1 files changed, 355 insertions, 0 deletions
diff --git a/app/javascript/flavours/glitch/components/scrollable_list.jsx b/app/javascript/flavours/glitch/components/scrollable_list.jsx
new file mode 100644
index 000000000..fc7dc989d
--- /dev/null
+++ b/app/javascript/flavours/glitch/components/scrollable_list.jsx
@@ -0,0 +1,355 @@
+import React, { PureComponent } from 'react';
+import ScrollContainer from 'flavours/glitch/containers/scroll_container';
+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/features/ui/util/intersection_observer_wrapper';
+import { throttle } from 'lodash';
+import { List as ImmutableList } from 'immutable';
+import classNames from 'classnames';
+import { attachFullscreenListener, detachFullscreenListener, isFullscreen } from '../features/ui/util/fullscreen';
+import LoadingIndicator from './loading_indicator';
+import { connect } from 'react-redux';
+
+const MOUSE_IDLE_DELAY = 300;
+
+const mapStateToProps = (state, { scrollKey }) => {
+  return {
+    preventScroll: scrollKey === state.getIn(['dropdown_menu', 'scroll_key']),
+  };
+};
+
+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,
+    isLoading: PropTypes.bool,
+    showLoading: PropTypes.bool,
+    hasMore: PropTypes.bool,
+    numPending: PropTypes.number,
+    prepend: PropTypes.node,
+    append: PropTypes.node,
+    alwaysPrepend: PropTypes.bool,
+    emptyMessage: PropTypes.node,
+    children: PropTypes.node,
+    bindToDocument: PropTypes.bool,
+    preventScroll: PropTypes.bool,
+  };
+
+  static defaultProps = {
+    trackScroll: true,
+  };
+
+  state = {
+    fullscreen: null,
+    cachedMediaWidth: 300,
+  };
+
+  intersectionObserverWrapper = new IntersectionObserverWrapper();
+
+  handleScroll = throttle(() => {
+    if (this.node) {
+      const scrollTop = this.getScrollTop();
+      const scrollHeight = this.getScrollHeight();
+      const clientHeight = this.getClientHeight();
+      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.getScrollTop() !== newScrollTop) {
+      this.lastScrollWasSynthetic = true;
+
+      if (this.props.bindToDocument) {
+        document.scrollingElement.scrollTop = newScrollTop;
+      } else {
+        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.getScrollTop() === 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.props.preventScroll) {
+      this.setScrollTop(0);
+    }
+    this.mouseMovedRecently = false;
+    this.scrollToTopOnMouseIdle = false;
+  };
+
+  componentDidMount () {
+    this.attachScrollListener();
+    this.attachIntersectionObserver();
+    attachFullscreenListener(this.onFullScreenChange);
+
+    // Handle initial scroll position
+    this.handleScroll();
+  }
+
+  getScrollPosition = () => {
+    if (this.node && (this.getScrollTop() > 0 || this.mouseMovedRecently)) {
+      return { height: this.getScrollHeight(), top: this.getScrollTop() };
+    } else {
+      return null;
+    }
+  };
+
+  getScrollTop = () => {
+    return this.props.bindToDocument ? document.scrollingElement.scrollTop : this.node.scrollTop;
+  };
+
+  getScrollHeight = () => {
+    return this.props.bindToDocument ? document.scrollingElement.scrollHeight : this.node.scrollHeight;
+  };
+
+  getClientHeight = () => {
+    return this.props.bindToDocument ? document.scrollingElement.clientHeight : this.node.clientHeight;
+  };
+
+  updateScrollBottom = (snapshot) => {
+    const newScrollTop = this.getScrollHeight() - 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);
+    const pendingChanged = (prevProps.numPending > 0) !== (this.props.numPending > 0);
+
+    if (pendingChanged || someItemInserted && (this.getScrollTop() > 0 || this.mouseMovedRecently || this.props.preventScroll)) {
+      return this.getScrollHeight() - this.getScrollTop();
+    } 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 () {
+    if (this.props.bindToDocument) {
+      document.addEventListener('scroll', this.handleScroll);
+      document.addEventListener('wheel', this.handleWheel);
+    } else {
+      this.node.addEventListener('scroll', this.handleScroll);
+      this.node.addEventListener('wheel', this.handleWheel);
+    }
+  }
+
+  detachScrollListener () {
+    if (this.props.bindToDocument) {
+      document.removeEventListener('scroll', this.handleScroll);
+      document.removeEventListener('wheel', this.handleWheel);
+    } else {
+      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();
+  };
+
+  handleLoadPending = e => {
+    e.preventDefault();
+    this.props.onLoadPending();
+    // Prevent the weird scroll-jumping behavior, as we explicitly don't want to
+    // scroll to top, and we know the scroll height is going to change
+    this.scrollToTopOnMouseIdle = false;
+    this.lastScrollWasSynthetic = false;
+    this.clearMouseIdleTimer();
+    this.mouseIdleTimer = setTimeout(this.handleMouseIdle, MOUSE_IDLE_DELAY);
+    this.mouseMovedRecently = true;
+  };
+
+  render () {
+    const { children, scrollKey, trackScroll, showLoading, isLoading, hasMore, numPending, prepend, alwaysPrepend, append, 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}
+
+            {!hasMore && append}
+          </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}>
+          {scrollableArea}
+        </ScrollContainer>
+      );
+    } else {
+      return scrollableArea;
+    }
+  }
+
+}
+
+export default connect(mapStateToProps, null, null, { forwardRef: true })(ScrollableList);