import {compose} from '@avocado/core';
import {hasGraphics, Image} from '@avocado/graphics';
import {Rectangle, Vector} from '@avocado/math';
import {Resource} from '@avocado/resource';

const decorate = compose(
  Vector.Mixin('tileSize', 'tileWidth', 'tileHeight', {
    default: [0, 0],
  }),
);

export class Tileset extends decorate(Resource) {

  constructor() {
    super();
    this._image = undefined;
    this.subimages = [];
  }

  destroy() {
    this.subimages.forEach((sprite) => {
      sprite.destroy();
    });
    this.subimages = [];
  }

  fromJSON(json) {
    let promise;
    if (json.tileSize) {
      this.tileSize = json.tileSize;
    }
    if (hasGraphics && json.imageUri) {
      promise = Image.load(json.imageUri).then((image) => {
        this.image = image;
      });
    }
    return Promise.resolve(promise).then(() => {
      return this;
    });
  }

  get image() {
    return this._image;
  }

  set image(image) {
    this._image = image
    this.recalculateSubimages();
  }

  recalculateSubimages() {
    const image = this._image;
    const tileSize = this.tileSize;
    if (!image || Vector.isZero(tileSize)) {
      return;
    }
    this.destroy();
    const grid = Vector.div(image.size, tileSize);
    const rectangle = Rectangle.compose([0, 0], tileSize);
    for (let j = 0; j < grid[1]; ++j) {
      for (let i = 0; i < grid[0]; ++i) {
        const subimage = image.subimage(rectangle);
        this.subimages.push(subimage);
        rectangle[0] += tileSize[0];
      }
      rectangle[0] = 0;
      rectangle[1] += tileSize[1];
    }
  }

  subimage(index) {
    return this.subimages[index];
  }

  get tileSize() {
    return super.tileSize;
  }

  set tileSize(tileSize) {
    super.tileSize = tileSize;
    this.recalculateSubimages();
  }

  toJSON() {
    return {
      tileSize: this.tileSize,
      imageUri: this.image.uri,
    }
  }

}