// @vitest-environment node
import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
import { randomBytes } from "node:crypto";
import { tmpdir } from "node:os";
import path from "node:path";
import { afterEach, beforeEach, describe, expect, it } from "vitest";
import { BUDGET_BYTES, MOTION_MARKERS, checkMotionBudget, isMotionChunk } from "./check-motion-budget.mjs";

const motionChunk = (filler: string, marker = MOTION_MARKERS[0]) => `/*${marker}*/var a="${marker}";${filler}`;
// Hex of random bytes is barely compressible by gzip (about 50 %).
const noise = (bytes: number) => randomBytes(bytes).toString("hex");

describe("check-motion-budget (spec 17.6: motion at most 30 kB gzip)", () => {
  let dir: string;
  beforeEach(() => {
    dir = mkdtempSync(path.join(tmpdir(), "motion-budget-"));
  });
  afterEach(() => rmSync(dir, { recursive: true, force: true }));

  it("adds up every motion chunk (the shell part and the lazily loaded features)", () => {
    writeFileSync(path.join(dir, "core.js"), motionChunk(noise(500), MOTION_MARKERS[0]));
    writeFileSync(path.join(dir, "features.js"), motionChunk(noise(500), MOTION_MARKERS.at(-1)));
    writeFileSync(path.join(dir, "app.js"), "console.log('Außerdem heute')");
    const result = checkMotionBudget(dir);
    expect(result.ok).toBe(true);
    expect(result.files.map(({ file }) => file).sort()).toEqual(["core.js", "features.js"]);
    expect(result.gzipBytes).toBe(result.files.reduce((sum, { gzipBytes }) => sum + gzipBytes, 0));
  });

  it("fails when the motion chunks together are over budget", () => {
    writeFileSync(path.join(dir, "a.js"), motionChunk(noise(400)));
    writeFileSync(path.join(dir, "b.js"), motionChunk(noise(400)));
    const result = checkMotionBudget(dir, 600);
    expect(result.ok).toBe(false);
    expect(result.gzipBytes).toBeGreaterThan(600);
  });

  it("fails when no motion chunk exists (check broken or bundle rebuilt)", () => {
    writeFileSync(path.join(dir, "app.js"), "export const a = 1;");
    const result = checkMotionBudget(dir);
    expect(result.ok).toBe(false);
    expect(result.files).toEqual([]);
  });

  it("does not count the three.js chunk", () => {
    expect(isMotionChunk(`/*WebGLRenderer*/window.__THREE__="186";${MOTION_MARKERS[0]}`)).toBe(false);
  });

  it("uses the spec budget of 30 kB by default", () => {
    expect(BUDGET_BYTES).toBe(30_000);
  });
});