From 3ddbbd4c2719dbd6ba00d2d574a5d3f472e9d8ff Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Sat, 3 Apr 2021 21:55:46 +0800
Subject: feat: Paged timeline posts.

---
 .../src/app/views/timeline-common/Timeline.tsx     | 10 ++--
 .../timeline-common/TimelinePagedPostListView.tsx  | 62 ++++++++++++++++++++++
 .../app/views/timeline-common/TimelinePostView.tsx |  1 +
 3 files changed, 67 insertions(+), 6 deletions(-)
 create mode 100644 FrontEnd/src/app/views/timeline-common/TimelinePagedPostListView.tsx

(limited to 'FrontEnd/src')

diff --git a/FrontEnd/src/app/views/timeline-common/Timeline.tsx b/FrontEnd/src/app/views/timeline-common/Timeline.tsx
index 3f2cbfb5..9b67b90b 100644
--- a/FrontEnd/src/app/views/timeline-common/Timeline.tsx
+++ b/FrontEnd/src/app/views/timeline-common/Timeline.tsx
@@ -7,7 +7,7 @@ import {
 } from "@/http/common";
 import { getHttpTimelineClient, HttpTimelinePostInfo } from "@/http/timeline";
 
-import TimelinePostListView from "./TimelinePostListView";
+import TimelinePagedPostListView from "./TimelinePagedPostListView";
 
 export interface TimelineProps {
   className?: string;
@@ -16,7 +16,6 @@ export interface TimelineProps {
   timelineName: string;
   reloadKey: number;
   onReload: () => void;
-  additionalPosts?: HttpTimelinePostInfo[];
   onLoad?: () => void;
 }
 
@@ -28,7 +27,6 @@ const Timeline: React.FC<TimelineProps> = (props) => {
     top,
     reloadKey,
     onReload,
-    additionalPosts,
     onLoad,
   } = props;
 
@@ -77,7 +75,7 @@ const Timeline: React.FC<TimelineProps> = (props) => {
     if (Array.isArray(posts)) {
       onLoad?.();
     }
-  }, [posts, additionalPosts, onLoad]);
+  }, [posts, onLoad]);
 
   switch (posts) {
     case "loading":
@@ -112,8 +110,8 @@ const Timeline: React.FC<TimelineProps> = (props) => {
       );
     default:
       return (
-        <TimelinePostListView
-          posts={[...posts, ...(additionalPosts ?? [])]}
+        <TimelinePagedPostListView
+          posts={posts}
           top={top}
           onReload={onReload}
         />
diff --git a/FrontEnd/src/app/views/timeline-common/TimelinePagedPostListView.tsx b/FrontEnd/src/app/views/timeline-common/TimelinePagedPostListView.tsx
new file mode 100644
index 00000000..b91357dd
--- /dev/null
+++ b/FrontEnd/src/app/views/timeline-common/TimelinePagedPostListView.tsx
@@ -0,0 +1,62 @@
+import React from "react";
+
+import { HttpTimelinePostInfo } from "@/http/timeline";
+import TimelinePostListView from "./TimelinePostListView";
+
+export interface TimelinePagedPostListViewProps {
+  className?: string;
+  style?: React.CSSProperties;
+  top?: string | number;
+  posts: HttpTimelinePostInfo[];
+  onReload: () => void;
+}
+
+const TimelinePagedPostListView: React.FC<TimelinePagedPostListViewProps> = (
+  props
+) => {
+  const { className, style, top, posts, onReload } = props;
+
+  const [lastViewCount, setLastViewCount] = React.useState<number>(10);
+
+  const viewingPosts = React.useMemo(() => {
+    if (lastViewCount >= posts.length) {
+      return posts;
+    } else {
+      return posts.slice(-lastViewCount, -1);
+    }
+  }, [posts, lastViewCount]);
+
+  React.useEffect(() => {
+    if (lastViewCount < posts.length) {
+      const listener = (): void => {
+        if (window.scrollY === 0 && lastViewCount < posts.length) {
+          setLastViewCount(lastViewCount + 10);
+        }
+      };
+      window.addEventListener("scroll", listener);
+      return () => window.removeEventListener("scroll", listener);
+    }
+  }, [lastViewCount, posts]);
+
+  React.useEffect(() => {
+    if (lastViewCount !== 10) {
+      document
+        .getElementById(
+          `timeline-post-${posts[posts.length - (lastViewCount - 10)].id}`
+        )
+        ?.scrollIntoView(true);
+    }
+  }, [lastViewCount, posts]);
+
+  return (
+    <TimelinePostListView
+      className={className}
+      style={style}
+      top={top}
+      posts={viewingPosts}
+      onReload={onReload}
+    />
+  );
+};
+
+export default TimelinePagedPostListView;
diff --git a/FrontEnd/src/app/views/timeline-common/TimelinePostView.tsx b/FrontEnd/src/app/views/timeline-common/TimelinePostView.tsx
index d01ecfa8..3d075f0e 100644
--- a/FrontEnd/src/app/views/timeline-common/TimelinePostView.tsx
+++ b/FrontEnd/src/app/views/timeline-common/TimelinePostView.tsx
@@ -31,6 +31,7 @@ const TimelinePostView: React.FC<TimelinePostViewProps> = (props) => {
 
   return (
     <div
+      id={`timeline-post-${post.id}`}
       className={clsx("timeline-item", current && "current", className)}
       style={style}
     >
-- 
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