import type { StreamActionResult } from "yt-dlp-transcript-common/jobs/streamCommand";

// The one bulk fan-out loop, shared by "Sync every channel" and the per-group
// stage buttons on /channels.
//
// Deliberately NOT in ../actions.ts: that file carries "use server", which means
// every non-type export in it must be an async server action — a shared helper
// taking callbacks cannot live there.

export type QueueOutcome = {
  queued: string[];
  skipped: { slug: string; reason: string }[];
  // THE JOB IDS, IN THE SAME ORDER AS `queued`. Added because a fan-out's
  // response carried no way to FOLLOW what it started: `pnpm ops relocate
  // --wait` read `{ok, queued:[slug], skipped:[]}`, found no `jobId`, decided
  // nothing had been started and returned 0 immediately — reporting success
  // about a 130 GB copy that had not begun.
  //
  // A separate array rather than turning `queued` into objects: `queued` is the
  // documented body shape of two public routes and a UI reads it as slugs.
  // Additive, never renamed.
  jobIds: string[];
};

export async function queueForSlugs(
  slugs: ReadonlyArray<string>,
  opts: {
    // Return a reason string to skip this slug, or null to run it.
    skip?: (slug: string) => string | null | Promise<string | null>;
    run: (slug: string) => Promise<StreamActionResult>;
  },
): Promise<QueueOutcome> {
  const queued: string[] = [];
  const jobIds: string[] = [];
  const skipped: { slug: string; reason: string }[] = [];
  for (const slug of slugs) {
    const reason = opts.skip ? await opts.skip(slug) : null;
    if (reason) {
      skipped.push({ slug, reason });
      continue;
    }
    const result = await opts.run(slug);
    if (!result.ok) {
      skipped.push({ slug, reason: result.error });
      continue;
    }
    queued.push(slug);
    jobIds.push(result.jobId);
    // Nobody will read the stream here — cancel it so the buffered chunks
    // can be GC'd. The job keeps running and writes to its log file via
    // runManagedFunction's onLog regardless.
    void result.stream.cancel();
  }
  return { queued, jobIds, skipped };
}