import {TickingPromise} from '@avocado/core';

import {Collection} from './collection';
import {Traversal} from './traversal';

export class Traversals extends Collection('traversal') {

  parallel(context) {
    const results = this.traversals.map((traversal) => {
      return traversal.traverse(context);
    });
    // Early out if no promises.
    if (!results.reduce((has, result) => {
      return has || result instanceof Promise;
    }, false)) {
      return results;
    }
    // Otherwise, wrap in a promise.
    const tpromise = new TickingPromise((resolve, reject) => {
      return Promise.all(results);
    });
    // Proxy all ticks.
    const tickableResults = results.filter((result) => {
      if (!(result instanceof TickingPromise)) return false;
      if ('function' !== typeof result.ticker) return false;
      return true;
    });
    if (tickableResults.length > 0) {
      tpromise.ticker = (elapsed) => {
        tickableResults.forEach((result) => result.ticker(elapsed));
      };
    }
    return tpromise;
  }

}