const canvas = document.getElementById('gameCanvas');
const ctx = canvas.getContext('2d');
const scoreEl = document.getElementById('score');
const finalScoreEl = document.getElementById('finalScore');
const gameOverEl = document.getElementById('gameOver');
const restartBtn = document.getElementById('restartBtn');

// Game State
let score = 0;
let gameActive = true;
let animationId;
let frames = 0;

// Entities
let bullets = [];
let particles = [];

// Mouse
const mouse = {
    x: innerWidth / 2,
    y: innerHeight / 2
};

// Resize handling
function resize() {
    canvas.width = window.innerWidth;
    canvas.height = window.innerHeight;
}
window.addEventListener('resize', resize);
resize();

// Input handling
window.addEventListener('mousemove', (e) => {
    mouse.x = e.clientX;
    mouse.y = e.clientY;
});

window.addEventListener('touchmove', (e) => {
    mouse.x = e.touches[0].clientX;
    mouse.y = e.touches[0].clientY;
});

// Utility
function randomRange(min, max) {
    return Math.random() * (max - min) + min;
}

// Classes
class Heart {
    constructor() {
        this.x = canvas.width / 2;
        this.y = canvas.height / 2;
        this.baseSize = 30;
        this.size = this.baseSize;
        this.pulseSpeed = 0.05;
        this.angle = 0;
    }

    draw() {
        // Update center position on resize
        this.x = canvas.width / 2;
        this.y = canvas.height / 2;

        // Pulse animation
        this.angle += this.pulseSpeed;
        const scale = 1 + Math.sin(this.angle) * 0.1;
        
        ctx.save();
        ctx.translate(this.x, this.y);
        ctx.scale(scale, scale);
        
        // Draw Heart
        ctx.beginPath();
        ctx.fillStyle = '#ff4d4d';
        ctx.shadowColor = '#ff4d4d';
        ctx.shadowBlur = 20;
        
        // Heart shape using bezier curves
        // Starting from top center
        ctx.moveTo(0, -10); 
        ctx.bezierCurveTo(15, -25, 35, -10, 0, 25);
        ctx.bezierCurveTo(-35, -10, -15, -25, 0, -10);
        
        ctx.fill();
        ctx.restore();
    }
}

class Shield {
    constructor() {
        this.radius = 80; // Distance from heart
        this.angle = 0;
        this.width = 60; // Arc length in radians (approx)
        this.thickness = 10;
        this.color = '#4d94ff';
    }

    update() {
        const dx = mouse.x - canvas.width / 2;
        const dy = mouse.y - canvas.height / 2;
        this.angle = Math.atan2(dy, dx);
    }

    draw() {
        const centerX = canvas.width / 2;
        const centerY = canvas.height / 2;

        ctx.save();
        ctx.translate(centerX, centerY);
        ctx.rotate(this.angle);

        ctx.beginPath();
        // Draw an arc for the shield
        // We want the shield to be centered on the angle
        // So we draw from -arcLength/2 to +arcLength/2
        const arcLength = 0.8; // Radians
        ctx.arc(0, 0, this.radius, -arcLength / 2, arcLength / 2);
        
        ctx.lineWidth = this.thickness;
        ctx.strokeStyle = this.color;
        ctx.lineCap = 'round';
        ctx.shadowColor = this.color;
        ctx.shadowBlur = 15;
        ctx.stroke();

        ctx.restore();
    }
}

class Bullet {
    constructor() {
        const edge = Math.floor(Math.random() * 4); // 0: top, 1: right, 2: bottom, 3: left
        
        if (edge === 0) { // Top
            this.x = Math.random() * canvas.width;
            this.y = -20;
        } else if (edge === 1) { // Right
            this.x = canvas.width + 20;
            this.y = Math.random() * canvas.height;
        } else if (edge === 2) { // Bottom
            this.x = Math.random() * canvas.width;
            this.y = canvas.height + 20;
        } else { // Left
            this.x = -20;
            this.y = Math.random() * canvas.height;
        }

        this.radius = 5;
        this.color = '#fff';
        
        // Calculate velocity towards center
        const centerX = canvas.width / 2;
        const centerY = canvas.height / 2;
        const angle = Math.atan2(centerY - this.y, centerX - this.x);
        
        // Speed increases with score
        const speedMultiplier = 1 + (score * 0.01);
        this.velocity = {
            x: Math.cos(angle) * (2 + Math.random()) * speedMultiplier,
            y: Math.sin(angle) * (2 + Math.random()) * speedMultiplier
        };
    }

    update() {
        this.x += this.velocity.x;
        this.y += this.velocity.y;
    }

    draw() {
        ctx.beginPath();
        ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2);
        ctx.fillStyle = this.color;
        ctx.shadowColor = this.color;
        ctx.shadowBlur = 5;
        ctx.fill();
    }
}

class Particle {
    constructor(x, y, color) {
        this.x = x;
        this.y = y;
        this.radius = Math.random() * 3;
        this.color = color;
        this.velocity = {
            x: (Math.random() - 0.5) * 5,
            y: (Math.random() - 0.5) * 5
        };
        this.alpha = 1;
    }

    update() {
        this.x += this.velocity.x;
        this.y += this.velocity.y;
        this.alpha -= 0.02;
    }

    draw() {
        ctx.save();
        ctx.globalAlpha = this.alpha;
        ctx.beginPath();
        ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2);
        ctx.fillStyle = this.color;
        ctx.fill();
        ctx.restore();
    }
}

// Game Objects
const heart = new Heart();
const shield = new Shield();

function spawnBullet() {
    // Spawn rate increases with score
    const spawnRate = Math.max(20, 100 - score); 
    if (frames % spawnRate === 0) {
        bullets.push(new Bullet());
    }
}

function checkCollisions() {
    const centerX = canvas.width / 2;
    const centerY = canvas.height / 2;

    bullets.forEach((bullet, index) => {
        // Distance to center (Heart)
        const distToCenter = Math.hypot(bullet.x - centerX, bullet.y - centerY);

        // 1. Check Shield Collision
        // Shield is at a specific radius. If bullet is at that radius, check angle difference.
        if (distToCenter < shield.radius + shield.thickness && distToCenter > shield.radius - shield.thickness) {
            const angleToBullet = Math.atan2(bullet.y - centerY, bullet.x - centerX);
            
            // Normalize angles to -PI to PI
            let angleDiff = angleToBullet - shield.angle;
            while (angleDiff > Math.PI) angleDiff -= Math.PI * 2;
            while (angleDiff < -Math.PI) angleDiff += Math.PI * 2;

            // Shield arc length is approx 0.8 radians. Half is 0.4.
            // Add a bit of buffer for the bullet size
            if (Math.abs(angleDiff) < 0.5) {
                // Hit Shield
                createExplosion(bullet.x, bullet.y, '#4d94ff');
                bullets.splice(index, 1);
                score += 10;
                scoreEl.textContent = `Score: ${score}`;
                return;
            }
        }

        // 2. Check Heart Collision
        if (distToCenter < 30) { // Heart approx radius
            endGame();
        }
    });
}

function createExplosion(x, y, color) {
    for (let i = 0; i < 8; i++) {
        particles.push(new Particle(x, y, color));
    }
}

function endGame() {
    gameActive = false;
    cancelAnimationFrame(animationId);
    gameOverEl.classList.remove('hidden');
    finalScoreEl.textContent = score;
}

function restartGame() {
    score = 0;
    scoreEl.textContent = `Score: 0`;
    bullets = [];
    particles = [];
    gameActive = true;
    gameOverEl.classList.add('hidden');
    animate();
}

restartBtn.addEventListener('click', restartGame);

function animate() {
    if (!gameActive) return;

    animationId = requestAnimationFrame(animate);
    frames++;

    // Clear with trail effect
    ctx.fillStyle = 'rgba(17, 17, 17, 0.2)';
    ctx.fillRect(0, 0, canvas.width, canvas.height);

    heart.draw();
    shield.update();
    shield.draw();

    spawnBullet();

    // Update and draw bullets
    bullets.forEach((bullet, index) => {
        bullet.update();
        bullet.draw();

        // Remove off-screen bullets (shouldn't happen often as they move to center)
        if (bullet.x < -50 || bullet.x > canvas.width + 50 || 
            bullet.y < -50 || bullet.y > canvas.height + 50) {
            bullets.splice(index, 1);
        }
    });

    // Update and draw particles
    particles.forEach((particle, index) => {
        if (particle.alpha <= 0) {
            particles.splice(index, 1);
        } else {
            particle.update();
            particle.draw();
        }
    });

    checkCollisions();
}

// Start
animate();