[MM-28363] User Limit Overage Warning Emails (#16053)

* Adding files, commit of UI in good shape

* Translations added, working with activation and deactivation

* Add check for error

* Fix i18n?

* Push without subscription check so Steve and Matt can look at it

* Fix font-weight in chrome

* Fix font-weight on button

* UX fixes

* Fixes for PR

* Add back subscription stuff

* Fix tests

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

app/app_iface.go

@@ -388,6 +388,7 @@ type AppIface interface {
 	CancelJob(jobId string) *model.AppError
 	ChannelMembersToAdd(since int64, channelID *string) ([]*model.UserChannelIDPair, *model.AppError)
 	ChannelMembersToRemove(teamID *string) ([]*model.ChannelMember, *model.AppError)
+	CheckAndSendUserLimitWarningEmails() *model.AppError
 	CheckForClientSideCert(r *http.Request) (string, string, string)
 	CheckPasswordAndAllCriteria(user *model.User, password string, mfaToken string) *model.AppError
 	CheckRolesExist(roleNames []string) *model.AppError

app/cloud.go

@@ -0,0 +1,57 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package app
+
+import (
+	"github.com/mattermost/mattermost-server/v5/model"
+)
+
+func (a *App) CheckAndSendUserLimitWarningEmails() *model.AppError {
+	if a.Srv().License() == nil || (a.Srv().License() != nil && !*a.Srv().License().Features.Cloud) {
+		// Not cloud instance, do nothing
+		return nil
+	}
+
+	subscription, subErr := a.Cloud().GetSubscription()
+	if subErr != nil {
+		return subErr
+	}
+
+	if subscription != nil && subscription.IsPaidTier == "true" {
+		// Paid subscription, do nothing
+		return nil
+	}
+
+	cloudUserLimit := *a.Config().ExperimentalSettings.CloudUserLimit
+	systemUserCount, _ := a.Srv().Store.User().Count(model.UserCountOptions{})
+	remainingUsers := cloudUserLimit - systemUserCount
+
+	if remainingUsers > 0 {
+		return nil
+	}
+	userOptions := &model.UserGetOptions{
+		Page:     0,
+		PerPage:  100,
+		Role:     model.SYSTEM_ADMIN_ROLE_ID,
+		Inactive: false,
+	}
+	sysAdmins, err := a.GetUsers(userOptions)
+	if err != nil {
+		return err
+	}
+
+	// -1 means they are 1 user over the limit - we only want to send the email for the 11th user
+	if remainingUsers == -1 {
+		// Over limit by 1 user
+		for admin := range sysAdmins {
+			a.Srv().EmailService.SendOverUserLimitWarningEmail(sysAdmins[admin].Email, sysAdmins[admin].Locale, *a.Config().ServiceSettings.SiteURL)
+		}
+	} else if remainingUsers == 0 {
+		// At limit
+		for admin := range sysAdmins {
+			a.Srv().EmailService.SendAtUserLimitWarningEmail(sysAdmins[admin].Email, sysAdmins[admin].Locale, *a.Config().ServiceSettings.SiteURL)
+		}
+	}
+	return nil
+}

app/email.go

@@ -589,3 +589,47 @@ func (es *EmailService) CreateVerifyEmailToken(userId string, newEmail string) (
 
 	return token, nil
 }
+
+func (es *EmailService) SendAtUserLimitWarningEmail(email string, locale string, siteURL string) (bool, *model.AppError) {
+	T := utils.GetUserTranslations(locale)
+
+	subject := T("api.templates.at_limit_subject")
+
+	bodyPage := es.newEmailTemplate("reached_user_limit_body", locale)
+	bodyPage.Props["SiteURL"] = siteURL
+	bodyPage.Props["Title"] = T("api.templates.at_limit_title")
+	bodyPage.Props["Info1"] = T("api.templates.at_limit_info1")
+	bodyPage.Props["Info2"] = T("api.templates.at_limit_info2")
+	bodyPage.Props["Button"] = T("api.templates.upgrade_mattermost_cloud")
+	bodyPage.Props["EmailUs"] = T("api.templates.email_us_anytime_at")
+
+	bodyPage.Props["Footer"] = T("api.templates.copyright")
+
+	if err := es.sendMail(email, subject, bodyPage.Render()); err != nil {
+		return false, model.NewAppError("SendAtUserLimitWarningEmail", "api.user.send_password_reset.send.app_error", nil, "err="+err.Message, http.StatusInternalServerError)
+	}
+
+	return true, nil
+}
+
+func (es *EmailService) SendOverUserLimitWarningEmail(email string, locale string, siteURL string) (bool, *model.AppError) {
+	T := utils.GetUserTranslations(locale)
+
+	subject := T("api.templates.over_limit_subject")
+
+	bodyPage := es.newEmailTemplate("reached_user_limit_body", locale)
+	bodyPage.Props["SiteURL"] = siteURL
+	bodyPage.Props["Title"] = T("api.templates.over_limit_title")
+	bodyPage.Props["Info1"] = T("api.templates.over_limit_info1")
+	bodyPage.Props["Info2"] = T("api.templates.over_limit_info2")
+	bodyPage.Props["Button"] = T("api.templates.upgrade_mattermost_cloud")
+	bodyPage.Props["EmailUs"] = T("api.templates.email_us_anytime_at")
+
+	bodyPage.Props["Footer"] = T("api.templates.copyright")
+
+	if err := es.sendMail(email, subject, bodyPage.Render()); err != nil {
+		return false, model.NewAppError("SendOverUserLimitWarningEmail", "api.user.send_password_reset.send.app_error", nil, "err="+err.Message, http.StatusInternalServerError)
+	}
+
+	return true, nil
+}

app/opentracing/opentracing_layer.go

@@ -1010,6 +1010,28 @@ func (a *OpenTracingAppLayer) ChannelMembersToRemove(teamID *string) ([]*model.C
 	return resultVar0, resultVar1
 }
 
+func (a *OpenTracingAppLayer) CheckAndSendUserLimitWarningEmails() *model.AppError {
+	origCtx := a.ctx
+	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.CheckAndSendUserLimitWarningEmails")
+
+	a.ctx = newCtx
+	a.app.Srv().Store.SetContext(newCtx)
+	defer func() {
+		a.app.Srv().Store.SetContext(origCtx)
+		a.ctx = origCtx
+	}()
+
+	defer span.Finish()
+	resultVar0 := a.app.CheckAndSendUserLimitWarningEmails()
+
+	if resultVar0 != nil {
+		span.LogFields(spanlog.Error(resultVar0))
+		ext.Error.Set(span, true)
+	}
+
+	return resultVar0
+}
+
 func (a *OpenTracingAppLayer) CheckForClientSideCert(r *http.Request) (string, string, string) {
 	origCtx := a.ctx
 	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.CheckForClientSideCert")