import React, { PureComponent } from 'react'; import { ScrollContainer } from 'react-router-scroll-4'; import PropTypes from 'prop-types'; import IntersectionObserverArticleContainer from 'flavours/glitch/containers/intersection_observer_article_container'; import LoadMore from './load_more'; import LoadPending from './load_pending'; import IntersectionObserverWrapper from 'flavours/glitch/util/intersection_observer_wrapper'; import { throttle } from 'lodash'; import { List as ImmutableList } from 'immutable'; import classNames from 'classnames'; import { attachFullscreenListener, detachFullscreenListener, isFullscreen } from 'flavours/glitch/util/fullscreen'; import LoadingIndicator from './loading_indicator'; const MOUSE_IDLE_DELAY = 300; export default class ScrollableList extends PureComponent { static contextTypes = { router: PropTypes.object, }; static propTypes = { scrollKey: PropTypes.string.isRequired, onLoadMore: PropTypes.func, onLoadPending: PropTypes.func, onScrollToTop: PropTypes.func, onScroll: PropTypes.func, trackScroll: PropTypes.bool, shouldUpdateScroll: PropTypes.func, isLoading: PropTypes.bool, showLoading: PropTypes.bool, hasMore: PropTypes.bool, numPending: PropTypes.number, prepend: PropTypes.node, alwaysPrepend: PropTypes.bool, emptyMessage: PropTypes.node, children: PropTypes.node, }; static defaultProps = { trackScroll: true, }; state = { fullscreen: null, cachedMediaWidth: 300, }; intersectionObserverWrapper = new IntersectionObserverWrapper(); handleScroll = throttle(() => { if (this.node) { const { scrollTop, scrollHeight, clientHeight } = this.node; const offset = scrollHeight - scrollTop - clientHeight; if (400 > offset && this.props.onLoadMore && this.props.hasMore && !this.props.isLoading) { this.props.onLoadMore(); } if (scrollTop < 100 && this.props.onScrollToTop) { this.props.onScrollToTop(); } else if (this.props.onScroll) { this.props.onScroll(); } if (!this.lastScrollWasSynthetic) { // If the last scroll wasn't caused by setScrollTop(), assume it was // intentional and cancel any pending scroll reset on mouse idle this.scrollToTopOnMouseIdle = false; } this.lastScrollWasSynthetic = false; } }, 150, { trailing: true, }); mouseIdleTimer = null; mouseMovedRecently = false; lastScrollWasSynthetic = false; scrollToTopOnMouseIdle = false; setScrollTop = newScrollTop => { if (this.node.scrollTop !== newScrollTop) { this.lastScrollWasSynthetic = true; this.node.scrollTop = newScrollTop; } }; clearMouseIdleTimer = () => { if (this.mouseIdleTimer === null) { return; } clearTimeout(this.mouseIdleTimer); this.mouseIdleTimer = null; }; handleMouseMove = throttle(() => { // As long as the mouse keeps moving, clear and restart the idle timer. this.clearMouseIdleTimer(); this.mouseIdleTimer = setTimeout(this.handleMouseIdle, MOUSE_IDLE_DELAY); if (!this.mouseMovedRecently && this.node.scrollTop === 0) { // Only set if we just started moving and are scrolled to the top. this.scrollToTopOnMouseIdle = true; } // Save setting this flag for last, so we can do the comparison above. this.mouseMovedRecently = true; }, MOUSE_IDLE_DELAY / 2); handleWheel = throttle(() => { this.scrollToTopOnMouseIdle = false; }, 150, { trailing: true, }); handleMouseIdle = () => { if (this.scrollToTopOnMouseIdle) { this.setScrollTop(0); } this.mouseMovedRecently = false; this.scrollToTopOnMouseIdle = false; } componentDidMount () { this.attachScrollListener(); this.attachIntersectionObserver(); attachFullscreenListener(this.onFullScreenChange); // Handle initial scroll posiiton this.handleScroll(); } getScrollPosition = () => { if (this.node && (this.node.scrollTop > 0 || this.mouseMovedRecently)) { return {height: this.node.scrollHeight, top: this.node.scrollTop}; } else { return null; } } updateScrollBottom = (snapshot) => { const newScrollTop = this.node.scrollHeight - snapshot; this.setScrollTop(newScrollTop); } cacheMediaWidth = (width) => { if (width && this.state.cachedMediaWidth != width) this.setState({ cachedMediaWidth: width }); } getSnapshotBeforeUpdate (prevProps, prevState) { const someItemInserted = React.Children.count(prevProps.children) > 0 && React.Children.count(prevProps.children) < React.Children.count(this.props.children) && this.getFirstChildKey(prevProps) !== this.getFirstChildKey(this.props); if (someItemInserted && (this.node.scrollTop > 0 || this.mouseMovedRecently)) { return this.node.scrollHeight - this.node.scrollTop; } else { return null; } } componentDidUpdate (prevProps, prevState, snapshot) { // Reset the scroll position when a new child comes in in order not to // jerk the scrollbar around if you're already scrolled down the page. if (snapshot !== null) this.updateScrollBottom(snapshot); } componentWillUnmount () { this.clearMouseIdleTimer(); this.detachScrollListener(); this.detachIntersectionObserver(); detachFullscreenListener(this.onFullScreenChange); } onFullScreenChange = () => { this.setState({ fullscreen: isFullscreen() }); } attachIntersectionObserver () { this.intersectionObserverWrapper.connect({ root: this.node, rootMargin: '300% 0px', }); } detachIntersectionObserver () { this.intersectionObserverWrapper.disconnect(); } attachScrollListener () { this.node.addEventListener('scroll', this.handleScroll); this.node.addEventListener('wheel', this.handleWheel); } detachScrollListener () { this.node.removeEventListener('scroll', this.handleScroll); this.node.removeEventListener('wheel', this.handleWheel); } getFirstChildKey (props) { const { children } = props; let firstChild = children; if (children instanceof ImmutableList) { firstChild = children.get(0); } else if (Array.isArray(children)) { firstChild = children[0]; } return firstChild && firstChild.key; } setRef = (c) => { this.node = c; } handleLoadMore = e => { e.preventDefault(); this.props.onLoadMore(); } defaultShouldUpdateScroll = (prevRouterProps, { location }) => { if ((((prevRouterProps || {}).location || {}).state || {}).mastodonModalOpen) return false; return !(location.state && location.state.mastodonModalOpen); } handleLoadPending = e => { e.preventDefault(); this.props.onLoadPending(); } render () { const { children, scrollKey, trackScroll, shouldUpdateScroll, showLoading, isLoading, hasMore, numPending, prepend, alwaysPrepend, emptyMessage, onLoadMore } = this.props; const { fullscreen } = this.state; const childrenCount = React.Children.count(children); const loadMore = (hasMore && onLoadMore) ? <LoadMore visible={!isLoading} onClick={this.handleLoadMore} /> : null; const loadPending = (numPending > 0) ? <LoadPending count={numPending} onClick={this.handleLoadPending} /> : null; let scrollableArea = null; if (showLoading) { scrollableArea = ( <div className='scrollable scrollable--flex' ref={this.setRef}> <div role='feed' className='item-list'> {prepend} </div> <div className='scrollable__append'> <LoadingIndicator /> </div> </div> ); } else if (isLoading || childrenCount > 0 || hasMore || !emptyMessage) { scrollableArea = ( <div className={classNames('scrollable', { fullscreen })} ref={this.setRef} onMouseMove={this.handleMouseMove}> <div role='feed' className='item-list'> {prepend} {loadPending} {React.Children.map(this.props.children, (child, index) => ( <IntersectionObserverArticleContainer key={child.key} id={child.key} index={index} listLength={childrenCount} intersectionObserverWrapper={this.intersectionObserverWrapper} saveHeightKey={trackScroll ? `${this.context.router.route.location.key}:${scrollKey}` : null} > {React.cloneElement(child, { getScrollPosition: this.getScrollPosition, updateScrollBottom: this.updateScrollBottom, cachedMediaWidth: this.state.cachedMediaWidth, cacheMediaWidth: this.cacheMediaWidth, })} </IntersectionObserverArticleContainer> ))} {loadMore} </div> </div> ); } else { scrollableArea = ( <div className={classNames('scrollable scrollable--flex', { fullscreen })} ref={this.setRef}> {alwaysPrepend && prepend} <div className='empty-column-indicator'> {emptyMessage} </div> </div> ); } if (trackScroll) { return ( <ScrollContainer scrollKey={scrollKey} shouldUpdateScroll={shouldUpdateScroll || this.defaultShouldUpdateScroll}> {scrollableArea} </ScrollContainer> ); } else { return scrollableArea; } } }