import { System } from '@serpentity/serpentity';

import LimitedVelocityNode from '../nodes/limited_velocity';

/**
 * Reduces velocity if it exceeds threshold
 *
 * @extends {external:Serpentity.System}
 * @class ReduceVelocitySystem
 * @param {object} config a configuration object to extend.
 */
export default class ReduceVelocitySystem extends System {

  constructor(config = {}) {

    super();

    /**
     * The node collection of entities that have external force
     *
     * @property {external:Serpentity.NodeCollection} limitedVelocityEntities
     * @instance
     * @memberof ReduceVelocitySystem
     */
    this.limitedVelocityEntities = null;
  }

  /**
   * Initializes system when added. Requests limited velocity nodes
   *
   * @function added
   * @memberof ReduceVelocitySystem
   * @instance
   * @param {external:Serpentity.Engine} engine the serpentity engine to
   * which we are getting added
   */
  added(engine) {

    this.limitedVelocityEntities = engine.getNodes(LimitedVelocityNode);
  }

  /**
   * Clears system resources when removed.
   *
   * @function removed
   * @instance
   * @memberof ReduceVelocitySystem
   */
  removed() {

    this.limitedVelocityEntities = null;
  }

  /**
   * Runs on every update of the loop. Checks current velocity and adjusts if necessary
   *
   * @function update
   * @instance
   * @param {Number} currentFrameDuration the duration of the current
   * frame
   * @memberof ReduceVelocitySystem
   */
  update(currentFrameDuration) {

    for (const limitedVelocityEntity of this.limitedVelocityEntities) {
      console.log(limitedVelocityEntity.body.body.velocity, limitedVelocityEntity.maxVelocity.maxVelocity);
    }
  }
}