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

#define SDA_PIN 6
#define SCL_PIN 7

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

#define W 128
#define H 64

uint8_t grid[W][H];
uint8_t newGrid[W][H];

void setup() {
  Wire.begin(SDA_PIN, SCL_PIN);

  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    while (1);
  }

  display.clearDisplay();

  randomSeed(analogRead(0));

  for (int x = 0; x < W; x++) {
    for (int y = 0; y < H; y++) {
      grid[x][y] = random(2); // 0 or 1
    }
  }
}

int countNeighbors(int x, int y) {
  int count = 0;

  for (int dx = -1; dx <= 1; dx++) {
    for (int dy = -1; dy <= 1; dy++) {
      if (dx == 0 && dy == 0) continue;

      int nx = (x + dx + W) % W;
      int ny = (y + dy + H) % H;

      count += grid[nx][ny];
    }
  }

  return count;
}

void loop() {
  for (int x = 0; x < W; x++) {
    for (int y = 0; y < H; y++) {
      int neighbors = countNeighbors(x, y);

      if (grid[x][y] == 1) {
        // Alive
        if (neighbors < 2 || neighbors > 3)
          newGrid[x][y] = 0;
        else
          newGrid[x][y] = 1;
      } else {
        // Dead
        if (neighbors == 3)
          newGrid[x][y] = 1;
        else
          newGrid[x][y] = 0;
      }
    }
  }

  for (int x = 0; x < W; x++) {
    for (int y = 0; y < H; y++) {
      grid[x][y] = newGrid[x][y];
    }
  }

  display.clearDisplay();

  for (int x = 0; x < W; x++) {
    for (int y = 0; y < H; y++) {
      if (grid[x][y]) {
        display.drawPixel(x, y, SSD1306_WHITE);
      }
    }
  }

  display.display();

  delay(50);
}