import { afterEach, describe, expect, it, vi } from "vitest";
import { decodeLocalImage } from "../../src/palette/decode";

const nativeUrl = globalThis.URL;

afterEach(() => {
  vi.unstubAllGlobals();
});

const installImageElementDecoder = (loadImmediately: boolean) => {
  const createObjectURL = vi.fn(() => "blob:local-image");
  const revokeObjectURL = vi.fn();
  class MockUrl extends nativeUrl {
    static createObjectURL = createObjectURL;
    static revokeObjectURL = revokeObjectURL;
  }
  class MockImage {
    decoding = "auto";
    naturalWidth = 320;
    naturalHeight = 180;
    onload: (() => void) | null = null;
    onerror: (() => void) | null = null;
    private source = "";

    set src(value: string) {
      this.source = value;
      if (value && loadImmediately) queueMicrotask(() => this.onload?.());
    }

    get src(): string {
      return this.source;
    }
  }

  vi.stubGlobal("URL", MockUrl);
  vi.stubGlobal("Image", MockImage);
  vi.stubGlobal("createImageBitmap", undefined);
  return { createObjectURL, revokeObjectURL };
};

describe("local image decoding", () => {
  it("revokes its object URL as soon as the image has decoded", async () => {
    const spies = installImageElementDecoder(true);
    const image = await decodeLocalImage(
      new File(["image"], "sample.png", { type: "image/png" }),
    );

    expect(image).toMatchObject({ width: 320, height: 180 });
    expect(spies.createObjectURL).toHaveBeenCalledOnce();
    expect(spies.revokeObjectURL).toHaveBeenCalledWith("blob:local-image");
    image.dispose();
  });

  it("revokes its object URL when decoding is cancelled", async () => {
    const spies = installImageElementDecoder(false);
    const controller = new AbortController();
    const decoding = decodeLocalImage(
      new File(["image"], "sample.png", { type: "image/png" }),
      controller.signal,
    );
    controller.abort();

    await expect(decoding).rejects.toMatchObject({ name: "AbortError" });
    expect(spies.revokeObjectURL).toHaveBeenCalledWith("blob:local-image");
  });
});