function parseVtt(vtt, options = {}) {
  const { mergeConsecutive = false } = options;
  const lines = vtt.split(/\r?\n/);
  const cues = [];
  let i = 0;

  while (i < lines.length && !/-->/.test(lines[i])) i++;

  while (i < lines.length) {
    const timeLine = lines[i];
    const timeMatch = timeLine.match(/(\d\d:\d\d:\d\d\.\d{3})\s+-->\s+(\d\d:\d\d:\d\d\.\d{3})/);
    if (!timeMatch) { i++; continue; }
    const start = timeMatch[1];
    const end = timeMatch[2];
    i++;

    const textLines = [];
    while (i < lines.length && lines[i].trim() !== '' && !/-->/.test(lines[i])) {
      textLines.push(lines[i]);
      i++;
    }
    const raw = textLines.join(' ').trim();
    if (!raw) continue;

    const speakerMatch = raw.match(/^<v\s+([^>]+)>([\s\S]*?)<\/v>$/);
    if (speakerMatch) {
      cues.push({ speaker: speakerMatch[1].trim(), text: speakerMatch[2].trim(), start, end });
    } else {
      cues.push({ speaker: null, text: raw, start, end });
    }
  }

  if (!mergeConsecutive) return cues;

  const merged = [];
  for (const cue of cues) {
    const last = merged[merged.length - 1];
    if (last && last.speaker === cue.speaker) {
      last.text = `${last.text} ${cue.text}`;
      last.end = cue.end;
    } else {
      merged.push({ ...cue });
    }
  }
  return merged;
}

function formatTranscript(cues) {
  return cues.map(c => `${c.speaker || '[unknown]'}: ${c.text}`).join('\n');
}

module.exports = { parseVtt, formatTranscript };