Fixed calculation of mention count for direct channels (#3831)

* Fixed clientside calculation of direct channel mention count

* Fixed serverside calculation of direct channel mention count

store/sql_user_store.go

@@ -982,7 +982,7 @@ func (us SqlUserStore) GetUnreadCount(userId string) StoreChannel {
 	go func() {
 		result := StoreResult{}
 
-		if count, err := us.GetReplica().SelectInt("SELECT SUM(CASE WHEN c.Type = 'D' THEN (c.TotalMsgCount - cm.MsgCount) ELSE 0 END + cm.MentionCount) FROM Channels c INNER JOIN ChannelMembers cm ON cm.ChannelId = c.Id AND cm.UserId = :UserId", map[string]interface{}{"UserId": userId}); err != nil {
+		if count, err := us.GetReplica().SelectInt("SELECT SUM(CASE WHEN c.Type = 'D' THEN (c.TotalMsgCount - cm.MsgCount) ELSE cm.MentionCount END) FROM Channels c INNER JOIN ChannelMembers cm ON cm.ChannelId = c.Id AND cm.UserId = :UserId", map[string]interface{}{"UserId": userId}); err != nil {
 			result.Err = model.NewLocAppError("SqlUserStore.GetMentionCount", "store.sql_user.get_unread_count.app_error", nil, err.Error())
 		} else {
 			result.Data = count

store/sql_user_store_test.go

@@ -647,12 +647,14 @@ func TestUserUnreadCount(t *testing.T) {
 	p2.UserId = u1.Id
 	p2.Message = "first message"
 	Must(store.Post().Save(&p2))
+	Must(store.Channel().IncrementMentionCount(c2.Id, u2.Id))
 
 	p3 := model.Post{}
 	p3.ChannelId = c2.Id
 	p3.UserId = u1.Id
 	p3.Message = "second message"
 	Must(store.Post().Save(&p3))
+	Must(store.Channel().IncrementMentionCount(c2.Id, u2.Id))
 
 	badge := (<-store.User().GetUnreadCount(u2.Id)).Data.(int64)
 	if badge != 3 {

webapp/stores/channel_store.jsx

@@ -325,7 +325,7 @@ class ChannelStoreClass extends EventEmitter {
         const chMember = this.getMember(id);
 
         let chMentionCount = chMember.mention_count;
-        let chUnreadCount = ch.total_msg_count - chMember.msg_count - chMentionCount;
+        let chUnreadCount = ch.total_msg_count - chMember.msg_count;
 
         if (ch.type === 'D') {
             chMentionCount = chUnreadCount;