(function(){
    const canvas = document.createElement('canvas');
    canvas.id = 'sakuraCanvas';
    canvas.style.position = 'fixed';
    canvas.style.top = '0';
    canvas.style.left = '0';
    canvas.style.width = '100vw';
    canvas.style.height = '100vh';
    canvas.style.pointerEvents = 'none';
    canvas.style.zIndex = '9999';
    document.body.appendChild(canvas);

    const ctx = canvas.getContext('2d');
    let width,height;
    let petals = [];

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

    class Petal {
        constructor(){
            this.reset();
        }
        reset(){
            this.x = Math.random() * width;
            this.y = Math.random() * -height;
            this.radius = Math.random() * 8 + 4;
            this.speedY = Math.random() * 1.5 + 0.8;
            this.speedX = Math.random() * 1 - 0.5;
            this.rotation = Math.random() * Math.PI * 2;
            this.rotateSpeed = (Math.random()-0.5)*0.02;
            this.opacity = Math.random()*0.4 + 0.6;
        }
        draw(){
            ctx.save();
            ctx.translate(this.x,this.y);
            ctx.rotate(this.rotation);
            ctx.beginPath();
            ctx.ellipse(0, 0, this.radius, this.radius/2, 0, 0, Math.PI*2);
            ctx.fillStyle = `rgba(255,183,200,${this.opacity})`;
            ctx.fill();
            ctx.restore();
        }
        update(){
            this.y += this.speedY;
            this.x += this.speedX;
            this.rotation += this.rotateSpeed;
            if(this.y > height + 10){
                this.reset();
            }
        }
    }

    const petalCount = 220;
    for(let i=0;i<petalCount;i++){
        petals.push(new Petal());
    }

    function animate(){
        ctx.clearRect(0,0,width,height);
        for(let p of petals){
            p.update();
            p.draw();
        }
        requestAnimationFrame(animate);
    }
    animate();
})();