import { MODULE } from '../pkg/justified-layout-wasm-module.js';
import { initSync, get_justified_layout } from '../pkg/justified-layout-wasm.js';

export interface LayoutOptions {
  rowHeight: number;
  rowWidth: number;
  spacing: number;
  heightTolerance: number;
}

/*
 * This is a wrapper class to interact with the layout generated by the Wasm function.
 * This design is used because:
 *   - The layout is stored in a Float32Array for efficiency, which is not very user-friendly
 *   - Creating objects from the Float32Array takes more time than the actual layout calculation
 *   - Using getter methods avoids dynamic heap allocation beyond the initial layout calculation
 *   - The class provides a static prototype that can be JIT-compiled efficiently, inlining all of its methods
 *   - V8 does not box float32 values, unlike most other data types
 */
export class JustifiedLayout {
  layout: Float32Array;

  constructor(aspectRatios: Float32Array, { rowHeight, rowWidth, spacing, heightTolerance }: LayoutOptions) {
    initSync(MODULE);
    if (aspectRatios.length === 0) {
      this.layout = new Float32Array(4);
    } else {
      this.layout = get_justified_layout(aspectRatios, rowHeight, rowWidth, spacing, heightTolerance);
    }
  }

  get containerWidth() {
    return this.layout[0];
  }

  get containerHeight() {
    return this.layout[1];
  }

  getTop(boxIdx: number) {
    return this.layout[boxIdx * 4 + 4]; // the first 4 elements are containerWidth, containerHeight, padding, padding
  }

  getLeft(boxIdx: number) {
    return this.layout[boxIdx * 4 + 5];
  }

  getWidth(boxIdx: number) {
    return this.layout[boxIdx * 4 + 6];
  }

  getHeight(boxIdx: number) {
    return this.layout[boxIdx * 4 + 7];
  }

  getPosition(boxIdx: number) {
    return {
      top: this.layout[boxIdx * 4 + 4],
      left: this.layout[boxIdx * 4 + 5],
      width: this.layout[boxIdx * 4 + 6],
      height: this.layout[boxIdx * 4 + 7]
    }
  }
}