Function useTextBuffer

packages/cli/src/ui/components/shared/text-buffer.ts:1491–1979

({
  initialText = '',
  initialCursorOffset = 0,
  viewport,
  stdin,
  setRawMode,
  onChange,
  isValidPath,
  shellModeActive = false,
}: UseTextBufferProps)

// --- End of reducer logic ---

export function useTextBuffer({
  initialText = '',
  initialCursorOffset = 0,
  viewport,
  stdin,
  setRawMode,
  onChange,
  isValidPath,
  shellModeActive = false,
}: UseTextBufferProps): TextBuffer {
  const initialState = useMemo((): TextBufferState => {
    const lines = initialText.split('\n');
    const [initialCursorRow, initialCursorCol] = calculateInitialCursorPosition(
      lines.length === 0 ? [''] : lines,
      initialCursorOffset,
    );
    return {
      lines: lines.length === 0 ? [''] : lines,
      cursorRow: initialCursorRow,
      cursorCol: initialCursorCol,
      preferredCol: null,
      undoStack: [],
      redoStack: [],
      clipboard: null,
      selectionAnchor: null,
      viewportWidth: viewport.width,
    };
  }, [initialText, initialCursorOffset, viewport.width]);

  const [state, dispatch] = useReducer(textBufferReducer, initialState);
  const { lines, cursorRow, cursorCol, preferredCol, selectionAnchor } = state;

  const text = useMemo(() => lines.join('\n'), [lines]);

  const visualLayout = useMemo(
    () =>
      calculateVisualLayout(lines, [cursorRow, cursorCol], state.viewportWidth),
    [lines, cursorRow, cursorCol, state.viewportWidth],
  );

  const { visualLines, visualCursor } = visualLayout;

  const [visualScrollRow, setVisualScrollRow] = useState<number>(0);

  useEffect(() => {
    if (onChange) {
      onChange(text);
    }
  }, [text, onChange]);

  useEffect(() => {
    dispatch({ type: 'set_viewport_width', payload: viewport.width });
  }, [viewport.width]);

  // Update visual scroll (vertical)
  useEffect(() => {
    const { height } = viewport;
    let newVisualScrollRow = visualScrollRow;