// Game variables
let ball = {
    x: 400,
    y: 250,
    dx: 5,
    dy: 5,
    radius: 10
};

let leftPaddle = {
    y: 200,
    height: 100,
    width: 15,
    speed: 8
};

let rightPaddle = {
    y: 200,
    height: 100,
    width: 15,
    speed: 8
};

let score = {
    left: 0,
    right: 0
};

let gameRunning = false;
let animationId;

// DOM elements
const ballElement = document.getElementById('ball');
const paddleLeftElement = document.getElementById('paddle-left');
const paddleRightElement = document.getElementById('paddle-right');
const scoreElement = document.getElementById('score');
const gameContainer = document.getElementById('game-container');
const startButton = document.getElementById('start-btn');
const resetButton = document.getElementById('reset-btn');

// Initialize game elements
function initGame() {
    const containerRect = gameContainer.getBoundingClientRect();
    
    // Ball position
    ball.x = containerRect.width / 2;
    ball.y = containerRect.height / 2;
    
    // Random initial direction
    ball.dx = Math.random() > 0.5 ? 5 : -5;
    ball.dy = (Math.random() * 4) - 2;
    
    // Paddle positions
    leftPaddle.y = (containerRect.height - leftPaddle.height) / 2;
    rightPaddle.y = (containerRect.height - rightPaddle.height) / 2;
    
    updateElements();
}

// Update DOM elements positions
function updateElements() {
    ballElement.style.left = `${ball.x}px`;
    ballElement.style.top = `${ball.y}px`;
    
    paddleLeftElement.style.top = `${leftPaddle.y}px`;
    paddleLeftElement.style.left = '20px';
    
    paddleRightElement.style.top = `${rightPaddle.y}px`;
    paddleRightElement.style.right = '20px';
    
    scoreElement.textContent = `${score.left} - ${score.right}`;
}

// Game loop
function gameLoop() {
    if (!gameRunning) return;
    
    const containerRect = gameContainer.getBoundingClientRect();
    
    // Move ball
    ball.x += ball.dx;
    ball.y += ball.dy;
    
    // Ball collision with top and bottom
    if (ball.y - ball.radius <= 0 || ball.y + ball.radius >= containerRect.height) {
        ball.dy = -ball.dy;
        ballElement.classList.add('ball-hit');
        setTimeout(() => ballElement.classList.remove('ball-hit'), 200);
    }
    
    // Ball collision with paddles
    if (
        (ball.x - ball.radius <= 35 && 
         ball.y >= leftPaddle.y && 
         ball.y <= leftPaddle.y + leftPaddle.height) ||
        (ball.x + ball.radius >= containerRect.width - 35 && 
         ball.y >= rightPaddle.y && 
         ball.y <= rightPaddle.y + rightPaddle.height)
    ) {
        ball.dx = -ball.dx * 1.05; // Increase speed slightly on hit
        ball.dy += (Math.random() * 2) - 1; // Add slight randomness
        ballElement.classList.add('ball-hit');
        setTimeout(() => ballElement.classList.remove('ball-hit'), 200);
    }
    
    // Score points
    if (ball.x - ball.radius <= 0) {
        score.right++;
        resetBall();
    } else if (ball.x + ball.radius >= containerRect.width) {
        score.left++;
        resetBall();
    }
    
    // Update elements
    updateElements();
    
    // Continue game loop
    animationId = requestAnimationFrame(gameLoop);
}

// Reset ball to center
function resetBall() {
    const containerRect = gameContainer.getBoundingClientRect();
    ball.x = containerRect.width / 2;
    ball.y = containerRect.height / 2;
    ball.dx = score.right > score.left ? -5 : 5; // Direction towards losing player
    ball.dy = (Math.random() * 4) - 2;
    
    // Pause briefly before continuing
    gameRunning = false;
    setTimeout(() => {
        gameRunning = true;
        gameLoop();
    }, 1000);
}

// Keyboard controls
const keys = {
    w: false,
    s: false,
    ArrowUp: false,
    ArrowDown: false
};

document.addEventListener('keydown', (e) => {
    if (['w', 's', 'ArrowUp', 'ArrowDown'].includes(e.key)) {
        keys[e.key] = true;
    }
});

document.addEventListener('keyup', (e) => {
    if (['w', 's', 'ArrowUp', 'ArrowDown'].includes(e.key)) {
        keys[e.key] = false;
    }
});

// Paddle movement
function movePaddles() {
    const containerRect = gameContainer.getBoundingClientRect();
    
    // Left paddle (W/S keys)
    if (keys.w && leftPaddle.y > 0) {
        leftPaddle.y -= leftPaddle.speed;
    }
    if (keys.s && leftPaddle.y < containerRect.height - leftPaddle.height) {
        leftPaddle.y += leftPaddle.speed;
    }
    
    // Right paddle (Up/Down arrows)
    if (keys.ArrowUp && rightPaddle.y > 0) {
        rightPaddle.y -= rightPaddle.speed;
    }
    if (keys.ArrowDown && rightPaddle.y < containerRect.height - rightPaddle.height) {
        rightPaddle.y += rightPaddle.speed;
    }
    
    updateElements();
}

// Start game
startButton.addEventListener('click', () => {
    if (!gameRunning) {
        gameRunning = true;
        startButton.disabled = true;
        initGame();
        gameLoop();
        
        // Paddle movement interval
        setInterval(movePaddles, 16);
    }
});

// Reset game
resetButton.addEventListener('click', () => {
    gameRunning = false;
    cancelAnimationFrame(animationId);
    score.left = 0;
    score.right = 0;
    startButton.disabled = false;
    initGame();
    updateElements();
});

// Initialize game on load
document.addEventListener('DOMContentLoaded', () => {
    initGame();
});