// 压缩包解压(沙箱内):zip 用 fflate,rar 用 node-unrar-js(WASM),7z 用 7z-wasm。
// WASM 库要读自己包里的 .wasm 文件:prepareArchives() 在撤销权限前预热(载入内存),之后只在内存里解压。
import SevenZip from "7z-wasm";
import { unzipSync } from "fflate";
import { createExtractorFromData } from "node-unrar-js";

type Seven = Awaited<ReturnType<typeof SevenZip>>;
let seven: Seven | null = null;
let warmed = false;

export async function prepareArchives(): Promise<void> {
  if (warmed) return;
  warmed = true;
  try {
    await createExtractorFromData({ data: new Uint8Array([0x52, 0x61, 0x72, 0x21]).buffer });
  } catch {
    // 只为载入 WASM,内容无效报错是预期的
  }
  seven = await SevenZip({ print: () => {}, printErr: () => {} });
}

export type AcceptEntry = (name: string, size: number) => boolean;

export function archiveKindOf(name: string): "zip" | "rar" | "7z" | null {
  const m = /\.(zip|rar|7z)$/i.exec(name);
  return m ? (m[1]!.toLowerCase() as "zip" | "rar" | "7z") : null;
}

/** 解出通过 accept 的条目;压缩包损坏 / 加密抛错 */
export async function extractArchive(
  kind: "zip" | "rar" | "7z",
  bytes: Uint8Array,
  accept: AcceptEntry,
): Promise<Record<string, Uint8Array>> {
  if (kind === "zip")
    return unzipSync(bytes, { filter: (e) => !e.name.endsWith("/") && accept(e.name, e.originalSize) });
  if (kind === "rar") {
    const ex = await createExtractorFromData({ data: bytes.slice().buffer });
    const out: Record<string, Uint8Array> = {};
    for (const f of ex.extract({ files: (h) => !h.flags.directory && accept(h.name, h.unpSize) }).files)
      if (f.extraction) out[f.fileHeader.name] = f.extraction;
    return out;
  }
  await prepareArchives();
  const z = seven!;
  const dir = `/x${crypto.randomUUID().slice(0, 8)}`;
  z.FS.writeFile(`${dir}.7z`, bytes);
  // callMain 出错时抛 ExitStatus 或静默不写文件:两种都当成损坏处理
  z.callMain(["x", `${dir}.7z`, `-o${dir}`, "-y", "-p-"]);
  try {
    z.FS.stat(dir);
  } catch {
    throw new Error("7z 解压失败");
  }
  const out: Record<string, Uint8Array> = {};
  const walk = (d: string, rel: string) => {
    for (const n of z.FS.readdir(d) as string[]) {
      if (n === "." || n === "..") continue;
      const p = `${d}/${n}`;
      const r = rel ? `${rel}/${n}` : n;
      if (z.FS.isDir(z.FS.stat(p).mode)) walk(p, r);
      else {
        const data = z.FS.readFile(p) as Uint8Array;
        if (accept(r, data.length)) out[r] = data;
      }
    }
  };
  walk(dir, "");
  return out;
}