// @vitest-environment node
import { mkdtempSync, readFileSync, rmSync } from "node:fs";
import { tmpdir } from "node:os";
import path from "node:path";
import { afterEach, beforeEach, describe, expect, it } from "vitest";
import { BRAND_CELL_PATHS } from "@/components/brand-mark";
import { AREAS } from "@/lib/areas";
import { ICON_FILES, SHORTCUT_ICONS, buildIco, generateIcons, readMasterPaths } from "./generate-icons.mjs";

const ROOT = process.cwd();

describe("generate-icons (spec 12.2)", () => {
  let outDir: string;
  beforeEach(() => {
    outDir = mkdtempSync(path.join(tmpdir(), "icons-"));
  });
  afterEach(() => rmSync(outDir, { recursive: true, force: true }));

  it("the master SVG has the BrandMark geometry", () => {
    expect(readMasterPaths(readFileSync(path.join(ROOT, "public/brand/apicore-mark.svg"), "utf8"))).toEqual(
      BRAND_CELL_PATHS,
    );
  });

  it("the lid sits centred over the cell, only lifted", () => {
    const xs = (d: string) => [...d.matchAll(/L([\d.]+)\s/g)].map((match) => Number(match[1]));
    const lidXs = xs(BRAND_CELL_PATHS.lid);
    expect(Math.min(...lidXs) + Math.max(...lidXs)).toBeCloseTo(64, 5);
  });

  it("shortcut icons use the icon of their area", () => {
    const pascal = (name: string) => name.replace(/(^|-)(\w)/g, (_, __, char: string) => char.toUpperCase());
    for (const shortcut of SHORTCUT_ICONS) {
      expect(AREAS[shortcut.area as keyof typeof AREAS].icon.displayName, shortcut.file).toBe(pascal(shortcut.lucide));
    }
  });

  it("running the icon script twice leaves the files byte-identical", async () => {
    const first = await generateIcons({ root: ROOT, outRoot: outDir });
    const snapshot = new Map(first.map((file) => [file, readFileSync(path.join(outDir, file))]));
    const second = await generateIcons({ root: ROOT, outRoot: outDir });

    expect(second).toEqual(first);
    expect([...first].sort()).toEqual([...ICON_FILES].sort());
    for (const file of second) {
      expect(readFileSync(path.join(outDir, file)).equals(snapshot.get(file) as Buffer), file).toBe(true);
    }
  });

  it("buildIco writes a header, one entry per PNG and the PNGs behind it", () => {
    const png = (size: number) => Buffer.concat([Buffer.from([0x89, 0x50, 0x4e, 0x47]), Buffer.alloc(size)]);
    const ico = buildIco([
      { size: 16, png: png(10) },
      { size: 256, png: png(20) },
    ]);

    expect([ico.readUInt16LE(0), ico.readUInt16LE(2), ico.readUInt16LE(4)]).toEqual([0, 1, 2]);
    // 256 px is written as 0 in the one-byte width and height fields.
    expect([ico.readUInt8(6), ico.readUInt8(22)]).toEqual([16, 0]);
    expect(ico.readUInt16LE(6 + 6)).toBe(32);
    const secondOffset = ico.readUInt32LE(22 + 12);
    expect(ico.readUInt32LE(6 + 12)).toBe(6 + 2 * 16);
    expect(secondOffset).toBe(6 + 2 * 16 + 14);
    expect(ico.length).toBe(secondOffset + 24);
  });
});