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

import {Image} from '../image';
import {Sprite} from '../sprite';

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

class PicturedBase extends Trait {

  static defaultParams() {
    return {
      images: {},
    };
  }

  static defaultState() {
    return {
      currentImage: 'initial',
    };
  }

  initialize() {
    this._images = this.params.get('images').toJS();
    this.sprites = undefined;
    // Bounding box update.
    this.entity.emit('visibleBoundingBoxesUpdated');
  }

  destroy() {
    if (this.sprites) {
      for (const key in this.sprites) {
        this.hideImage(key);
        const sprite = this.sprites[key];
        sprite.destroy();
      }
    }
  }

  hideImage(key) {
    if (!this.sprites) {
      return;
    }
    const sprite = this.sprites[key];
    if (!sprite) {
      return;
    }
    this.entity.container.removeChild(sprite);
  }

  loadImagesIfPossible() {
    if (!this.entity.container) {
      return;
    }
    if (this.sprites) {
      return;
    }
    // Load all images.
    this.sprites = {};
    for (const key in this._images) {
      const {uri} = this._images[key];
      Image.load(uri).then((image) => {
        const sprite = this.sprites[key] = new Sprite(image);
        // Calculate any offset.
        sprite.position = this.viewPositionFor(key);
        // Set current image upfront.
        const isCurrentImage = key === this.entity.currentImage;
        if (isCurrentImage) {
          this.showImage(key);
        }
      });
    }
  }

  offsetFor(key) {
    if (!this._images[key] || !this._images[key].offset) {
      return [0, 0];
    }
    return this._images[key].offset;
  }

  showImage(key) {
    if (!this.sprites) {
      return;
    }
    const sprite = this.sprites[key];
    if (!sprite) {
      return;
    }
    this.entity.container.addChild(sprite);
  }

  sizeFor(key) {
    if (!this._images[key] || !this._images[key].size) {
      return [0, 0];
    }
    return this._images[key].size;
  }

  viewPositionFor(key) {
    const image = this._images[key];
    if (!image) {
      return [0, 0];
    }
    const size = this.sizeFor(key);
    const halfway = Vector.scale(size, -0.5);
    const offset = this.offsetFor(key);
    return Vector.add(halfway, offset);
  }

  hooks() {
    return {

      visibleBoundingBoxes: () => {
        const key = this.entity.currentImage;
        const image = this._images[key];
        if (!image) {
          return [0, 0, 0, 0];
        }
        const viewPosition = this.viewPositionFor(key);
        const position = Vector.add(this.entity.position, viewPosition);
        return Rectangle.compose(position, this.sizeFor(key));
      }
    }
  }

  listeners() {
    return {
      currentImageChanged: (oldKey) => {
        // Bounding box update.
        this.entity.emit('visibleBoundingBoxesUpdated');
        // Only client/graphics.
        if (!this.sprites) {
          return;
        }
        // Swap the image.
        this.hideImage(oldKey);
        this.showImage(this.entity.currentImage);
      },
      traitAdded: (type) => {
        if (-1 === [
          'visible',
          'pictured',
        ].indexOf(type)) {
          return;
        }
        this.loadImagesIfPossible();
      },
    };
  }

}

export class Pictured extends decorate(PicturedBase) {}