avocado/packages/timing/src/timed-index.js

import {Property} from '@avocado/core';
import {compose, EventEmitter} from '@flecks/core';

import Ticker from './ticker';

export default function TimedIndexMixin(indexName = 'index') {
  return (Superclass) => {
    const $$indexCount = `${indexName}Count`;
    const $$indexRate = `${indexName}Rate`;
    const decorate = compose(
      EventEmitter,
      Property('index', {
        default: 0,
        track: true,
      }),
      Property('isTicking', {
        default: true,
      }),
      Property($$indexCount, {
        default: 0,
      }),
      Property($$indexRate, {
        default: 0.1,
        get: function get() {
          return this.ticker.frequency;
        },
        set: function set(frequency) {
          this.ticker.frequency = frequency;
        },
      }),
    );
    return class TimedIndex extends decorate(Superclass) {

      constructor(...args) {
        super(...args);

        this.ticker = new Ticker(0.1);
        this.ticker.on('tick', this.onTick, this);
      }

      destroy() {
        if (super.destroy) {
          super.destroy();
        }
        this.ticker.off('tick', this.onTick);
      }

      get index() {
        return super.index;
      }

      set index(index) {
        super.index = 0 === this[$$indexCount] ? 0 : index % this[$$indexCount];
      }

      onTick() {
        const index = this.index + 1;
        if (index >= this[$$indexCount]) {
          this.emit('rollingOver');
        }
        this.index = index;
      }

      reset() {
        this.ticker.reset();
      }

      start() {
        this.isTicking = true;
      }

      stop() {
        this.isTicking = false;
      }

      tick(elapsed) {
        if (this.isTicking) {
          this.ticker.tick(elapsed);
        }
      }

    };
  };
}