#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128  // OLED display width, in pixels
#define SCREEN_HEIGHT 64  // OLED display height, in pixels

// Declaration for SSD1306 display connected using I2C
#define OLED_RESET -1  // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3C
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
#define buttonPullup 19
long currentTime = 0;
bool startStopTimer = false;
long referenceTime;



void setup() {
  Serial.begin(9600);

  // initialize the OLED object
  if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;)
      ;
  }
  pinMode(buttonPullup,INPUT_PULLUP);
  // Clear the buffer.
  display.clearDisplay();
  }
  /*// Display Text
  display.setTextSize(1);       // Set text size
  display.setTextColor(WHITE);  // Set text color
  display.setCursor(0, 28);     // Set cursor position
  display.println("Hello world!");
  display.display();  // Display the content on the screen
  delay(2000);
  display.clearDisplay();  // Clear the screen

  // Display Inverted Text
  display.setTextColor(BLACK, WHITE);  // 'inverted' text
  display.setCursor(0, 28);
  display.println("Hello world!");
  display.display();
  delay(2000);
  display.clearDisplay();

  // Changing Font Size
  display.setTextColor(WHITE);
  display.setCursor(0, 24);
  display.setTextSize(2);
  display.println("Hello!");
  display.display();
  delay(2000);
  display.clearDisplay();

  // Display Numbers
  display.setTextSize(1);
  display.setCursor(0, 28);
  display.println(123456789);
  display.display();
  delay(2000);
  display.clearDisplay();

  // Display ASCII Characters
  display.setCursor(0, 24);
  display.setTextSize(2);
  for (int i = 1; i < 8; i++) {
    display.write(i);
  }
  display.display();
  delay(2000);
  display.clearDisplay();

  // Scroll full screen
  display.setCursor(0, 0);
  display.setTextSize(1);
  display.println("Full");
  display.println("screen");
  display.println("scrolling!");
  display.display();
  display.startscrollright(0x00, 0x07);  // Scroll the screen to the right
  delay(5000);
  display.stopscroll();
  delay(1000);
  display.startscrollleft(0x00, 0x07);  // Scroll the screen to the left
  delay(5000);
  display.stopscroll();
  delay(1000);
  display.clearDisplay();

  // Scroll part of the screen
  display.setCursor(0, 0);
  display.setTextSize(1);
  display.println("Scroll");
  display.println("some part");
  display.println("of the screen.");
  display.display();
  display.startscrollright(0x00, 0x00);  // Scroll the first column of the screen to the right
  delay(4000);
  display.stopscroll();
  display.clearDisplay();

  // Display bitmap
  display.drawBitmap(32, 0, sunfounderIcon, 64, 64, WHITE);
  display.display();*/

void StartTimer()
{
  startStopTimer = !startStopTimer;
  if(startStopTimer)
  {
    referenceTime = millis();
  }
}
void DisplayTimer()
{
  display.clearDisplay();
  long displayNumber = (referenceTime + 900000) - millis();
  display.setTextSize(1);
  display.setCursor(0, 28);
  display.println(displayNumber);
  display.display();
  
}
void loop() {
  if(digitalRead(buttonPullup)==0)
  {
    while((digitalRead(buttonPullup)==0)){}
    delay(5);
    StartTimer();
  }
  if(startStopTimer)
  {
    DisplayTimer();
  }
  delay(5);
}