import { Editor } from 'slate';
import { NextType } from '@guestbell/slate-common/lib/types/next';

import Options from '../options';
import { unwrapList, splitListItem, decreaseItemDepth } from '../changes';
import { getCurrentItem, getItemDepth } from '../utils';

/**
 * User pressed Enter in an editor
 *
 * Enter in a list item should split the list item
 * Enter in an empty list item should remove it
 * Shift+Enter in a list item should make a new line
 */
function onEnter(
  event: React.KeyboardEvent,
  editor: Editor,
  opts: Options,
  next: NextType
): void | undefined | Editor {
  // Pressing Shift+Enter
  // should split block normally
  if (event.shiftKey) {
    return next();
  }

  const { value } = editor;
  const currentItem = getCurrentItem(opts)(value);

  // Not in a list
  if (!currentItem) {
    return next();
  }

  event.preventDefault();

  // If expanded, delete first.
  if (value.selection.isExpanded) {
    editor.delete();
  }

  if (currentItem.nodes.every(node => node.text === '')) {
    // Block is empty, we exit the list
    if (getItemDepth(opts)(value) > 1) {
      return decreaseItemDepth(opts, editor);
    }
    // Exit list
    return unwrapList(opts, editor);
  }
  // Split list item
  return splitListItem(opts, editor);
}

export default onEnter;