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

#define OLED_RESET -1
Adafruit_SSD1306 display(OLED_RESET);

const byte BUTTON_PIN = 2;
const int SYMBOL_SIZE = 20;
unsigned char symbol1[SYMBOL_SIZE] = { 0x00, 0x18, 0x3C, 0x7E, 0x7E, 0x3C, 0x18, 0x00 };
const unsigned char* symbol_list[] = { symbol1 };
const int num_symbols = sizeof(symbol_list) / sizeof(symbol_list[0]);

int current_symbol = 0;
volatile bool button_pressed = false;

void button_isr() {
  button_pressed = true;
}

void setup() {
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), button_isr, FALLING);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.display();
}

void loop() {
  if (button_pressed) {
    current_symbol = (current_symbol) % num_symbols;
    display.clearDisplay();
    display.drawBitmap(54, 0, symbol_list[current_symbol], 8, 8, WHITE);
    display.display();
    button_pressed = false;
    delay(100); // debounce delay
  }
}