// Bring notes written elsewhere (a Word file or Markdown from another app) into a study. A passage heading starts
// each section ("## John 3:16–18"), and labelled lines or sub-headings ("Observe: …", "### Interpret") hold the
// notes. Sections are matched to your chunks by passage. Nothing already written is overwritten.
import { parsePassageRef } from './passageRef.js';
import { withPaste } from './ownWork.js';

const LABELS = [
  [/^observ(?:e|ation|ations)$/i, 'observation'],
  [/^interpret(?:ation)?$/i, 'interpretation'],
  [/^appl(?:y|ication)$/i, 'application'],
  [/^(?:background|notes?|general notes)$/i, 'generalNotes'],
  [/^(?:discussion )?questions$/i, 'discussionQuestions'],
];
const FIELD_NAMES = { observation: 'Observe', interpretation: 'Interpret', application: 'Apply', generalNotes: 'Background', discussionQuestions: 'Questions' };
export const importFieldName = (f) => FIELD_NAMES[f] ?? f;

const clean = (line) => line.replace(/^\s*#+\s*/, '').replace(/\*\*|__/g, '').trim();
const labelOf = (word) => LABELS.find(([re]) => re.test(word.trim()))?.[1] ?? null;

// A heading that is just a passage ("John 3:16-18", "Session 2: Romans 8:1–4") -> { book, chapter, verse, text } or null.
export function passageHeading(line) {
  const text = clean(line).replace(/^(?:session|lesson|week|episode|part)\s*\d+\s*[:.\-–—]\s*/i, '');
  const m = text.match(/^((?:[1-3]\s*)?[A-Za-z][A-Za-z .]*?)\s+(\d{1,3})(?:\s*:\s*(\d{1,3}))?(?:\s*[-–—]\s*\d{1,3}(?:\s*:\s*\d{1,3})?)?\s*$/);
  if (!m || text.length > 60) return null;
  const ref = parsePassageRef(`${m[1]} ${m[2]}${m[3] ? `:${m[3]}` : ''}`)[0];
  return ref ? { book: ref.book, chapter: ref.chapter, verse: m[3] ? Number(m[3]) : null, text } : null;
}

// -> [{ heading, ref, observation?, interpretation?, application?, generalNotes?, discussionQuestions? }]
export function parseNotesText(raw) {
  const sections = [];
  let current = null;
  let field = null;
  const append = (value) => {
    if (!current || !field) return;
    current[field] = current[field] ? `${current[field]}\n${value}` : value;
  };
  for (const line of String(raw ?? '').replace(/\r/g, '').split('\n')) {
    const heading = passageHeading(line);
    if (heading) { current = { heading: heading.text, ref: heading }; sections.push(current); field = null; continue; }
    if (!current) continue;
    const stripped = clean(line).replace(/^[-*•]\s+/, '');
    const labelled = stripped.match(/^([A-Za-z ]{3,22}?)\s*[:\-–]\s*(.*)$/);
    const bare = /^\s*(?:#+\s|\*\*|__)/.test(line) ? labelOf(stripped.replace(/[:\-–]\s*$/, '')) : null; // "### Observe", "**Observe**"
    if (labelled && labelOf(labelled[1])) { field = labelOf(labelled[1]); current[field] = current[field] ?? ''; if (labelled[2].trim()) append(labelled[2].trim()); continue; }
    if (bare) { field = bare; current[field] = current[field] ?? ''; continue; }
    if (field) append(line.trim());
  }
  return sections.map((s) => Object.fromEntries(Object.entries(s).map(([k, v]) => [k, typeof v === 'string' ? v.replace(/^\n+|\n+$/g, '').trim() : v])))
    .filter((s) => Object.keys(FIELD_NAMES).some((f) => s[f]));
}

// Which chunk a section belongs to: the one whose verses include the heading's verse (or the first in that chapter).
export function matchChunk(project, ref) {
  for (const chapter of project?.chapters ?? []) {
    if (chapter.bookAbbrev !== ref.book || Number(chapter.chapter) !== ref.chapter) continue;
    const chunks = chapter.chunks ?? [];
    const hit = ref.verse == null ? chunks[0] : chunks.find((c) => ref.verse >= c.startVerse && ref.verse <= c.endVerse);
    if (hit) return hit;
  }
  return null;
}

const MARKER = '— imported —';

// -> { project, matched: [{ heading, fields }], unmatched: [heading] }. Where a note already has text, the imported
// text is added below a marker instead of replacing it. `own: false` records the text as pasted, not your own work.
export function applyImportedNotes(project, sections, { own = true, now = Date.now() } = {}) {
  const patches = new Map(); // chunk id -> merged chunk
  const matched = [];
  const unmatched = [];
  for (const section of sections) {
    const chunk = matchChunk(project, section.ref);
    if (!chunk) { unmatched.push(section.heading); continue; }
    const next = { ...(patches.get(chunk.id) ?? chunk) };
    const fields = [];
    for (const f of Object.keys(FIELD_NAMES)) {
      const incoming = section[f];
      if (!incoming) continue;
      const have = (next[f] ?? '').trim();
      if (have.includes(incoming)) continue;
      next[f] = have ? `${next[f].replace(/\s+$/, '')}\n\n${MARKER}\n${incoming}` : incoming;
      if (!own && ['observation', 'interpretation', 'application'].includes(f)) next.aiPastes = withPaste({ aiPastes: next.aiPastes }, f, incoming) ?? { ...(next.aiPastes ?? {}), [f]: [...(next.aiPastes?.[f] ?? []), incoming] };
      fields.push(importFieldName(f));
    }
    if (fields.length) { next.editedAt = now; patches.set(chunk.id, next); matched.push({ heading: section.heading, fields }); }
  }
  const out = { ...project, chapters: project.chapters.map((ch) => ({ ...ch, chunks: ch.chunks.map((c) => patches.get(c.id) ?? c) })) };
  return { project: out, matched, unmatched };
}