// THE OPERATOR'S CAPTION-TRACK PICK. The editor's "Set as transcript" copies
// the chosen track to transcript.en.vtt and writes this sidecar beside it;
// while it is present, the caption-track rule ranks transcript.en.vtt first
// (lib/videoStatus.ts, englishVttsByPreference) — above en-orig, which the rule
// otherwise prefers. Only the file's PRESENCE is read by the rule; the record
// says which track was copied and when, for a person reading the dir.
//
// SERVER-ONLY (node:fs).

import { TRANSCRIPT_PIN_FILENAME } from "./videoStatus";
import { sidecar, sidecarField } from "./sidecar-server";

export type TranscriptPinRecord = {
  // The track the operator picked (copied to transcript.en.vtt).
  from: string;
  pinnedAt: string;
};

// Any parseable record still pins: the rule reads presence, so the record's
// shape must never make a pin read as absent here and present there.
export function coerceTranscriptPin(value: unknown): TranscriptPinRecord {
  const v = value as Partial<TranscriptPinRecord> | null;
  return {
    from: typeof v?.from === "string" ? v.from : "",
    pinnedAt: typeof v?.pinnedAt === "string" ? v.pinnedAt : "",
  };
}

export const transcriptPinSidecar = sidecar(
  TRANSCRIPT_PIN_FILENAME,
  sidecarField(coerceTranscriptPin),
);

export async function pinTranscript(videoDir: string, from: string): Promise<void> {
  await transcriptPinSidecar.write(videoDir, {
    from,
    pinnedAt: new Date().toISOString(),
  });
}