PLT-2672 Refactored posts view with caching (#3054)

* Refactored posts view to use view controller design

* Add post view caching

* Required updates after rebase

* Fixed bug where current channel not set yet was causing breakage

webapp/utils/post_utils.jsx

@@ -0,0 +1,32 @@
+// Copyright (c) 2016 Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+import Client from 'utils/web_client.jsx';
+
+import Constants from 'utils/constants.jsx';
+
+export function isSystemMessage(post) {
+    return post.type && (post.type.lastIndexOf(Constants.SYSTEM_MESSAGE_PREFIX) === 0);
+}
+
+export function isComment(post) {
+    if ('root_id' in post) {
+        return post.root_id !== '' && post.root_id != null;
+    }
+    return false;
+}
+
+export function getProfilePicSrcForPost(post, timestamp) {
+    let src = Client.getUsersRoute() + '/' + post.user_id + '/image?time=' + timestamp;
+    if (post.props && post.props.from_webhook && global.window.mm_config.EnablePostIconOverride === 'true') {
+        if (post.props.override_icon_url) {
+            src = post.props.override_icon_url;
+        } else {
+            src = Constants.DEFAULT_WEBHOOK_LOGO;
+        }
+    } else if (isSystemMessage(post)) {
+        src = Constants.SYSTEM_MESSAGE_PROFILE_IMAGE;
+    }
+
+    return src;
+}