#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <LiquidCrystal_I2C.h>

// OLED setup
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define OLED_ADDR 0x3C
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// LCD setup
#define LCD_ADDR 0x27
LiquidCrystal_I2C lcd(LCD_ADDR, 16, 2);

// Button pin
#define BUTTON_PIN 4

// Game constants
#define GRAVITY 0.25      // Acceleration downward
#define FLAP_VELOCITY -5  // Upward velocity on flap
#define PIPE_SPEED 2      // Pixels per frame
#define PIPE_WIDTH 20     // Width of pipes
#define PIPE_GAP 35       // Vertical gap between pipes
#define PIPE_INTERVAL 80  // Frames between new pipes
#define BIRD_RADIUS 4     // Size of bird (circle)
#define GROUND_HEIGHT 8   // Height of ground at bottom
#define MAX_PIPES 4       // Max pipes on screen

// Game variables
float birdY = SCREEN_HEIGHT / 2;  // Bird starting Y position
float birdVelocity = 0;           // Bird vertical velocity
int score = 0;                    // Current score
bool gameOver = true;             // Start in game over state (wait for start)
bool gameStarted = false;

// Interrupt handling
volatile bool buttonPressedFlag = false;
unsigned long lastDebounceTime = 0;
unsigned long debounceDelay = 50; // 50ms debounce

// Pipe structure
struct Pipe {
  int x;          // X position
  int gapY;       // Y position of the top of the gap
  bool scored;    // Has the bird passed this pipe?
};

Pipe pipes[MAX_PIPES];
int pipeCount = 0;
int frameCounter = 0;

// Interrupt Service Routine
void IRAM_ATTR buttonISR() {
  unsigned long now = millis();
  if (now - lastDebounceTime > debounceDelay) {
    buttonPressedFlag = true;
    lastDebounceTime = now;
  }
}

void setup() {
  Serial.begin(115200);
  
  // Initialize button with pull-up and attach interrupt
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), buttonISR, FALLING);
  
  // Initialize OLED
  if (!display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);  // Halt if failed
  }
  display.clearDisplay();
  display.display();
  
  // Initialize LCD
  lcd.init();
  lcd.backlight();
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Flappy Bird");
  lcd.setCursor(0, 1);
  lcd.print("Score: 0");
  
  showStartScreen();
}

void loop() {
  // Check for button press via interrupt flag
  bool buttonJustPressed = false;
  if (buttonPressedFlag) {
    buttonPressedFlag = false;
    buttonJustPressed = true;
    Serial.println("Button pressed!");  // Debug print
  }
  
  if (gameOver) {
    // Wait for button press to start/restart
    if (buttonJustPressed) {
      resetGame();
      Serial.println("Starting game...");  // Debug
    }
    return;
  }
  
  // Flap on button press
  if (buttonJustPressed && gameStarted) {
    birdVelocity = FLAP_VELOCITY;
    Serial.println("Flap!");  // Debug
  }
  
  // Update physics
  birdVelocity += GRAVITY;
  birdY += birdVelocity;
  
  // Check ground/ceiling collision
  if (birdY + BIRD_RADIUS >= SCREEN_HEIGHT - GROUND_HEIGHT || birdY - BIRD_RADIUS <= 0) {
    gameOver = true;
    showGameOver();
    return;
  }
  
  // Update pipes
  updatePipes();
  
  // Check collisions with pipes
  if (checkCollisions()) {
    gameOver = true;
    showGameOver();
    return;
  }
  
  // Rendering
  renderGame();
  
  // Frame delay (approx 50 FPS)
  delay(20);
  frameCounter++;
}

// Reset game state
void resetGame() {
  birdY = SCREEN_HEIGHT / 2;
  birdVelocity = 0;
  score = 0;
  pipeCount = 0;
  frameCounter = 0;
  gameOver = false;
  gameStarted = true;
  updateScoreDisplay();
  display.clearDisplay();
  display.display();
}

// Update pipes: move, add new, remove old, score
void updatePipes() {
  // Add new pipe periodically
  if (frameCounter % PIPE_INTERVAL == 0 && pipeCount < MAX_PIPES) {
    pipes[pipeCount].x = SCREEN_WIDTH;
    pipes[pipeCount].gapY = random(PIPE_GAP + 10, SCREEN_HEIGHT - GROUND_HEIGHT - PIPE_GAP - 10);  // Random gap position
    pipes[pipeCount].scored = false;
    pipeCount++;
  }
  
  // Move pipes and check scoring
  for (int i = 0; i < pipeCount; i++) {
    pipes[i].x -= PIPE_SPEED;
    
    // Score if bird passes pipe
    if (!pipes[i].scored && pipes[i].x + PIPE_WIDTH < SCREEN_WIDTH / 4) {  // Bird is at fixed X (assume SCREEN_WIDTH / 4)
      pipes[i].scored = true;
      score++;
      updateScoreDisplay();
    }
    
    // Remove off-screen pipes
    if (pipes[i].x + PIPE_WIDTH < 0) {
      // Shift array left
      for (int j = i; j < pipeCount - 1; j++) {
        pipes[j] = pipes[j + 1];
      }
      pipeCount--;
      i--;  // Re-check current index
    }
  }
}

// Check if bird collides with any pipe
bool checkCollisions() {
  int birdX = SCREEN_WIDTH / 4;  // Bird fixed X position
  for (int i = 0; i < pipeCount; i++) {
    // Check top pipe
    if (birdX + BIRD_RADIUS > pipes[i].x && birdX - BIRD_RADIUS < pipes[i].x + PIPE_WIDTH &&
        birdY - BIRD_RADIUS < pipes[i].gapY) {
      return true;
    }
    // Check bottom pipe
    if (birdX + BIRD_RADIUS > pipes[i].x && birdX - BIRD_RADIUS < pipes[i].x + PIPE_WIDTH &&
        birdY + BIRD_RADIUS > pipes[i].gapY + PIPE_GAP) {
      return true;
    }
  }
  return false;
}

// Render game on OLED
void renderGame() {
  display.clearDisplay();
  
  // Draw bird (simple circle)
  display.fillCircle(SCREEN_WIDTH / 4, birdY, BIRD_RADIUS, SSD1306_WHITE);
  
  // Draw pipes
  for (int i = 0; i < pipeCount; i++) {
    // Top pipe
    display.fillRect(pipes[i].x, 0, PIPE_WIDTH, pipes[i].gapY, SSD1306_WHITE);
    // Bottom pipe
    display.fillRect(pipes[i].x, pipes[i].gapY + PIPE_GAP, PIPE_WIDTH, SCREEN_HEIGHT - GROUND_HEIGHT - (pipes[i].gapY + PIPE_GAP), SSD1306_WHITE);
  }
  
  // Draw ground
  display.fillRect(0, SCREEN_HEIGHT - GROUND_HEIGHT, SCREEN_WIDTH, GROUND_HEIGHT, SSD1306_WHITE);
  
  display.display();
}

// Update score on LCD
void updateScoreDisplay() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Score: ");
  lcd.print(score);
}

// Show start screen on OLED
void showStartScreen() {
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(10, 20);
  display.println(F("Flappy Bird"));
  display.setCursor(10, 35);
  display.println(F("Press button to start"));
  display.display();
}

// Show game over on OLED
void showGameOver() {
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(10, 20);
  display.println(F("Game Over!"));
  display.setCursor(10, 35);
  display.print(F("Score: "));
  display.println(score);
  display.setCursor(10, 50);
  display.println(F("Press to restart"));
  display.display();
}