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

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);

#define ENCODER_CLK 2
#define ENCODER_DT 3
#define ENCODER_SW 4

volatile int counter = 0;
int lastStateCLK;
int currentStateCLK;

void setup() {

  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0, 0);
  display.println("Encoder Test");
  display.display();

  pinMode(ENCODER_CLK, INPUT);
  pinMode(ENCODER_DT, INPUT);
  pinMode(ENCODER_SW, INPUT_PULLUP);

  lastStateCLK = digitalRead(ENCODER_CLK);

  attachInterrupt(digitalPinToInterrupt(ENCODER_CLK), updateEncoder, CHANGE);
}

void loop() {
  display.clearDisplay();
  display.setCursor(0, 0);
  display.print("Counter: ");
  display.println(counter);
  display.display();

  if (digitalRead(ENCODER_SW) == LOW) {
    counter = 0; 
    delay(200); 
  }
}

void updateEncoder() {
  currentStateCLK = digitalRead(ENCODER_CLK);

  if (currentStateCLK != lastStateCLK && currentStateCLK == 1) {
    if (digitalRead(ENCODER_DT) != currentStateCLK) {
      counter--;
    } else {
      counter++;
    }
  }

  lastStateCLK = currentStateCLK;
}