#ifndef FDB_LIQUID_CRYSTAL_I2C_H
#define FDB_LIQUID_CRYSTAL_I2C_H

#include <inttypes.h>
#include <Print.h>

// commands
#define LCD_CLEARDISPLAY 0x01
#define LCD_RETURNHOME 0x02
#define LCD_ENTRYMODESET 0x04
#define LCD_DISPLAYCONTROL 0x08
#define LCD_CURSORSHIFT 0x10
#define LCD_FUNCTIONSET 0x20
#define LCD_SETCGRAMADDR 0x40
#define LCD_SETDDRAMADDR 0x80

// flags for display entry mode
#define LCD_ENTRYRIGHT 0x00
#define LCD_ENTRYLEFT 0x02
#define LCD_ENTRYSHIFTINCREMENT 0x01
#define LCD_ENTRYSHIFTDECREMENT 0x00

// flags for display on/off control
#define LCD_DISPLAYON 0x04
#define LCD_DISPLAYOFF 0x00
#define LCD_CURSORON 0x02
#define LCD_CURSOROFF 0x00
#define LCD_BLINKON 0x01
#define LCD_BLINKOFF 0x00

// flags for display/cursor shift
#define LCD_DISPLAYMOVE 0x08
#define LCD_CURSORMOVE 0x00
#define LCD_MOVERIGHT 0x04
#define LCD_MOVELEFT 0x00

// flags for function set
#define LCD_8BITMODE 0x10
#define LCD_4BITMODE 0x00
#define LCD_2LINE 0x08
#define LCD_1LINE 0x00
#define LCD_5x10DOTS 0x04
#define LCD_5x8DOTS 0x00

// flags for backlight control
#define LCD_BACKLIGHT 0x08
#define LCD_NOBACKLIGHT 0x00

#define En B00000100  // Enable bit
#define Rw B00000010  // Read/Write bit
#define Rs B00000001  // Register select bit

/**
 * This is the driver for the Liquid Crystal LCD displays that use the I2C bus.
 *
 * After creating an instance of this class, first call begin() before anything else.
 * The backlight is on by default, since that is the most likely operating mode in
 * most cases.
 */
class LiquidCrystal_I2C : public Print {
public:
	/**
	 * Constructor
	 *
	 * @param lcd_addr	I2C slave address of the LCD display. Most likely printed on the
	 *					LCD circuit board, or look in the supplied LCD documentation.
	 * @param lcd_cols	Number of columns your LCD display has.
	 * @param lcd_rows	Number of rows your LCD display has.
	 * @param charsize	The size in dots that the display has, use LCD_5x10DOTS or LCD_5x8DOTS.
	 */
	LiquidCrystal_I2C(uint8_t lcd_addr, uint8_t lcd_cols, uint8_t lcd_rows, uint8_t charsize = LCD_5x8DOTS);

	/**
	 * Set the LCD display in the correct begin state, must be called before anything else is done.
	 */
	void begin();

	 /**
	  * Remove all the characters currently shown. Next print/write operation will start
	  * from the first position on LCD display.
	  */
	void clear();

	/**
	 * Next print/write operation will will start from the first position on the LCD display.
	 */
	void home();

	 /**
	  * Do not show any characters on the LCD display. Backlight state will remain unchanged.
	  * Also all characters written on the display will return, when the display in enabled again.
	  */
	void noDisplay();

	/**
	 * Show the characters on the LCD display, this is the normal behaviour. This method should
	 * only be used after noDisplay() has been used.
	 */
	void display();

	/**
	 * Do not blink the cursor indicator.
	 */
	void noBlink();

	/**
	 * Start blinking the cursor indicator.
	 */
	void blink();

	/**
	 * Do not show a cursor indicator.
	 */
	void noCursor();

	/**
 	 * Show a cursor indicator, cursor can blink on not blink. Use the
	 * methods blink() and noBlink() for changing cursor blink.
	 */
	void cursor();

	void scrollDisplayLeft();
	void scrollDisplayRight();
	void printLeft();
	void printRight();
	void leftToRight();
	void rightToLeft();
	void shiftIncrement();
	void shiftDecrement();
	void noBacklight();
	void backlight();
	bool getBacklight();
	void autoscroll();
	void noAutoscroll();
	void createChar(uint8_t, uint8_t[]);
	void setCursor(uint8_t, uint8_t);
	virtual size_t write(uint8_t);
	void command(uint8_t);

	inline void blink_on() { blink(); }
	inline void blink_off() { noBlink(); }
	inline void cursor_on() { cursor(); }
	inline void cursor_off() { noCursor(); }

// Compatibility API function aliases
	void setBacklight(uint8_t new_val);				// alias for backlight() and nobacklight()
	void load_custom_character(uint8_t char_num, uint8_t *rows);	// alias for createChar()
	void printstr(const char[]);

private:
	void send(uint8_t, uint8_t);
	void write4bits(uint8_t);
	void expanderWrite(uint8_t);
	void pulseEnable(uint8_t);
	uint8_t _addr;
	uint8_t _displayfunction;
	uint8_t _displaycontrol;
	uint8_t _displaymode;
	uint8_t _cols;
	uint8_t _rows;
	uint8_t _charsize;
	uint8_t _backlightval;
};

#endif // FDB_LIQUID_CRYSTAL_I2C_H


/////////////////////////////
#include <wiring.c>

LiquidCrystal_I2C lcd(0x27,16,2);

// Define the button pins
const int startButtonPin = 6;
const int stopButtonPin = 7;

// Variables to keep the timing
unsigned long startTime = 0;
unsigned long stopTime = 0;
unsigned long elapsedTime = 0;
bool isTiming = false;

void setup() {
  // Set the button pins
  pinMode(startButtonPin, INPUT_PULLUP);
  pinMode(stopButtonPin, INPUT_PULLUP);

  // Start up LCD
  lcd.begin();
  lcd.clear();         
  lcd.backlight();  
  lcd.setCursor(0,0);
  lcd.print("-- Hot Wheels --");  
  lcd.setCursor(0,1);
  lcd.print("  00:00:00:00  ");
}

void loop() {
  // Start the stopwatch
  if (digitalRead(startButtonPin) == LOW && !isTiming) {
    isTiming = true;
    startTime = millis();
  }

  // Stop the stopwatch
  if (digitalRead(stopButtonPin) == LOW && isTiming) {
    isTiming = false;
    stopTime = millis();
  }

  if (isTiming) {
    elapsedTime = millis() - startTime;
  } else {
    elapsedTime = stopTime - startTime;
  }

  // Calculate hh:mm:ss:mm
  int hours = (elapsedTime / 3600000) % 24; // Hours
  int minutes = (elapsedTime / 60000) % 60; // Minutes
  int seconds = (elapsedTime / 1000) % 60; // Seconds
  int milliseconds = elapsedTime % 1000; // Milliseconds

  // Output the time in hh:mm:ss:mm format
  if (isTiming || (stopTime != 0)) {
    String timeString = "";

    lcd.setCursor(2,1);
    lcd.print((hours < 10 ? "0" : "") + String(hours) + ":");

    lcd.setCursor(5,1);
    lcd.print((minutes < 10 ? "0" : "") + String(minutes) + ":");

    lcd.setCursor(8,1);
    lcd.print((seconds < 10 ? "0" : "") + String(seconds) + ":");

    lcd.setCursor(11,1);
    lcd.print((milliseconds < 100 ? (milliseconds < 10 ? "00" : "0") : ""));
  }

  delay(1); // Update every 1 ms
}