import {compose, virtualize} from '@avocado/core';
import {Vector} from '@avocado/math';

const decorate = compose(
  virtualize([
    'addBody',
    'createBody',
  ]),
);

export class AbstractWorld extends decorate(class {}) {

  constructor() {
    super();
    this.entities = new Map();
    this.entitiesList = [];
  }

  associateBodyWithEntity(body, entity) {
    this.entities.set(body, entity);
    this.entitiesList.push(entity);
    body.position = entity.position;
  }

  removeBody(body) {
    if (this.entities.has(body)) {
      const entity = this.entities.get(body);
      this.entities.delete(body);
      const index = this.entitiesList.indexOf(entity);
      if (-1 !== index) {
        this.entitiesList.splice(index, 1);
      }
    }
  }

  tick(elapsed) {
    // Propagate position updates.
    for (let i = 0; i < this.entitiesList.length; ++i) {
      const entity = this.entitiesList[i];
      const [entityX, entityY] = entity.position;
      const [bodyX, bodyY] = entity.body.position;
      // Hot.
      if (entityX === bodyX && entityY === bodyY) {
        continue;
      }
      entity.position = entity.body.position;
    }
  }

}