// Build WebVTT captions for a training video, in English and in any of the site's
// languages, WITHOUT re-rendering or re-voicing anything.
//
// Why this shape (Marty + Manson, 2026-09-17): Manson asked for the training videos in
// other languages. A real dub means re-rendering every video per language, because
// translated Romance-language speech runs 15-25% longer than English and these are slide
// videos with fixed beat timings, so swapped audio drifts off what is on screen. Captions
// keep ONE video file and add small text tracks beside it, so editing a lesson re-captions
// that lesson only.
//
//   node tools/captions.mjs <video.mp4> [--langs it,fr,es,de] [--out public/captions]
//
// Steps: ffmpeg pulls the audio, ElevenLabs Scribe transcribes it with word timings
// (the same STT we already use to verify voiceovers), words are grouped into SENTENCES,
// and only then translated. Translating cue-by-cue produces nonsense at cue boundaries,
// which is the usual reason auto-captions read badly.
//
// Translation goes through the site's own /api/public/translate, so every phrase is
// cached forever in translations.json and costs once across the whole site.
import fs from 'node:fs';
import path from 'node:path';
import { execFileSync } from 'node:child_process';

const args = process.argv.slice(2);
const VIDEO = args.find(a => !a.startsWith('--'));
const argOf = (n, d) => { const a = args.find(x => x.startsWith('--' + n + '=')); return a ? a.split('=')[1] : d; };
const LANGS = argOf('langs', 'it').split(',').map(s => s.trim()).filter(Boolean);
const OUT = argOf('out', 'public/captions');
const SITE = argOf('site', 'https://rmcircle.team');
const FFDIR = argOf('ffmpeg', 'C:/Users/Marty/AppData/Local/Microsoft/WinGet/Packages/Gyan.FFmpeg_Microsoft.Winget.Source_8wekyb3d8bbwe/ffmpeg-8.0.1-full_build/bin');
const KEYFILE = argOf('key', 'D:/Projects/MarketingAgent/.elevenlabs-key');
if (!VIDEO) { console.error('usage: node tools/captions.mjs <video.mp4> [--langs it,fr] [--out dir]'); process.exit(2); }

const base = path.basename(VIDEO).replace(/\.mp4$/i, '');
const work = path.join('D:/tmp/captions', base);
fs.mkdirSync(work, { recursive: true });
fs.mkdirSync(OUT, { recursive: true });

// Two lines of about 42 characters is the readable ceiling for a video overlay.
const MAX_LINE = 42, MAX_LINES = 2, MIN_CUE = 1.0, MAX_CUE = 6.5;

// ---------- 1. transcribe (cached: STT costs money, never pay twice) ----------
const sttPath = path.join(work, 'stt.json');
if (!fs.existsSync(sttPath)) {
  const mp3 = path.join(work, 'audio.mp3');
  if (!fs.existsSync(mp3)) {
    console.log('extracting audio...');
    execFileSync(path.join(FFDIR, 'ffmpeg'), ['-y', '-i', VIDEO, '-vn', '-ac', '1', '-ar', '16000', '-c:a', 'libmp3lame', '-b:a', '64k', mp3], { stdio: 'ignore' });
  }
  const key = fs.readFileSync(KEYFILE, 'utf8').trim().replace(/^.*=/, '');
  console.log('transcribing with scribe_v1...');
  const fd = new FormData();
  fd.append('model_id', 'scribe_v1');
  fd.append('timestamps_granularity', 'word');
  fd.append('language_code', 'eng');
  fd.append('file', new Blob([fs.readFileSync(mp3)]), 'audio.mp3');
  const r = await fetch('https://api.elevenlabs.io/v1/speech-to-text', { method: 'POST', headers: { 'xi-api-key': key }, body: fd });
  if (!r.ok) { console.error('STT failed', r.status, (await r.text()).slice(0, 300)); process.exit(1); }
  fs.writeFileSync(sttPath, JSON.stringify(await r.json()));
}
const stt = JSON.parse(fs.readFileSync(sttPath, 'utf8'));
const words = (stt.words || []).filter(w => w.type === 'word' && String(w.text || '').trim());
console.log('words: ' + words.length + ' | audio ' + Math.round(stt.audio_duration_secs || 0) + 's');

// ---------- 2. words -> sentences (the unit we translate) ----------
const sentences = [];
let cur = null;
for (const w of words) {
  if (!cur) cur = { start: w.start, end: w.end, words: [] };
  cur.words.push(w); cur.end = w.end;
  const endsSentence = /[.!?]["')\]]?$/.test(w.text);
  const tooLong = cur.words.map(x => x.text).join(' ').length > 240;
  if (endsSentence || tooLong) { sentences.push(cur); cur = null; }
}
if (cur) sentences.push(cur);
for (const s of sentences) s.text = s.words.map(w => w.text).join(' ').replace(/\s+([,.!?;:])/g, '$1').trim();
console.log('sentences: ' + sentences.length);

// ---------- 3. sentence -> cues, splitting only where a sentence is too long to show ----------
function wrap(text) {
  const out = []; let line = '';
  for (const w of text.split(/\s+/)) {
    if (!line) line = w;
    else if ((line + ' ' + w).length <= MAX_LINE) line += ' ' + w;
    else { out.push(line); line = w; }
  }
  if (line) out.push(line);
  return out;
}
// Chunk a sentence's words into display-sized pieces, keeping real timings.
function cuesFor(sent) {
  // Chunk by the ACTUAL wrapped line count, not a character guess. A character cap of
  // MAX_LINE * MAX_LINES lets text through that then wraps to three lines.
  const fits = t => wrap(t).length <= MAX_LINES;
  if (fits(sent.text) && (sent.end - sent.start) <= MAX_CUE) return [{ start: sent.start, end: sent.end, text: sent.text, sent }];
  const pieces = []; let chunk = [];
  for (const w of sent.words) {
    const next = chunk.concat([w]);
    const dur = w.end - next[0].start;
    if (chunk.length && (!fits(next.map(x => x.text).join(' ')) || dur > MAX_CUE)) { pieces.push(chunk); chunk = [w]; }
    else chunk = next;
  }
  if (chunk.length) {
    // A one or two word tail reads as a glitch on screen ("sentence." alone), so fold it
    // back into the previous cue whenever the result still fits.
    const prev = pieces[pieces.length - 1];
    if (prev && chunk.length <= 2 && fits(prev.concat(chunk).map(x => x.text).join(' '))) pieces[pieces.length - 1] = prev.concat(chunk);
    else pieces.push(chunk);
  }
  return pieces.map(p => ({ start: p[0].start, end: p[p.length - 1].end, text: p.map(x => x.text).join(' ').replace(/\s+([,.!?;:])/g, '$1'), sent }));
}
let cues = [];
for (const s of sentences) cues = cues.concat(cuesFor(s));
// never flash a cue, and never let one overlap the next
for (let i = 0; i < cues.length; i++) {
  if (cues[i].end - cues[i].start < MIN_CUE) cues[i].end = cues[i].start + MIN_CUE;
  if (i + 1 < cues.length && cues[i].end > cues[i + 1].start) cues[i].end = Math.max(cues[i].start + 0.4, cues[i + 1].start - 0.04);
}
console.log('cues: ' + cues.length);

const ts = s => { const h = Math.floor(s / 3600), m = Math.floor(s % 3600 / 60), x = s % 60;
  return String(h).padStart(2, '0') + ':' + String(m).padStart(2, '0') + ':' + x.toFixed(3).padStart(6, '0'); };
// NEVER slice the wrapped lines here. Truncating to MAX_LINES silently DELETED words:
// "the whole plan fits in one sentence" shipped as "fits in" then "sentence". Chunking
// below keeps cues to two lines almost always; a rare third line beats a lost word.
const toVtt = list => 'WEBVTT\n\n' + list.map((c, i) =>
  (i + 1) + '\n' + ts(c.start) + ' --> ' + ts(c.end) + '\n' + wrap(c.text).join('\n') + '\n').join('\n');

fs.writeFileSync(path.join(OUT, base + '.en.vtt'), toVtt(cues));
console.log('wrote ' + base + '.en.vtt');

// ---------- 4. translate whole sentences, then lay them back over the same timings ----------
async function translate(texts, tl) {
  const out = [];
  for (let i = 0; i < texts.length; i += 20) {
    const batch = texts.slice(i, i + 20).map(t => t.slice(0, 300));
    let got = null;
    for (let attempt = 0; attempt < 3 && !got; attempt++) {
      try {
        const r = await fetch(SITE + '/api/public/translate', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ tl, texts: batch }) });
        if (r.status === 429) { console.log('  rate limited, waiting 45s'); await new Promise(z => setTimeout(z, 45000)); continue; }
        const d = await r.json();
        // the endpoint answers { t: [...] }, and on failure it passes the ENGLISH back
        // rather than erroring, so count identical strings and warn instead of shipping
        // a "translated" track that is really English.
        if (Array.isArray(d.t)) got = d.t;
        else { console.error('  unexpected reply', JSON.stringify(d).slice(0, 200)); }
      } catch (e) { console.error('  translate error', e.message); await new Promise(z => setTimeout(z, 3000)); }
    }
    if (!got) { console.error('translation failed for batch at ' + i); process.exit(1); }
    out.push(...got);
    process.stdout.write('  ' + Math.min(i + 20, texts.length) + '/' + texts.length + '\r');
  }
  console.log('');
  return out;
}
// Spread one translated sentence across that sentence's cues, in proportion to how much
// of the English sentence each cue carried. Word counts differ between languages, so this
// is an approximation, but it keeps text on screen while its own audio is playing.
function spread(translated, sentCues) {
  if (sentCues.length === 1) return [translated];
  const words = translated.split(/\s+/);
  const weights = sentCues.map(c => c.text.length);
  const total = weights.reduce((a, b) => a + b, 0) || 1;
  const out = []; let idx = 0;
  sentCues.forEach((c, i) => {
    const take = i === sentCues.length - 1 ? words.length - idx : Math.max(1, Math.round(words.length * weights[i] / total));
    out.push(words.slice(idx, idx + take).join(' ')); idx += take;
  });
  return out;
}
for (const tl of LANGS) {
  console.log('translating to ' + tl + '...');
  const src = sentences.map(s => s.text);
  const tr = await translate(src, tl);
  const same = tr.filter((t, i) => String(t).trim() === String(src[i]).trim()).length;
  if (same > src.length * 0.2) {
    console.error('REFUSING ' + tl + ': ' + same + ' of ' + src.length + ' sentences came back identical to English. ' +
      'The endpoint returns the original when the model call fails, so this track would be English wearing a ' + tl + ' label.');
    continue;
  }
  if (same) console.log('  note: ' + same + ' sentence(s) unchanged (short or brand-only lines)');
  const bySent = new Map();
  cues.forEach(c => { if (!bySent.has(c.sent)) bySent.set(c.sent, []); bySent.get(c.sent).push(c); });
  const translatedCues = [];
  sentences.forEach((s, i) => {
    const sc = bySent.get(s) || [];
    const parts = spread(String(tr[i] || s.text), sc);
    sc.forEach((c, j) => translatedCues.push({ start: c.start, end: c.end, text: parts[j] || '' }));
  });
  fs.writeFileSync(path.join(OUT, base + '.' + tl + '.vtt'), toVtt(translatedCues.filter(c => c.text.trim())));
  console.log('wrote ' + base + '.' + tl + '.vtt');
}
console.log('done');