import { System } from '@serpentity/serpentity';
import { Graphics } from 'pixi.js';

import PositionComponent from '@serpentity/components.position';

import RenderableCoupleNode from '../nodes/renderable_couple';

/**
 * Renders renderable objects using pixi
 *
 * @extends {external:Serpentity.System}
 * @class CreateCouplingLineSystem
 * @param {object} config a configuration object to extend.
 */
export default class CreateCouplingLineSystem extends System {

  constructor(config = {}) {

    super();

    /**
     * The node collection of coupled entities entities
     *
     * @property {external:Serpentity.NodeCollection} coupledEntities
     * @instance
     * @memberof CreateCouplingLineSystem
     */
    this.coupledEntities = null;
  }

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

    this.coupledEntities = engine.getNodes(RenderableCoupleNode);
  }

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

    this.coupledEntities = null;
  }

  /**
   * Runs on every update of the loop. Does nothing.
   *
   * @function update
   * @instance
   * @param {Number} currentFrameDuration the duration of the current
   * frame
   * @memberof CreateCouplingLineSystem
   */
  update(currentFrameDuration) {

    for (const rootEntity of this.coupledEntities) {

      const rootGraphic = rootEntity.container.container;
      rootGraphic.removeChildren();

      let lineGraphic = new Graphics();
      lineGraphic = lineGraphic.lineStyle(5, 0xffffff, 0.9);

      let initialPosition = false;

      for (const coupledEntity of rootEntity.coupledEntities.coupledEntities) {
        if (coupledEntity.hasComponent(PositionComponent)) {

          const position = coupledEntity.getComponent(PositionComponent);

          if (!initialPosition) {
            lineGraphic = lineGraphic.moveTo(position.x, position.y);
            initialPosition = true;
            continue;
          }

          lineGraphic = lineGraphic.lineTo(position.x, position.y);
        }
      }

      rootGraphic.addChild(lineGraphic);
    }
  }
}