Do not sync users when there is no need (#512)

server/plugin.go

@@ -694,7 +694,7 @@ func (p *Plugin) syncUsers() {
 		if msUser.Type == msteamsUserTypeGuest {
 			// Check if syncing of MS Teams guest users is disabled.
 			if !syncGuestUsers {
-				if isUserPresent && isRemoteUser(mmUser) {
+				if isUserPresent && isRemoteUser(mmUser) && mmUser.DeleteAt == 0 {
 					// Deactivate the Mattermost user corresponding to the MS Teams guest user.
 					p.API.LogInfo("Deactivating the guest user account", "user_id", mmUser.Id, "teams_user_id", msUser.ID)
 					if err := p.API.UpdateUserActive(mmUser.Id, false); err != nil {
@@ -767,23 +767,34 @@ func (p *Plugin) syncUsers() {
 			if err = p.store.SetUserInfo(newUser.Id, msUser.ID, nil); err != nil {
 				p.API.LogWarn("Unable to set user info during sync user job", "user_id", newUser.Id, "teams_user_id", msUser.ID, "error", err.Error())
 			}
-		} else if (username != mmUser.Username || msUser.DisplayName != mmUser.FirstName) && mmUser.RemoteId != nil {
-			mmUser.Username = username
-			mmUser.FirstName = msUser.DisplayName
-			for {
-				_, err := p.API.UpdateUser(mmUser)
-				if err != nil {
-					if err.Id == "app.user.save.username_exists.app_error" {
-						mmUser.Username += "-" + fmt.Sprint(userSuffixID)
-						userSuffixID++
-						continue
+		} else if mmUser.RemoteId != nil {
+			shouldUpdate := false
+			if !strings.HasPrefix(mmUser.Username, "msteams_") && username != mmUser.Username {
+				mmUser.Username = username
+				shouldUpdate = true
+			}
+
+			if mmUser.FirstName != msUser.DisplayName {
+				mmUser.FirstName = msUser.DisplayName
+				shouldUpdate = true
+			}
+
+			if shouldUpdate {
+				for {
+					_, err := p.API.UpdateUser(mmUser)
+					if err != nil {
+						if err.Id == "app.user.save.username_exists.app_error" {
+							mmUser.Username = username + "-" + fmt.Sprint(userSuffixID)
+							userSuffixID++
+							continue
+						}
+
+						p.API.LogWarn("Unable to update user during sync user job", "user_id", mmUser.Id, "teams_user_id", msUser.ID, "error", err.Error())
+						break
 					}
 
-					p.API.LogWarn("Unable to update user during sync user job", "user_id", mmUser.Id, "teams_user_id", msUser.ID, "error", err.Error())
 					break
 				}
-
-				break
 			}
 		}
 	}