import type { Neko as DesktopWindow } from "https://deno.land/x/neko/core/Neko.ts";

export default class MemViz {
  #width?: number;
  #height?: number;
  #framebuffer?: Uint8Array;
  #window?: DesktopWindow;

  static async new(buffer: ArrayBufferLike, title = "memviz") {
    if (!("window" in globalThis)) throw "MemViz must be in Main thread";
    const self = new MemViz(MemViz._guard);
    self.#height = self.#width = Math.floor(Math.sqrt(buffer.byteLength) / 2);

    if ("Deno" in globalThis) {
      self.#window = new (await import("https://deno.land/x/neko/core/Neko.ts"))
        .Neko({
        width: self.#width,
        height: self.#height,
        title,
        // resize: true,
        topmost: true,
      });
      self.#framebuffer = new Uint8Array(buffer);
    } else {
      self.#img = new ImageData(
        new Uint8ClampedArray(buffer),
        self.#width,
        self.#height,
      );
      const canvas: HTMLCanvasElement =
        document.querySelector("canvas#memviz") ??
          document.createElement("canvas");
      self.#ctx = canvas.getContext("2d")!;
      document.body.append(canvas);
    }
    return self;
  }

  draw() {
    if ("Deno" in globalThis) {
      this.#window!.setFrameBuffer(
        this.#framebuffer!,
        this.#width,
        this.#height,
      );
    } else this.#ctx!.putImageData(this.#img!, 0, 0);
  }

  #ctx?: CanvasRenderingContext2D;
  #img?: ImageData;

  private static readonly _guard = Symbol(); // to bad typesccrypt can't do typeof MemViz.#guard
  constructor(guard: typeof MemViz._guard) {
    if (guard !== MemViz._guard) throw null;
  }
}