import { mkdir, readFile, writeFile, access } from "node:fs/promises";
import { createHash } from "node:crypto";
import { unzipSync } from "fflate";
export const assetsRoot = ".cache/minecraft/1.21.11";
export async function prepareAssets() {
  try {
    await access(`${assetsRoot}/assets/minecraft/blockstates/grass_block.json`);
    return;
  } catch {}
  const manifest = await (
    await fetch(
      "https://piston-meta.mojang.com/mc/game/version_manifest_v2.json",
    )
  ).json();
  const entry = manifest.versions.find((v) => v.id === "1.21.11");
  if (!entry) throw new Error("Official Minecraft 1.21.11 metadata missing");
  const version = await (await fetch(entry.url)).json();
  await mkdir(".cache/minecraft", { recursive: true });
  const jarPath = ".cache/minecraft/client-1.21.11.jar";
  let jar;
  try {
    jar = await readFile(jarPath);
  } catch {
    const response = await fetch(version.downloads.client.url);
    if (!response.ok) throw new Error("Minecraft asset download failed");
    jar = Buffer.from(await response.arrayBuffer());
    await writeFile(jarPath, jar);
  }
  if (
    createHash("sha1").update(jar).digest("hex") !==
    version.downloads.client.sha1
  )
    throw new Error("Minecraft client checksum mismatch");
  const entries = unzipSync(jar, {
    filter: (f) =>
      /^assets\/minecraft\/(models|blockstates|textures\/block)\//.test(
        f.name,
      ) && /\.(json|png)$/.test(f.name),
  });
  for (const [name, bytes] of Object.entries(entries)) {
    const path = `${assetsRoot}/${name}`;
    await mkdir(path.slice(0, path.lastIndexOf("/")), { recursive: true });
    await writeFile(path, bytes);
  }
  console.log(
    `Prepared ${Object.keys(entries).length} verified vanilla model/texture assets.`,
  );
}