/*--------------------
Vars
--------------------*/
const deg = a => Math.PI / 180 * a;
const rand = (v1, v2) => Math.floor(v1 + Math.random() * (v2 - v1));
const opt = {
  particles: window.width / 500 ? 250 : 125,
  noiseScale: 0.005,
  angle: Math.PI / 180 * -90,
  h1: rand(0, 360),
  h2: rand(0, 360),
  s1: rand(20, 90),
  s2: rand(20, 90),
  l1: rand(30, 80),
  l2: rand(30, 80),
  strokeWeight: 2,
  tail: 82 };

changeTitleColor();

const Particles = [];
let time = 0;
document.body.addEventListener("click", () => {
  if (inGame) {
    return;
  }
  opt.h1 = rand(0, 360);
  opt.h2 = rand(0, 360);
  opt.s1 = rand(20, 90);
  opt.s2 = rand(20, 90);
  opt.l1 = rand(30, 80);
  opt.l2 = rand(30, 80);
  opt.angle += deg(random(60, 60)) * (Math.random() > 0.5 ? 1 : -1);
  setTimeout(() => {
    changeTitleColor();
  }, 120);

  for (let p of Particles) {
    p.randomize();
  }
});

/*--------------------
Particle
--------------------*/
class Particle {
  constructor(x, y) {
    this.x = x;
    this.y = y;
    this.lx = x;
    this.ly = y;
    this.vx = 0;
    this.vy = 0;
    this.ax = 0;
    this.ay = 0;
    this.hueSem = Math.random();
    this.hue = this.hueSem > 0.5 ? 20 + opt.h1 : 20 + opt.h2;
    this.sat = this.hueSem > 0.5 ? opt.s1 : opt.s2;
    this.light = this.hueSem > 0.5 ? opt.l1 : opt.l2;
    this.maxSpeed = this.hueSem > 0.5 ? 3 : 2;
  }

  randomize() {
    this.hueSem = Math.random();
    this.hue = this.hueSem > 0.5 ? 20 + opt.h1 : 20 + opt.h2;
    this.sat = this.hueSem > 0.5 ? opt.s1 : opt.s2;
    this.light = this.hueSem > 0.5 ? opt.l1 : opt.l2;
    this.maxSpeed = this.hueSem > 0.5 ? 3 : 2;
  }

  update() {
    this.follow();

    this.vx += this.ax;
    this.vy += this.ay;

    var p = Math.sqrt(this.vx * this.vx + this.vy * this.vy);
    var a = Math.atan2(this.vy, this.vx);
    var m = Math.min(this.maxSpeed, p);
    this.vx = Math.cos(a) * m;
    this.vy = Math.sin(a) * m;

    this.x += this.vx;
    this.y += this.vy;
    this.ax = 0;
    this.ay = 0;

    this.edges();
  }

  follow() {
    let angle =
    noise(
    this.x * opt.noiseScale,
    this.y * opt.noiseScale,
    time * opt.noiseScale) *

    Math.PI *
    0.5 +
    opt.angle;

    this.ax += Math.cos(angle);
    this.ay += Math.sin(angle);
  }

  updatePrev() {
    this.lx = this.x;
    this.ly = this.y;
  }

  edges() {
    if (this.x < 0) {
      this.x = width;
      this.updatePrev();
    }
    if (this.x > width) {
      this.x = 0;
      this.updatePrev();
    }
    if (this.y < 0) {
      this.y = height;
      this.updatePrev();
    }
    if (this.y > height) {
      this.y = 0;
      this.updatePrev();
    }
  }

  render() {
    stroke(`hsla(${this.hue}, ${this.sat}%, ${this.light}%, .5)`);
    line(this.x, this.y, this.lx, this.ly);
    this.updatePrev();
  }}


/*--------------------
Setup
--------------------*/
function setup() {
  let canvas = createCanvas(windowWidth, windowHeight);
  canvas.parent("particles");

  for (let i = 0; i < opt.particles; i++) {
    Particles.push(new Particle(Math.random() * width, Math.random() * height));
  }
  strokeWeight(opt.strokeWeight);
}

/*--------------------
Draw
--------------------*/

let inGame = false;
function draw() {
  if (!inGame && document.visibilityState == "visible") {
    time++;
    background(0, 100 - opt.tail);
  
    for (let p of Particles) {
      p.update();
      p.render();
    }  
  }
}

/*--------------------
Resize
--------------------*/
function windowResized() {
  resizeCanvas(windowWidth, windowHeight);
}

function changeTitleColor() {
  document.getElementById("title").style.backgroundImage = `linear-gradient(hsl(${opt.h1 + 20}, ${opt.s1}%, ${opt.l1}%), hsl(${opt.h2}, ${opt.s2}%, ${opt.l2}%))`;
}