// Comparing translations of one chunk: which chapter(s) and verses to fetch, and the verses lined up by number.
import { getChunkVerseEntries } from './bibleUtils.jsx';
import { diffVerses } from './textDiff.js';

// -> [{ bookAbbrev, book, chapter, from, to }]: one entry per chapter the chunk covers (two when it spills over).
export function translationSpans(project, chapterIndex, chunk) {
  const spans = [];
  for (const v of getChunkVerseEntries(project, chapterIndex, chunk)) {
    const last = spans[spans.length - 1];
    if (last && last.chapter === v.chapter && last.book === v.book) { last.to = Math.max(last.to, v.number); last.from = Math.min(last.from, v.number); continue; }
    const chapter = project.chapters.find((c) => c.book === v.book && String(c.chapter) === String(v.chapter));
    spans.push({ bookAbbrev: chapter?.bookAbbrev, book: v.book, chapter: v.chapter, from: v.number, to: v.number });
  }
  return spans;
}

// byTranslation: { BSB: { verses: [{ number, text }] }, … } for the chapters in `spans`; `loaded` is keyed by
// `${chapter}` inside each translation. -> [{ key, label, texts: { BSB: 'text' | null } }] one row per verse, in order.
export function alignVerses(spans, byTranslation) {
  const rows = [];
  for (const span of spans) {
    for (let n = span.from; n <= span.to; n += 1) {
      const texts = {};
      for (const [id, chapters] of Object.entries(byTranslation)) {
        texts[id] = chapters?.[`${span.book}|${span.chapter}`]?.find((v) => v.number === n)?.text ?? null;
      }
      rows.push({ key: `${span.book}${span.chapter}:${n}`, noteKey: `${span.chapter}:${n}`, label: spans.length > 1 ? `${span.chapter}:${n}` : String(n), texts });
    }
  }
  return rows;
}

// For one verse in several translations: which words in each text the others lack, measured against the first
// translation (and the first against the second). -> { BSB: [{ start, end }], NET: [...] }
export function differencesFor(texts, ids) {
  const out = Object.fromEntries(ids.map((id) => [id, []]));
  const present = ids.filter((id) => texts[id]);
  if (present.length < 2) return out;
  const [base, ...rest] = present;
  out[base] = diffVerses(texts[base], texts[rest[0]]).a;
  for (const id of rest) out[id] = diffVerses(texts[base], texts[id]).b;
  return out;
}

// Cuts a text at the ranges -> [{ text, mark }] so a view can wrap the marked parts.
export function markRanges(text, ranges) {
  const parts = [];
  let at = 0;
  for (const r of [...(ranges ?? [])].sort((a, b) => a.start - b.start)) {
    if (r.start > at) parts.push({ text: text.slice(at, r.start), mark: false });
    parts.push({ text: text.slice(r.start, r.end), mark: true });
    at = r.end;
  }
  if (at < text.length) parts.push({ text: text.slice(at), mark: false });
  return parts;
}