You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: security_update_check.go
    path of file: ./repos/mattermost/server/channels/app
    
    the code of the file until where you have to start completion: // Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.

package app

import (
	"encoding/json"
	"io"
	"net/http"
	"net/url"
	"runtime"
	"strconv"

	"github.com/mattermost/mattermost/server/public/model"
	"github.com/mattermost/mattermost/server/public/shared/i18n"
	"github.com/mattermost/mattermost/server/public/shared/mlog"
	"github.com/mattermost/mattermost/server/v8/platform/shared/mail"
)

const (
	PropSecurityURL      = "https://securityupdatecheck.mattermost.com"
	SecurityUpdatePeriod = 86400000 // 24 hours in milliseconds.

	PropSecurityID              = "id"
	PropSecurityBuild           = "b"
	PropSecurityEnterpriseReady = "be"
	PropSecurityDatabase        = "db"
	PropSecuri
    
func (s *Server) DoSecurityUpdateCheck() {
	if !*s.platform.Config().ServiceSettings.EnableSecurityFixAlert {
		return
	}

	props, err := s.Store().System().Get()
	if err != nil {
		return
	}

	lastSecurityTime, _ := strconv.ParseInt(props[model.SystemLastSecurityTime], 10, 0)
	currentTime := model.GetMillis()

	if (currentTime - lastSecurityTime) > SecurityUpdatePeriod {
		mlog.Debug("Checking for security update from Mattermost")

		v := url.Values{}

		v.Set(PropSecurityID, s.TelemetryId())
		v.Set(PropSecurityBuild, model.CurrentVersion+"."+model.BuildNumber)
		v.Set(PropSecurityEnterpriseReady, model.BuildEnterpriseReady)
		v.Set(PropSecurityDatabase, *s.platform.Config().SqlSettings.DriverName)
		v.Set(PropSecurityOS, runtime.GOOS)

		if props[model.SystemRanUnitTests] != "" {
			v.Set(PropSecurityUnitTests, "1")
		} else {
			v.Set(PropSecurityUnitTests, "0")
		}

		systemSecurityLastTime := &model.System{Name: model.SystemLastSecurityTime, Value: strconv.FormatInt(currentTime, 10)}
		if lastSecurityTime == 0 {
			s.Store().System().Save(systemSecurityLastTime)
		} else {
			s.Store().System().Update(systemSecurityLastTime)
		}

		if count, err := s.Store().User().Count(model.UserCountOptions{IncludeDeleted: true}); err == nil {
			v.Set(PropSecurityUserCount, strconv.FormatInt(count, 10))
		}

		if ucr, err := s.Store().Status().GetTotalActiveUsersCount(); err == nil {
			v.Set(PropSecurityActiveUserCount, strconv.FormatInt(ucr, 10))
		}

		if teamCount, err := s.Store().Team().AnalyticsTeamCount(nil); err == nil {
			v.Set(PropSecurityTeamCount, strconv.FormatInt(teamCount, 10))
		}

		res, err := http.Get(PropSecurityURL + "/security?" + v.Encode())
		if err != nil {
			mlog.Error("Failed to get security update information from Mattermost.")
			return
		}

		defer res.Body.Close()

		var bulletins model.SecurityBulletins
		if jsonErr := json.NewDecoder(res.Body).Decode(&bulletins); jsonErr != nil {
			s.Log().Error("Failed to decode JSON", mlog.Err(jsonErr))
			return
		}

		for _, bulletin := range bulletins {
			if bulletin.AppliesToVersion == model.CurrentVersion {
				if props["SecurityBulletin_"+bulletin.Id] == "" {
					users, userErr := s.Store().User().GetSystemAdminProfiles()
					if userErr != nil {
						mlog.Error("Failed to get system admins for security update information from Mattermost.")
						return
					}

					resBody, err := http.Get(PropSecurityURL + "/bulletins/" + bulletin.Id)
					if err != nil {
						mlog.Error("Failed to get security bulletin details")
						return
					}

					body, err := io.ReadAll(resBody.Body)
					resBody.Body.Close()
					if err != nil || resBody.StatusCode != 200 {
						mlog.Error("Failed to read security bulletin details")
						return
					}

					for _, user := range users {
						mlog.Info("Sending security bulletin", mlog.String("bulletin_id", bulletin.Id), mlog.String("user_email", user.Email))
						license := s.License()
						mailConfig := s.MailServiceConfig()
						mail.SendMailUsingConfig(user.Email, i18n.T("mattermost.bulletin.subject"), string(body), mailConfig, license != nil && *license.Features.Compliance, "", "", "", "", "SecurityUpdateCheck")
					}

					bulletinSeen := &model.System{Name: "SecurityBulletin_" + bulletin.Id, Value: bulletin.Id}
					s.Store().System().Save(bulletinSeen)
				}
			}
		}
	}
}