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

//define pages
#define page_home 1
#define page_sub 2

//define menu items
#define home_item_one 1
#define home_item_two 2

#define sub_item_one 1
#define sub_item_two 2

//define default contrast
int contrast=57

//buttons
volatile boolean up = false;
volatile boolean down = false;
volatile boolean select = false;

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

// Variables declared as volatile to ensure they wont be optomised out of the code
volatile int homeItem = 1;
volatile int subItem = 1;
volatile int page = 1;

Adafruit_PCD8544 display = Adafruit_PCD8544(7, 6, 5, 4, 3);

void setup() {

  pinMode(10, INPUT_PULLUP); //button UP
  pinMode(11, INPUT_PULLUP); //button SELECT
  pinMode(12, INPUT_PULLUP); //button DOWN

  Serial.begin(9600);
 
  display.begin();     
  display.setContrast(contrast); //Set contrast to 57 in this case
  display.clearDisplay();
  display.display();   

}

void loop() {

  downButtonState = digitalRead(12);
  selectButtonState = digitalRead(11);
  upButtonState =   digitalRead(10);
 
  checkIfDownButtonIsPressed();
  checkIfUpButtonIsPressed();
  checkIfSelectButtonIsPressed();

  switch(page) {
    case page_home:
      drawHome();
    break;
    case page_sub:
      drawSub();
    break;
  }
}

void drawHome() {
 
  display.setTextSize(1);
  display.clearDisplay();
  display.setTextColor(BLACK, WHITE);
  display.setCursor(15, 0);
  display.print("MAIN MENU");
  display.drawFastHLine(0,8,84,BLACK);
  display.setCursor(0, 10);

  if(homeItem == home_item_one) {
    display.setTextColor(WHITE, BLACK);
    } else {
      display.setTextColor(BLACK, WHITE);
    }
  display.print("Home Item 1");
  display.setCursor(0, 20);

  if(homeItem == home_item_two) {
    display.setTextColor(WHITE, BLACK);
    } else {
      display.setTextColor(BLACK, WHITE);
    }
  display.print("Home Item 2");
  display.display();
}

void drawSub() {
 
  display.setTextSize(1);
  display.clearDisplay();
  display.setTextColor(BLACK, WHITE);
  display.setCursor(15, 0);
  display.print("SUB MENU");
  display.drawFastHLine(0,8,84,BLACK);
  display.setCursor(0, 18);

  if(subItem == sub_item_one) {
    display.setTextColor(WHITE, BLACK);
    } else {
      display.setTextColor(BLACK, WHITE);
    }
  display.print(">Sub Item 1");
  display.setCursor(0, 28);

  if(subItem == sub_item_two) {
    display.setTextColor(WHITE, BLACK);
    } else {
      display.setTextColor(BLACK, WHITE);
    }
  display.print(">Sub Item 2");
  display.display();
}

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) {
      select=true;
    }
    delay(50);
  }
   lastSelectButtonState = selectButtonState;
}