[MM-36431] Logic to support multiple configurable tabs per server (#1655)

* Updated config, added types and classes for messaging tab

* Working app with tabs and servers

* Remainder of logic

* Make base tab abstract class

* Account for new app case

* Merge'd

* PR feedback

src/common/tabs/TabView.ts

@@ -0,0 +1,61 @@
+// Copyright (c) 2016-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+import {Tab, Team} from 'types/config';
+
+import {MattermostServer} from 'common/servers/MattermostServer';
+
+import MessagingTabView from './MessagingTabView';
+import FocalboardTabView from './FocalboardTabView';
+import PlaybooksTabView from './PlaybooksTabView';
+
+export const TAB_MESSAGING = 'TAB_MESSAGING';
+export const TAB_FOCALBOARD = 'TAB_FOCALBOARD';
+export const TAB_PLAYBOOKS = 'TAB_PLAYBOOKS';
+export type TabType = typeof TAB_MESSAGING | typeof TAB_FOCALBOARD | typeof TAB_PLAYBOOKS;
+
+export interface TabView {
+    server: MattermostServer;
+
+    get name(): string;
+    get type(): TabType;
+    get url(): URL;
+}
+
+export function getDefaultTeamWithTabsFromTeam(team: Team) {
+    return {
+        ...team,
+        tabs: [
+            {
+                name: TAB_MESSAGING,
+                order: 0,
+            },
+            {
+                name: TAB_FOCALBOARD,
+                order: 1,
+            },
+            {
+                name: TAB_PLAYBOOKS,
+                order: 2,
+            },
+        ],
+    };
+}
+
+// TODO: Might need to move this out
+export function getServerView(srv: MattermostServer, tab: Tab) {
+    switch (tab.name) {
+    case TAB_MESSAGING:
+        return new MessagingTabView(srv);
+    case TAB_FOCALBOARD:
+        return new FocalboardTabView(srv);
+    case TAB_PLAYBOOKS:
+        return new PlaybooksTabView(srv);
+    default:
+        throw new Error('Not implemeneted');
+    }
+}
+
+export function getTabViewName(serverName: string, tabType: string) {
+    return `${serverName}___${tabType}`;
+}