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

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET    -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Pin Definitions
#define BUTTON_PIN 2

// Game Variables
float birdY = 32.0;
float velocity = 0.0;
const float gravity = 0.4;
const float flapForce = -3.5;
const int birdRadius = 3;

int pipeX = 128;
int gapY = 24;
const int gapHeight = 22;
const int pipeWidth = 10;
const float pipeSpeed = 2.0;

int score = 0;
bool gameOver = false;
bool gameStarted = false;

// Custom 5x5 Bird Bitmap
const unsigned char PROGMEM bird_bmp[] = {
  0b01110000,
  0b11111000,
  0b11101000,
  0b11110000,
  0b01110000
};

void setup() {
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  
  // Initialize I2C for ESP32-C3 (Default pins: SDA=5, SCL=6)
  Wire.begin(5, 6);
  
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { 
    for(;;); // Stop if OLED initialization fails
  }
  
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  randomSeed(analogRead(0));
}

void resetGame() {
  birdY = 32.0;
  velocity = 0.0;
  pipeX = 128;
  gapY = random(10, SCREEN_HEIGHT - gapHeight - 10);
  score = 0;
  gameOver = false;
}

void loop() {
  // Read button (LOW means pressed due to INPUT_PULLUP)
  bool buttonPressed = (digitalRead(BUTTON_PIN) == LOW);

  if (!gameStarted) {
    display.clearDisplay();
    display.setTextSize(1);
    display.setCursor(30, 20);
    display.print("FLAPPY ROBOT");
    display.setCursor(25, 40);
    display.print("Press to Start");
    display.display();
    
    if (buttonPressed) {
      gameStarted = true;
      resetGame();
      delay(300); // Debounce
    }
    return;
  }

  if (gameOver) {
    display.clearDisplay();
    display.setTextSize(2);
    display.setCursor(10, 10);
    display.print("GAME OVER");
    display.setTextSize(1);
    display.setCursor(40, 35);
    display.print("Score: ");
    display.print(score);
    display.setCursor(20, 50);
    display.print("Press to Restart");
    display.display();

    if (buttonPressed) {
      resetGame();
      delay(300); // Debounce
    }
    return;
  }

  // --- GAME LOGIC ---

  // Apply bird physics
  if (buttonPressed) {
    velocity = flapForce;
  }
  velocity += gravity;
  birdY += velocity;

  // Move pipes
  pipeX -= pipeSpeed;
  if (pipeX < -pipeWidth) {
    pipeX = SCREEN_WIDTH;
    gapY = random(10, SCREEN_HEIGHT - gapHeight - 10);
    score++;
  }

  // Collision Detection: Floor or Ceiling
  if (birdY - birdRadius < 0 || birdY + birdRadius > SCREEN_HEIGHT) {
    gameOver = true;
  }

  // Collision Detection: Pipes
  if (pipeX < (16 + birdRadius) && (pipeX + pipeWidth) > (16 - birdRadius)) {
    if (birdY - birdRadius < gapY || birdY + birdRadius > (gapY + gapHeight)) {
      gameOver = true;
    }
  }

  // --- RENDER SCREEN ---
  display.clearDisplay();

  // Draw Bird (Offset slightly to center bitmap)
  display.drawBitmap(16 - 2, (int)birdY - 2, bird_bmp, 5, 5, SSD1306_WHITE);

  // Draw Top Pipe
  display.fillRect(pipeX, 0, pipeWidth, gapY, SSD1306_WHITE);
  // Draw Bottom Pipe
  display.fillRect(pipeX, gapY + gapHeight, pipeWidth, SCREEN_HEIGHT - (gapY + gapHeight), SSD1306_WHITE);

  // Draw Score
  display.setTextSize(1);
  display.setCursor(2, 2);
  display.print(score);

  display.display();
  delay(20); // Frame rate controller (~50 FPS)
}