// ==UserScript==
// @name         Xilly - Mouse Trail
// @namespace    http://experimenting.website/
// @version      0.1
// @description  Add firefly mouse trail
// @author       EXPERIMENTING
// @match        https://x.com/*
// @grant        none
// @run-at       document-start
// ==/UserScript==

(function () {
  'use strict';

  // ----- CONFIG -----
  const MAX_PARTICLES = 10;
  const SPAWN_RATE = 0.4;
  const BASE_SIZE = 1.0;
  const SIZE_VARIATION = 2.2;
  const LIFE_MIN = 700;
  const LIFE_MAX = 1600;
  const SPEED_FACTOR = 0.02;
  const TAIL_SMOOTH = 0.85;
  const FRAME_LIMIT_MS = 16.67;
  const IGNORE_INPUTS = true;

  const COLORS = [
    '255,210,120',
    '255,200,90',
    '255,170,70',
    '255,230,160'
  ];

  // ----- CREATE CANVAS OVERLAY -----
  let canvas, ctx;
  function createCanvas() {
    canvas = document.createElement('canvas');
    canvas.style.position = 'fixed';
    canvas.style.left = '0';
    canvas.style.top = '0';
    canvas.style.width = '100%';
    canvas.style.height = '100%';
    canvas.style.pointerEvents = 'none';
    canvas.style.zIndex = '2147483646';
    canvas.id = 'firefly-trail-canvas';
    document.documentElement.appendChild(canvas);

    ctx = canvas.getContext('2d', { alpha: true });
    resizeCanvas();
    window.addEventListener('resize', resizeCanvas, { passive: true });
  }

  function resizeCanvas() {
    if (!canvas) return;
    const dpr = Math.max(1, window.devicePixelRatio || 1);
    const w = Math.max(document.documentElement.clientWidth, window.innerWidth || 0);
    const h = Math.max(document.documentElement.clientHeight, window.innerHeight || 0);
    canvas.width = Math.floor(w * dpr);
    canvas.height = Math.floor(h * dpr);
    canvas.style.width = w + 'px';
    canvas.style.height = h + 'px';
    ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
  }

  // ----- PARTICLE SYSTEM -----
  class Particle {
    constructor() {
      this.reset(0, 0);
    }
    reset(x, y) {
      this.x = x;
      this.y = y;
      this.vx = (Math.random() - 0.5) * 0.3;
      this.vy = (Math.random() - 0.5) * 0.3;
      this.size = BASE_SIZE + Math.random() * SIZE_VARIATION;
      this.life = 0;
      this.maxLife = LIFE_MIN + Math.random() * (LIFE_MAX - LIFE_MIN);
      this.hue = COLORS[Math.floor(Math.random() * COLORS.length)];
      this.alpha = 1;
      this.alive = true;
      this.age = 0;
    }
    update(dt) {
      this.vx *= TAIL_SMOOTH;
      this.vy *= TAIL_SMOOTH;
      this.x += this.vx * dt;
      this.y += this.vy * dt;
      this.age += dt;
      this.life = this.age;
      this.alpha = Math.max(0, 1 - this.life / this.maxLife);
      if (this.life >= this.maxLife) this.alive = false;
    }
    draw(ctx) {
      const g = ctx;
      const s = this.size;
      g.save();
      // additive blending for glow
      g.globalCompositeOperation = 'lighter';
      // radial gradient for soft glow
      const grad = g.createRadialGradient(this.x, this.y, 0, this.x, this.y, s * 8);
      const rgba = (a) => `rgba(${this.hue},${a})`;
      grad.addColorStop(0, rgba(0.95 * this.alpha));
      grad.addColorStop(0.2, rgba(0.6 * this.alpha));
      grad.addColorStop(0.5, rgba(0.18 * this.alpha));
      grad.addColorStop(1, rgba(0));
      g.fillStyle = grad;
      g.beginPath();
      g.arc(this.x, this.y, s * 8, 0, Math.PI * 2);
      g.fill();

      // small core
      g.globalCompositeOperation = 'source-over';
      g.shadowColor = `rgba(${this.hue}, ${0.9 * this.alpha})`;
      g.shadowBlur = Math.max(6, s * 6);
      g.fillStyle = `rgba(${this.hue}, ${1 * this.alpha})`;
      g.beginPath();
      g.arc(this.x, this.y, s, 0, Math.PI * 2);
      g.fill();

      g.restore();
    }
  }

  let particles = [];
  let freeList = [];
  function createParticle(x, y) {
    let p;
    if (freeList.length) {
      p = freeList.pop();
      p.reset(x, y);
    } else if (particles.length < MAX_PARTICLES) {
      p = new Particle();
      p.reset(x, y);
      particles.push(p);
    } else {
      // recycle the oldest or dead one
      for (let i = 0; i < particles.length; i++) {
        if (!particles[i].alive) {
          p = particles[i];
          p.reset(x, y);
          break;
        }
      }
      if (!p) {
        // fallback: overwrite random
        p = particles[Math.floor(Math.random() * particles.length)];
        p.reset(x, y);
      }
    }
    return p;
  }

  // ----- MOUSE HANDLING -----
  let lastX = 0, lastY = 0, lastTime = performance.now();
  let enabled = true;

  function onMove(e) {
    if (!enabled) return;
    if (IGNORE_INPUTS) {
      const t = e.target;
      if (t && (t.tagName === 'INPUT' || t.tagName === 'TEXTAREA' || t.isContentEditable)) return;
    }
    const x = e.clientX;
    const y = e.clientY;
    const now = performance.now();
    const dt = Math.max(1, now - lastTime);
    const dx = x - lastX;
    const dy = y - lastY;
    const dist = Math.sqrt(dx * dx + dy * dy) || 0.001;

    let toSpawn = Math.min(6, Math.ceil(dist * SPAWN_RATE));

    for (let i = 0; i < toSpawn; i++) {
      const t = i / Math.max(1, toSpawn);
      const sx = lastX + dx * t + (Math.random() - 0.5) * 2;
      const sy = lastY + dy * t + (Math.random() - 0.5) * 2;
      const p = createParticle(sx, sy);
      p.vx += dx * SPEED_FACTOR * (0.6 + Math.random() * 0.9);
      p.vy += dy * SPEED_FACTOR * (0.6 + Math.random() * 0.9) + (Math.random() - 0.5) * 0.8;
    }

    lastX = x;
    lastY = y;
    lastTime = now;
  }

  function onTouchMove(e) {
    if (!e.touches || e.touches.length === 0) return;
    const t = e.touches[0];
    onMove({ clientX: t.clientX, clientY: t.clientY, target: t.target });
  }

  // ----- RENDER LOOP -----
  let rafId = null;
  function frame(now) {
    if (!ctx) return;
    
    ctx.clearRect(0, 0, canvas.width, canvas.height);

    const dt = 16;
    for (let i = 0; i < particles.length; i++) {
      const p = particles[i];
      if (!p.alive) continue;
      p.update(dt);
      p.draw(ctx);
    }

    for (let i = 0; i < particles.length; i++) {
      if (!particles[i].alive) {
        freeList.push(particles[i]);
      }
    }

    rafId = requestAnimationFrame(frame);
  }

  // ----- ENABLE / DISABLE CONTROL -----
  function enable() {
    if (enabled) return;
    enabled = true;
    canvas.style.display = '';
    window.addEventListener('mousemove', onMove, { passive: true });
    window.addEventListener('touchmove', onTouchMove, { passive: true });
    if (!rafId) rafId = requestAnimationFrame(frame);
  }

  function disable() {
    if (!enabled) return;
    enabled = false;
    canvas.style.display = 'none';
    window.removeEventListener('mousemove', onMove);
    window.removeEventListener('touchmove', onTouchMove);
    if (rafId) {
      cancelAnimationFrame(rafId);
      rafId = null;
    }
  }

  // toggle with Ctrl+Shift+K
  window.addEventListener('keydown', (e) => {
    if (e.ctrlKey && e.shiftKey && e.key.toLowerCase() === 'k') {
      if (enabled) {
        disable();
        flashStatus('Mouse trail: OFF');
      } else {
        enable();
        flashStatus('Mouse trail: ON');
      }
    }
  });

  // small on-screen hint that auto-hides
  let hintEl;
  function flashStatus(text) {
    if (!hintEl) {
      hintEl = document.createElement('div');
      hintEl.style.position = 'fixed';
      hintEl.style.right = '18px';
      hintEl.style.bottom = '18px';
      hintEl.style.padding = '8px 12px';
      hintEl.style.fontSize = '13px';
      hintEl.style.background = 'rgba(20,20,20,0.7)';
      hintEl.style.color = '#fff';
      hintEl.style.borderRadius = '8px';
      hintEl.style.zIndex = '2147483647';
      hintEl.style.pointerEvents = 'none';
      document.documentElement.appendChild(hintEl);
    }
    hintEl.textContent = text;
    hintEl.style.opacity = '1';
    setTimeout(() => {
      if (hintEl) hintEl.style.transition = 'opacity 700ms';
      if (hintEl) hintEl.style.opacity = '0';
    }, 900);
  }

  // ----- INIT -----
  function init() {
    // avoid running inside some embedded frames or if canvas already present
    try {
      if (window.top !== window.self) return;
    } catch (e) {}

    if (document.readyState === 'loading') {
      document.addEventListener('DOMContentLoaded', setup, { once: true });
    } else {
      setup();
    }
  }

  function setup() {
    createCanvas();
    // initial mouse pos center
    lastX = (window.innerWidth || document.documentElement.clientWidth) / 2;
    lastY = (window.innerHeight || document.documentElement.clientHeight) / 2;
    lastTime = performance.now();

    window.addEventListener('mousemove', onMove, { passive: true });
    window.addEventListener('touchmove', onTouchMove, { passive: true });

    rafId = requestAnimationFrame(frame);
    // initial simple hint
    flashStatus('Firefly trail enabled — Ctrl+Shift+K to toggle');
  }

  init();

})();