/**
 * @jest-environment node
 *
 * We need to use Node.js since the default "jsdom" environment results in a
 * "ReferenceError: TextDecoder is not defined" error.
 **/

import { readFileSync } from "fs";
import { CmMip, extractCmMips } from "../dist/cmMips.js";
import { LogObservable } from "../dist/Observable/LogObservable.js";

const logger = new LogObservable();

let onlyInternal: Uint8Array | undefined = undefined;
let partlyExternal: Uint8Array | undefined = undefined;

const emptyCmMips = new Uint8Array([
	0x77, // magic
	0xee,
	1, // version
	0,
	0,
	0,
	1, // suffix length
	65, // suffix string ("A")
	3, // format length
	82, // format string ("RGB")
	71,
	66,
	1, // averageR
	2, // averageG
	3, // averageB
	4, // minWidth
	0,
	0,
	0,
	5, // minHeight
	0,
	0,
	0,
	0, // mipLevels
	0,
	0,
	0,
]);

beforeAll(() => {
	onlyInternal = new Uint8Array(
		readFileSync("./packages/web-utilities/__tests__/images/onlyInternal.cmmips")
	);
	partlyExternal = new Uint8Array(
		readFileSync("./packages/web-utilities/__tests__/images/partlyExternal.cmmips")
	);
});

afterAll(() => {
	onlyInternal = undefined;
	partlyExternal = undefined;
});

function checkBasics(mip: CmMip) {
	expect(mip).toBeDefined();
	expect(mip.name).toBeTruthy();
	expect(mip.suffix).toBeTruthy();
	expect(mip.width).toBeGreaterThan(0);
	expect(mip.height).toBeGreaterThan(0);
	expect(mip.data?.length).toBeGreaterThan(0);
}

test("Default Mip from CmMips file with only internal images", () => {
	checkBasics(extractCmMips(onlyInternal, logger));
});

test("Default Mip from CmMips file with some external images", () => {
	checkBasics(extractCmMips(partlyExternal, logger));
});

test("Requesting exact Mip size", () => {
	const mip = extractCmMips(onlyInternal, logger, 16);
	checkBasics(mip);
	expect(mip.width).toEqual(16);
	expect(mip.height).toEqual(16);
});

test("Requesting closest smaller Mip size", () => {
	const mip = extractCmMips(onlyInternal, logger, 15);
	checkBasics(mip);
	expect(mip.width).toEqual(8);
	expect(mip.height).toEqual(8);
});

test("Requesting impossible Mip size", () => {
	// We should always get a Mip back, if there are any internal at all in the file.
	const mip = extractCmMips(onlyInternal, logger, 0);
	checkBasics(mip);
	expect(mip.width).toEqual(1);
	expect(mip.height).toEqual(1);
});

test("Undefined array", () => {
	expect(extractCmMips(undefined, logger, 0)).toBeUndefined();
});

test("Wrong magic", () => {
	expect(extractCmMips(new Uint8Array([0x39, 0x30, 0, 0, 0, 0]), logger)).toBeUndefined();
});

test("Only header", () => {
	expect(extractCmMips(emptyCmMips, logger)).toBeUndefined();
});

test("Truncated data", () => {
	// Slice and Subarray will give internal buffers of different sizes.
	// Slice is safest and can therefor be considered the reference if the tests differ.
	const mip = extractCmMips(onlyInternal.subarray(0, 15), logger);
	expect(mip).toBeUndefined();
	expect(extractCmMips(onlyInternal.slice(0, 15), logger)).toEqual(mip);
});

test("Subarray with non-zero offset", () => {
	// Slice and Subarray will give internal buffers of different sizes and offsets.
	// Slice is safest and can therefor be considered the reference if the tests differ.
	const array = new Uint8Array(onlyInternal.length + 1);
	array.set(onlyInternal, 1);
	array[0] = 42;
	const mip = extractCmMips(array.subarray(1, array.length), logger);
	checkBasics(mip);
	expect(extractCmMips(array.slice(1, array.length), logger)).toEqual(mip);
});