// ── Audiobook span segmentation ─────────────────────────────────────────────
// Deterministic split of a book's text into narration and dialogue spans from
// its own quotation typography. The LLM is then only asked WHO speaks each
// dialogue span, never to re-emit the text: that removes the fusion, dropped
// and duplicated text an LLM introduces when it rewrites a whole passage.
//
// Pure functions, no DOM: loaded in the browser and importable from Node so
// the segmentation can be scored against the hand-corrected references.
(function (root) {
'use strict';

const STYLES = [
  { name: 'guillemets-inward', open: '»', close: '«' },   // German »…«
  { name: 'low-high', open: '„', close: '“' },             // German „…“
  { name: 'curly', open: '“', close: '”' },                // English “…”
  { name: 'guillemets-outward', open: '«', close: '»' },   // French «…»
];
const MIN_PAIRS = 5;
const MAX_SPEECH_CHARS = 12000;   // a speech longer than this is treated as a lost closer

// Counts well-formed open…close pairs per style; the style with the most wins.
// One style per document: nested/secondary marks (›‹, ‘’) are deliberately ignored.
function detectStyle(text) {
  let best = null, bestPairs = 0;
  for (const st of STYLES) {
    let pairs = 0, inside = false;
    for (let i = 0; i < text.length; i++) {
      const ch = text[i];
      if (ch === st.open) inside = true;
      else if (ch === st.close && inside) { pairs++; inside = false; }
    }
    if (pairs > bestPairs) { best = st; bestPairs = pairs; }
  }
  return bestPairs >= MIN_PAIRS ? best : null;
}

// Sentences of text[a,b) as [start,end) ranges, each ending at . ! ? … plus
// any trailing quote/bracket marks.
function sentenceRanges(text, a, b) {
  const out = [];
  const re = /[^.!?…]*[.!?…]+[»«“”"’)\]]*\s*|[^.!?…]+$/g;
  const slice = text.slice(a, b);
  let m;
  while ((m = re.exec(slice)) && m[0].length) out.push([a + m.index, a + m.index + m[0].length]);
  return out;
}

// First/second-person pronouns and possessives are strong speech evidence in
// prose; third-person narration almost never contains them. `ihr`/`sie` are
// excluded (3rd-person possessive/pronoun) and polite `Ihr/Euch` only count
// when not sentence-initial.
const SPEECH_PRONOUN = /\b(?:ich|mich|mir|mein\w*|du|dich|dir|dein\w*|wir|uns|unser\w*|euch|euer|eure\w*|Euch|Euer|Eure\w*|I|me|my|you|your|we|us|our)\b/;
function looksLikeSpeech(sentence) {
  const s = sentence.trim();
  if (!s) return false;
  if (SPEECH_PRONOUN.test(s)) return true;
  if (/\?["»«”’)]*$/.test(s)) return true;
  if (/!["»«”’)]*$/.test(s) && s.split(/\s+/).length <= 12) return true;
  return false;
}

// A closing mark with no opener: the opener was lost in extraction. The
// speech starts at the earliest run of speech-like sentences directly before
// the mark, never before `floor` (the end of the previous span).
function recoverStart(text, floor, closeIdx) {
  const sents = sentenceRanges(text, floor, closeIdx);
  if (!sents.length) return closeIdx;
  let k = sents.length - 1;
  while (k > 0 && looksLikeSpeech(text.slice(sents[k - 1][0], sents[k - 1][1])) &&
         !/\n\s*\n/.test(text.slice(sents[k - 1][1], sents[k][0]))) k--;
  return sents[k][0];
}

// An opening mark whose closer is missing: the speech ends after the last of
// the leading run of speech-like sentences.
function recoverEnd(text, openEnd, limit) {
  const sents = sentenceRanges(text, openEnd, limit);
  if (!sents.length) return limit;
  let k = 0;
  while (k + 1 < sents.length && looksLikeSpeech(text.slice(sents[k + 1][0], sents[k + 1][1]))) k++;
  return sents[k][1];
}

// A quote that is really a quoted term or title inside a narration sentence
// (»den gewundenen Weg der Krieger« handelte…) is not speech.
function isQuotedTerm(text, a, b) {
  const inner = text.slice(a, b).trim();
  if (!inner) return true;
  if (/[.!?…]["»«”’)]*$/.test(inner)) return false;
  const before = text.slice(0, a).trimEnd();
  const after = text.slice(b).replace(/^[»«“”"’)\s]+/, '');
  const beforeOpen = before && !/[.!?…:]["»«”’)]*$/.test(before);
  const afterCont = /^[a-zäöüß,;]/.test(after);
  return beforeOpen && afterCont;
}

function segmentByQuotes(text, opts) {
  const style = (opts && opts.style) || detectStyle(text);
  if (!style) return null;
  const spans = [];
  const push = (kind, a, b) => { if (text.slice(a, b).trim()) spans.push({ kind, start: a, end: b }); };
  const paraBreakNext = (i) => /^\s*\n\s*\n/.test(text.slice(i, i + 6));
  let narrStart = 0, qStart = 0, inQuote = false;

  for (let i = 0; i < text.length; i++) {
    const ch = text[i];
    if (!inQuote) {
      if (ch === style.open) { push('narration', narrStart, i); inQuote = true; qStart = i + 1; }
      else if (ch === style.close) {
        const s = recoverStart(text, Math.max(narrStart, 0), i);
        push('narration', narrStart, s); push('dialogue', s, i); narrStart = i + 1;
      }
    } else if (ch === style.close) {
      push('dialogue', qStart, i); inQuote = false; narrStart = i + 1;
    } else if (ch === style.open) {
      // A second opener with no closer between: the first quote lost its closer.
      const end = recoverEnd(text, qStart, i);
      push('dialogue', qStart, end); push('narration', end, i);
      qStart = i + 1; narrStart = i + 1;
    } else if (ch === '\n' && paraBreakNext(i)) {
      // Paragraph break inside a quote. A long speech simply continues across
      // paragraphs (some typesetting re-opens each one, some only closes the
      // last), so keep going while a closing mark still follows before the next
      // opener; only when it never does was the closer lost.
      const rest = text.slice(i).replace(/^\s+/, '');
      if (rest[0] !== style.open) {
        const nextClose = text.indexOf(style.close, i), nextOpen = text.indexOf(style.open, i);
        const closesFirst = nextClose !== -1 && (nextOpen === -1 || nextClose < nextOpen) && nextClose - i <= MAX_SPEECH_CHARS;
        if (!closesFirst) {
          const end = recoverEnd(text, qStart, i);
          push('dialogue', qStart, end); push('narration', end, i);
          inQuote = false; narrStart = i;
        }
      }
    }
  }
  if (inQuote) {
    const end = recoverEnd(text, qStart, text.length);
    push('dialogue', qStart, end); push('narration', end, text.length);
  } else push('narration', narrStart, text.length);

  // Quoted terms/titles are narration; then merge neighbouring narration.
  for (const sp of spans) if (sp.kind === 'dialogue' && isQuotedTerm(text, sp.start, sp.end)) sp.kind = 'narration';
  const merged = [];
  for (const sp of spans) {
    const last = merged[merged.length - 1];
    if (last && last.kind === 'narration' && sp.kind === 'narration') last.end = sp.end;
    else merged.push(Object.assign({}, sp));
  }
  return merged.map((sp, index) => ({
    index, kind: sp.kind, start: sp.start, end: sp.end,
    text: text.slice(sp.start, sp.end).replace(/[»«]/g, '').replace(/[ \t]+/g, ' ').trim(),
  })).filter(sp => sp.text);
}

// Groups consecutive spans into passages for one LLM call each. Cuts prefer a
// paragraph boundary once a window is reasonably full; a window never exceeds
// `hardChars` unless a single span alone does. Ids are global to the book
// (N/D + running index) so a window can be re-sent or resumed unchanged.
function buildWindows(spans, text, opts) {
  const target = (opts && opts.targetChars) || 2400;
  const hard = (opts && opts.hardChars) || 3600;
  const windows = [];
  let cur = [], chars = 0;
  const flush = () => { if (cur.length) windows.push(cur); cur = []; chars = 0; };
  for (let i = 0; i < spans.length; i++) {
    const sp = spans[i];
    if (cur.length && chars + sp.text.length > hard) flush();
    cur.push(sp); chars += sp.text.length;
    const next = spans[i + 1];
    if (next && chars >= target) {
      const gap = text.slice(sp.end, next.start);
      if (/\n\s*\n/.test(gap) || chars >= hard * 0.9) flush();
    }
  }
  flush();
  // Attribution only needs the edges of a long span (speech tags sit there), so
  // what is sent to the LLM is abbreviated; the caller keeps the full text.
  const forLlm = (t, max) => t.length <= max ? t : t.slice(0, Math.ceil(max * 0.6)).trimEnd() + ' [...] ' + t.slice(-Math.floor(max * 0.4)).trimStart();
  return windows.map((w, index) => ({
    index,
    spans: w.map(sp => ({
      id: (sp.kind === 'dialogue' ? 'D' : 'N') + sp.index, kind: sp.kind, text: sp.text,
      llmText: forLlm(sp.text, sp.kind === 'dialogue' ? 1500 : 900), start: sp.start, end: sp.end,
    })),
    hasDialogue: w.some(sp => sp.kind === 'dialogue'),
  }));
}

const spansApi = { detectStyle, segmentByQuotes, buildWindows, looksLikeSpeech, recoverStart, recoverEnd, isQuotedTerm };
root.TTVC = root.TTVC || {};
root.TTVC.audiobook = root.TTVC.audiobook || {};
root.TTVC.audiobook.spans = spansApi;
if (typeof module !== 'undefined' && module.exports) module.exports = spansApi;
})(typeof window !== 'undefined' ? window : globalThis);