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

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

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

function actualReducer( state: State, action: Action ): State {
	switch ( action.type ) {
		case 'ADD_SEGMENTATION_RULE_TYPES': {
			const newTypes = action.segmentationRuleTypes.filter(
				( type ) =>
					! isEqual( state.segmentationRuleTypes[ type.name ], type )
			);
			if ( ! newTypes.length ) {
				return state;
			}

			return {
				...state,
				segmentationRuleTypes: {
					...state.segmentationRuleTypes,
					...keyBy( newTypes, 'name' ),
				},
			};
		}

		case 'REMOVE_SEGMENTATION_RULE_TYPES': {
			const newTypes = omit( state.segmentationRuleTypes, action.names );
			if ( isEqual( state.segmentationRuleTypes, newTypes ) ) {
				return state;
			}
			return {
				...state,
				segmentationRuleTypes: newTypes,
			};
		}

		case 'ADD_SEGMENTATION_RULE_TYPE_CATEGORIES': {
			const newCategories = action.categories.filter(
				( category ) =>
					! isEqual( state.categories[ category.name ], category )
			);
			if ( ! newCategories.length ) {
				return state;
			}

			return {
				...state,
				categories: {
					...state.categories,
					...keyBy( newCategories, 'name' ),
				},
			};
		}

		case 'REMOVE_SEGMENTATION_RULE_TYPE_CATEGORIES': {
			const newCategories = omit( state.categories, action.names );
			if ( isEqual( state.categories, newCategories ) ) {
				return state;
			}
			return {
				...state,
				categories: newCategories,
			};
		}
	}
}