/**
 * External dependencies
 */
import {
	useCallback,
	useEffect,
	useMemo,
	useRef,
	useState,
} from '@wordpress/element';
import { useSelect, useDispatch, select } from '@wordpress/data';
import { BlockInstance, cloneBlock } from '@wordpress/blocks';
import { close } from '@wordpress/icons';
import { __ } from '@wordpress/i18n';
import { getNewPath, navigateTo } from '@woocommerce/navigation';
import { capitalize } from 'lodash';
import { Button, Spinner } from '@wordpress/components';
import {
	unlock,
	// @ts-expect-error No types for this exist yet.
} from '@wordpress/edit-site/build-module/lock-unlock';
// @ts-expect-error No types for this exist yet.
// eslint-disable-next-line @woocommerce/dependency-group
import { useIsSiteEditorLoading } from '@wordpress/edit-site/build-module/components/layout/hooks';
// eslint-disable-next-line @woocommerce/dependency-group
import {
	store as coreStore,
	// @ts-expect-error No types for this exist yet.
} from '@wordpress/core-data';
// eslint-disable-next-line @woocommerce/dependency-group
import {
	__experimentalBlockPatternsList as BlockPatternList,
	store as blockEditorStore,
	// @ts-expect-error No types for this exist yet.
} from '@wordpress/block-editor';

/**
 * Internal dependencies
 */
import { usePatternsByCategory } from '../../hooks/use-patterns';
import './style.scss';
import { useEditorBlocks } from '../../hooks/use-editor-blocks';
import { PATTERN_CATEGORIES } from './categories';
import { THEME_SLUG } from '~/customize-store/data/constants';
import { Pattern } from '~/customize-store/types/pattern';

/**
 * Sorts patterns by category. For 'intro' and 'about' categories
 * priorizied DotCom Patterns. For intro category, it also prioritizes the "centered-content-with-image-below" pattern.
 * For other categories, it simply sorts patterns to prioritize Woo Patterns.
 */
const sortPatternsByCategory = (
	patterns: Pattern[],
	category: keyof typeof PATTERN_CATEGORIES
) => {
	const prefix = 'woocommerce-blocks';
	if ( category === 'intro' || category === 'about' ) {
		return patterns.sort( ( a, b ) => {
			if (
				a.name ===
				'woocommerce-blocks/centered-content-with-image-below'
			) {
				return -1;
			}

			if (
				b.name ===
				'woocommerce-blocks/centered-content-with-image-below'
			) {
				return 1;
			}

			if ( a.name.includes( prefix ) && ! b.name.includes( prefix ) ) {
				return 1;
			}
			if ( ! a.name.includes( prefix ) && b.name.includes( prefix ) ) {
				return -1;
			}
			return 0;
		} );
	}

	return patterns.sort( ( a, b ) => {
		if ( a.name.includes( prefix ) && ! b.name.includes( prefix ) ) {
			return -1;
		}
		if ( ! a.name.includes( prefix ) && b.name.includes( prefix ) ) {
			return 1;
		}
		return 0;
	} );
};

export const SidebarPatternScreen = ( { category }: { category: string } ) => {
	const { patterns, isLoading } = usePatternsByCategory( category );

	const sortedPatterns = useMemo( () => {
		const patternsWithoutThemePatterns = patterns.filter(
			( pattern ) =>
				! pattern.name.includes( THEME_SLUG ) &&
				pattern.source !== 'pattern-directory/theme' &&
				pattern.source !== 'pattern-directory/core'
		);

		return sortPatternsByCategory(
			patternsWithoutThemePatterns,
			category as keyof typeof PATTERN_CATEGORIES
		);
	}, [ category, patterns ] );

	const [ patternPagination, setPatternPagination ] = useState( 10 );

	const refElement = useRef< HTMLDivElement >( null );

	const currentTemplate = useSelect(
		( sel ) =>
			// @ts-expect-error No types for this exist yet.
			sel( coreStore ).__experimentalGetTemplateForLink( '/' ),
		[]
	);

	const [ blocks ] = useEditorBlocks(
		'wp_template',
		currentTemplate?.id ?? ''
	);

	const blockToScroll = useRef< string | null >( null );

	const isEditorLoading = useIsSiteEditorLoading();

	const isSpinnerVisible = isLoading || isEditorLoading;

	useEffect( () => {
		if ( isEditorLoading ) {
			return;
		}
		const iframe = window.document.querySelector(
			'.woocommerce-customize-store-assembler > iframe[name="editor-canvas"]'
		) as HTMLIFrameElement;

		const blockList = iframe?.contentWindow?.document.body.querySelector(
			'.block-editor-block-list__layout'
		);

		const observer = new MutationObserver( () => {
			if ( blockToScroll.current ) {
				const block = blockList?.querySelector(
					`[id="block-${ blockToScroll.current }"]`
				);

				if ( block ) {
					block.scrollIntoView();
					blockToScroll.current = null;
				}
			}
		} );

		if ( blockList ) {
			observer.observe( blockList, { childList: true } );
		}

		return () => {
			observer.disconnect();
		};
	}, [ isEditorLoading ] );

	// @ts-expect-error No types for this exist yet.
	const { insertBlocks } = useDispatch( blockEditorStore );

	const insertableIndex = useMemo( () => {
		return blocks.findLastIndex(
			( block ) => block.name === 'core/template-part'
		);
	}, [ blocks ] );

	const onClickPattern = useCallback(
		( pattern ) => {
			const parsedPattern = unlock(
				select( blockEditorStore )
			).__experimentalGetParsedPattern( pattern.name );

			const cloneBlocks = parsedPattern.blocks.map(
				( blockInstance: BlockInstance ) => cloneBlock( blockInstance )
			);

			insertBlocks( cloneBlocks, insertableIndex, undefined, false );

			blockToScroll.current = cloneBlocks[ 0 ].clientId;
		},
		[ insertBlocks, insertableIndex ]
	);

	return (
		<div
			className="woocommerce-customize-store-edit-site-layout__sidebar-extra__pattern"
			onScroll={ ( event ) => {
				const element = event.target as HTMLElement;
				const scrollTop = element.scrollTop;
				const percentage =
					scrollTop / ( element.scrollHeight - element.clientHeight );

				if ( percentage > 0.5 ) {
					setPatternPagination( ( prev ) => prev + 10 );
				}
			} }
		>
			<div className="woocommerce-customize-store-edit-site-layout__sidebar-extra__pattern__header">
				<h1>
					{ capitalize(
						PATTERN_CATEGORIES[
							category as keyof typeof PATTERN_CATEGORIES
						].label
					) }
				</h1>
				<Button
					onClick={ () => {
						const homepageUrl = getNewPath(
							{ customizing: true },
							`/customize-store/assembler-hub/homepage`,
							{}
						);

						navigateTo( { url: homepageUrl } );
					} }
					iconSize={ 18 }
					icon={ close }
					label={ __( 'Close', 'woocommerce' ) }
				/>
			</div>
			<div className="woocommerce-customize-store-edit-site-layout__sidebar-extra__pattern__description">
				<span>
					{
						PATTERN_CATEGORIES[
							category as keyof typeof PATTERN_CATEGORIES
						].description
					}
				</span>
			</div>
			{ isSpinnerVisible && (
				<span className="components-placeholder__preview">
					<Spinner />
				</span>
			) }
			{ ! isSpinnerVisible && (
				<BlockPatternList
					shownPatterns={ sortedPatterns.slice(
						0,
						patternPagination
					) }
					blockPatterns={ sortedPatterns.slice(
						0,
						patternPagination
					) }
					onClickPattern={ onClickPattern }
					label={ 'Homepage' }
					orientation="vertical"
					category={ category }
					isDraggable={ false }
					showTitlesAsTooltip={ true }
					ref={ refElement }
				/>
			) }
		</div>
	);
};