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,
  }),
);

export class Pictured extends decorate(Trait) {

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

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

  initialize() {
    this._cachedAabbs = {};
    this._images = this.params.get('images').toJS();
    this.sprites = undefined;
  }

  destroy() {
    if (this.sprites) {
      for (const key in this.sprites) {
        this.hideImage(key);
        const sprite = this.sprites[key];
        sprite.image.destroy();
        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.
    const imagePromises = [];
    this.sprites = {};
    for (const key in this._images) {
      const {uri} = this._images[key];
      const imagePromise = Image.load(uri).then((image) => {
        const sprite = this.sprites[key] = new Sprite(image);
        // Calculate any offset.
        sprite.position = this.offsetFor(key);
        // Set current image upfront.
        const isCurrentImage = key === this.entity.currentImage;
        if (isCurrentImage) {
          this.showImage(key);
        }
      });
      imagePromises.push(imagePromise);
    }
    Promise.all(imagePromises).then((images) => {
      // Bounding box update.
      this.entity.updateVisibleBoundingBox();
      this.setSpriteScale();
    });
  }

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

  setSpriteScale() {
    if (!this.sprites) {
      return;
    }
    const rawScale = this.entity.rawVisibleScale;
    for (const key in this.sprites) {
      const sprite = this.sprites[key];
      sprite.scale = rawScale;
    }
  }

  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;
  }

  hooks() {
    return {

      visibleAabbs: () => {
        const key = this.entity.currentImage;
        if (this._cachedAabbs[key]) {
          return this._cachedAabbs[key];
        }
        const image = this._images[key];
        if (!image) {
          return [0, 0, 0, 0];
        }
        const viewPosition = this.offsetFor(key);
        const size = this.sizeFor(key);
        const rectangle = Rectangle.compose(viewPosition, size);
        const expanded = Rectangle.expand(
          rectangle,
          Vector.sub(Vector.mul(size, this.entity.rawVisibleScale), size),
        );
        return this._cachedAabbs[key] = expanded;
      },

    }
  }

  listeners() {
    return {

      currentImageChanged: (oldKey) => {
        // Bounding box update.
        this.entity.updateVisibleBoundingBox();
        // Only client/graphics.
        if (!this.sprites) {
          return;
        }
        // Swap the image.
        this.hideImage(oldKey);
        this.showImage(this.entity.currentImage);
      },

      visibleScaleChanged: () => {
        this.setSpriteScale();
      },

      traitAdded: (type) => {
        if (-1 === [
          'visible',
          'pictured',
        ].indexOf(type)) {
          return;
        }
        this.loadImagesIfPossible();
      },

    };
  }

}