import { __, _x, sprintf } from '@wordpress/i18n';
import { useMemo, useState } from '@wordpress/element';
import { useDispatch, useSelect, useRegistry } from '@wordpress/data';
import {
	Button,
	FlexBlock,
	FlexItem,
	SelectControl,
	__experimentalHStack as HStack,
	__experimentalSpacer as Spacer,
} from '@wordpress/components';
import { store as coreStore } from '@wordpress/core-data';
import { store as noticesStore } from '@wordpress/notices';
import { useCreateTemplatePartFromBlocks } from './utils/hooks';
import { transformWidgetToBlock } from './utils/transformers';

const SIDEBARS_QUERY = {
	per_page: -1,
	_fields: 'id,name,description,status,widgets',
};

export function TemplatePartImportControls( { area, setAttributes } ) {
	const [ selectedSidebar, setSelectedSidebar ] = useState( '' );
	const [ isBusy, setIsBusy ] = useState( false );

	const registry = useRegistry();
	const { sidebars, hasResolved } = useSelect( ( select ) => {
		const { getSidebars, hasFinishedResolution } = select( coreStore );

		return {
			sidebars: getSidebars( SIDEBARS_QUERY ),
			hasResolved: hasFinishedResolution( 'getSidebars', [
				SIDEBARS_QUERY,
			] ),
		};
	}, [] );
	const { createErrorNotice } = useDispatch( noticesStore );

	const createFromBlocks = useCreateTemplatePartFromBlocks(
		area,
		setAttributes
	);

	const options = useMemo( () => {
		const sidebarOptions = ( sidebars ?? [] )
			.filter(
				( widgetArea ) =>
					widgetArea.id !== 'wp_inactive_widgets' &&
					widgetArea.widgets.length > 0
			)
			.map( ( widgetArea ) => {
				return {
					value: widgetArea.id,
					label: widgetArea.name,
				};
			} );

		if ( ! sidebarOptions.length ) {
			return [];
		}

		return [
			{ value: '', label: __( 'Select widget area' ) },
			...sidebarOptions,
		];
	}, [ sidebars ] );

	// Render an empty node while data is loading to avoid SlotFill re-positioning bug.
	// See: https://github.com/WordPress/gutenberg/issues/15641.
	if ( ! hasResolved ) {
		return <Spacer marginBottom="0" />;
	}

	if ( hasResolved && ! options.length ) {
		return null;
	}

	async function createFromWidgets( event ) {
		event.preventDefault();

		if ( isBusy || ! selectedSidebar ) {
			return;
		}

		setIsBusy( true );

		const sidebar = options.find(
			( { value } ) => value === selectedSidebar
		);
		const { getWidgets } = registry.resolveSelect( coreStore );

		// The widgets API always returns a successful response.
		const widgets = await getWidgets( {
			sidebar: sidebar.value,
			_embed: 'about',
		} );

		const skippedWidgets = new Set();
		const blocks = widgets.flatMap( ( widget ) => {
			const block = transformWidgetToBlock( widget );

			// Skip the block if we have no matching transformations.
			if ( ! block ) {
				skippedWidgets.add( widget.id_base );
				return [];
			}

			return block;
		} );

		await createFromBlocks(
			blocks,
			/* translators: %s: name of the widget area */
			sprintf( __( 'Widget area: %s' ), sidebar.label )
		);

		if ( skippedWidgets.size ) {
			createErrorNotice(
				sprintf(
					/* translators: %s: the list of widgets */
					__( 'Unable to import the following widgets: %s.' ),
					Array.from( skippedWidgets ).join( ', ' )
				),
				{
					type: 'snackbar',
				}
			);
		}

		setIsBusy( false );
	}

	return (
		<Spacer marginBottom="4">
			<HStack as="form" onSubmit={ createFromWidgets }>
				<FlexBlock>
					<SelectControl
						label={ __( 'Import widget area' ) }
						value={ selectedSidebar }
						options={ options }
						onChange={ ( value ) => setSelectedSidebar( value ) }
						disabled={ ! options.length }
					/>
				</FlexBlock>
				<FlexItem
					style={ {
						marginBottom: '8px',
						marginTop: 'auto',
					} }
				>
					<Button
						__next40pxDefaultSize
						variant="primary"
						type="submit"
						isBusy={ isBusy }
						aria-disabled={ isBusy || ! selectedSidebar }
					>
						{ _x( 'Import', 'button label' ) }
					</Button>
				</FlexItem>
			</HStack>
		</Spacer>
	);
}