(function () {
    const CHARS = ['~', '-', '_', '·', '°', '*', 'o', '+', '×', '=', '≈', '∿', '◦'];

    function pick(arr) {
        return arr[Math.floor(Math.random() * arr.length)];
    }

    class Swirl {
        constructor(container) {
            this.container = container;
            this.cx = container.offsetWidth / 2 || window.innerWidth / 2;
            this.cy = container.offsetHeight / 2 || window.innerHeight / 2;
            this.elements = [];
            this.frameCount = 0;
            this.angle = 0;
            this.radius = 2;
            this.hue = Math.random() * 360;
            this.hueSpeed = 0.25;
            this.angleStep = 0.18;
            this.radiusStep = 0.55;
            this.globalRotation = 0;

            this.loop = this.loop.bind(this);
            requestAnimationFrame(this.loop);

            window.addEventListener('resize', () => {
                this.cx = container.offsetWidth / 2 || window.innerWidth / 2;
                this.cy = container.offsetHeight / 2 || window.innerHeight / 2;
            });
        }

        createChar(x, y, hue, scale) {
            const color = `hsl(${hue}, 60%, 68%)`;
            const el = document.createElement('span');
            el.textContent = pick(CHARS);
            el.classList.add('swirl-char');
            el.style.cssText =
                `position:absolute;` +
                `left:${x}px;top:${y}px;` +
                `font-family:"Courier New",Courier,monospace;` +
                `font-size:15px;line-height:1;` +
                `color:${color};` +
                `pointer-events:none;user-select:none;` +
                `opacity:0.85;`;
            el.style.transform = `scale(${scale}) rotate(${Math.random() * 360}deg)`;
            el.style.display = 'inline-block';

            this.container.appendChild(el);
            this.elements.push({
                el,
                born: this.frameCount,
                maxAge: 900 + Math.floor(Math.random() * 400),
            });
        }

        ageElements() {
            if (this.frameCount % 12 !== 0) return;
            const now = this.frameCount;
            let pruneCount = 0;
            const maxPrune = 12;
            for (let i = 0; i < this.elements.length && pruneCount < maxPrune; i++) {
                const item = this.elements[i];
                const age = now - item.born;
                if (age >= item.maxAge) {
                    item.el.remove();
                    this.elements.splice(i, 1);
                    i--;
                    pruneCount++;
                } else if (age > item.maxAge - 150) {
                    const fade = 1 - (age - (item.maxAge - 150)) / 150;
                    item.el.style.opacity = Math.max(0, fade * 0.85);
                }
            }
        }

        update() {
            this.frameCount++;

            // Rotation globale du tourbillon
            this.globalRotation += 0.002;

            // Évolution de la couleur
            this.hue = (this.hue + this.hueSpeed) % 360;

            // Ajouter un nouveau caractère à la spirale
            if (this.frameCount % 2 === 0) {
                this.angle += this.angleStep;
                // L'espacement augmente avec le rayon (spirale qui s'écarte)
                const dynamicStep = this.radiusStep + (this.radius / 100) * 0.18;
                this.radius += dynamicStep;

                const effectiveAngle = this.angle + this.globalRotation;
                const x = this.cx + Math.cos(effectiveAngle) * this.radius;
                const y = this.cy + Math.sin(effectiveAngle) * this.radius * 0.6;

                // Scale qui grandit avec le rayon
                const scale = 0.6 + (this.radius / 600) * 0.6;

                this.createChar(x, y, this.hue, scale);
            }

            // Quand le rayon dépasse l'écran, on recommence plus petit
            const maxRadius = Math.max(this.cx, this.cy) + 80;
            if (this.radius > maxRadius) {
                this.radius = 8 + Math.random() * 12;
                this.hue = (this.hue + 60 + Math.random() * 120) % 360;
            }

            this.ageElements();
        }

        loop() {
            this.update();
            requestAnimationFrame(this.loop);
        }
    }

    document.addEventListener('DOMContentLoaded', () => {
        const container = document.getElementById('swirl-container');
        if (container) {
            new Swirl(container);
        }
    });
})();