From 41825ea3d063ebf5a1dca562e4bd048d647409e1 Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Fri, 12 Jun 2020 00:51:39 +0800
Subject: feat(front): Fix #98 . Fix #99 .

---
 Timeline/ClientApp/src/app/timeline/Timeline.tsx   | 13 +++--
 .../src/app/timeline/TimelinePageTemplateUI.tsx    | 66 ++++++++++++++++------
 2 files changed, 56 insertions(+), 23 deletions(-)

(limited to 'Timeline/ClientApp/src')

diff --git a/Timeline/ClientApp/src/app/timeline/Timeline.tsx b/Timeline/ClientApp/src/app/timeline/Timeline.tsx
index 35d6490b..0a68c5db 100644
--- a/Timeline/ClientApp/src/app/timeline/Timeline.tsx
+++ b/Timeline/ClientApp/src/app/timeline/Timeline.tsx
@@ -1,6 +1,5 @@
 import React from 'react';
 import clsx from 'clsx';
-import { Container } from 'reactstrap';
 
 import { TimelinePostInfo } from '../data/timeline';
 import { useUser } from '../data/user';
@@ -19,6 +18,7 @@ export interface TimelineProps {
   posts: TimelinePostInfoEx[];
   onDelete: TimelineDeleteCallback;
   onResize?: () => void;
+  containerRef?: React.Ref<HTMLDivElement>;
 }
 
 const Timeline: React.FC<TimelineProps> = (props) => {
@@ -56,9 +56,12 @@ const Timeline: React.FC<TimelineProps> = (props) => {
   }, [posts, onDelete]);
 
   return (
-    <Container
-      fluid
-      className={clsx('d-flex flex-column position-relative', props.className)}
+    <div
+      ref={props.containerRef}
+      className={clsx(
+        'container-fluid d-flex flex-column position-relative',
+        props.className
+      )}
     >
       <div className="timeline-enter-animation-mask" />
       {(() => {
@@ -92,7 +95,7 @@ const Timeline: React.FC<TimelineProps> = (props) => {
           );
         });
       })()}
-    </Container>
+    </div>
   );
 };
 
diff --git a/Timeline/ClientApp/src/app/timeline/TimelinePageTemplateUI.tsx b/Timeline/ClientApp/src/app/timeline/TimelinePageTemplateUI.tsx
index 275e9ae0..5eb6a310 100644
--- a/Timeline/ClientApp/src/app/timeline/TimelinePageTemplateUI.tsx
+++ b/Timeline/ClientApp/src/app/timeline/TimelinePageTemplateUI.tsx
@@ -69,29 +69,58 @@ export default function TimelinePageTemplateUI<
     }
   }, []);
 
+  const timelineRef = React.useRef<HTMLDivElement | null>(null);
+
   const [getResizeEvent, triggerResizeEvent] = useEventEmiiter();
 
   React.useEffect(() => {
-    let scrollToBottom = true;
-    const disableScrollToBottom = (): void => {
-      scrollToBottom = false;
-    };
-
-    const subscriptions = [
-      fromEvent(window, 'wheel').subscribe(disableScrollToBottom),
-      fromEvent(window, 'pointerdown').subscribe(disableScrollToBottom),
-      fromEvent(window, 'keydown').subscribe(disableScrollToBottom),
-      getResizeEvent().subscribe(() => {
-        if (scrollToBottom) {
+    const { current: timelineElement } = timelineRef;
+    if (timelineElement != null) {
+      let loadingScrollToBottom = true;
+      let pinBottom = false;
+
+      const isAtBottom = (): boolean =>
+        window.innerHeight + window.scrollY + 10 >= document.body.scrollHeight;
+
+      const disableLoadingScrollToBottom = (): void => {
+        loadingScrollToBottom = false;
+        if (isAtBottom()) pinBottom = true;
+      };
+
+      const checkAndScrollToBottom = (): void => {
+        if (loadingScrollToBottom || pinBottom) {
           window.scrollTo(0, document.body.scrollHeight);
         }
-      }),
-    ];
-
-    return () => {
-      subscriptions.forEach((s) => s.unsubscribe());
-    };
-  }, [getResizeEvent, timeline, props.posts]);
+      };
+
+      const subscriptions = [
+        fromEvent(timelineElement, 'wheel').subscribe(
+          disableLoadingScrollToBottom
+        ),
+        fromEvent(timelineElement, 'pointerdown').subscribe(
+          disableLoadingScrollToBottom
+        ),
+        fromEvent(timelineElement, 'keydown').subscribe(
+          disableLoadingScrollToBottom
+        ),
+        fromEvent(window, 'scroll').subscribe(() => {
+          if (loadingScrollToBottom) return;
+
+          if (isAtBottom()) {
+            pinBottom = true;
+          } else {
+            pinBottom = false;
+          }
+        }),
+        fromEvent(window, 'resize').subscribe(checkAndScrollToBottom),
+        getResizeEvent().subscribe(checkAndScrollToBottom),
+      ];
+
+      return () => {
+        subscriptions.forEach((s) => s.unsubscribe());
+      };
+    }
+  }, [getResizeEvent, triggerResizeEvent, timeline, props.posts]);
 
   const [cardHeight, setCardHeight] = React.useState<number>(0);
 
@@ -125,6 +154,7 @@ export default function TimelinePageTemplateUI<
         } else {
           timelineBody = (
             <Timeline
+              containerRef={timelineRef}
               posts={props.posts}
               onDelete={props.onDelete}
               onResize={triggerResizeEvent}
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