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

#define W 128
#define H 64
#define OLED_RESET -1
#define OLED_ADDR 0x3C

Adafruit_SSD1306 display(W, H, &Wire, OLED_RESET);

/* ---- TEXT GEOMETRY ---- */
#define TXT_Y 22
#define DIGIT_W 18
#define DIGIT_H 24

int digitX[4] = {22, 40, 58, 76}; // positions for digits

void setup() {
  display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR);
  randomSeed(analogRead(A0));
}

void loop() {
  show2025();
  snakeEat2025Smooth();
  airBombs();
  snakeReveal2026Smooth();
  finalWish();
}

/* ---------------- SHOW 2025 ---------------- */
void show2025() {
  display.clearDisplay();
  display.setTextSize(3);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(digitX[0], TXT_Y);
  display.print("2025");
  display.display();
  delay(1500);
}

/* ---------------- SMOOTH SNAKE EATING 2025 ---------------- */
void snakeEat2025Smooth() {

  for (int headX = -10; headX <= W + 10; headX++) {
    display.clearDisplay();

    /* Draw full 2025 */
    display.setTextSize(3);
    display.setCursor(digitX[0], TXT_Y);
    display.print("2025");

    /* Smooth erase using mask */
    int maskW = constrain(headX - digitX[0], 0, 4 * DIGIT_W);
    display.fillRect(digitX[0], TXT_Y, maskW, DIGIT_H, SSD1306_BLACK);

    drawSnake(headX, true);

    display.display();
    delay(20);  // smaller delay = smoother
  }

  display.clearDisplay();
  display.display();
}

/* ---------------- AIR BOMB BLASTS ---------------- */
void airBombs() {
  for (int i = 0; i < 4; i++) {
    int cx = random(20, W - 20);
    int cy = random(8, 28);

    for (int r = 2; r < 26; r++) {
      display.clearDisplay();
      display.drawCircle(cx, cy, r, SSD1306_WHITE);

      for (int s = 0; s < 10; s++) {
        display.drawPixel(cx + random(-r, r),
                          cy + random(-r, r),
                          SSD1306_WHITE);
      }

      display.display();
      delay(25);
    }
  }
}

/* ---------------- SMOOTH SNAKE REVEAL 2026 ---------------- */
void snakeReveal2026Smooth() {

  for (int headX = W + 10; headX >= -10; headX--) {
    display.clearDisplay();

    /* Draw full 2026 */
    display.setTextSize(3);
    display.setCursor(digitX[0], TXT_Y);
    display.print("2026");

    /* Smooth reveal mask (RIGHT → LEFT) */
    int revealW = constrain((digitX[0] + 4 * DIGIT_W) - headX,
                            0, 4 * DIGIT_W);

    display.fillRect(digitX[0], TXT_Y,
                     4 * DIGIT_W - revealW,
                     DIGIT_H,
                     SSD1306_BLACK);

    drawSnake(headX, false);

    display.display();
    delay(20);
  }
}

/* ---------------- DRAW SNAKE ---------------- */
void drawSnake(int headX, bool leftToRight) {
  int dir = leftToRight ? -1 : 1;

  for (int i = 0; i < 22; i += 4) {
    display.fillCircle(headX + dir * i, 36, 3, SSD1306_WHITE);
  }

  display.fillCircle(headX, 36, 4, SSD1306_WHITE);
  display.drawPixel(headX + (leftToRight ? 2 : -2), 35, SSD1306_BLACK);
}

/* ---------------- FINAL WISH ---------------- */
void finalWish() {
  display.clearDisplay();
  display.setTextSize(1);
  display.setCursor(20, 2);
  display.print("HAPPY NEW YEAR");

  display.setTextSize(3);
  display.setCursor(digitX[0], TXT_Y);
  display.print("2026");

  display.display();
  delay(4000);
}