// Commentary and interlinear text for the chapter of the selected chunk.
// Each loads only while its section is expanded; results are cached for the visit.
import { useEffect, useState } from 'react';

const commentaryCache = {}; // "commentaryId/BOOK/chapter" -> data
const interlinearCache = {}; // BOOK -> whole-book interlinear data

export function useStudyResources({ project, selectedChunk, selectedChunkChapterIndex, collapsedSections }) {
  const [commentarySource, setCommentarySource] = useState('matthew-henry');
  const [commentaryData, setCommentaryData] = useState(null); // { content: [...] } for current chapter
  const [commentaryLoading, setCommentaryLoading] = useState(false);
  const [commentaryError, setCommentaryError] = useState('');
  const [interlinearData, setInterlinearData] = useState(null);
  const [interlinearLoading, setInterlinearLoading] = useState(false);
  const [interlinearError, setInterlinearError] = useState('');

  const loadInterlinearChapter = async (bookAbbrev, chapterNumber) => {
    if (interlinearCache[bookAbbrev]) return interlinearCache[bookAbbrev];
    const res = await fetch(`/interlinear/${bookAbbrev}.json`);
    if (!res.ok) throw new Error('No interlinear data for this book.');
    const data = await res.json();
    interlinearCache[bookAbbrev] = data;
    return data;
  };

  const loadCommentaryChapter = async (commentaryId, bookAbbrev, chapterNumber) => {
    const cacheKey = `${commentaryId}/${bookAbbrev}/${chapterNumber}`;
    if (commentaryCache[cacheKey]) return commentaryCache[cacheKey];
    const res = await fetch(`https://bible.helloao.org/api/c/${commentaryId}/${bookAbbrev}/${chapterNumber}.json`);
    const contentType = res.headers.get('content-type') || '';
    if (!res.ok || !contentType.includes('json')) throw new Error(`No ${commentaryId} commentary for this chapter.`);
    const data = await res.json();
    commentaryCache[cacheKey] = data;
    return data;
  };

  useEffect(() => {
    if (collapsedSections.commentary) return;
    if (selectedChunkChapterIndex < 0) return;
    const chapter = project.chapters[selectedChunkChapterIndex];
    setCommentaryLoading(true);
    setCommentaryError('');
    loadCommentaryChapter(commentarySource, chapter.bookAbbrev, chapter.chapter)
      .then((data) => setCommentaryData(data))
      .catch((err) => {
        setCommentaryData(null);
        setCommentaryError(err.message);
      })
      .finally(() => setCommentaryLoading(false));
  }, [commentarySource, selectedChunk?.id, selectedChunkChapterIndex, collapsedSections.commentary]);

  useEffect(() => {
    if (collapsedSections.interlinear) return;
    if (selectedChunkChapterIndex < 0) return;
    const chapter = project.chapters[selectedChunkChapterIndex];
    setInterlinearLoading(true);
    setInterlinearError('');
    loadInterlinearChapter(chapter.bookAbbrev, chapter.chapter)
      .then((data) => setInterlinearData(data?.[String(chapter.chapter)] ?? null))
      .catch((err) => {
        setInterlinearData(null);
        setInterlinearError(err.message);
      })
      .finally(() => setInterlinearLoading(false));
  }, [selectedChunk?.id, selectedChunkChapterIndex, collapsedSections.interlinear]);

  return {
    commentarySource, setCommentarySource,
    commentaryData,
    commentaryLoading,
    commentaryError,
    interlinearData,
    interlinearLoading,
    interlinearError,
  };
}