Function useHighlightedSource

src/ui/diff/useHighlightedSource.ts:29–77

({
  file,
  text,
  theme,
  shouldLoadHighlight,
}: {
  file: DiffFile | undefined;
  text: string | undefined;
  theme: AppTheme;
  shouldLoadHighlight?: boolean;
})

/** Resolve highlighted full-source content for expanded unchanged rows. */
export function useHighlightedSource({
  file,
  text,
  theme,
  shouldLoadHighlight,
}: {
  file: DiffFile | undefined;
  text: string | undefined;
  theme: AppTheme;
  shouldLoadHighlight?: boolean;
}) {
  const [state, setState] = useState<HighlightedSourceState | null>(null);
  const cacheKey = useMemo(
    () => (file && text !== undefined ? buildSourceCacheKey(theme, file, text) : null),
    [file, text, theme],
  );

  useLayoutEffect(() => {
    if (!file || text === undefined || !cacheKey) {
      setState(null);
      return;
    }

    if (state?.cacheKey === cacheKey || !shouldLoadHighlight) {
      return;
    }

    let cancelled = false;
    setState(null);

    loadHighlightedSourceLines({ file, text, theme })
      .then((highlighted) => {
        if (!cancelled) {
          setState({ cacheKey, highlighted });
        }
      })
      .catch(() => {
        if (!cancelled) {
          setState({ cacheKey, highlighted: { lines: [] } });
        }
      });

    return () => {
      cancelled = true;
    };
  }, [cacheKey, file, shouldLoadHighlight, state?.cacheKey, text]);

  return state?.cacheKey === cacheKey ? state.highlighted : null;
}