import { afterEach, beforeEach, expect, test } from "vitest";
import { loadImage } from "./loadImage.ts";

class MockImage {
	static instances: MockImage[] = [];

	onload: (() => void) | null = null;
	onerror: ((error: unknown) => void) | null = null;
	src = "";

	constructor() {
		MockImage.instances.push(this);
	}
}

const RealImage = globalThis.Image;
const realError = console.error;
const errors: unknown[][] = [];

beforeEach(() => {
	globalThis.Image = MockImage as unknown as typeof Image;
	console.error = (...args: unknown[]) => {
		errors.push(args);
	};
});

afterEach(() => {
	globalThis.Image = RealImage;
	console.error = realError;
	MockImage.instances = [];
	errors.length = 0;
});

test("loadImage", async () => {
	const promise = loadImage("image.png");
	const image = MockImage.instances[0];

	expect(image.src).toBe("image.png");

	image.onload!();

	await expect(promise).resolves.toBe(image);
	expect(errors).toEqual([]);
});

test("loadImage error", async () => {
	const promise = loadImage("missing.png");
	const image = MockImage.instances[0];

	image.onerror!("missing");

	// errors are logged, but the promise still resolves with the image
	await expect(promise).resolves.toBe(image);
	expect(errors).toEqual([["missing"]]);
});