12 files changed, 455 insertions, 470 deletions
diff --git a/Timeline/ClientApp/src/app/common/AppBar.tsx b/Timeline/ClientApp/src/app/common/AppBar.tsx
index 061ba08c..8349aef7 100644
--- a/Timeline/ClientApp/src/app/common/AppBar.tsx
+++ b/Timeline/ClientApp/src/app/common/AppBar.tsx
@@ -5,14 +5,15 @@ import { Navbar, NavbarToggler, Collapse, Nav, NavItem } from 'reactstrap';
 import { useMediaQuery } from 'react-responsive';
 import { useTranslation } from 'react-i18next';
 
-import { useUser, useAvatarUrl } from '../data/user';
+import { useUser, useAvatar } from '../data/user';
 
 import TimelineLogo from './TimelineLogo';
+import BlobImage from './BlobImage';
 
 const AppBar: React.FC = (_) => {
   const history = useHistory();
   const user = useUser();
-  const avatarUrl = useAvatarUrl(user?.username);
+  const avatar = useAvatar(user?.username);
 
   const { t } = useTranslation();
 
@@ -34,9 +35,9 @@ const AppBar: React.FC = (_) => {
     <div className="ml-auto mr-2">
       {user != null ? (
         <NavLink to={`/users/${user.username}`}>
-          <img
+          <BlobImage
             className="avatar small rounded-circle bg-white"
-            src={avatarUrl}
+            blob={avatar}
           />
         </NavLink>
       ) : (
diff --git a/Timeline/ClientApp/src/app/common/BlobImage.tsx b/Timeline/ClientApp/src/app/common/BlobImage.tsx
new file mode 100644
index 00000000..91497705
--- /dev/null
+++ b/Timeline/ClientApp/src/app/common/BlobImage.tsx
@@ -0,0 +1,27 @@
+import React from 'react';
+
+import { ExcludeKey } from '../utilities/type';
+
+const BlobImage: React.FC<
+  ExcludeKey<React.ImgHTMLAttributes<HTMLImageElement>, 'src'> & { blob?: Blob }
+> = (props) => {
+  const { blob, ...otherProps } = props;
+
+  const [url, setUrl] = React.useState<string | undefined>(undefined);
+
+  React.useEffect(() => {
+    if (blob != null) {
+      const url = URL.createObjectURL(blob);
+      setUrl(url);
+      return () => {
+        URL.revokeObjectURL(url);
+      };
+    } else {
+      setUrl(undefined);
+    }
+  }, [blob]);
+
+  return <img {...otherProps} src={url} />;
+};
+
+export default BlobImage;
diff --git a/Timeline/ClientApp/src/app/data/SubscriptionHub.ts b/Timeline/ClientApp/src/app/data/SubscriptionHub.ts
index c127c31a..87592da6 100644
--- a/Timeline/ClientApp/src/app/data/SubscriptionHub.ts
+++ b/Timeline/ClientApp/src/app/data/SubscriptionHub.ts
@@ -16,7 +16,7 @@ export class Subscription {
   }
 }
 
-class NoValue {}
+export class NoValue {}
 
 export class SubscriptionLine<TData> {
   private _current: TData | NoValue = new NoValue();
@@ -30,7 +30,6 @@ export class SubscriptionLine<TData> {
     if (!(this._current instanceof NoValue)) {
       subscriber(this._current);
     }
-
     return new Subscription(() => this.unsubscribe(subscriber));
   }
 
@@ -43,6 +42,13 @@ export class SubscriptionLine<TData> {
   }
 
   next(value: TData): void {
+    this._current = value;
+    this._observers.forEach((observer) => observer(value));
+  }
+
+  nextWithOld(updator: (old: TData | NoValue) => TData): void {
+    const value = updator(this._current);
+    this._current = value;
     this._observers.forEach((observer) => observer(value));
   }
 }
@@ -56,7 +62,8 @@ export class SubscriptionHub<TKey, TData>
   private keyToString: (key: TKey) => string;
   private setup?: (
     key: TKey,
-    next: (value: TData) => void
+    next: (value: TData) => void,
+    line: SubscriptionLine<TData>
   ) => (() => void) | void;
 
   private readonly subscriptionLineMap = new Map<
@@ -103,7 +110,7 @@ export class SubscriptionHub<TKey, TData>
             }
           },
         });
-        const destroyer = setup?.(key, newLine.next.bind(newLine));
+        const destroyer = setup?.(key, newLine.next.bind(newLine), newLine);
         this.subscriptionLineMap.set(keyString, {
           line: newLine,
           destroyer: destroyer != null ? destroyer : undefined,
@@ -127,4 +134,12 @@ export class SubscriptionHub<TKey, TData>
       info.line.next(value);
     }
   }
+
+  updateWithOld(key: TKey, updator: (old: TData | NoValue) => TData): void {
+    const keyString = this.keyToString(key);
+    const info = this.subscriptionLineMap.get(keyString);
+    if (info != null) {
+      info.line.nextWithOld(updator);
+    }
+  }
 }
diff --git a/Timeline/ClientApp/src/app/data/common.ts b/Timeline/ClientApp/src/app/data/common.ts
index 9f985ce6..786279f2 100644
--- a/Timeline/ClientApp/src/app/data/common.ts
+++ b/Timeline/ClientApp/src/app/data/common.ts
@@ -6,11 +6,6 @@ export const dataStorage = localforage.createInstance({
   driver: localforage.INDEXEDDB,
 });
 
-export interface BlobWithUrl {
-  blob: Blob;
-  url: string;
-}
-
 export class ForbiddenError extends Error {
   constructor(message?: string) {
     super(message);
diff --git a/Timeline/ClientApp/src/app/data/timeline.ts b/Timeline/ClientApp/src/app/data/timeline.ts
index 8680e9b8..fb8a3874 100644
--- a/Timeline/ClientApp/src/app/data/timeline.ts
+++ b/Timeline/ClientApp/src/app/data/timeline.ts
@@ -6,10 +6,10 @@ import { pull } from 'lodash';
 
 import { convertError } from '../utilities/rxjs';
 
-import { BlobWithUrl, dataStorage, ForbiddenError } from './common';
-import { SubscriptionHub, ISubscriptionHub } from './SubscriptionHub';
+import { dataStorage } from './common';
+import { SubscriptionHub, ISubscriptionHub, NoValue } from './SubscriptionHub';
 
-import { UserAuthInfo, checkLogin, userService } from './user';
+import { UserAuthInfo, checkLogin, userService, userInfoService } from './user';
 
 export { kTimelineVisibilities } from '../http/timeline';
 
@@ -24,15 +24,13 @@ import {
   HttpTimelinePostPostRequestTextContent,
   HttpTimelinePostPostRequestImageContent,
   HttpTimelinePostInfo,
-  HttpTimelinePostContent,
   HttpTimelinePostTextContent,
-  HttpTimelinePostImageContent,
   getHttpTimelineClient,
   HttpTimelineNotExistError,
   HttpTimelineNameConflictError,
-  HttpTimelineGenericPostInfo,
 } from '../http/timeline';
 import { BlobWithEtag, NotModified, HttpNetworkError } from '../http/common';
+import { HttpUser } from '../http/user';
 
 export type TimelineInfo = HttpTimelineInfo;
 export type TimelineChangePropertyRequest = HttpTimelinePatchRequest;
@@ -41,13 +39,24 @@ export type TimelineCreatePostContent = HttpTimelinePostPostRequestContent;
 export type TimelineCreatePostTextContent = HttpTimelinePostPostRequestTextContent;
 export type TimelineCreatePostImageContent = HttpTimelinePostPostRequestImageContent;
 
-export interface TimelinePostInfo extends HttpTimelinePostInfo {
-  timelineName: string;
+export type TimelinePostTextContent = HttpTimelinePostTextContent;
+
+export interface TimelinePostImageContent {
+  type: 'image';
+  data: Blob;
 }
 
-export type TimelinePostContent = HttpTimelinePostContent;
-export type TimelinePostTextContent = HttpTimelinePostTextContent;
-export type TimelinePostImageContent = HttpTimelinePostImageContent;
+export type TimelinePostContent =
+  | TimelinePostTextContent
+  | TimelinePostImageContent;
+
+export interface TimelinePostInfo {
+  id: number;
+  content: TimelinePostContent;
+  time: Date;
+  lastUpdated: Date;
+  author: HttpUser;
+}
 
 export const timelineVisibilityTooltipTranslationMap: Record<
   TimelineVisibility,
@@ -61,21 +70,6 @@ export const timelineVisibilityTooltipTranslationMap: Record<
 export class TimelineNotExistError extends Error {}
 export class TimelineNameConflictError extends Error {}
 
-export interface PostKey {
-  timelineName: string;
-  postId: number;
-}
-
-export interface TimelinePostListState {
-  state:
-    | 'loading' // Loading posts from cache. `posts` is empty array.
-    | 'forbid' // The list is forbidden to see.
-    | 'syncing' // Cache loaded and syncing now.
-    | 'synced' // Sync succeeded.
-    | 'offline'; // Sync failed and use cache.
-  posts: TimelinePostInfo[];
-}
-
 export type TimelineWithSyncState =
   | {
       syncState:
@@ -88,12 +82,20 @@ export type TimelineWithSyncState =
       timeline: TimelineInfo;
     };
 
+export interface TimelinePostsWithSyncState {
+  state:
+    | 'forbid' // The list is forbidden to see.
+    | 'synced' // Sync succeeded.
+    | 'offline'; // Sync failed and use cache.
+  posts: TimelinePostInfo[];
+}
+
 interface TimelineCache {
   timeline: TimelineInfo;
   lastUpdated: string;
 }
 
-interface PostListInfo {
+interface PostsInfoCache {
   idList: number[];
   lastUpdated: string;
 }
@@ -195,25 +197,6 @@ export class TimelineService {
     return this._timelineSubscriptionHub;
   }
 
-  // TODO: Remove this! This is currently only used to avoid multiple fetch of timeline. Because post list need to use the timeline id and call this method. But after timeline is also saved locally, this should be removed.
-  private timelineCache = new Map<string, Promise<TimelineInfo>>();
-
-  // TODO: Remove this.
-  getTimeline(timelineName: string): Observable<TimelineInfo> {
-    const cache = this.timelineCache.get(timelineName);
-    let promise: Promise<TimelineInfo>;
-    if (cache == null) {
-      promise = getHttpTimelineClient().getTimeline(timelineName);
-      this.timelineCache.set(timelineName, promise);
-    } else {
-      promise = cache;
-    }
-
-    return from(promise).pipe(
-      convertError(HttpTimelineNotExistError, TimelineNotExistError)
-    );
-  }
-
   createTimeline(timelineName: string): Observable<TimelineInfo> {
     const user = checkLogin();
     return from(
@@ -234,7 +217,15 @@ export class TimelineService {
   ): Observable<TimelineInfo> {
     const user = checkLogin();
     return from(
-      getHttpTimelineClient().patchTimeline(timelineName, req, user.token)
+      getHttpTimelineClient()
+        .patchTimeline(timelineName, req, user.token)
+        .then((timeline) => {
+          this._timelineSubscriptionHub.update(timelineName, {
+            syncState: 'synced',
+            timeline,
+          });
+          return timeline;
+        })
     );
   }
 
@@ -248,36 +239,57 @@ export class TimelineService {
   addMember(timelineName: string, username: string): Observable<unknown> {
     const user = checkLogin();
     return from(
-      getHttpTimelineClient().memberPut(timelineName, username, user.token)
+      getHttpTimelineClient()
+        .memberPut(timelineName, username, user.token)
+        .then(() => {
+          userInfoService.getUserInfo(username).subscribe((newUser) => {
+            this._timelineSubscriptionHub.updateWithOld(timelineName, (old) => {
+              if (old instanceof NoValue || old.timeline == null)
+                throw new Error('Timeline not loaded.');
+
+              return {
+                ...old,
+                timeline: {
+                  ...old.timeline,
+                  members: [...old.timeline.members, newUser],
+                },
+              };
+            });
+          });
+        })
     );
   }
 
   removeMember(timelineName: string, username: string): Observable<unknown> {
     const user = checkLogin();
     return from(
-      getHttpTimelineClient().memberDelete(timelineName, username, user.token)
-    );
-  }
+      getHttpTimelineClient()
+        .memberDelete(timelineName, username, user.token)
+        .then(() => {
+          this._timelineSubscriptionHub.updateWithOld(timelineName, (old) => {
+            if (old instanceof NoValue || old.timeline == null)
+              throw new Error('Timeline not loaded.');
 
-  // TODO: Remove this.
-  getPosts(timelineName: string): Observable<TimelinePostInfo[]> {
-    const token = userService.currentUser?.token;
-    return from(getHttpTimelineClient().listPost(timelineName, token)).pipe(
-      map((posts) => {
-        return posts.map((post) => ({
-          ...post,
-          timelineName,
-        }));
-      })
+            return {
+              ...old,
+              timeline: {
+                ...old.timeline,
+                members: old.timeline.members.filter(
+                  (u) => u.username !== username
+                ),
+              },
+            };
+          });
+        })
     );
   }
 
   // post list storage structure:
-  // each timeline has a PostListInfo saved with key created by getPostListInfoKey
+  // each timeline has a PostsInfoCache saved with key created by getPostsInfoKey
   // each post of a timeline has a HttpTimelinePostInfo with key created by getPostKey
   // each post with data has BlobWithEtag with key created by getPostDataKey
 
-  private getPostListInfoKey(timelineUniqueId: string): string {
+  private getPostsInfoKey(timelineUniqueId: string): string {
     return `timeline.${timelineUniqueId}.postListInfo`;
   }
 
@@ -289,274 +301,262 @@ export class TimelineService {
     return `timeline.${timelineUniqueId}.post.${id}.data`;
   }
 
-  private async getCachedPostList(
-    timelineName: string
-  ): Promise<TimelinePostInfo[]> {
-    const timeline = await this.getTimeline(timelineName).toPromise();
-    if (!this.hasReadPermission(userService.currentUser, timeline)) {
-      throw new ForbiddenError(
-        'You are not allowed to get posts of this timeline.'
-      );
-    }
-
-    const postListInfo = await dataStorage.getItem<PostListInfo | null>(
-      this.getPostListInfoKey(timeline.uniqueId)
-    );
-    if (postListInfo == null) {
-      return [];
+  private convertPost = async (
+    post: HttpTimelinePostInfo,
+    dataProvider: () => Promise<Blob | null | undefined>
+  ): Promise<TimelinePostInfo> => {
+    const { content } = post;
+    if (content.type === 'text') {
+      return {
+        ...post,
+        content,
+      };
     } else {
-      return (
-        await Promise.all(
-          postListInfo.idList.map((postId) =>
-            dataStorage.getItem<HttpTimelinePostInfo>(
-              this.getPostKey(timeline.uniqueId, postId)
-            )
-          )
-        )
-      ).map((post) => ({ ...post, timelineName }));
+      const data = await dataProvider();
+      if (data == null) throw new Error('This post requires data.');
+      return {
+        ...post,
+        content: {
+          type: 'image',
+          data,
+        },
+      };
     }
-  }
+  };
 
-  async syncPostList(timelineName: string): Promise<TimelinePostInfo[]> {
-    const timeline = await this.getTimeline(timelineName).toPromise();
+  async fetchAndCachePosts(
+    timeline: TimelineInfo
+  ): Promise<
+    | { posts: TimelinePostInfo[]; type: 'synced' | 'cache' }
+    | 'forbid'
+    | 'offline'
+  > {
     if (!this.hasReadPermission(userService.currentUser, timeline)) {
-      this._postListSubscriptionHub.update(timelineName, () =>
-        Promise.resolve({
-          state: 'forbid',
-          posts: [],
-        })
-      );
-      throw new ForbiddenError(
-        'You are not allowed to get posts of this timeline.'
-      );
+      return 'forbid';
     }
 
-    const postListInfoKey = this.getPostListInfoKey(timeline.uniqueId);
-    const postListInfo = await dataStorage.getItem<PostListInfo | null>(
-      postListInfoKey
+    const postsInfoKey = this.getPostsInfoKey(timeline.uniqueId);
+    const postsInfo = await dataStorage.getItem<PostsInfoCache | null>(
+      postsInfoKey
     );
 
+    const convertPostList = (
+      posts: HttpTimelinePostInfo[],
+      dataProvider: (
+        post: HttpTimelinePostInfo,
+        index: number
+      ) => Promise<Blob | null | undefined>
+    ): Promise<TimelinePostInfo[]> => {
+      return Promise.all(
+        posts.map((post, index) =>
+          this.convertPost(post, () => dataProvider(post, index))
+        )
+      );
+    };
+
     const now = new Date();
-    let posts: TimelinePostInfo[];
-    if (postListInfo == null) {
-      let httpPosts: HttpTimelinePostInfo[];
+    if (postsInfo == null) {
       try {
-        httpPosts = await getHttpTimelineClient().listPost(
-          timelineName,
-          userService.currentUser?.token
+        const token = userService.currentUser?.token;
+
+        const httpPosts = await getHttpTimelineClient().listPost(
+          timeline.name,
+          token
         );
-      } catch (e) {
-        this._postListSubscriptionHub.update(timelineName, (_, old) =>
-          Promise.resolve({
-            state: 'offline',
-            posts: old.posts,
+
+        const dataList: (BlobWithEtag | null)[] = await Promise.all(
+          httpPosts.map(async (post) => {
+            const { content } = post;
+            if (content.type === 'image') {
+              return await getHttpTimelineClient().getPostData(
+                timeline.name,
+                post.id,
+                token
+              );
+            } else {
+              return null;
+            }
           })
         );
-        throw e;
-      }
 
-      await dataStorage.setItem<PostListInfo>(postListInfoKey, {
-        idList: httpPosts.map((post) => post.id),
-        lastUpdated: now.toISOString(),
-      });
+        await dataStorage.setItem<PostsInfoCache>(postsInfoKey, {
+          idList: httpPosts.map((post) => post.id),
+          lastUpdated: now.toISOString(),
+        });
+
+        for (const [i, post] of httpPosts.entries()) {
+          await dataStorage.setItem<HttpTimelinePostInfo>(
+            this.getPostKey(timeline.uniqueId, post.id),
+            post
+          );
+          const data = dataList[i];
+          if (data != null) {
+            await dataStorage.setItem<BlobWithEtag>(
+              this.getPostDataKey(timeline.uniqueId, post.id),
+              data
+            );
+          }
+        }
 
-      for (const post of httpPosts) {
-        await dataStorage.setItem<HttpTimelinePostInfo>(
-          this.getPostKey(timeline.uniqueId, post.id),
-          post
+        const posts: TimelinePostInfo[] = await convertPostList(
+          httpPosts,
+          (post, i) => Promise.resolve(dataList[i]?.data)
         );
-      }
 
-      posts = httpPosts.map((post) => ({
-        ...post,
-        timelineName,
-      }));
+        return { posts, type: 'synced' };
+      } catch (e) {
+        if (e instanceof HttpNetworkError) {
+          return 'offline';
+        } else {
+          throw e;
+        }
+      }
     } else {
-      let httpPosts: HttpTimelineGenericPostInfo[];
       try {
-        httpPosts = await getHttpTimelineClient().listPost(
-          timelineName,
-          userService.currentUser?.token,
+        const token = userService.currentUser?.token;
+        const httpPosts = await getHttpTimelineClient().listPost(
+          timeline.name,
+          token,
           {
-            modifiedSince: new Date(postListInfo.lastUpdated),
+            modifiedSince: new Date(postsInfo.lastUpdated),
             includeDeleted: true,
           }
         );
-      } catch (e) {
-        this._postListSubscriptionHub.update(timelineName, (_, old) =>
-          Promise.resolve({
-            state: 'offline',
-            posts: old.posts,
+
+        const dataList: (BlobWithEtag | null)[] = await Promise.all(
+          httpPosts.map(async (post) => {
+            if (post.deleted) return null;
+            const { content } = post;
+            if (content.type === 'image') {
+              return await getHttpTimelineClient().getPostData(
+                timeline.name,
+                post.id,
+                token
+              );
+            } else {
+              return null;
+            }
           })
         );
-        throw e;
-      }
 
-      const newPosts: HttpTimelinePostInfo[] = [];
+        const newPosts: HttpTimelinePostInfo[] = [];
+        const newPostDataList: (BlobWithEtag | null)[] = [];
+
+        for (const [i, post] of httpPosts.entries()) {
+          if (post.deleted) {
+            pull(postsInfo.idList, post.id);
+            await dataStorage.removeItem(
+              this.getPostKey(timeline.uniqueId, post.id)
+            );
+            await dataStorage.removeItem(
+              this.getPostDataKey(timeline.uniqueId, post.id)
+            );
+          } else {
+            await dataStorage.setItem<HttpTimelinePostInfo>(
+              this.getPostKey(timeline.uniqueId, post.id),
+              post
+            );
+            const data = dataList[i];
+            if (data != null) {
+              await dataStorage.setItem<BlobWithEtag>(
+                this.getPostDataKey(timeline.uniqueId, post.id),
+                data
+              );
+            }
+            newPosts.push(post);
+            newPostDataList.push(data);
+          }
+        }
 
-      for (const post of httpPosts) {
-        if (post.deleted) {
-          pull(postListInfo.idList, post.id);
-          await dataStorage.removeItem(
-            this.getPostKey(timeline.uniqueId, post.id)
+        const oldIdList = postsInfo.idList;
+
+        postsInfo.idList = [...oldIdList, ...newPosts.map((post) => post.id)];
+        postsInfo.lastUpdated = now.toISOString();
+        await dataStorage.setItem<PostsInfoCache>(postsInfoKey, postsInfo);
+
+        const posts: TimelinePostInfo[] = [
+          ...(await convertPostList(
+            await Promise.all(
+              oldIdList.map((postId) =>
+                dataStorage.getItem<HttpTimelinePostInfo>(
+                  this.getPostKey(timeline.uniqueId, postId)
+                )
+              )
+            ),
+            (post) =>
+              dataStorage
+                .getItem<BlobWithEtag | null>(
+                  this.getPostDataKey(timeline.uniqueId, post.id)
+                )
+                .then((d) => d?.data)
+          )),
+          ...(await convertPostList(newPosts, (post, i) =>
+            Promise.resolve(newPostDataList[i]?.data)
+          )),
+        ];
+        return { posts, type: 'synced' };
+      } catch (e) {
+        if (e instanceof HttpNetworkError) {
+          const httpPosts = await Promise.all(
+            postsInfo.idList.map((postId) =>
+              dataStorage.getItem<HttpTimelinePostInfo>(
+                this.getPostKey(timeline.uniqueId, postId)
+              )
+            )
           );
-          await dataStorage.removeItem(
-            this.getPostDataKey(timeline.uniqueId, post.id)
+
+          const posts = await convertPostList(httpPosts, (post) =>
+            dataStorage
+              .getItem<BlobWithEtag | null>(
+                this.getPostDataKey(timeline.uniqueId, post.id)
+              )
+              .then((d) => d?.data)
           );
+
+          return { posts, type: 'cache' };
         } else {
-          await dataStorage.setItem<HttpTimelinePostInfo>(
-            this.getPostKey(timeline.uniqueId, post.id),
-            post
-          );
-          newPosts.push(post);
+          throw e;
         }
       }
-
-      const oldIdList = postListInfo.idList;
-
-      postListInfo.idList = [...oldIdList, ...newPosts.map((post) => post.id)];
-      postListInfo.lastUpdated = now.toISOString();
-      await dataStorage.setItem<PostListInfo>(postListInfoKey, postListInfo);
-
-      posts = [
-        ...(await Promise.all(
-          oldIdList.map((postId) =>
-            dataStorage.getItem<HttpTimelinePostInfo>(
-              this.getPostKey(timeline.uniqueId, postId)
-            )
-          )
-        )),
-        ...newPosts,
-      ].map((post) => ({ ...post, timelineName }));
     }
-
-    this._postListSubscriptionHub.update(timelineName, () =>
-      Promise.resolve({
-        state: 'synced',
-        posts,
-      })
-    );
-
-    return posts;
   }
 
-  private _postListSubscriptionHub = new SubscriptionHub<
+  private _postsSubscriptionHub = new SubscriptionHub<
     string,
-    TimelinePostListState
-  >(
-    (key) => key,
-    () => ({
-      state: 'loading',
-      posts: [],
-    }),
-    async (key) => {
-      const state: TimelinePostListState = {
-        state: 'syncing',
-        posts: await this.getCachedPostList(key),
+    TimelinePostsWithSyncState
+  >({
+    setup: (key, next) => {
+      const sub = this.timelineHub.subscribe(key, (timelineState) => {
+        if (timelineState.timeline == null) {
+          if (timelineState.syncState === 'offline') {
+            next({ state: 'offline', posts: [] });
+          } else {
+            next({ state: 'synced', posts: [] });
+          }
+        } else {
+          void this.fetchAndCachePosts(timelineState.timeline).then(
+            (result) => {
+              if (result === 'forbid') {
+                next({ state: 'forbid', posts: [] });
+              } else if (result === 'offline') {
+                next({ state: 'offline', posts: [] });
+              } else if (result.type === 'synced') {
+                next({ state: 'synced', posts: result.posts });
+              } else {
+                next({ state: 'offline', posts: result.posts });
+              }
+            }
+          );
+        }
+      });
+      return () => {
+        sub.unsubscribe();
       };
-      void this.syncPostList(key);
-      return state;
-    }
-  );
-
-  get postListHub(): ISubscriptionHub<string, TimelinePostListState> {
-    return this._postListSubscriptionHub;
-  }
-
-  private async getCachePostData(
-    timelineName: string,
-    postId: number
-  ): Promise<Blob | null> {
-    const timeline = await this.getTimeline(timelineName).toPromise();
-    const cache = await dataStorage.getItem<BlobWithEtag | null>(
-      this.getPostDataKey(timeline.uniqueId, postId)
-    );
-    if (cache == null) {
-      return null;
-    } else {
-      return cache.data;
-    }
-  }
-
-  private async syncCachePostData(
-    timelineName: string,
-    postId: number
-  ): Promise<Blob | null> {
-    const timeline = await this.getTimeline(timelineName).toPromise();
-    const dataKey = this.getPostDataKey(timeline.uniqueId, postId);
-    const cache = await dataStorage.getItem<BlobWithEtag | null>(dataKey);
-
-    if (cache == null) {
-      const dataWithEtag = await getHttpTimelineClient().getPostData(
-        timelineName,
-        postId,
-        userService.currentUser?.token
-      );
-      await dataStorage.setItem<BlobWithEtag>(dataKey, dataWithEtag);
-      this._postDataSubscriptionHub.update(
-        {
-          postId,
-          timelineName,
-        },
-        () =>
-          Promise.resolve({
-            blob: dataWithEtag.data,
-            url: URL.createObjectURL(dataWithEtag.data),
-          })
-      );
-      return dataWithEtag.data;
-    } else {
-      const res = await getHttpTimelineClient().getPostData(
-        timelineName,
-        postId,
-        userService.currentUser?.token,
-        cache.etag
-      );
-      if (res instanceof NotModified) {
-        return cache.data;
-      } else {
-        await dataStorage.setItem<BlobWithEtag>(dataKey, res);
-        this._postDataSubscriptionHub.update(
-          {
-            postId,
-            timelineName,
-          },
-          () =>
-            Promise.resolve({
-              blob: res.data,
-              url: URL.createObjectURL(res.data),
-            })
-        );
-        return res.data;
-      }
-    }
-  }
-
-  private _postDataSubscriptionHub = new SubscriptionHub<
-    PostKey,
-    BlobWithUrl | null
-  >(
-    (key) => `${key.timelineName}/${key.postId}`,
-    () => null,
-    async (key) => {
-      const blob = await this.getCachePostData(key.timelineName, key.postId);
-      const result =
-        blob == null
-          ? null
-          : {
-              blob,
-              url: URL.createObjectURL(blob),
-            };
-      void this.syncCachePostData(key.timelineName, key.postId);
-      return result;
     },
-    (_key, data) => {
-      if (data != null) URL.revokeObjectURL(data.url);
-    }
-  );
+  });
 
-  get postDataHub(): ISubscriptionHub<PostKey, BlobWithUrl | null> {
-    return this._postDataSubscriptionHub;
+  get postsHub(): ISubscriptionHub<string, TimelinePostsWithSyncState> {
+    return this._postsSubscriptionHub;
   }
 
   createPost(
@@ -567,14 +567,24 @@ export class TimelineService {
     return from(
       getHttpTimelineClient()
         .postPost(timelineName, request, user.token)
-        .then((res) => {
-          this._postListSubscriptionHub.update(timelineName, (_, old) => {
-            return Promise.resolve({
+        .then((post) =>
+          this.convertPost(post, () =>
+            Promise.resolve(
+              (request.content as TimelineCreatePostImageContent).data
+            )
+          )
+        )
+        .then((post) => {
+          this._postsSubscriptionHub.updateWithOld(timelineName, (old) => {
+            if (old instanceof NoValue) {
+              throw new Error('Posts has not been loaded.');
+            }
+            return {
               ...old,
-              posts: [...old.posts, { ...res, timelineName }],
-            });
+              posts: [...old.posts, post],
+            };
           });
-          return res;
+          return post;
         })
     ).pipe(map((post) => ({ ...post, timelineName })));
   }
@@ -585,11 +595,14 @@ export class TimelineService {
       getHttpTimelineClient()
         .deletePost(timelineName, postId, user.token)
         .then(() => {
-          this._postListSubscriptionHub.update(timelineName, (_, old) => {
-            return Promise.resolve({
+          this._postsSubscriptionHub.updateWithOld(timelineName, (old) => {
+            if (old instanceof NoValue) {
+              throw new Error('Posts has not been loaded.');
+            }
+            return {
               ...old,
               posts: old.posts.filter((post) => post.id != postId),
-            });
+            };
           });
         })
     );
@@ -663,19 +676,14 @@ export function validateTimelineName(name: string): boolean {
   return timelineNameReg.test(name);
 }
 
-export function usePostList(
-  timelineName: string | null | undefined
-): TimelinePostListState | undefined {
-  const [state, setState] = React.useState<TimelinePostListState | undefined>(
+export function useTimelineInfo(
+  timelineName: string
+): TimelineWithSyncState | undefined {
+  const [state, setState] = React.useState<TimelineWithSyncState | undefined>(
     undefined
   );
   React.useEffect(() => {
-    if (timelineName == null) {
-      setState(undefined);
-      return;
-    }
-
-    const subscription = timelineService.postListHub.subscribe(
+    const subscription = timelineService.timelineHub.subscribe(
       timelineName,
       (data) => {
         setState(data);
@@ -688,30 +696,27 @@ export function usePostList(
   return state;
 }
 
-export function usePostDataUrl(
-  enable: boolean,
-  timelineName: string,
-  postId: number
-): string | undefined {
-  const [url, setUrl] = React.useState<string | undefined>(undefined);
+export function usePostList(
+  timelineName: string | null | undefined
+): TimelinePostsWithSyncState | undefined {
+  const [state, setState] = React.useState<
+    TimelinePostsWithSyncState | undefined
+  >(undefined);
   React.useEffect(() => {
-    if (!enable) {
-      setUrl(undefined);
+    if (timelineName == null) {
+      setState(undefined);
       return;
     }
 
-    const subscription = timelineService.postDataHub.subscribe(
-      {
-        timelineName,
-        postId,
-      },
+    const subscription = timelineService.postsHub.subscribe(
+      timelineName,
       (data) => {
-        setUrl(data?.url);
+        setState(data);
       }
     );
     return () => {
       subscription.unsubscribe();
     };
-  }, [timelineName, postId, enable]);
-  return url;
+  }, [timelineName]);
+  return state;
 }
diff --git a/Timeline/ClientApp/src/app/data/user.ts b/Timeline/ClientApp/src/app/data/user.ts
index dec9929f..7d522b26 100644
--- a/Timeline/ClientApp/src/app/data/user.ts
+++ b/Timeline/ClientApp/src/app/data/user.ts
@@ -19,8 +19,6 @@ import {
   HttpUser,
 } from '../http/user';
 
-import { BlobWithUrl } from './common';
-
 export type User = HttpUser;
 
 export interface UserAuthInfo {
@@ -230,27 +228,16 @@ export function checkLogin(): UserWithToken {
 
 export class UserNotExistError extends Error {}
 
-export type AvatarInfo = BlobWithUrl;
-
 export class UserInfoService {
-  private _avatarSubscriptionHub = new SubscriptionHub<
-    string,
-    AvatarInfo | null
-  >(
-    (key) => key,
-    () => null,
-    async (key) => {
-      const blob = (await getHttpUserClient().getAvatar(key)).data;
-      const url = URL.createObjectURL(blob);
-      return {
-        blob,
-        url,
-      };
+  private _avatarSubscriptionHub = new SubscriptionHub<string, Blob>({
+    setup: (key, next) => {
+      void getHttpUserClient()
+        .getAvatar(key)
+        .then((res) => {
+          next(res.data);
+        });
     },
-    (_key, data) => {
-      if (data != null) URL.revokeObjectURL(data.url);
-    }
-  );
+  });
 
   getUserInfo(username: string): Observable<User> {
     return from(getHttpUserClient().get(username)).pipe(
@@ -261,40 +248,33 @@ export class UserInfoService {
   async setAvatar(username: string, blob: Blob): Promise<void> {
     const user = checkLogin();
     await getHttpUserClient().putAvatar(username, blob, user.token);
-    this._avatarSubscriptionHub.update(username, () =>
-      Promise.resolve({
-        blob,
-        url: URL.createObjectURL(blob),
-      })
-    );
+    this._avatarSubscriptionHub.update(username, blob);
   }
 
-  get avatarHub(): ISubscriptionHub<string, AvatarInfo | null> {
+  get avatarHub(): ISubscriptionHub<string, Blob> {
     return this._avatarSubscriptionHub;
   }
 }
 
 export const userInfoService = new UserInfoService();
 
-export function useAvatarUrl(username?: string): string | undefined {
-  const [avatarUrl, setAvatarUrl] = React.useState<string | undefined>(
-    undefined
-  );
+export function useAvatar(username?: string): Blob | undefined {
+  const [state, setState] = React.useState<Blob | undefined>(undefined);
   React.useEffect(() => {
     if (username == null) {
-      setAvatarUrl(undefined);
+      setState(undefined);
       return;
     }
 
     const subscription = userInfoService.avatarHub.subscribe(
       username,
-      (info) => {
-        setAvatarUrl(info?.url);
+      (blob) => {
+        setState(blob);
       }
     );
     return () => {
       subscription.unsubscribe();
     };
   }, [username]);
-  return avatarUrl;
+  return state;
 }
diff --git a/Timeline/ClientApp/src/app/timeline/TimelineInfoCard.tsx b/Timeline/ClientApp/src/app/timeline/TimelineInfoCard.tsx
index c25b2376..ece7d38a 100644
--- a/Timeline/ClientApp/src/app/timeline/TimelineInfoCard.tsx
+++ b/Timeline/ClientApp/src/app/timeline/TimelineInfoCard.tsx
@@ -10,10 +10,11 @@ import {
 import { useTranslation } from 'react-i18next';
 import { fromEvent } from 'rxjs';
 
-import { useAvatarUrl } from '../data/user';
+import { useAvatar } from '../data/user';
 import { timelineVisibilityTooltipTranslationMap } from '../data/timeline';
 
 import { TimelineCardComponentProps } from './TimelinePageTemplateUI';
+import BlobImage from '../common/BlobImage';
 
 export type OrdinaryTimelineManageItem = 'delete';
 
@@ -26,7 +27,7 @@ const TimelineInfoCard: React.FC<TimelineInfoCardProps> = (props) => {
 
   const { t } = useTranslation();
 
-  const avatarUrl = useAvatarUrl(props.timeline.owner.username);
+  const avatar = useAvatar(props.timeline.owner.username);
 
   // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
   const containerRef = React.useRef<HTMLDivElement>(null!);
@@ -60,8 +61,8 @@ const TimelineInfoCard: React.FC<TimelineInfoCardProps> = (props) => {
         {props.timeline.name}
       </h3>
       <div className="d-inline-block align-middle">
-        <img
-          src={avatarUrl}
+        <BlobImage
+          blob={avatar}
           onLoad={notifyHeight}
           className="avatar small rounded-circle"
         />
diff --git a/Timeline/ClientApp/src/app/timeline/TimelineItem.tsx b/Timeline/ClientApp/src/app/timeline/TimelineItem.tsx
index 11ac9f08..727de1fe 100644
--- a/Timeline/ClientApp/src/app/timeline/TimelineItem.tsx
+++ b/Timeline/ClientApp/src/app/timeline/TimelineItem.tsx
@@ -16,8 +16,10 @@ import Svg from 'react-inlinesvg';
 import chevronDownIcon from 'bootstrap-icons/icons/chevron-down.svg';
 import trashIcon from 'bootstrap-icons/icons/trash.svg';
 
-import { useAvatarUrl } from '../data/user';
-import { TimelinePostInfo, usePostDataUrl } from '../data/timeline';
+import BlobImage from '../common/BlobImage';
+
+import { useAvatar } from '../data/user';
+import { TimelinePostInfo } from '../data/timeline';
 
 const TimelinePostDeleteConfirmDialog: React.FC<{
   toggle: () => void;
@@ -70,13 +72,7 @@ const TimelineItem: React.FC<TimelineItemProps> = (props) => {
 
   const { more, onResize } = props;
 
-  const avatarUrl = useAvatarUrl(props.post.author.username);
-
-  const dataUrl = usePostDataUrl(
-    props.post.content.type === 'image',
-    props.post.timelineName,
-    props.post.id
-  );
+  const avatar = useAvatar(props.post.author.username);
 
   const [deleteDialog, setDeleteDialog] = React.useState<boolean>(false);
   const toggleDeleteDialog = React.useCallback(
@@ -132,7 +128,11 @@ const TimelineItem: React.FC<TimelineItemProps> = (props) => {
             className="float-right float-sm-left mx-2"
             to={'/users/' + props.post.author.username}
           >
-            <img onLoad={onResize} src={avatarUrl} className="avatar rounded" />
+            <BlobImage
+              onLoad={onResize}
+              blob={avatar}
+              className="avatar rounded"
+            />
           </Link>
           {(() => {
             const { content } = props.post;
@@ -140,9 +140,9 @@ const TimelineItem: React.FC<TimelineItemProps> = (props) => {
               return content.text;
             } else {
               return (
-                <img
+                <BlobImage
                   onLoad={onResize}
-                  src={dataUrl}
+                  blob={content.data}
                   className="timeline-content-image"
                 />
               );
diff --git a/Timeline/ClientApp/src/app/timeline/TimelineMember.tsx b/Timeline/ClientApp/src/app/timeline/TimelineMember.tsx
index 8c637f46..39af412e 100644
--- a/Timeline/ClientApp/src/app/timeline/TimelineMember.tsx
+++ b/Timeline/ClientApp/src/app/timeline/TimelineMember.tsx
@@ -10,9 +10,10 @@ import {
   Button,
 } from 'reactstrap';
 
-import { User, useAvatarUrl } from '../data/user';
+import { User, useAvatar } from '../data/user';
 
 import SearchInput from '../common/SearchInput';
+import BlobImage from '../common/BlobImage';
 
 const TimelineMemberItem: React.FC<{
   user: User;
@@ -21,13 +22,13 @@ const TimelineMemberItem: React.FC<{
 }> = ({ user, owner, onRemove }) => {
   const { t } = useTranslation();
 
-  const avatarUrl = useAvatarUrl(user.username);
+  const avatar = useAvatar(user.username);
 
   return (
     <ListGroupItem className="container">
       <Row>
         <Col className="col-auto">
-          <img src={avatarUrl} className="avatar small" />
+          <BlobImage blob={avatar} className="avatar small" />
         </Col>
         <Col>
           <Row>{user.nickname}</Row>
@@ -84,7 +85,7 @@ const TimelineMember: React.FC<TimelineMemberProps> = (props) => {
     | { type: 'init' }
   >({ type: 'init' });
 
-  const userSearchAvatarUrl = useAvatarUrl(
+  const userSearchAvatar = useAvatar(
     userSearchState.type === 'user' ? userSearchState.data.username : undefined
   );
 
@@ -156,8 +157,8 @@ const TimelineMember: React.FC<TimelineMemberProps> = (props) => {
                       <Container className="mb-3">
                         <Row>
                           <Col className="col-auto">
-                            <img
-                              src={userSearchAvatarUrl}
+                            <BlobImage
+                              blob={userSearchAvatar}
                               className="avatar small"
                             />
                           </Col>
diff --git a/Timeline/ClientApp/src/app/timeline/TimelinePageTemplate.tsx b/Timeline/ClientApp/src/app/timeline/TimelinePageTemplate.tsx
index a68d08c6..afa9464a 100644
--- a/Timeline/ClientApp/src/app/timeline/TimelinePageTemplate.tsx
+++ b/Timeline/ClientApp/src/app/timeline/TimelinePageTemplate.tsx
@@ -1,8 +1,7 @@
 import React from 'react';
 import { useTranslation } from 'react-i18next';
-import { concat, without } from 'lodash';
 import { of } from 'rxjs';
-import { catchError, map } from 'rxjs/operators';
+import { catchError } from 'rxjs/operators';
 
 import { ExcludeKey } from '../utilities/type';
 import { pushAlert } from '../common/alert-service';
@@ -10,8 +9,8 @@ import { useUser, userInfoService, UserNotExistError } from '../data/user';
 import {
   timelineService,
   TimelineInfo,
-  TimelineNotExistError,
   usePostList,
+  useTimelineInfo,
 } from '../data/timeline';
 
 import { TimelineDeleteCallback } from './Timeline';
@@ -51,34 +50,22 @@ export default function TimelinePageTemplate<
   const [dialog, setDialog] = React.useState<null | 'property' | 'member'>(
     null
   );
-  const [timeline, setTimeline] = React.useState<TimelineInfo | undefined>(
-    undefined
-  );
 
-  const postListState = usePostList(timeline?.name);
-
-  const [error, setError] = React.useState<string | undefined>(undefined);
-
-  React.useEffect(() => {
-    const subscription = service.getTimeline(name).subscribe(
-      (ti) => {
-        setTimeline(ti);
-      },
-      (error) => {
-        if (error instanceof TimelineNotExistError) {
-          setError(t(props.notFoundI18nKey));
-        } else {
-          setError(
-            // TODO: Convert this to a function.
-            (error as { message?: string })?.message ?? 'Unknown error'
-          );
-        }
-      }
-    );
-    return () => {
-      subscription.unsubscribe();
-    };
-  }, [name, service, user, t, props.dataVersion, props.notFoundI18nKey]);
+  const timelineState = useTimelineInfo(name);
+
+  const timeline = timelineState?.timeline;
+
+  const postListState = usePostList(name);
+
+  const error: string | undefined = (() => {
+    if (timelineState != null) {
+      const { syncState, timeline } = timelineState;
+      if (syncState === 'offline' && timeline == null) return 'Network Error';
+      if (syncState !== 'offline' && timeline == null)
+        return t(props.notFoundI18nKey);
+    }
+    return undefined;
+  })();
 
   const closeDialog = React.useCallback((): void => {
     setDialog(null);
@@ -102,14 +89,7 @@ export default function TimelinePageTemplate<
           description: timeline.description,
         }}
         onProcess={(req) => {
-          return service
-            .changeTimelineProperty(name, req)
-            .pipe(
-              map((newTimeline) => {
-                setTimeline(newTimeline);
-              })
-            )
-            .toPromise();
+          return service.changeTimelineProperty(name, req).toPromise().then();
         }}
       />
     );
@@ -143,33 +123,10 @@ export default function TimelinePageTemplate<
                     .toPromise();
                 },
                 onAddUser: (u) => {
-                  return service
-                    .addMember(name, u.username)
-                    .pipe(
-                      map(() => {
-                        setTimeline({
-                          ...timeline,
-                          members: concat(timeline.members, u),
-                        });
-                      })
-                    )
-                    .toPromise();
+                  return service.addMember(name, u.username).toPromise().then();
                 },
                 onRemoveUser: (u) => {
-                  service.removeMember(name, u).subscribe(() => {
-                    const toDelete = timeline.members.find(
-                      (m) => m.username === u
-                    );
-                    if (toDelete == null) {
-                      throw new UiLogicError(
-                        'The member to delete is not in list.'
-                      );
-                    }
-                    setTimeline({
-                      ...timeline,
-                      members: without(timeline.members, toDelete),
-                    });
-                  });
+                  service.removeMember(name, u);
                 },
               }
             : null
@@ -220,7 +177,7 @@ export default function TimelinePageTemplate<
     <>
       <UiComponent
         error={error}
-        timeline={timeline}
+        timeline={timeline ?? undefined}
         postListState={postListState}
         onDelete={onDelete}
         onPost={
diff --git a/Timeline/ClientApp/src/app/timeline/TimelinePageTemplateUI.tsx b/Timeline/ClientApp/src/app/timeline/TimelinePageTemplateUI.tsx
index dc5bfda8..42171e13 100644
--- a/Timeline/ClientApp/src/app/timeline/TimelinePageTemplateUI.tsx
+++ b/Timeline/ClientApp/src/app/timeline/TimelinePageTemplateUI.tsx
@@ -12,7 +12,7 @@ import { getAlertHost } from '../common/alert-service';
 import { useEventEmiiter, UiLogicError } from '../common';
 import {
   TimelineInfo,
-  TimelinePostListState,
+  TimelinePostsWithSyncState,
   timelineService,
 } from '../data/timeline';
 import { userService } from '../data/user';
@@ -24,8 +24,10 @@ import Timeline, {
 import AppBar from '../common/AppBar';
 import TimelinePostEdit, { TimelinePostSendCallback } from './TimelinePostEdit';
 
+type TimelinePostSyncState = 'syncing' | 'synced' | 'offline';
+
 const TimelinePostSyncStateBadge: React.FC<{
-  state: 'syncing' | 'synced' | 'offline';
+  state: TimelinePostSyncState;
   style?: CSSProperties;
   className?: string;
 }> = ({ state, style, className }) => {
@@ -84,7 +86,7 @@ export interface TimelineCardComponentProps<TManageItems> {
 export interface TimelinePageTemplateUIProps<TManageItems> {
   avatarKey?: string | number;
   timeline?: TimelineInfo;
-  postListState?: TimelinePostListState;
+  postListState?: TimelinePostsWithSyncState;
   CardComponent: React.ComponentType<TimelineCardComponentProps<TManageItems>>;
   onMember: () => void;
   onManage?: (item: TManageItems | 'property') => void;
@@ -197,7 +199,7 @@ export default function TimelinePageTemplateUI<TManageItems>(
   } else {
     if (timeline != null) {
       let timelineBody: React.ReactElement;
-      if (postListState != null && postListState.state !== 'loading') {
+      if (postListState != null) {
         if (postListState.state === 'forbid') {
           timelineBody = (
             <p className="text-danger">{t('timeline.messageCantSee')}</p>
diff --git a/Timeline/ClientApp/src/app/user/UserInfoCard.tsx b/Timeline/ClientApp/src/app/user/UserInfoCard.tsx
index 8b1294c4..0f321f32 100644
--- a/Timeline/ClientApp/src/app/user/UserInfoCard.tsx
+++ b/Timeline/ClientApp/src/app/user/UserInfoCard.tsx
@@ -11,9 +11,10 @@ import { useTranslation } from 'react-i18next';
 import { fromEvent } from 'rxjs';
 
 import { timelineVisibilityTooltipTranslationMap } from '../data/timeline';
-import { useAvatarUrl } from '../data/user';
+import { useAvatar } from '../data/user';
 
 import { TimelineCardComponentProps } from '../timeline/TimelinePageTemplateUI';
+import BlobImage from '../common/BlobImage';
 
 export type PersonalTimelineManageItem = 'avatar' | 'nickname';
 
@@ -25,7 +26,7 @@ const UserInfoCard: React.FC<UserInfoCardProps> = (props) => {
   const { onHeight, onManage } = props;
   const { t } = useTranslation();
 
-  const avatarUrl = useAvatarUrl(props.timeline.owner.username);
+  const avatar = useAvatar(props.timeline.owner.username);
 
   // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
   const containerRef = React.useRef<HTMLDivElement>(null!);
@@ -55,8 +56,8 @@ const UserInfoCard: React.FC<UserInfoCardProps> = (props) => {
       className={clsx('rounded border bg-light p-2', props.className)}
       onTransitionEnd={notifyHeight}
     >
-      <img
-        src={avatarUrl}
+      <BlobImage
+        blob={avatar}
         onLoad={notifyHeight}
         className="avatar large mr-2 mb-2 rounded-circle float-left"
       />