#include <Adafruit_GFX.h>
#include <Adafruit_PCD8544.h>

boolean backlight = true;
int contrast = 50;

int menuitem = 1;
int page = 1;

volatile boolean up = false;
volatile boolean down = false;
volatile boolean middle = false;

int downButtonState = 0;
int upButtonState = 0;
int selectButtonState = 0;
int lastDownButtonState = 0;
int lastSelectButtonState = 0;
int lastUpButtonState = 0;

Adafruit_PCD8544 display = Adafruit_PCD8544( 5, 4, 3);

void setup() 
{
  pinMode(2, INPUT_PULLUP);
  pinMode(1, INPUT_PULLUP);
  pinMode(0, INPUT_PULLUP);
  pinMode(7, OUTPUT);

  digitalWrite(7, LOW); //Turn Backlight ON

  Serial.begin(9600);

  display.begin(84, 48);
  display.setContrast(contrast); //Set contrast to 50
  display.clearDisplay();
  display.display();
}

void loop() 
{
  drawMenu();

  downButtonState = digitalRead(2);
  selectButtonState = digitalRead(1);
  upButtonState =   digitalRead(0);

  checkIfDownButtonIsPressed();
  checkIfUpButtonIsPressed();
  checkIfSelectButtonIsPressed();

  if (up && page == 1 ) 
  {
    up = false;
    menuitem--;
    if (menuitem == 0)
    {
      menuitem = 3;
    }
  } 
  else if (up && page == 2 ) 
  {
    up = false;
    contrast--;
    setContrast();
  }

  if (down && page == 1) 
  {
    down = false;
    menuitem++;
    if (menuitem == 4)
    {
      menuitem = 1;
    }
  } 
  else if (down && page == 2 ) 
  {
    down = false;
    contrast++;
    setContrast();
  }


  if (middle) 
  {
    middle = false;

    if (page == 1 && menuitem == 2)
    {
      if (backlight)
      {
        backlight = false;
        turnBacklightOff();
      }
      else
      {
        backlight = true;
        turnBacklightOn();
      }
    }

    if (page == 1 && menuitem == 3)
    {
      resetDefaults();
    }
    else if (page == 1 && menuitem == 1) 
    {
      page = 2;
    }
    else if (page == 2) 
    {
      page = 1;
    }
  }
}

void checkIfDownButtonIsPressed()
{
  if (downButtonState != lastDownButtonState)
  {
    if (downButtonState == 0)
    {
      down = true;
    }
    delay(50);
  }
  lastDownButtonState = downButtonState;
}

void checkIfUpButtonIsPressed()
{
  if (upButtonState != lastUpButtonState)
  {
    if (upButtonState == 0) {
      up = true;
    }
    delay(50);
  }
  lastUpButtonState = upButtonState;
}

void checkIfSelectButtonIsPressed()
{
  if (selectButtonState != lastSelectButtonState)
  {
    if (selectButtonState == 0) {
      middle = true;
    }
    delay(50);
  }
  lastSelectButtonState = selectButtonState;
}

void drawMenu()
{
  if (page == 1)
  {
    display.setTextSize(1);
    display.clearDisplay();
    display.setTextColor(BLACK, WHITE);
    display.setCursor(15, 0);
    display.print("MAIN MENU");
    display.drawFastHLine(0, 10, 83, BLACK);
    display.setCursor(0, 15);

    if (menuitem == 1)
    {
      display.setTextColor(WHITE, BLACK);
    }
    else
    {
      display.setTextColor(BLACK, WHITE);
    }
    display.print(">Contrast");
    display.setCursor(0, 25);

    if (menuitem == 2)
    {
      display.setTextColor(WHITE, BLACK);
    }
    else
    {
      display.setTextColor(BLACK, WHITE);
    }
    display.print(">Light: ");

    if (backlight)
    {
      display.print("ON");
    }
    else
    {
      display.print("OFF");
    }
    display.display();

    if (menuitem == 3)
    {
      display.setTextColor(WHITE, BLACK);
    }
    else
    {
      display.setTextColor(BLACK, WHITE);
    }
    display.setCursor(0, 35);
    display.print(">Reset");
    display.display();
  }
  else if (page == 2)
  {
    display.setTextSize(1);
    display.clearDisplay();
    display.setTextColor(BLACK, WHITE);
    display.setCursor(15, 0);
    display.print("CONTRAST");
    display.drawFastHLine(0, 10, 83, BLACK);
    display.setCursor(5, 15);
    display.print("Value");
    display.setTextSize(2);
    display.setCursor(5, 25);
    display.print(contrast);

    display.setTextSize(2);
    display.display();
  }
}

void resetDefaults()
{
  contrast = 50;
  setContrast();
  backlight = true;
  turnBacklightOn();
}

void setContrast()
{
  display.setContrast(contrast);
  display.display();
}

void turnBacklightOn()
{
  digitalWrite(7, LOW);
}

void turnBacklightOff()
{
  digitalWrite(7, HIGH);
}