react-dnd/dnd-core

import without from 'lodash/without';
import { BEGIN_DRAG, PUBLISH_DRAG_SOURCE, HOVER, END_DRAG, DROP } from '../actions/dragDrop';
import { REMOVE_TARGET } from '../actions/registry';

const initialState = {
  itemType: null,
  item: null,
  sourceId: null,
  targetIds: [],
  dropResult: null,
  didDrop: false,
  isSourcePublic: null,
};

export default function dragOperation(state = initialState, action) {
  switch (action.type) {
    case BEGIN_DRAG:
      return {
        ...state,
        itemType: action.itemType,
        item: action.item,
        sourceId: action.sourceId,
        isSourcePublic: action.isSourcePublic,
        dropResult: null,
        didDrop: false,
      };
    case PUBLISH_DRAG_SOURCE:
      return {
        ...state,
        isSourcePublic: true,
      };
    case HOVER:
      return {
        ...state,
        targetIds: action.targetIds,
      };
    case REMOVE_TARGET:
      if (state.targetIds.indexOf(action.targetId) === -1) {
        return state;
      }
      return {
        ...state,
        targetIds: without(state.targetIds, action.targetId),
      };
    case DROP:
      return {
        ...state,
        dropResult: action.dropResult,
        didDrop: true,
        targetIds: [],
      };
    case END_DRAG:
      return {
        ...state,
        itemType: null,
        item: null,
        sourceId: null,
        dropResult: null,
        didDrop: false,
        isSourcePublic: null,
        targetIds: [],
      };
    default:
      return state;
  }
}