/**
 * External dependencies
 */
import { isEqual, keyBy } from 'lodash';
import type { AnyAction } from '@nab/types';

/**
 * Internal dependencies
 */
import { INIT_STATE } from '../config';
import type { State as FullState } from '../types';
import type { EntityAction as Action } from '../actions/entities';

type State = FullState[ 'entities' ];

export function entities(
	state = INIT_STATE.entities,
	action: AnyAction
): State {
	return actualReducer( state, action as Action ) ?? state;
}

function actualReducer( state: State, action: Action ): State {
	switch ( action.type ) {
		case 'RECEIVE_TYPE_QUERY': {
			if ( isEqual( state.config, action.kindEntities ) ) {
				return state;
			}
			return {
				...state,
				config: action.kindEntities,
			};
		}

		case 'RECEIVE_ITEMS': {
			const newItems = action.items.filter(
				( item ) =>
					! isEqual( state.data[ action.kind ]?.[ item.id ], item )
			);
			if ( ! newItems.length ) {
				return state;
			}

			return {
				...state,
				data: {
					...state.data,
					[ action.kind ]: {
						...state.data[ action.kind ],
						...keyBy( newItems, 'id' ),
					},
				},
			};
		}
	}
}