import {compose} from '@avocado/core';

import {simpleState, Trait} from '../trait';

const decorate = compose(
  simpleState('x', {
    track: true,
  }),
  simpleState('y', {
    track: true,
  }),
);

class PositionedBase extends Trait {

  static defaultState() {
    return {
      x: 0,
      y: 0,
    };
  }

  get position() {
    return [
      this.state.get('x'),
      this.state.get('y'),
    ];
  }

  set position([x, y]) {
    const positionChanged = x !== entity.x || y !== entity.y;
    const lastPosition = entity.position;
    this.entity.x = x;
    this.entity.y = y;
    if (positionChanged) {
      this.entity.emit('positionChanged', lastPosition, entity.position);
    }
  }

  listeners() {
    return {
      xChanged: (x, oldX) => {
        this.entity.emit(
          'positionChanged',
          this.entity.position,
          [oldX, this.entity.y]
        );
      },
      yChanged: (y, oldY) => {
        this.entity.emit(
          'positionChanged',
          this.entity.position,
          [this.entity.x, oldY]
        );
      },
    }
  }

}

export class Positioned extends decorate(PositionedBase) {}