MM-18054 CherryPick for 1.26 (#3698)

CherryPick for 1.26

app/components/post/index.js

@@ -10,6 +10,7 @@ import {isChannelReadOnlyById} from 'mattermost-redux/selectors/entities/channel
 import {getPost, makeGetCommentCountForPost, makeIsPostCommentMention} from 'mattermost-redux/selectors/entities/posts';
 import {getUser, getCurrentUserId} from 'mattermost-redux/selectors/entities/users';
 import {getMyPreferences, getTheme} from 'mattermost-redux/selectors/entities/preferences';
+import {isStartOfNewMessages} from 'mattermost-redux/utils/post_list';
 import {isPostFlagged, isSystemMessage} from 'mattermost-redux/utils/post_utils';
 
 import {insertToDraft, setPostTooltipVisible} from 'app/actions/views/channel';
@@ -40,7 +41,8 @@ function makeMapStateToProps() {
     const isPostCommentMention = makeIsPostCommentMention();
     return function mapStateToProps(state, ownProps) {
         const post = ownProps.post || getPost(state, ownProps.postId);
-        const previousPost = getPost(state, ownProps.previousPostId);
+        const previousPostId = isStartOfNewMessages(ownProps.previousPostId) ? ownProps.beforePrevPostId : ownProps.previousPostId;
+        const previousPost = getPost(state, previousPostId);
         const beforePrevPost = getPost(state, ownProps.beforePrevPostId);
 
         const myPreferences = getMyPreferences(state);
@@ -52,7 +54,7 @@ function makeMapStateToProps() {
         let commentedOnPost = null;
 
         if (ownProps.renderReplies && post && post.root_id) {
-            if (ownProps.previousPostId) {
+            if (previousPostId) {
                 if (previousPost && (previousPost.id === post.root_id || previousPost.root_id === post.root_id)) {
                     // Previous post is root post or previous post is in same thread
                     isFirstReply = false;

app/components/post/post.js

@@ -254,7 +254,6 @@ export default class Post extends PureComponent {
             isLandscape,
             previousPostExists,
             beforePrevPostUserId,
-            isFirstReply,
         } = this.props;
 
         if (!post) {
@@ -306,7 +305,6 @@ export default class Post extends PureComponent {
                     theme={theme}
                     previousPostExists={previousPostExists}
                     beforePrevPostUserId={beforePrevPostUserId}
-                    isFirstReply={isFirstReply}
                 />
             );
         }

app/components/post_header/__snapshots__/post_header.test.js.snap

@@ -311,6 +311,23 @@ exports[`PostHeader should match snapshot when post is same thread, so dont disp
       />
     </View>
   </View>
+  <FormattedText
+    defaultMessage="Commented on {name}{apostrophe} message: "
+    id="post_body.commentedOn"
+    style={
+      Object {
+        "color": "rgba(61,60,64,0.65)",
+        "lineHeight": 21,
+        "marginBottom": 3,
+      }
+    }
+    values={
+      Object {
+        "apostrophe": "'s",
+        "name": "John Doe",
+      }
+    }
+  />
 </React.Fragment>
 `;
 

app/components/post_header/post_header.js

@@ -46,7 +46,6 @@ export default class PostHeader extends PureComponent {
         previousPostExists: PropTypes.bool,
         post: PropTypes.object,
         beforePrevPostUserId: PropTypes.string,
-        isFirstReply: PropTypes.bool,
     };
 
     static defaultProps = {
@@ -69,9 +68,8 @@ export default class PostHeader extends PureComponent {
             previousPostExists,
             renderReplies,
             theme,
-            isFirstReply,
         } = this.props;
-        if (!isFirstReply || !renderReplies || !commentedOnDisplayName || (!previousPostExists && post.user_id === beforePrevPostUserId)) {
+        if (!renderReplies || !commentedOnDisplayName || (!previousPostExists && post.user_id === beforePrevPostUserId)) {
             return null;
         }