import { readSong, readVerdicts, verdictsFile, isVerdict, type VerdictEntry } from "@/lib/browse";
import { withStateLock, writeJsonAtomic } from "@/lib/state";

export const dynamic = "force-dynamic";

// Record a judgement against one file.
//
// The verdicts live WITH THE DELIVERABLES -- videos/<song>/verdicts.json --
// rather than in umtool/song/ where the clip state lives. A tree of songs is a
// thing that gets copied and moved, and its judgements should travel with it.
// That is the only reason this does not use stateFile().
//
// The write is still read-modify-write under withStateLock + writeJsonAtomic,
// because the CLI scripts may read this file and a torn read of a judgement is
// a lost one.

export async function POST(request: Request) {
  let body: { song?: string; rel?: string; verdict?: string; note?: string };
  try {
    body = await request.json();
  } catch {
    return Response.json({ error: "bad json" }, { status: 400 });
  }

  const { song: id, rel, verdict, note } = body;
  if (!id || !rel) return Response.json({ error: "song and rel are required" }, { status: 400 });
  if (!verdict || !isVerdict(verdict)) {
    return Response.json({ error: "verdict must be keep, reject or undecided" }, { status: 400 });
  }

  const song = await readSong(id);
  if (!song) return Response.json({ error: "no such song" }, { status: 404 });

  // Membership in the current scan is the gate. A well-formed name for a file
  // that is not there would otherwise accumulate judgements about nothing.
  const known = [
    ...song.cuts.flatMap((c) => [c.shipped, ...c.variants]),
    ...song.unattributed,
  ].some((r) => r && r.rel === rel);
  if (!known) return Response.json({ error: "not a file in this song" }, { status: 404 });

  const entry: VerdictEntry = {
    verdict,
    at: new Date().toISOString(),
    ...(note?.trim() ? { note: note.trim() } : {}),
  };

  await withStateLock(async () => {
    const map = await readVerdicts(id);
    if (verdict === "undecided" && !entry.note) {
      // Undecided with nothing to say is the default. Storing it would grow the
      // file with rows that mean "no judgement", and make an untouched tree
      // indistinguishable from one somebody has been through.
      delete map[rel];
    } else {
      map[rel] = entry;
    }
    await writeJsonAtomic(verdictsFile(id), map);
  });

  return Response.json({ ok: true, rel, entry }, { headers: { "cache-control": "no-store" } });
}