/**************************/
/*         main()         */
/**************************/

int main()
{
  global RFID_flag;
  global LCDmod_flag;
  global keypress_flag;

  LCDinit()

  while (1)
  {
    // check flags
    if (RFID_flag == 1)
    {
      // RFID was received
      HandleRFID();
    }
    if (LCDmod_flag == 1)
    {
      // LCD needs to be updated
      UpdateLCD(); 
    }
    if (keypress_flag == 1)
    {
      // key was pressed
      PollKeypad();
    } 
  }
}



/**************************/
/*     HandleRFID()       */
/**************************/

void HandleRFID()
{
  global item_name;
  global item_desc;
  global item_price;
  global cust_name;
  global cust_pin;
  global cust_email;
  global total;
  global keystate;

  int pin_try = 0;

  // RFID scanned is in memory at addr 0x__
  // query DB to check if RFID was valid

  valid = DBCheck()

  if (valid == 1 and item == 1)
  {
    // valid item was scanned
    // item name, description, and weight stored in memory at addr 0x__
    UpdateLCD()     // show item name, description, cost
    wait (3 sec)    // hold info on screen for 3 seconds

    // add item to shopping cart

    total += total + item_price; 

    UpdateLCD()     // show new shopping cart with most recent item added
  }

  else if (valid == 1 and item == 0)
  {
    // valid person was scanned
    // person name, PIN, email address stored in memory at addr 0x__
    UpdateLCD()      // show welcome with person's name, prompt for PIN entry

    // get 4 keypresses
    good_pin = ComparePIN()

    while (pin_try < 3)
    {
      // get 4 keypresses, store to pin_attempt

      // compare entered PIN with one cust_pin
      good_pin = ComparePIN()
 
      if (good_pin)
      {
        keystate++;
        UpdateLCD()  // show screen to prompt user to scan first item
        return;
      }
      else
      {
        // increment pin count
        pin_try++;
        UpdateLCD()  // show "incorrect PIN.. please try again"
      }
    }

    // once here, pin_try = 3 and attempts are up
    UpdateLCD()      // show "sorry, you have maximized PIN attempts, please come back later"
    wait (3 secs)    // hold info on screen for 3 seconds
    UpdateLCD()      // show logo screen with prompt to swipe keyfob
  }
  
  else if (valid == 0 and item == 1)
  {
    // invalid item was scanned
    UpdateLCD()      // display "item not recognized"
    wait (3 sec)     // hold info on screen for 3 seconds
    UpdateLCD()      // show original shopping cart
  }

  else
  {
    // invalid person scanned keyfob
    UpdateLCD()      // display "person not recognized"
    wait (3 sec)     // hold info on screen for 3 seconds
    UpdateLCD()      // show logo screen with prompt to swipe keyfob
  }

  return;
}



/**************************/
/*     PollKeypad()       */
/**************************/

void PollKeypad()
{
  global keystate;	// 0 = idle
			// 1 = PIN entered, user is swiping
			// 2 = user completed checkout
                        // 3 = final

  // key was pressed

  if (keystate == 0)
  {
    // first use in this session, so user needs to swipe keyfob
    UpdateLCD()        // show "you must first swipe your keyfob"
    wait (3 secs)
    UpdateLCD()        // show logo screen with prompt to swipe keyfob

  }
  if (keystate == 1)
  {
    // PIN already entered... check press:
  
    if (key == numberpad OR key == cancel)
    {
      UpdateLCD()      // show "I'm sorry, that function is not recognized"
      wait (3 secs)
      UpdateLCD()      // show unmodified shopping cart
    }
    else if (key == '?')
    {
      UpdateLCD()      // show some help (probably tell them to scan tag on item
      wait (3 secs)
      UpdateLCD()      // show unmodified shopping cart 
    }
    else if (key == 'clear')
    {
      // user wants to remove last item
      if (item_cnt < 1)
      {
        UpdateLCD()    // show "sorry, you have no items in your cart.  Swipe tag to begin checkout"
        wait (3 secs)
        UpdateLCD()    // show empty shopping cart
      }
      else
      {
        UpdateLCD()    // show "Are you sure you want to delete the last item, press enter to confirm, cancel to quit"
        
        // wait for keypress received
        if (key == 'enter')
        {
          // remove most recent item from shopping cart
          UpdateLCD()    // show updated shopping cart
        }
        else if (key == 'cancel')
        {
          UpdateLCD()    // show unmodified shopping cart
        }
        else 
        {
          // do nothing
        }
    }
    else if (key == 'enter')
    {
      // user is finished shopping
      UpdateLCD()       // show "Are you sure you are finished shopping, enter to confirm, cancel to return"
 
      // wait for keypress received
      if (key == 'enter')
      {
        UpdateLCD()    // show "Would you like a printed receipt?"
        
        // wait for keypress received
       
        if (key == 'enter')
        { 
          PrintReceipt()
          EmailReceipt()
        }
        else if (key == 'cancel')
        {
          EmailReceipt()
        } 
      }
      else if (key == 'cancel')
      {
        UpdateLCD()   // show unmodified shopping cart
      }
      else
      {
        UpdateLCD()      // show "I'm sorry, that function is not recognized"
        wait (3 secs)
        UpdateLCD()      // show unmodified shopping cart
      }
    }
  }

  return;
}


/**************************/
/*     PrintReceipt()     */
/**************************/

void PrintReceipt()
{
  UpdateLCD()   // show "printing receipt"
 
  // print data

  UpdateLCD()      // show "please take your receipt"

  return;
}

/**************************/
/*    EmailReceipt()      */
/**************************/

void EmailReceipt()
{

  UpdateLCD()    // show "emailing receipt to *cust_email*"

  // email receipt

  // wait for confirmation

  // if confirmation received,
  UpdateLCD()    // show "email sent.  Thank you for shopping RFID Xpr3ss.  Have a Nice Day."

  return; 
}