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

/**
 * External dependencies
 */
import { EMPTY_ARRAY } from '@nelio-content/constants';
import { isEmpty } from '@nelio-content/utils';
import type {
	AuthorId,
	Maybe,
	PostId,
	PostTypeName,
} from '@nelio-content/types';

/**
 * Internal dependencies
 */
import { stringifyCriteria } from './utils';
import type {
	FilterCriteria,
	PeriodMode,
	PeriodValue,
	SortCriterion,
	State,
} from './types';

export function getSortingCriterion( state: State ): SortCriterion {
	return state.sortBy;
}

export function getPeriodFilterMode( state: State ): PeriodMode {
	return state.filters.period.mode;
}

export function getPeriodFilterValue( state: State ): PeriodValue {
	return state.filters.period.value;
}

export function getAuthorFilter( state: State ): Maybe< AuthorId > {
	return state.filters.author;
}

export function getPostTypeFilter( state: State ): Maybe< PostTypeName > {
	return state.filters.postType;
}

export const getFilterCriteria = createSelector(
	( state: State ): FilterCriteria => ( {
		sortBy: getSortingCriterion( state ),
		author: getAuthorFilter( state ),
		postType: getPostTypeFilter( state ),
		periodMode: getPeriodFilterMode( state ),
		periodValue: getPeriodFilterValue( state ),
	} ),
	( state: State ) => [
		getSortingCriterion( state ),
		getAuthorFilter( state ),
		getPostTypeFilter( state ),
		getPeriodFilterMode( state ),
		getPeriodFilterValue( state ),
	]
);

export function getPostIdsMatchingCriteria(
	state: State,
	criteria: FilterCriteria
): ReadonlyArray< PostId > {
	return (
		state.postsByCriteria[ stringifyCriteria( criteria ) ] || EMPTY_ARRAY
	);
}

export function isLoadingPostsWithCriteria(
	state: State,
	criteria: FilterCriteria
): boolean {
	return state.status.loading.includes( stringifyCriteria( criteria ) );
}

export function arePostsWithCriteriaFullyLoaded(
	state: State,
	criteria: FilterCriteria
): boolean {
	const pagination = state.status.pagination[ stringifyCriteria( criteria ) ];
	if ( isEmpty( pagination ) ) {
		return false;
	}
	return !! pagination.isFullyLoaded;
}

export function getNextPageToLoad(
	state: State,
	criteria: FilterCriteria
): number {
	const pagination = state.status.pagination[ stringifyCriteria( criteria ) ];
	return ( pagination?.lastLoadedPage ?? 0 ) + 1;
}

export function getPostIds( state: State ): ReadonlyArray< PostId > {
	const criteria = getFilterCriteria( state );
	return getPostIdsMatchingCriteria( state, criteria );
}

export function isLoadingPosts( state: State ): boolean {
	const criteria = getFilterCriteria( state );
	return isLoadingPostsWithCriteria( state, criteria );
}

export function arePostsFullyLoaded( state: State ): boolean {
	const criteria = getFilterCriteria( state );
	return arePostsWithCriteriaFullyLoaded( state, criteria );
}