import {compose} from '@avocado/core';
import {StateProperty, Trait} from '@avocado/entity';
import {Vector} from '@avocado/math';

import {BodyView} from '../body-view';

const decorate = compose(
  StateProperty('addedToPhysics', {
    track: true,
  }),
);

export class Physical extends decorate(Trait) {

  static defaultState() {
    return {
      addedToPhysics: true,
    };
  }

  initialize() {
    this._body = undefined;
    this.bodyView = undefined;
    this._world = undefined;
  }

  destroy() {
    this.world = undefined;
  }

  addToWorld() {
    const world = this._world;
    if (world) {
      const body = world.createBody(this.entity.shape);
      world.associateBodyWithEntity(body, this.entity);
      body.setCollisionForEntity(this.entity);
      world.addBody(body);
      this._body = body;
      if (this.entity.container) {
        this.bodyView = new BodyView(body);
        this.bodyView.position = Vector.scale(this.entity.position, -1);
        this.bodyView.zIndex = 101;
        this.entity.container.addChild(this.bodyView);
      }
    }
  }

  get body() {
    return this._body;
  }

  removeFromWorld() {
    if (this._world && this._body) {
      this._world.removeBody(this._body);
    }
    this._body = undefined;
    if (this.bodyView) {
      if (this.entity.is('visible')) {
        this.entity.container.removeChild(this.bodyView);
      }
      this.bodyView.destroy();
    }
    this.bodyView = undefined;
  }

  set world(world) {
    this.removeFromWorld();
    this._world = world;
    this.addToWorld();
  }

  listeners() {
    return {

      addedToRoom: () => {
        this.entity.world = this.entity.room.world;
      },

      addedToPhysicsChanged: () => {
        if (this.entity.addedToPhysics) {
          if (!this._body) {
            this.addToWorld();
          }
        }
        else {
          if (this._body) {
            this.removeFromWorld();
          }
        }
      },

      positionChanged: () => {
        if (this._body) {
          const position = this.entity.position;
          this._body.position = position;
        }
      },

    };
  }

  methods() {
    return {

      applyForce: (force) => {
        if (this._world) {
          this._body.applyForce(force);
        }
      },

      applyImpulse: (impulse, elapsed) => {
        if (this._world) {
          this._body.applyImpulse(impulse, elapsed);
        }
      },

    }
  }

}