import { mkdir, readdir, rm, stat } from "node:fs/promises";
import { tmpdir } from "node:os";
import path from "node:path";

const JOB_TTL_MS = 15 * 60 * 1000;
const JOBS_ROOT = path.join(tmpdir(), "kk-card-jobs");
const JOB_ID_RE =
  /^[0-9a-f]{8}-[0-9a-f]{4}-[1-8][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i;

export function isJobId(id: string): boolean {
  return JOB_ID_RE.test(id);
}

export function jobDir(id: string): string {
  return path.join(JOBS_ROOT, id);
}

export function jobZipPath(id: string): string {
  return path.join(jobDir(id), "ids.zip");
}

export async function sweepExpiredJobs(): Promise<void> {
  let names: string[] = [];
  try {
    names = await readdir(JOBS_ROOT);
  } catch {
    return;
  }

  const cutoff = Date.now() - JOB_TTL_MS;
  await Promise.all(
    names.map(async (name) => {
      const dir = path.join(JOBS_ROOT, name);
      try {
        const info = await stat(dir);
        if (info.mtimeMs >= cutoff) return;
        await rm(dir, { recursive: true, force: true });
      } catch {
        // ignore missing or locked job folders
      }
    }),
  );
}

export async function createJobDir(): Promise<{
  id: string;
  dir: string;
  pngDir: string;
  imagePath: string;
  zipPath: string;
}> {
  await sweepExpiredJobs();
  const id = crypto.randomUUID();
  const dir = jobDir(id);
  const pngDir = path.join(dir, "png");
  await mkdir(pngDir, { recursive: true });
  return {
    id,
    dir,
    pngDir,
    imagePath: path.join(dir, "base"),
    zipPath: jobZipPath(id),
  };
}

export async function getJobZip(
  id: string,
): Promise<{ zipPath: string; size: number } | null> {
  if (!isJobId(id)) return null;
  const zipPath = jobZipPath(id);
  try {
    const info = await stat(zipPath);
    if (!info.isFile() || info.size === 0) return null;
    return { zipPath, size: info.size };
  } catch {
    return null;
  }
}