recharts/src/state/keyboardEventsMiddleware.ts

import { createAction, createListenerMiddleware, ListenerEffectAPI } from '@reduxjs/toolkit';
import { setKeyboardInteraction } from './tooltipSlice';
import { AppDispatch, RechartsRootState } from './store';
import { selectTooltipAxisTicks, selectTooltipDisplayedData } from './selectors/tooltipSelectors';
import { selectCoordinateForDefaultIndex } from './selectors/selectors';
import { selectChartDirection } from './selectors/axisSelectors';
import { combineActiveTooltipIndex } from './selectors/combiners/combineActiveTooltipIndex';

export const keyDownAction = createAction<KeyboardEvent['key']>('keyDown');
export const focusAction = createAction('focus');

export const keyboardEventsMiddleware = createListenerMiddleware();

keyboardEventsMiddleware.startListening({
  actionCreator: keyDownAction,
  effect: (
    action: ReturnType<typeof keyDownAction>,
    listenerApi: ListenerEffectAPI<RechartsRootState, AppDispatch>,
  ) => {
    const state: RechartsRootState = listenerApi.getState();
    const accessibilityLayerIsActive = state.rootProps.accessibilityLayer !== false;
    if (!accessibilityLayerIsActive) {
      return;
    }
    const { keyboardInteraction } = state.tooltip;
    const key = action.payload;
    if (key !== 'ArrowRight' && key !== 'ArrowLeft' && key !== 'Enter') {
      return;
    }

    // TODO this is lacking index for charts that do not support numeric indexes
    const currentIndex: number = Number(
      combineActiveTooltipIndex(keyboardInteraction, selectTooltipDisplayedData(state)),
    );
    const tooltipTicks = selectTooltipAxisTicks(state);
    if (key === 'Enter') {
      const coordinate = selectCoordinateForDefaultIndex(state, 'axis', 'hover', String(keyboardInteraction.index));
      listenerApi.dispatch(
        setKeyboardInteraction({
          active: !keyboardInteraction.active,
          activeIndex: keyboardInteraction.index,
          activeDataKey: keyboardInteraction.dataKey,
          activeCoordinate: coordinate,
        }),
      );
      return;
    }

    const direction = selectChartDirection(state);
    const directionMultiplier = direction === 'left-to-right' ? 1 : -1;
    const movement = key === 'ArrowRight' ? 1 : -1;
    const nextIndex = currentIndex + movement * directionMultiplier;
    if (tooltipTicks == null || nextIndex >= tooltipTicks.length || nextIndex < 0) {
      return;
    }
    const coordinate = selectCoordinateForDefaultIndex(state, 'axis', 'hover', String(nextIndex));

    listenerApi.dispatch(
      setKeyboardInteraction({
        active: true,
        activeIndex: nextIndex.toString(),
        activeDataKey: undefined,
        activeCoordinate: coordinate,
      }),
    );
  },
});

keyboardEventsMiddleware.startListening({
  actionCreator: focusAction,
  effect: (_action, listenerApi: ListenerEffectAPI<RechartsRootState, AppDispatch>) => {
    const state: RechartsRootState = listenerApi.getState();
    const accessibilityLayerIsActive = state.rootProps.accessibilityLayer !== false;
    if (!accessibilityLayerIsActive) {
      return;
    }
    const { keyboardInteraction } = state.tooltip;
    if (keyboardInteraction.active) {
      return;
    }
    if (keyboardInteraction.index == null) {
      const nextIndex = '0';
      const coordinate = selectCoordinateForDefaultIndex(state, 'axis', 'hover', String(nextIndex));
      listenerApi.dispatch(
        setKeyboardInteraction({
          activeDataKey: undefined,
          active: true,
          activeIndex: nextIndex,
          activeCoordinate: coordinate,
        }),
      );
    }
  },
});