MM-11272 Added initial post metadata (#9175)

* MM-11272 Added app.PreparePostForClient

* MM-11272 Added app.PreparePostListForClient

* MM-11272 Added EmojiStore.GetMultipleByName

* MM-11272 Added emojis to PreparePostForClient

* MM-11272 Added unit tests for getting reaction counts

* MM-11272 Added unit tests for TestPreparePostForClient

* MM-11272 Added emojis from reactions to Post.Emojis

* MM-11272 Always update post.UpdateAt when reactions change to bust cache

* Fixed merge conflicts

* Moved post metadata-related code into its own file

* Update store mocks

* Fixed typo

* Add missing license headers

* Updated post metadata tests when custom emojis are disabled

* Fix unreliable unit tests

* Fix inconsistent casing in SQL statements

* Fix blank line

* Invalidate store cache after making changes

* Clear post cache synchronously with reactions

app/reaction.go

@@ -6,6 +6,7 @@ package app
 import (
 	"net/http"
 
+	"github.com/mattermost/mattermost-server/mlog"
 	"github.com/mattermost/mattermost-server/model"
 )
 
@@ -42,6 +43,9 @@ func (a *App) SaveReactionForPost(reaction *model.Reaction) (*model.Reaction, *m
 
 	reaction = result.Data.(*model.Reaction)
 
+	// The post is always modified since the UpdateAt always changes
+	a.InvalidateCacheForChannelPosts(post.ChannelId)
+
 	a.Go(func() {
 		a.sendReactionEvent(model.WEBSOCKET_EVENT_REACTION_ADDED, reaction, post, true)
 	})
@@ -92,6 +96,9 @@ func (a *App) DeleteReactionForPost(reaction *model.Reaction) *model.AppError {
 		return result.Err
 	}
 
+	// The post is always modified since the UpdateAt always changes
+	a.InvalidateCacheForChannelPosts(post.ChannelId)
+
 	a.Go(func() {
 		a.sendReactionEvent(model.WEBSOCKET_EVENT_REACTION_REMOVED, reaction, post, hasReactions)
 	})
@@ -105,11 +112,15 @@ func (a *App) sendReactionEvent(event string, reaction *model.Reaction, post *mo
 	message.Add("reaction", reaction.ToJson())
 	a.Publish(message)
 
-	// The post is always modified since the UpdateAt always changes
-	a.InvalidateCacheForChannelPosts(post.ChannelId)
-	post.HasReactions = hasReactions
-	post.UpdateAt = model.GetMillis()
+	clientPost, err := a.PreparePostForClient(post)
+	if err != nil {
+		mlog.Error("Failed to prepare new post for client after reaction", mlog.Any("err", err))
+	}
+
+	clientPost.HasReactions = hasReactions
+	clientPost.UpdateAt = model.GetMillis()
+
 	umessage := model.NewWebSocketEvent(model.WEBSOCKET_EVENT_POST_EDITED, "", post.ChannelId, "", nil)
-	umessage.Add("post", a.PostWithProxyAddedToImageURLs(post).ToJson())
+	umessage.Add("post", clientPost.ToJson())
 	a.Publish(umessage)
 }