'undefined' !== typeof window ? require('web-animations-js') : '';

import {Proton} from './proton';

import {Vector} from '@avocado/math';

export class TextNode {

  constructor(text) {
    this.text = text;
  }

  createDom() {
    const div = window.document.createElement('div');
    div.className = 'particle';
    const span = window.document.createElement('span');
    span.className = this.spanClassName();
    span.textContent = this.text;
    span.style.fontSize = `${this.sizeInPx()}px`;
    this.span = span;
    div.appendChild(span);
    this.div = div;
  }

  sizeInPx() {
    return 12;
  }

  spanClassName() {
    return 'text';
  }

  particleStateToCssRules(particle) {
    const color = particle.color;
    // Position.
    const transforms = [];
    const position = [particle.p.x, particle.p.y];
    const scale = particle.scale;
    // Offset for font size.
    const {style, textContent} = particle.target.span;
    const fontSize = this.sizeInPx();
    const length = textContent.length;
    const offset = (fontSize / 2) * (particle.scale / 2);
    position[0] -= offset * length;
    position[1] += offset;
    transforms.push(`translate(${position[0]}px, ${-position[1]}px)`);
    // Angle.
    const angle = 360 * (particle.rotation.x / (Math.PI * 2));
    transforms.push(`rotate(${angle}deg)`);
    // Scale.
    transforms.push(`scale(${scale})`);
    const rules = {
      transform: transforms.join(' '),
    };
    // Alpha?
    if (particle.useAlpha) {
      rules.opacity = particle.alpha || 1;
    }
    // Color?
    if (particle.useColor) {
      rules.color = `rgb(${color.r * 255}, ${color.g * 255}, ${color.b * 255})`;
    }
    return rules;
  }

}

export class TextNodeRenderer extends Proton.BaseRender {

  static get freeList() {
    if (!this._freeList) {
      this._freeList = [];
    }
    return this._freeList;
  }

  static pushToFreeList(target) {
    const freeList = this.freeList;
    freeList.push(target);
  }

  static pullFromFreeList() {
    const freeList = this.freeList;
    return freeList.pop();
  }

  constructor(selector, stage) {
    super();
    this._body = new TextNode('');
    this.name = 'NodeRenderer';
    this.queued = [];
    const promise = stage.findUiElement(selector);
    promise.then((element) => {
      if (this.parent) {
        let freeNode;
        while (freeNode = this.constructor.pullFromFreeList()) {
          this.parent.removeChild(freeNode.div);
        }
      }
      this.parent = element;
      // Start with a warm cache.
      if (this.parent && 0 === this.constructor.freeList.length) {
        for (let i = 0; i < 200; ++i) {
          const target = new TextNode();
          target.createDom();
          this.parent.appendChild(target.div);
          target.div.style.opacity = 0;
          this.constructor.pushToFreeList(target);
        }
      }
    });
  }

  onParticleCreated(particle) {
    // Clone global body if none was passed.
    if (!particle.body) {
      particle.body = this._body.clone();
    }
    // Pull from free list if we can.
    const target = this.constructor.pullFromFreeList();
    if (target) {
      particle.target = target;
      particle.target.span.className = particle.body.spanClassName();
      particle.target.span.textContent = particle.body.text;
      particle.target.span.style.fontSize = `${particle.body.sizeInPx()}px`;
      particle.target.div.style.opacity = 1;
    }
    else {
      particle.target = particle.body;
      particle.target.createDom();
      if (this.parent) {
        this.parent.appendChild(particle.target.div);
      }
    }
    // Queue if we don't have a parent yet.
    if (!this.parent) {
      this.queued.push(particle.target);
    }
    else {
      for (let i = 0; i < this.queued.length; ++i) {
        this.parent.appendChild(this.queued[i].div);
      }
      this.queued = [];
    }
    // Simulate the particle in discrete steps to build keyframes for
    // animation.
    const life = particle.life;
    particle.life = life * 1.01;
    const stepsPerSec = 10;
    let stepCount = life * stepsPerSec;
    const keyframes = [];
    const damping = 1 - .006;
    const time = 1 / stepsPerSec;
    while (stepCount--) {
      const keyframe = particle.target.particleStateToCssRules(
        particle,
      );
      particle.update(time, 0);
      Proton.integrator.integrate(particle, time, damping);
      keyframes.push(keyframe);
    }
    particle.life = Infinity;
    // Start animation.
    const animation = particle.target.div.animate(keyframes, {
      duration: life * 1000,
    });
    animation.addEventListener('finish', () => {
      particle.dead = true;
      particle.target.div.style.opacity = 0;
      this.constructor.pushToFreeList(particle.target);
      particle.target = undefined;
    });
  }

  onParticleUpdate(particle) {}

  onParticleDead(particle) {}

}