export default function dragOperation(
	state: State = initialState,
	action: Action<{
		itemType: Identifier | Identifier[]
		item: any
		sourceId: string
		targetId: string
		targetIds: string[]
		isSourcePublic: boolean
		dropResult: any
	}>,
) {
	const { payload } = action
	switch (action.type) {
		case BEGIN_DRAG:
			return {
				...state,
				itemType: payload.itemType,
				item: payload.item,
				sourceId: payload.sourceId,
				isSourcePublic: payload.isSourcePublic,
				dropResult: null,
				didDrop: false,
			}
		case PUBLISH_DRAG_SOURCE:
			return {
				...state,
				isSourcePublic: true,
			}
		case HOVER:
			return {
				...state,
				targetIds: payload.targetIds,
			}
		case REMOVE_TARGET:
			if (state.targetIds.indexOf(payload.targetId) === -1) {
				return state
			}
			return {
				...state,
				targetIds: without(state.targetIds, payload.targetId),
			}
		case DROP:
			return {
				...state,
				dropResult: payload.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
	}
}

 remove(accessor){
   if(!accessor){
     return
   }
   accessor.decrementRef()
   if(accessor.refCount === 0){
     if(accessor instanceof StatefulAccessor){
       if(this.queryAccessor == accessor){
         this.queryAccessor = noopQueryAccessor
       }
       delete this.statefulAccessors[accessor.key]
     }
     this.accessors = without(this.accessors, accessor)
   }
 }

 remove(val) {
   return this.create(without(this.getValue(), val))
 }

 remove(level:number, val) {
   return this.create(update(this.getValue(), {
     [level]:{$set:without(this.getValue()[level], val)}
   }))
 }