import { useCallback } from 'react';
import { DraggingPosition, TreeItem } from '../types';
import { useTreeEnvironment } from './ControlledTreeEnvironment';
import { useCanDropAt } from './useCanDropAt';

export const useGetViableDragPositions = () => {
  const environment = useTreeEnvironment();
  const canDropAt = useCanDropAt();

  return useCallback(
    (treeId: string, draggingItems: TreeItem[]) => {
      const linearItems = environment.linearItems[treeId];
      return linearItems
        .map<DraggingPosition>(({ item }) => ({
          targetType: 'item',
          targetItem: item,
          treeId,
        }))
        .filter(position => canDropAt(position, draggingItems));
    },
    [canDropAt, environment.linearItems]
  );
};