study-bible-project/src/components/reader/ReaderText.jsx

// The page itself: chapter heading, translation notice, and verses set in a
// serif face. Tap a verse to open the verse sheet; select text to highlight.
import { useMemo } from 'react';
import { formatCrossRef } from '../../utils/wordStudy.js';
import { diffChapter, differenceLabel } from '../../utils/textDiff.js';
import { DiffText } from './DiffText.jsx';

// How each typeface choice is set. "Easy to read" is a sans face with extra letter and word spacing.
const FONT_STYLES = {
  serif: { fontFamily: undefined },
  sans: { fontFamily: "ui-sans-serif, system-ui, -apple-system, 'Segoe UI', sans-serif" },
  easy: { fontFamily: "'Atkinson Hyperlegible', Verdana, 'Trebuchet MS', ui-sans-serif, sans-serif", letterSpacing: '0.02em', wordSpacing: '0.12em' },
};
const LINE_HEIGHTS = { snug: 1.6, normal: 1.85, airy: 2.15 };

// `parallel` ({ translation, name, notice, verses, loading, error }) shows a second Bible beside the first.
export default function ReaderText({
  title, translation, translationId, notice, verses, loading, error, layout, fontSize, wide,
  font = 'serif', spacing = 'normal', showVerseNumbers = true, parallel = null, showDiff = true,
  bookmarks, bookKey, chapter, selectedVerse, onSelectVerse, renderVerseText, searchLower,
  crossRefs, showCrossRefs, onSelectionEnd, footer,
}) {
  // How much the second Bible's wording differs from the first, over the chapter and verse by verse
  const diff = useMemo(
    () => (parallel && showDiff && !parallel.loading && !parallel.error && parallel.verses?.length ? diffChapter(verses, parallel.verses) : null),
    [parallel, showDiff, verses],
  );
  const diffByVerse = useMemo(() => new Map((diff?.verses ?? []).map((d) => [d.number, d])), [diff]);
  const jumpToVerse = (n) => document.getElementById(`reader-verse-${n}`)?.scrollIntoView?.({ block: 'center', behavior: window.matchMedia?.('(prefers-reduced-motion: reduce)').matches ? 'auto' : 'smooth' });

  const handleTap = (n) => {
    const sel = window.getSelection();
    if (sel && !sel.isCollapsed && sel.toString().trim()) return; // user is selecting text, not tapping
    onSelectVerse(selectedVerse === n ? null : n);
  };

  const verseProps = (v) => {
    const bm = bookmarks[`${bookKey}-${chapter}-${v.number}`];
    const selected = selectedVerse === v.number;
    return {
      id: `reader-verse-${v.number}`,
      'data-verse-num': v.number,
      onClick: () => handleTap(v.number),
      // Verses can be reached and chosen from the keyboard too
      role: 'button',
      tabIndex: 0,
      'aria-pressed': selected,
      onKeyDown: (e) => { if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); handleTap(v.number); } },
      className: 'cursor-pointer rounded-sm transition-colors focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-1 focus-visible:outline-[var(--r-accent)]',
      style: selected
        ? { backgroundColor: 'var(--r-hl)' }
        : bm ? { backgroundColor: `${bm}66`, boxShadow: `0 0 0 2px ${bm}66` } : undefined,
    };
  };

  const chips = (v) => showCrossRefs && crossRefs?.[v.number]?.length > 0 && (
    <span className="ml-1 inline-flex flex-wrap gap-1 align-baseline font-sans">
      {crossRefs[v.number].slice(0, 4).map((ref, i) => (
        <span key={i} className="rounded-full border border-[var(--r-line)] px-1.5 py-px text-[10px] text-[var(--r-sub)]">{formatCrossRef(ref)}</span>
      ))}
    </span>
  );

  const num = (n) => (showVerseNumbers ? <sup className="mr-1 select-none font-sans text-[0.6em] text-[var(--r-sub)]">{n}</sup> : null);

  // Both Bibles by verse number, so a verse one translation leaves out still lines up with the other.
  const parallelRows = parallel && !parallel.error ? (() => {
    const second = new Map(parallel.verses.map((v) => [v.number, v]));
    const first = new Map(verses.map((v) => [v.number, v]));
    return [...new Set([...first.keys(), ...second.keys()])].sort((a, b) => a - b)
      .map((n) => ({ number: n, first: first.get(n), second: second.get(n) }));
  })() : null;
  const sideBySide = !!parallel;
  const bodyStyle = {
    ...FONT_STYLES[font],
    lineHeight: LINE_HEIGHTS[spacing] ?? LINE_HEIGHTS.normal,
  };
  // The page grows with the screen: type is 18px on a phone, ~20px on an iPad and ~24px on a big
  // monitor (times your text-size choice), and the column is measured in the type's own width (em), so
  // the line length stays comfortable (~70 characters) instead of becoming a narrow strip on a wide
  // screen. Two columns / side-by-side take more room.
  const pageStyle = {
    fontSize: `calc(clamp(1.125rem, 0.9rem + 0.7vw, 1.55rem) * ${fontSize})`,
    maxWidth: wide || sideBySide ? 'min(100%, 72em)' : 'min(100%, 40em)',
  };

  return (
    <article
      className="mx-auto px-5 pb-32 pt-6 text-[var(--r-text)] md:px-8"
      style={pageStyle}
      onPointerUp={onSelectionEnd}
    >
      <header className="mb-5 text-center">
        <h1 className="font-serif text-3xl font-normal tracking-tight">{title}</h1>
        <p className="mt-1 font-sans text-xs text-[var(--r-sub)]">{translation}{parallel ? ` · beside ${parallel.name}` : ''}</p>
      </header>

      {loading && <ChapterSkeleton />}
      {error && <p role="alert" className="text-center font-sans text-sm text-[var(--r-danger,#b42318)]">{error}</p>}
      {!loading && !error && parallel?.error && (
        <p role="alert" className="mb-4 text-center font-sans text-sm text-[var(--r-danger,#b42318)]">Couldn’t load {parallel.name}: {parallel.error}</p>
      )}

      {!loading && !error && sideBySide && !parallel.error && (
        <div style={bodyStyle} className="font-serif">
          {diff && (
            <div className="mb-4 rounded-xl border border-[var(--r-line)] bg-[var(--r-bar)] px-4 py-3 font-sans text-sm" style={{ fontSize: '0.875rem' }}>
              <p>
                <strong>{parallel.translation}</strong>{diff.similarity === 1 ? ' uses the same words as ' : <> is <strong>{differenceLabel(diff.similarity)}</strong> from </>}{translationId} in this chapter
                {diff.total > 0 && <span className="text-[var(--r-sub)]"> · {diff.differing} of {diff.total} verses differ</span>}
              </p>
              {diff.mostDifferent.length > 0 && (
                <p className="mt-1 text-xs text-[var(--r-sub)]">
                  Most different:{' '}
                  {diff.mostDifferent.map((v, i) => (
                    <span key={v.number}>{i > 0 && ', '}<button type="button" onClick={() => jumpToVerse(v.number)} className="font-medium text-[var(--r-accent)] hover:underline">verse {v.number}</button> ({Math.round((1 - v.similarity) * 100)}%)</span>
                  ))}
                </p>
              )}
              <p className="mt-1 text-xs text-[var(--r-sub)]"><span className="diff-hl">Marked words</span> aren’t in the other wording.</p>
            </div>
          )}
          <div className="mb-3 hidden grid-cols-2 gap-x-10 border-b border-[var(--r-line)] pb-1 font-sans text-[11px] uppercase tracking-wide text-[var(--r-sub)] md:grid">
            <span>{translationId}</span><span>{parallel.translation}</span>
          </div>
          {parallelRows.map((row) => (
            <div key={row.number} className="mb-4 grid gap-x-10 gap-y-1 md:grid-cols-2">
              <p>
                {row.first
                  ? <span {...verseProps(row.first)}>{num(row.first.number)}{renderVerseText(row.first.number, row.first.text, searchLower, diffByVerse.get(row.number)?.a)}{chips(row.first)}</span>
                  : <span className="text-[var(--r-sub)]">{num(row.number)}—</span>}
              </p>
              <p className="border-l-2 border-[var(--r-line)] pl-3 text-[0.95em] text-[var(--r-sub)] md:border-l-0 md:pl-0 md:text-[var(--r-text)]">
                <span className="mr-1.5 font-sans text-[10px] uppercase tracking-wide md:hidden">{parallel.translation}</span>
                {row.second ? <>{num(row.second.number)}<DiffText text={row.second.text} ranges={diffByVerse.get(row.number)?.b} />{diffByVerse.get(row.number) && !diffByVerse.get(row.number).same && (
                  <span className="ml-2 whitespace-nowrap font-sans text-[10px] text-[var(--r-sub)]">{differenceLabel(diffByVerse.get(row.number).similarity)}</span>
                )}</> : parallel.loading ? <span className="font-sans text-xs" aria-label="Loading">…</span> : '—'}
              </p>
            </div>
          ))}
        </div>
      )}

      {!loading && !error && !sideBySide && (
        <div
          className={`font-serif ${wide ? 'md:columns-2 md:gap-x-12' : ''}`}
          style={bodyStyle}
        >
          {layout === 'flow' ? (
            <p className="text-pretty">
              {verses.map((v) => (
                <span key={v.number} {...verseProps(v)}>
                  {num(v.number)}{renderVerseText(v.number, v.text, searchLower)}{chips(v)}{' '}
                </span>
              ))}
            </p>
          ) : (
            verses.map((v) => (
              <p key={v.number} className="mb-3 break-inside-avoid">
                <span {...verseProps(v)}>{num(v.number)}{renderVerseText(v.number, v.text, searchLower)}{chips(v)}</span>
              </p>
            ))
          )}
        </div>
      )}

      {!loading && !error && <div style={{ fontSize: '1rem' }}>{footer}</div>}

      {notice && !loading && <p className="mt-10 border-t border-[var(--r-line)] pt-3 font-sans text-[11px] leading-snug text-[var(--r-sub)]">{notice}</p>}
      {parallel?.notice && !loading && !parallel.loading && <p className="mt-2 font-sans text-[11px] leading-snug text-[var(--r-sub)]">{parallel.notice}</p>}
    </article>
  );
}

// Grey bars the shape of a page, so a slow chapter load doesn't just show the word "Loading".
function ChapterSkeleton() {
  return (
    <div role="status" aria-label="Loading chapter" className="animate-pulse motion-reduce:animate-none space-y-3 pt-2">
      {[100, 96, 92, 98, 84, 100, 90, 70].map((w, i) => <div key={i} className="h-4 rounded bg-[var(--r-line)]" style={{ width: `${w}%` }} />)}
      <span className="sr-only">Loading…</span>
    </div>
  );
}