remember last used chat page

src/ViewModel/chatViewModel.tsx

@@ -1,12 +1,14 @@
 import * as React from "bloatless-react";
 
+import StorageModel, { storageKeys } from "../Model/storageModel";
+
 import ChatListViewModel from "./chatListViewModel";
 import { ChatModel } from "../Model/chatModel";
-import StorageModel from "../Model/storageModel";
 
 export default class ChatViewModel {
   chatModel: ChatModel;
   chatListViewModel: ChatListViewModel;
+  storageModel: StorageModel;
 
   // state
   primaryChannel: React.State<string> = new React.State("");
@@ -25,30 +27,46 @@ export default class ChatViewModel {
   );
 
   // methods
-  open = () => {
+  open = (): void => {
     this.chatListViewModel.openChat(this);
   };
 
-  close = () => {
+  close = (): void => {
     this.chatListViewModel.closeChat();
   };
 
+  // restore
+  restorePageSelection = (): void => {
+    const path: string[] = storageKeys.chatLastUsedPage(this.chatModel.id);
+    const lastUsedPage: string | null = this.storageModel.restore(path);
+    if (lastUsedPage != null) {
+      this.selectedPage.value = lastUsedPage as any;
+    }
+
+    this.selectedPage.subscribeSilent((newPage) => {
+      this.storageModel.store(path, newPage);
+    });
+  };
+
   // init
   constructor(chatListViewModel: ChatListViewModel, chatModel: ChatModel) {
     this.chatModel = chatModel;
+    this.storageModel = chatModel.storageModel;
     this.chatListViewModel = chatListViewModel;
 
     this.primaryChannel.value = chatModel.info.primaryChannel;
     this.primaryChannelInput.value = chatModel.info.primaryChannel;
+
+    this.restorePageSelection();
   }
 }
 
 // types
 export enum ChatPageType {
-  Settings,
-  Messages,
-  AllObjects,
-  Kanban,
-  Calendar,
-  Progress,
+  Settings = "settings",
+  Messages = "messages",
+  AllObjects = "all",
+  Kanban = "kanban",
+  Calendar = "calendar",
+  Progress = "progress",
 }