wp-calypso/client/a8c-for-agencies/components/a4a-carousel/index.tsx

import { Button } from '@wordpress/components';
import { Icon, chevronLeft, chevronRight } from '@wordpress/icons';
import clsx from 'clsx';
import { useCallback, useEffect, useRef, useState } from 'react';

import './style.scss';

type Props = {
	className?: string;
	children: React.ReactNode;
};

export default function A4ACarousel( { children, className }: Props ) {
	const [ offsetX, setOffsetX ] = useState( 0 );
	const [ touchStart, setTouchStart ] = useState< number | null >( null );

	const contentRef = useRef< HTMLDivElement >( null );
	const containerRef = useRef< HTMLDivElement >( null );

	const [ containerWidth, setContainerWidth ] = useState( 0 );
	const [ contentWidth, setContentWidth ] = useState( 0 );

	const maxOffset = Math.max( 0, contentWidth - containerWidth );

	const offsetStep = containerWidth;

	const requiresNavigation = contentWidth > containerWidth;

	const moveLeft = useCallback( () => {
		if ( ! requiresNavigation ) {
			return;
		}

		setOffsetX( Math.min( offsetX + offsetStep, 0 ) );
	}, [ offsetStep, offsetX, requiresNavigation ] );

	const moveRight = useCallback( () => {
		if ( ! requiresNavigation ) {
			return;
		}

		setOffsetX( Math.max( offsetX - offsetStep, -maxOffset ) );
	}, [ requiresNavigation, offsetX, offsetStep, maxOffset ] );

	const onTouchStart = useCallback(
		( e: React.TouchEvent ) => {
			if ( ! requiresNavigation ) {
				return;
			}

			setTouchStart( e.targetTouches[ 0 ].clientX );
		},
		[ requiresNavigation ]
	);

	const onTouchMove = useCallback(
		( e: React.TouchEvent ) => {
			e.stopPropagation();

			if ( ! requiresNavigation ) {
				return;
			}

			if ( ! touchStart ) {
				return;
			}

			const currentTouch = e.targetTouches[ 0 ].clientX;
			const distance = touchStart - currentTouch;

			// If distance is greater than threshold, snap to next/previous
			const snapThreshold = containerWidth * 0.2; // 20% of container width
			if ( Math.abs( distance ) > snapThreshold ) {
				const newOffset =
					distance > 0
						? Math.max( offsetX - offsetStep, -maxOffset )
						: Math.min( offsetX + offsetStep, 0 );
				setOffsetX( newOffset );
			} else {
				// Otherwise do smooth tracking
				const newOffset = Math.max( Math.min( offsetX - distance, 0 ), -maxOffset );
				setOffsetX( newOffset );
			}

			setTouchStart( currentTouch );
		},
		[ requiresNavigation, touchStart, containerWidth, offsetX, offsetStep, maxOffset ]
	);

	const onTouchEnd = useCallback( () => {
		setTouchStart( null );
	}, [] );

	useEffect( () => {
		setContainerWidth( containerRef.current?.clientWidth ?? 0 );
		setContentWidth( contentRef.current?.clientWidth ?? 0 );
	}, [ containerRef, contentRef ] );

	return (
		<div
			className={ clsx( 'a4a-carousel-wrapper', className, {
				'is-with-navigation': requiresNavigation,
			} ) }
		>
			<div
				className={ clsx( 'a4a-carousel', { 'is-touch-active': !! touchStart } ) }
				ref={ containerRef }
				onTouchStart={ onTouchStart }
				onTouchMove={ onTouchMove }
				onTouchEnd={ onTouchEnd }
			>
				{ requiresNavigation && (
					<div className="a4a-carousel__navigation">
						<Button
							className="a4a-carousel__navigation-button"
							onClick={ moveLeft }
							disabled={ offsetX === 0 }
						>
							<Icon icon={ chevronLeft } size={ 20 } />
						</Button>
						<Button
							className="a4a-carousel__navigation-button"
							onClick={ moveRight }
							disabled={ offsetX === -maxOffset }
						>
							<Icon icon={ chevronRight } size={ 20 } />
						</Button>
					</div>
				) }
				<div
					className="a4a-carousel__content"
					style={ { transform: `translateX(${ offsetX }px)` } }
					ref={ contentRef }
				>
					{ children }
				</div>
			</div>
		</div>
	);
}