[MM-27535] User invite limits for MM Cloud (#15197)

* Add a config for MM User Limit

* Adding graceful errors for if an administrator invites people passed their user limit

* Including changed vendor files

* Adding unit test

* Fix a bug

* Push up working tests (Thanks Joram)

* Add more cases, clean up logs in code

* One more case

* Refactoring based on PR comments

* Updating i18n

* Some changes based on PR review

* Remove a comment

* Bring back some translations that were somehow removed

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/team.go

@@ -1127,6 +1127,47 @@ func (a *App) prepareInviteNewUsersToTeam(teamId, senderId string) (*model.User,
 	return user, team, nil
 }
 
+func genEmailInviteWithErrorList(emailList []string) []*model.EmailInviteWithError {
+	invitesNotSent := make([]*model.EmailInviteWithError, len(emailList))
+	for i := range emailList {
+		invite := &model.EmailInviteWithError{
+			Email: emailList[i],
+			Error: model.NewAppError("inviteUsersToTeam", "api.team.invite_members.limit_reached.app_error", map[string]interface{}{"Addresses": emailList[i]}, "", http.StatusBadRequest),
+		}
+		invitesNotSent[i] = invite
+	}
+	return invitesNotSent
+}
+
+func (a *App) GetErrorListForEmailsOverLimit(emailList []string, cloudUserLimit int64) ([]string, []*model.EmailInviteWithError, *model.AppError) {
+	var invitesNotSent []*model.EmailInviteWithError
+	if cloudUserLimit <= 0 {
+		return emailList, invitesNotSent, nil
+	}
+	systemUserCount, _ := a.Srv().Store.User().Count(model.UserCountOptions{})
+	remainingUsers := cloudUserLimit - systemUserCount
+	if remainingUsers <= 0 {
+		// No remaining users so all fail
+		invitesNotSent = genEmailInviteWithErrorList(emailList)
+		emailList = nil
+	} else if remainingUsers < int64(len(emailList)) {
+		// Trim the email list to only invite as many users as are remaining in subscription
+		// Set graceful errors for the remaining email addresses
+		emailsAboveLimit := emailList[remainingUsers:]
+		invitesNotSent = genEmailInviteWithErrorList(emailsAboveLimit)
+		// If 1 user remaining we have to prevent 0:0 reslicing
+		if remainingUsers == 1 {
+			email := emailList[0]
+			emailList = nil
+			emailList = append(emailList, email)
+		} else {
+			emailList = emailList[:(remainingUsers - 1)]
+		}
+	}
+
+	return emailList, invitesNotSent, nil
+}
+
 func (a *App) InviteNewUsersToTeamGracefully(emailList []string, teamId, senderId string) ([]*model.EmailInviteWithError, *model.AppError) {
 	if !*a.Config().ServiceSettings.EnableEmailInvitations {
 		return nil, model.NewAppError("InviteNewUsersToTeam", "api.team.invite_members.disabled.app_error", nil, "", http.StatusNotImplemented)
@@ -1136,7 +1177,6 @@ func (a *App) InviteNewUsersToTeamGracefully(emailList []string, teamId, senderI
 		err := model.NewAppError("InviteNewUsersToTeam", "api.team.invite_members.no_one.app_error", nil, "", http.StatusBadRequest)
 		return nil, err
 	}
-
 	user, team, err := a.prepareInviteNewUsersToTeam(teamId, senderId)
 	if err != nil {
 		return nil, err