remirror/remirror

import { useCallback, useState } from 'react';
import { PluginsExtension } from '@remirror/core';

import { useExtensionEvent } from './use-extension-event';

const noReason: UpdateReason = { doc: false, selection: false, storedMark: false };

/**
 * Provide the reason for the latest state update with boolean flags.
 */
export function useUpdateReason(): UpdateReason {
  const [updateReason, setUpdateReason] = useState<UpdateReason>(noReason);
  // Attach the editor state handler to the instance of the remirror editor.
  useExtensionEvent(
    PluginsExtension,
    'applyState',
    useCallback(({ tr }) => {
      const reason: UpdateReason = { ...noReason };

      if (tr.docChanged) {
        reason.doc = true;
      }

      if (tr.selectionSet) {
        reason.selection = true;
      }

      if (tr.storedMarksSet) {
        reason.storedMark = true;
      }

      setUpdateReason(reason);
    }, []),
  );

  return updateReason;
}

export interface UpdateReason {
  /**
   * The selection changed.
   */
  selection: boolean;

  /**
   * The document changed.
   */
  doc: boolean;

  /**
   * A stored mark was added to the current selection
   */
  storedMark: boolean;
}