servo;
}
item [] = {
  { 38, 'A', '1', 1.00, "cookie" },
  { 40, 'A', '2', 1.20, "charm" },
  { 42, 'B', '3', 0.25, "shake" },
  { 44, 'C', '7', 1.00, "candy" },
};
const int Nitem = sizeof (item) / sizeof (Item);

// ---------------------------------------------------------
const int           ServoClose = 90;
const int           ServoOpen  = 180;

const unsigned long ServoRunTime = 5000; // 5 seconds

const char         *MakeSel = "Make Selection";

char row;
char col;

// -----------------------------------------------------------------------------
void
lcdDisp (
  const char *s0,
  const char *s1 )
{
  lcd.clear     ();
  lcd.print     (s0);

  lcd.setCursor (0, 1);
  lcd.print     (s1);
}

// -----------------------------------------------------------------------------
void setup ()
{
  Serial.begin (9600);
  Serial.println ("ready");

  // initialize Servos
  for (int n = 0; n < Nitem; n++)  {
    Serial.println (n);
    item [n].servo.attach (item [n].PinServo);
    item [n].servo.write  (ServoClose);
  }

  // Initialize LCD
  lcd.init ();
  lcd.backlight ();
  lcdDisp ("Welcome to SuperVending", "");
  delay (3000);
  reset ();;
}

// -----------------------------------------------------------------------------
void reset ()
{
  row = col = 0;
  lcdDisp ("Welcome to SuperVending", "");
}

// -----------------------------------------------------------------------------
void processSel (
  int  itemIdx )
{
  lcdDisp ("enjoy your", item [itemIdx].label);

  item [itemIdx].servo.write (ServoOpen);
  delay (ServoRunTime);
  item [itemIdx].servo.write (ServoClose);
}

// -----------------------------------------------------------------------------
void checkSel ()
{
  for (int n = 0; n < Nitem; n++)  {
    if (item [n].Row == row && item [n].Col == col)  {
      processSel (n);
      return;
    }
  }

  lcdDisp ("Invalid Selection", " return coins");
  delay (3000);
}

// -----------------------------------------------------------------------------
void loop ()
{
  // Handle keypad input
  char key = customKeypad.getKey ();
  if (key) {
    Serial.print("pressed key=");
    Serial.println(key);
  }

  if (! key)
    return;         // no key pressed

  char s [50];

  if ('A' <= key && key <= 'F')
    row = key;
  else if ('0' <= key && key <= '9')
    col = key;
  else if ('#' == key)  {
    lcdDisp ("Cancel", "");
    delay (3000);
    reset ();
  }

  if (row && col)  {
    sprintf (s, "row %c, col %c", row, col);
    lcdDisp ("Your Selection", s);
    checkSel ();
    reset ();
  }
  else {
    sprintf (s, "row %c, col %c", row, col);
    lcdDisp (MakeSel, s);
  }
}