/**
 * WordPress dependencies
 */
import { useSelect } from '@safe-wordpress/data';

/**
 * External dependencies
 */
import { castArray, filter, isFunction } from 'lodash';
import { store as NAB_DATA } from '@nab/data';
import { store as NAB_EXPERIMENTS } from '@nab/experiments';
import { EMPTY_ARRAY } from '@nab/utils';

import type { ExperimentTypeName, EntityKind } from '@nab/types';

export const usePostTypes = (
	experimentType: ExperimentTypeName
): {
	readonly postTypes: ReadonlyArray< EntityKind >;
	readonly showSinglePostType: boolean;
	readonly isLoadingPostTypes: boolean;
} => {
	const data = useSelect(
		( select ) => {
			const { hasExperimentSupport, getExperimentSupport } =
				select( NAB_EXPERIMENTS );

			const { getKindEntities, hasFinishedResolution } =
				select( NAB_DATA );
			const kindEntities = getKindEntities() || EMPTY_ARRAY;

			if ( hasExperimentSupport( experimentType, 'postTypes' ) ) {
				return {
					type: 'accepted' as const,
					kindEntities,
					acceptedPostTypes: getExperimentSupport(
						experimentType,
						'postTypes'
					),
					isLoadingPostTypes:
						! hasFinishedResolution( 'getKindEntities' ),
				};
			}

			if (
				hasExperimentSupport( experimentType, 'postTypeExceptions' )
			) {
				const postTypeExceptions = getExperimentSupport(
					experimentType,
					'postTypeExceptions'
				);
				const excludedPostTypes = isFunction( postTypeExceptions )
					? postTypeExceptions( select )
					: castArray( postTypeExceptions );
				return {
					type: 'exclusions' as const,
					excludedPostTypes,
					kindEntities,
					isLoadingPostTypes:
						! hasFinishedResolution( 'getKindEntities' ),
				};
			}

			return {
				type: 'default' as const,
				isLoadingPostTypes:
					! hasFinishedResolution( 'getKindEntities' ),
			};
		},
		[ experimentType ]
	);

	switch ( data.type ) {
		case 'accepted': {
			const acceptedPostTypes = castArray( data.acceptedPostTypes );

			const postTypes = filter(
				data.kindEntities.filter( ( pt ) => 'entity' === pt.kind ),
				( { name } ) => acceptedPostTypes.includes( name )
			);
			return {
				postTypes,
				showSinglePostType: 1 !== acceptedPostTypes.length,
				isLoadingPostTypes: data.isLoadingPostTypes,
			};
		}

		case 'exclusions': {
			const postTypes = filter(
				data.kindEntities.filter( ( pt ) => 'entity' === pt.kind ),
				( { name } ) => ! data.excludedPostTypes.includes( name )
			);
			return {
				postTypes,
				showSinglePostType: true,
				isLoadingPostTypes: data.isLoadingPostTypes,
			};
		}

		case 'default':
			return {
				postTypes: EMPTY_ARRAY,
				showSinglePostType: true,
				isLoadingPostTypes: data.isLoadingPostTypes,
			};
	}
};