import {Canvas, Container, Sprite} from '@avocado/graphics';
import {Rectangle, Vector} from '@avocado/math';

export class TilesRenderer {

  constructor(tiles, tileset) {
    this.tiles = tiles;
    this.tileset = tileset;
  }

  renderChunk(renderer, rectangle) {
    // No rectangle? Render all.
    if (!rectangle) {
      rectangle = Rectangle.compose([0, 0], this.tiles.size);
    }
    const slice = this.tiles.slice(rectangle);
    if (!slice) {
      return undefined;
    }
    // Precalcs.
    const size = Rectangle.size(rectangle);
    const tileSize = this.tileset.tileSize;
    const rowWidth = size[0] * tileSize[0];
    // Render all tiles.
    const container = new Container();
    const position = [0, 0];
    for (let i = 0; i < slice.length; ++i) {
      const index = slice[i];
      // Lookup subimage.
      const subimage = this.tileset.subimage(index);
      if (subimage) {
        const sprite = new Sprite(subimage);
        sprite.anchor = [0, 0];
        sprite.position = position;
        container.addChild(sprite);
      }
      // Only adds, please.
      position[0] += tileSize[0];
      if (rowWidth === position[0]) {
        position[0] = 0;
        position[1] += tileSize[1];
      }
    }
    // Blit to canvas.
    const canvasSize = Vector.mul(size, tileSize);
    const canvas = new Canvas(canvasSize);
    canvas.render(container, renderer);
    container.destroy();
    // Convert to image and return.
    const image = canvas.toImage();
    canvas.destroy();
    return image;
  }

}