import memoize from 'memize';
import { calendar as icon } from '@wordpress/icons';
import { Placeholder, Spinner } from '@wordpress/components';
import { useSelect } from '@wordpress/data';
import { useServerSideRender } from '@wordpress/server-side-render';
import { useBlockProps } from '@wordpress/block-editor';
import { store as coreStore } from '@wordpress/core-data';
import { __, sprintf } from '@wordpress/i18n';
import { useDisabled } from '@wordpress/compose';
import HtmlRenderer from '../utils/html-renderer';

/**
 * Returns the year and month of a specified date.
 *
 * @see `WP_REST_Posts_Controller::prepare_date_response()`.
 *
 * @param {string} date Date in `ISO8601/RFC3339` format.
 * @return {Object} Year and date of the specified date.
 */
const getYearMonth = memoize( ( date ) => {
	if ( ! date ) {
		return {};
	}
	const dateObj = new Date( date );
	return {
		year: dateObj.getFullYear(),
		month: dateObj.getMonth() + 1,
	};
} );

export default function CalendarEdit( { attributes, name } ) {
	const { date, hasPosts, hasPostsResolved } = useSelect( ( select ) => {
		const { getEntityRecords, hasFinishedResolution } = select( coreStore );

		const singlePublishedPostQuery = {
			status: 'publish',
			per_page: 1,
		};
		const posts = getEntityRecords(
			'postType',
			'post',
			singlePublishedPostQuery
		);
		const postsResolved = hasFinishedResolution( 'getEntityRecords', [
			'postType',
			'post',
			singlePublishedPostQuery,
		] );

		let _date;

		// FIXME: @wordpress/block-library should not depend on @wordpress/editor.
		// Blocks can be loaded into a *non-post* block editor.
		// eslint-disable-next-line @wordpress/data-no-store-string-literals
		const editorSelectors = select( 'core/editor' );
		if ( editorSelectors ) {
			const postType = editorSelectors.getEditedPostAttribute( 'type' );
			// Dates are used to overwrite year and month used on the calendar.
			// This overwrite should only happen for 'post' post types.
			// For other post types the calendar always displays the current month.
			if ( postType === 'post' ) {
				_date = editorSelectors.getEditedPostAttribute( 'date' );
			}
		}

		return {
			date: _date,
			hasPostsResolved: postsResolved,
			hasPosts: postsResolved && posts?.length === 1,
		};
	}, [] );

	const { content, status, error } = useServerSideRender( {
		attributes: {
			...attributes,
			...getYearMonth( date ),
		},
		block: name,
	} );

	const disabledRef = useDisabled();
	const blockProps = useBlockProps( { ref: disabledRef } );

	if ( ! hasPosts ) {
		return (
			<div { ...blockProps }>
				<Placeholder icon={ icon } label={ __( 'Calendar' ) }>
					{ ! hasPostsResolved ? (
						<Spinner />
					) : (
						__( 'No published posts found.' )
					) }
				</Placeholder>
			</div>
		);
	}

	return (
		<>
			{ status === 'loading' && (
				<div { ...blockProps }>
					<Spinner />
				</div>
			) }
			{ status === 'error' && (
				<div { ...blockProps }>
					<p>
						{ sprintf(
							/* translators: %s: error message returned when rendering the block. */
							__( 'Error: %s' ),
							error
						) }
					</p>
				</div>
			) }
			{ status === 'success' && (
				<HtmlRenderer wrapperProps={ blockProps } html={ content } />
			) }
		</>
	);
}