// What a read-only outline link shows: the outlines of a study (the whole-study one and each chunk's)
// and nothing else — no observations, interpretations, applications, scripts or word notes. The
// outline data comes from the browser, so it is rebuilt field by field instead of passed through.
const MAX_NODES = 2000;
const MAX_DEPTH = 8;
const KINDS = new Set(['', 'illustration', 'application', 'quote', 'question', 'transition']);

const str = (v, max) => (typeof v === 'string' ? v.slice(0, max) : '');

function cleanTree(nodes, depth, counter) {
  if (!Array.isArray(nodes) || depth > MAX_DEPTH) return [];
  const out = [];
  for (const n of nodes) {
    if (!n || typeof n !== 'object' || counter.n >= MAX_NODES) continue;
    counter.n += 1;
    const minutes = Number.isFinite(n.minutes) && n.minutes >= 0 && n.minutes <= 600 ? n.minutes : null;
    out.push({
      id: str(n.id, 64) || `n${counter.n}`,
      text: str(n.text, 2000),
      ref: str(n.ref, 200),
      kind: KINDS.has(n.kind) ? n.kind : '',
      minutes,
      note: str(n.note, 8000),
      scripture: n.scripture && typeof n.scripture.text === 'string'
        ? { ref: str(n.scripture.ref, 200), text: str(n.scripture.text, 6000), translation: str(n.scripture.translation, 12) }
        : null,
      attachments: (Array.isArray(n.attachments) ? n.attachments : []).slice(0, 50)
        .filter((a) => a && typeof a === 'object')
        .map((a) => ({ id: str(a.id, 100), type: a.type === 'word' ? 'word' : 'xref', label: str(a.label, 200), ...(a.detail ? { detail: str(a.detail, 500) } : {}) })),
      children: cleanTree(n.children, depth + 1, counter),
    });
  }
  return out;
}

const chunkLabel = (chapters, chapterIndex, chunk) => {
  const ch = chapters[chapterIndex];
  const next = chapters[chapterIndex + 1];
  if (Number.isInteger(chunk.spilloverEndVerse) && next && next.bookAbbrev === ch.bookAbbrev) {
    return `${ch.book} ${ch.chapter}:${chunk.startVerse}–${next.chapter}:${chunk.spilloverEndVerse}`;
  }
  return chunk.startVerse === chunk.endVerse ? `${ch.book} ${ch.chapter}:${chunk.startVerse}` : `${ch.book} ${ch.chapter}:${chunk.startVerse}–${chunk.endVerse}`;
};

// -> { title, translation, outlines: [{ scope, label, tree }] } with only the outlines that have points
export function buildOutlinePayload(project) {
  const counter = { n: 0 };
  const outlines = [];
  const whole = cleanTree(project?.outline, 0, counter);
  if (whole.length > 0) outlines.push({ scope: 'study', label: 'Whole study', tree: whole });
  const chapters = Array.isArray(project?.chapters) ? project.chapters : [];
  chapters.forEach((ch, chapterIndex) => {
    for (const chunk of Array.isArray(ch?.chunks) ? ch.chunks : []) {
      const tree = cleanTree(chunk?.outline, 0, counter);
      if (tree.length > 0) outlines.push({ scope: str(chunk.id, 64), label: str(chunkLabel(chapters, chapterIndex, chunk), 200), tree });
    }
  });
  return { title: str(project?.title, 500), translation: str(project?.translation, 12) || 'BSB', outlines };
}