import {compose} from '@avocado/core';
import {Vector} from '@avocado/math';
import {EventEmitter} from '@avocado/mixins';

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

const decorate = compose(
  EventEmitter,
  Vector.Mixin('_position', 'x', 'y', {
    track: true,
  }),
);

// < 16768 will pack into 1 short per axe and give +/- 0.25 precision.
class PositionedBase extends Trait {

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

  initialize() {
    this.on('_positionChanged', (oldPosition, newPosition) => {
      const x = Math.floor(newPosition[0]) * 4;
      const y = Math.floor(newPosition[1]) * 4;
      this.state = this.state.withMutations((state) => {
        state.set('x', x).set('y', y);
      });
      this.entity.emit('positionChanged', oldPosition, newPosition);
    });
    const x = this.state.get('x') / 4;
    const y = this.state.get('y') / 4;
    this._position = [x, y];
  }

  get position() {
    return this._position;
  }

  set position(position) {
    this._position = position;
  }

  transformPatchValue(key, value) {
    if (-1 !== ['x', 'y'].indexOf(key)) {
      return value / 4;
    }
    super.transformPatchValue(key, value);
  }

  get x() {
    return this.x;
  }

  set x(x) {
    this.x = x;
  }

  get y() {
    return this.y;
  }

  set y(y) {
    this.y = y;
  }

}

export class Positioned extends decorate(PositionedBase) {}