import * as I from 'immutable';

import {compose} from '@avocado/core';
import {EventEmitter, Property} from '@avocado/mixins';

import {Layers} from './layers';

const decorate = compose(
  EventEmitter,
  Property('world', {
    track: true,
  }),
);

export class Room extends decorate(class {}) {

  constructor() {
    super();
    this.layers = new Layers();
    this._state = I.Map();
    // Listeners.
    this.onEntityAddedToRoom = this.onEntityAddedToRoom.bind(this);
    this.onEntityRemovedFromRoom = this.onEntityRemovedFromRoom.bind(this);
    this.onWorldChanged = this.onWorldChanged.bind(this);
    this.layers.on('entityAdded', this.onEntityAddedToRoom);
    this.layers.on('entityRemoved', this.onEntityRemovedFromRoom);
    this.on('worldChanged', this.onWorldChanged);
  }

  acceptStateChange(change) {
    if (change.layers) {
      this.layers.acceptStateChange(change.layers);
    }
  }

  addEntityToLayer(entity, layerIndex = 0) {
    this.layers.addEntityToLayer(entity, layerIndex);
  }

  destroy() {
    this.layers.destroy();
    this.layers.off('entityAdded', this.onEntityAddedToRoom);
    this.layers.off('entityRemoved', this.onEntityRemovedFromRoom);
    this.off('worldChanged', this.onWorldChanged);
  }

  findEntity(uuid) {
    return this.layers.findEntity(uuid);
  }

  fromJSON(json) {
    if (json.layers) {
      this.layers.fromJSON(json.layers);
    }
    return this;
  }

  layer(index) {
    return this.layers.layer(index);
  }

  onEntityAddedToRoom(entity) {
    entity.addTrait('roomed');
    entity.room = this;
    this.emit('entityAdded', entity)
  }

  onEntityRemovedFromRoom(entity) {
    if (entity.is('roomed')) {
      entity.removeTrait('roomed');
    }
    this.emit('entityRemoved', entity);
  }

  onWorldChanged() {
    for (const {layer} of this.layers) {
      for (const entity of layer.entityList) {
        if (entity.is('physical')) {
          entity.world = this.world;
        }
      }
    }
  }

  removeEntityFromLayer(entity, layerIndex = 0) {
    this.layers.removeEntityFromLayer(entity, layerIndex);
  }

  get state() {
    return this._state;
  }

  tick(elapsed) {
    this.layers.tick(elapsed);
    this._state = this._state.set('layers', this.layers.state);
    if (this.world) {
      this.world.tick(elapsed);
    }
  }

}