/*
  Button

  Turns on and off a light emitting diode(LED) connected to digital pin 13,
  when pressing a pushbutton attached to pin 2.

  The circuit:
  - LED attached from pin 13 to ground through 220 ohm resistor
  - pushbutton attached to pin 2 from +5V
  - 10K resistor attached to pin 2 from ground

  - Note: on most Arduinos there is already an LED on the board
    attached to pin 13.

  created 2005
  by DojoDave <http://www.0j0.org>
  modified 30 Aug 2011
  by Tom Igoe

  This example code is in the public domain.

  https://www.arduino.cc/en/Tutorial/BuiltInExamples/Button
*/

// constants won't change. They're used here to set pin numbers:
const int buttonPin = 4;  // the number of the pushbutton pin
const int ledPin = 13;    // the number of the LED pin
int State;
#include <SPI.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Wire.h>
#define OLED_RESET     -1 
#define SCREEN_WIDTH 128 // OLED width,  in pixels
#define SCREEN_HEIGHT 64 // OLED height, in pixels
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
// variables will change:
int buttonState = 0;  // variable for reading the pushbutton status

void setup() {
  Serial.begin(9600);
  Serial.begin(115200);
  // initialize the LED pin as an output:
  pinMode(ledPin, OUTPUT);
  // initialize the pushbutton pin as an input:
  pinMode(buttonPin, INPUT);
  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;); // Don't proceed, loop forever
}
}

void loop() {
  // read the state of the pushbutton value:
  buttonState = digitalRead(buttonPin);

  // check if the pushbutton is pressed. If it is, the buttonState is HIGH:
  if (buttonState == HIGH && State==0 ) {
    // turn LED on:
    digitalWrite(ledPin, HIGH);
    delay(50);
    State=1;
    Serial.println(State);
    // Display Numbers
  display.setTextSize(1);
  display.setCursor(0, 28);
  display.println(123456789);
  display.display();
  delay(2000);
  display.clearDisplay();
  }
  else if (buttonState == HIGH && State==1 ) {
    // turn LED on:
    digitalWrite(ledPin, HIGH);
    delay(50);
    State=2;
    Serial.println(State);
    display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0, 24);
  display.setTextSize(1);
  display.println("Hello!");
  //display.display();
  display.setCursor(10, 15);
  display.setTextSize(1);
  display.println("aa!");
  display.display();
  delay(2000);
  display.clearDisplay();
  }
  else if (buttonState == HIGH && State==2 ) {
    // turn LED on:
    digitalWrite(ledPin, HIGH);
    delay(50);
    State=0;
    Serial.println(State);
     display.setTextColor(WHITE);
  display.setCursor(0, 24);
  display.setTextSize(2);
  display.println("Hello!");
  display.display();
  delay(2000);
  display.clearDisplay();
  } 
  else {
    // turn LED off:
    digitalWrite(ledPin, LOW);
  }
}