// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.

package email

import (
	"bytes"
	"encoding/json"
	"fmt"
	"html/template"
	"io"
	"net/http"
	"net/url"
	"strings"
	"time"

	"github.com/pkg/errors"

	"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/public/shared/request"
	"github.com/mattermost/mattermost/server/v8/platform/shared/mail"
	"github.com/mattermost/mattermost/server/v8/platform/shared/templates"

	"github.com/microcosm-cc/bluemonday"
)

// Returns category if enabled is true (default false)
// If "" is returned when enabled is false, the category headers aren't attached to the email
func getSendGridCategory(category string, enabled bool) string {
	if enabled {
		return category
	}
	return ""
}

func (es *Service) SendChangeUsernameEmail(newUsername, email, locale, siteURL string) error {
	T := i18n.GetUserTranslations(locale)

	subject := T("api.templates.username_change_subject",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName,
			"TeamDisplayName": es.config().TeamSettings.SiteName})

	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = T("api.templates.username_change_body.title")
	data.Props["Info"] = T("api.templates.username_change_body.info",
		map[string]any{"TeamDisplayName": es.config().TeamSettings.SiteName, "NewUsername": newUsername})
	data.Props["Warning"] = T("api.templates.email_warning")

	body, err := es.templatesContainer.RenderToString("email_change_body", data)
	if err != nil {
		return err
	}

	if err := es.sendMail(email, subject, body, "ChangeUsernameEmail"); err != nil {
		return err
	}

	return nil
}

func (es *Service) SendEmailChangeVerifyEmail(newUserEmail, locale, siteURL, token string) error {
	T := i18n.GetUserTranslations(locale)

	link := fmt.Sprintf("%s/do_verify_email?token=%s&email=%s", siteURL, token, url.QueryEscape(newUserEmail))

	subject := T("api.templates.email_change_verify_subject",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName,
			"TeamDisplayName": es.config().TeamSettings.SiteName})

	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = T("api.templates.email_change_verify_body.title")
	data.Props["Info"] = T("api.templates.email_change_verify_body.info",
		map[string]any{"TeamDisplayName": es.config().TeamSettings.SiteName})
	data.Props["VerifyUrl"] = link
	data.Props["VerifyButton"] = T("api.templates.email_change_verify_body.button")
	data.Props["QuestionTitle"] = T("api.templates.questions_footer.title")
	data.Props["EmailInfo1"] = T("api.templates.email_us_anytime_at")
	data.Props["SupportEmail"] = "feedback@mattermost.com"
	data.Props["FooterV2"] = T("api.templates.email_footer_v2", map[string]any{"CurrentYear": time.Now().Year()})

	body, err := es.templatesContainer.RenderToString("email_change_verify_body", data)
	if err != nil {
		return err
	}

	if err := es.sendMail(newUserEmail, subject, body, "EmailChangeVerifyEmail"); err != nil {
		return err
	}

	return nil
}

func (es *Service) SendEmailChangeEmail(oldEmail, newEmail, locale, siteURL string) error {
	T := i18n.GetUserTranslations(locale)

	subject := T("api.templates.email_change_subject",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName,
			"TeamDisplayName": es.config().TeamSettings.SiteName})

	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = T("api.templates.email_change_body.title")
	data.Props["Info"] = T("api.templates.email_change_body.info",
		map[string]any{"TeamDisplayName": es.config().TeamSettings.SiteName, "NewEmail": newEmail})
	data.Props["Warning"] = T("api.templates.email_warning")

	body, err := es.templatesContainer.RenderToString("email_change_body", data)
	if err != nil {
		return err
	}

	if err := es.sendMail(oldEmail, subject, body, "EmailChangeEmail"); err != nil {
		return err
	}

	return nil
}

func (es *Service) SendVerifyEmail(userEmail, locale, siteURL, token, redirect string) error {
	T := i18n.GetUserTranslations(locale)

	link := fmt.Sprintf("%s/do_verify_email?token=%s&email=%s", siteURL, token, url.QueryEscape(userEmail))
	if redirect != "" {
		link += fmt.Sprintf("&redirect_to=%s", redirect)
	}

	serverURL := condenseSiteURL(siteURL)

	subject := T("api.templates.verify_subject",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName})

	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = T("api.templates.verify_body.title")
	data.Props["SubTitle1"] = T("api.templates.verify_body.subTitle1")
	data.Props["ServerURL"] = T("api.templates.verify_body.serverURL", map[string]any{"ServerURL": serverURL})
	data.Props["SubTitle2"] = T("api.templates.verify_body.subTitle2")
	data.Props["ButtonURL"] = link
	data.Props["Button"] = T("api.templates.verify_body.button")
	data.Props["Info"] = T("api.templates.verify_body.info")
	data.Props["Info1"] = T("api.templates.verify_body.info1")
	data.Props["QuestionTitle"] = T("api.templates.questions_footer.title")
	data.Props["QuestionInfo"] = T("api.templates.questions_footer.info")

	body, err := es.templatesContainer.RenderToString("verify_body", data)
	if err != nil {
		return err
	}

	if err := es.sendMail(userEmail, subject, body, "VerifyEmail"); err != nil {
		return err
	}

	return nil
}

func (es *Service) SendSignInChangeEmail(email, method, locale, siteURL string) error {
	T := i18n.GetUserTranslations(locale)

	subject := T("api.templates.signin_change_email.subject",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName})

	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = T("api.templates.signin_change_email.body.title")
	data.Props["Info"] = T("api.templates.signin_change_email.body.info",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName, "Method": method})
	data.Props["Warning"] = T("api.templates.email_warning")

	body, err := es.templatesContainer.RenderToString("signin_change_body", data)
	if err != nil {
		return err
	}

	if err := es.sendMail(email, subject, body, "SignInChangeEmail"); err != nil {
		return err
	}

	return nil
}

func (es *Service) SendWelcomeEmail(userID string, email string, verified bool, disableWelcomeEmail bool, locale, siteURL, redirect string) error {
	if disableWelcomeEmail {
		return nil
	}
	if !*es.config().EmailSettings.SendEmailNotifications && !*es.config().EmailSettings.RequireEmailVerification {
		return errors.New("send email notifications and require email verification is disabled in the system console")
	}

	T := i18n.GetUserTranslations(locale)

	serverURL := condenseSiteURL(siteURL)

	subject := T("api.templates.welcome_subject",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName,
			"ServerURL": serverURL})

	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = T("api.templates.welcome_body.title")
	data.Props["SubTitle1"] = T("api.templates.welcome_body.subTitle1")
	data.Props["ServerURL"] = T("api.templates.welcome_body.serverURL", map[string]any{"ServerURL": serverURL})
	data.Props["SubTitle2"] = T("api.templates.welcome_body.subTitle2")
	data.Props["Button"] = T("api.templates.welcome_body.button")
	data.Props["Info"] = T("api.templates.welcome_body.info")
	data.Props["Info1"] = T("api.templates.welcome_body.info1")
	data.Props["SiteURL"] = siteURL

	if *es.config().NativeAppSettings.AppDownloadLink != "" {
		data.Props["AppDownloadTitle"] = T("api.templates.welcome_body.app_download_title")
		data.Props["AppDownloadInfo"] = T("api.templates.welcome_body.app_download_info")
		data.Props["AppDownloadButton"] = T("api.templates.welcome_body.app_download_button")
		data.Props["AppDownloadLink"] = *es.config().NativeAppSettings.AppDownloadLink
	}

	if !verified && *es.config().EmailSettings.RequireEmailVerification {
		token, err := es.CreateVerifyEmailToken(userID, email)
		if err != nil {
			return err
		}
		link := fmt.Sprintf("%s/do_verify_email?token=%s&email=%s", siteURL, token.Token, url.QueryEscape(email))
		if redirect != "" {
			link += fmt.Sprintf("&redirect_to=%s", redirect)
		}
		data.Props["ButtonURL"] = link
	}

	body, err := es.templatesContainer.RenderToString("welcome_body", data)
	if err != nil {
		return err
	}

	if err := es.sendMail(email, subject, body, "WelcomeEmail"); err != nil {
		return err
	}

	return nil
}

// SendCloudWelcomeEmail sends the cloud version of the welcome email
func (es *Service) SendCloudWelcomeEmail(userEmail, locale, teamInviteID, workSpaceName, dns, siteURL string) error {
	T := i18n.GetUserTranslations(locale)
	subject := T("api.templates.cloud_welcome_email.subject")

	data := es.NewEmailTemplateData(locale)
	data.Props["Title"] = T("api.templates.cloud_welcome_email.title")
	data.Props["SubTitle"] = T("api.templates.cloud_welcome_email.subtitle")
	data.Props["SubTitleInfo"] = T("api.templates.cloud_welcome_email.subtitle_info")
	data.Props["Info"] = T("api.templates.cloud_welcome_email.info")
	data.Props["Info2"] = T("api.templates.cloud_welcome_email.info2")
	data.Props["WorkSpacePath"] = siteURL
	data.Props["DNS"] = dns
	data.Props["InviteInfo"] = T("api.templates.cloud_welcome_email.invite_info")
	data.Props["InviteSubInfo"] = T("api.templates.cloud_welcome_email.invite_sub_info", map[string]any{"WorkSpace": workSpaceName})
	data.Props["InviteSubInfoLink"] = fmt.Sprintf("%s/signup_user_complete/?id=%s", siteURL, teamInviteID)
	data.Props["AddAppsInfo"] = T("api.templates.cloud_welcome_email.add_apps_info")
	data.Props["AddAppsSubInfo"] = T("api.templates.cloud_welcome_email.add_apps_sub_info")
	data.Props["AppMarketPlace"] = T("api.templates.cloud_welcome_email.app_market_place")
	data.Props["AppMarketPlaceLink"] = "https://integrations.mattermost.com/"
	data.Props["DownloadMMInfo"] = T("api.templates.cloud_welcome_email.download_mm_info")
	data.Props["SignInSubInfo"] = T("api.templates.cloud_welcome_email.signin_sub_info")
	data.Props["MMApps"] = T("api.templates.cloud_welcome_email.mm_apps")
	data.Props["SignInSubInfo2"] = T("api.templates.cloud_welcome_email.signin_sub_info2")
	if es.config().NativeAppSettings.AppDownloadLink != nil && *es.config().NativeAppSettings.AppDownloadLink != "" {
		data.Props["DownloadMMAppsLink"] = es.config().NativeAppSettings.AppDownloadLink
	} else {
		data.Props["DownloadMMAppsLink"] = "https://mattermost.com/pl/download-apps"
	}
	data.Props["Button"] = T("api.templates.cloud_welcome_email.button")
	data.Props["GettingStartedQuestions"] = T("api.templates.cloud_welcome_email.start_questions")

	body, err := es.templatesContainer.RenderToString("cloud_welcome_email", data)
	if err != nil {
		return err
	}

	if err := es.sendEmailWithCustomReplyTo(userEmail, subject, body, *es.config().SupportSettings.SupportEmail, "CloudWelcomeEmail"); err != nil {
		return err
	}

	return nil
}

func (es *Service) SendPasswordChangeEmail(email, method, locale, siteURL string) error {
	T := i18n.GetUserTranslations(locale)

	subject := T("api.templates.password_change_subject",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName,
			"TeamDisplayName": es.config().TeamSettings.SiteName})

	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = T("api.templates.password_change_body.title")
	data.Props["Info"] = T("api.templates.password_change_body.info",
		map[string]any{"TeamDisplayName": es.config().TeamSettings.SiteName, "TeamURL": siteURL, "Method": method})
	data.Props["Warning"] = T("api.templates.email_warning")

	body, err := es.templatesContainer.RenderToString("password_change_body", data)
	if err != nil {
		return err
	}

	if err := es.sendMail(email, subject, body, "PasswordChangeEmail"); err != nil {
		return err
	}

	return nil
}

func (es *Service) SendUserAccessTokenAddedEmail(email, locale, siteURL string) error {
	T := i18n.GetUserTranslations(locale)

	subject := T("api.templates.user_access_token_subject",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName})

	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = T("api.templates.user_access_token_body.title")
	data.Props["Info"] = T("api.templates.user_access_token_body.info",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName, "SiteURL": siteURL})
	data.Props["Warning"] = T("api.templates.email_warning")

	body, err := es.templatesContainer.RenderToString("password_change_body", data)
	if err != nil {
		return err
	}

	if err := es.sendMail(email, subject, body, "UserAccessTokenAddedEmail"); err != nil {
		return err
	}

	return nil
}

func (es *Service) SendUserAccessTokenRotatedEmail(email, locale, siteURL string) error {
	T := i18n.GetUserTranslations(locale)

	subject := T("api.templates.user_access_token_rotated_subject",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName})

	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = T("api.templates.user_access_token_rotated_body.title")
	data.Props["Info"] = T("api.templates.user_access_token_rotated_body.info",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName, "SiteURL": siteURL})
	data.Props["Warning"] = T("api.templates.email_warning")

	body, err := es.templatesContainer.RenderToString("password_change_body", data)
	if err != nil {
		return err
	}

	if err := es.sendMail(email, subject, body, "UserAccessTokenRotatedEmail"); err != nil {
		return err
	}

	return nil
}

func (es *Service) SendPasswordResetEmail(email string, token *model.Token, locale, siteURL string) (bool, error) {
	T := i18n.GetUserTranslations(locale)

	link := fmt.Sprintf("%s/reset_password_complete?token=%s", siteURL, url.QueryEscape(token.Token))

	subject := T("api.templates.reset_subject",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName})

	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = T("api.templates.reset_body.title")
	data.Props["SubTitle"] = T("api.templates.reset_body.subTitle")
	data.Props["Info"] = T("api.templates.reset_body.info")
	data.Props["ButtonURL"] = link
	data.Props["Button"] = T("api.templates.reset_body.button")
	data.Props["QuestionTitle"] = T("api.templates.questions_footer.title")
	data.Props["QuestionInfo"] = T("api.templates.questions_footer.info")

	body, err := es.templatesContainer.RenderToString("reset_body", data)
	if err != nil {
		return false, err
	}

	if err := es.sendMail(email, subject, body, "PasswordResetEmail"); err != nil {
		return false, err
	}

	return true, nil
}

func (es *Service) SendMfaChangeEmail(email string, activated bool, locale, siteURL string) error {
	T := i18n.GetUserTranslations(locale)

	subject := T("api.templates.mfa_change_subject",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName})

	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL

	if activated {
		data.Props["Info"] = T("api.templates.mfa_activated_body.info", map[string]any{"SiteURL": siteURL})
		data.Props["Title"] = T("api.templates.mfa_activated_body.title")
	} else {
		data.Props["Info"] = T("api.templates.mfa_deactivated_body.info", map[string]any{"SiteURL": siteURL})
		data.Props["Title"] = T("api.templates.mfa_deactivated_body.title")
	}
	data.Props["Warning"] = T("api.templates.email_warning")

	body, err := es.templatesContainer.RenderToString("mfa_change_body", data)
	if err != nil {
		return err
	}

	if err := es.sendMail(email, subject, body, "MfaChangeEmail"); err != nil {
		return err
	}

	return nil
}

func buildInviteTokenData(team *model.Team, invite string, profile *model.MemberInviteProfile) (map[string]string, map[string]string) {
	tokenExtra := map[string]string{"teamId": team.Id, "email": invite}
	tokenProps := map[string]string{
		"email":        invite,
		"display_name": team.DisplayName,
		"name":         team.Name,
	}

	// The token extra is authoritative at signup; the link props are prefill only.
	if profile != nil {
		for key, value := range map[string]string{
			"username":   profile.Username,
			"first_name": profile.FirstName,
			"last_name":  profile.LastName,
		} {
			tokenExtra[key] = value
			tokenProps[key] = value
		}
	}

	return tokenExtra, tokenProps
}

func (es *Service) SendInviteEmails(rctx request.CTX, inviteData InviteEmailData) error {
	if es.perHourEmailRateLimiter == nil {
		return NoRateLimiterError
	}
	rateLimited, result, err := es.perHourEmailRateLimiter.RateLimitCtx(rctx.Context(), inviteData.SenderUserID, len(inviteData.Invites))
	if err != nil {
		return SetupRateLimiterError
	}

	if rateLimited {
		mlog.Error("rate limit exceeded", mlog.Duration("retry_after", result.RetryAfter), mlog.Duration("reset_after", result.ResetAfter), mlog.String("user_id", inviteData.SenderUserID),
			mlog.String("team_id", inviteData.Team.Id), mlog.String("retry_after_secs", fmt.Sprintf("%f", result.RetryAfter.Seconds())), mlog.String("reset_after_secs", fmt.Sprintf("%f", result.ResetAfter.Seconds())))
		return RateLimitExceededError
	}

	for _, invite := range inviteData.Invites {
		if invite != "" {
			subject := i18n.T("api.templates.invite_subject",
				map[string]any{"SenderName": inviteData.SenderName,
					"TeamDisplayName": inviteData.Team.DisplayName,
					"SiteName":        es.config().TeamSettings.SiteName})

			data := es.NewEmailTemplateData("")
			data.Props["SiteURL"] = inviteData.SiteURL
			data.Props["SubTitle"] = i18n.T("api.templates.invite_body.subTitle")
			data.Props["Button"] = i18n.T("api.templates.invite_body.button")
			data.Props["SenderName"] = inviteData.SenderName
			data.Props["InviteFooterTitle"] = i18n.T("api.templates.invite_body_footer.title")
			data.Props["InviteFooterInfo"] = i18n.T("api.templates.invite_body_footer.info")
			data.Props["InviteFooterLearnMore"] = i18n.T("api.templates.invite_body_footer.learn_more")

			tokenExtra, tokenProps := buildInviteTokenData(inviteData.Team, invite, inviteData.Profiles[invite])

			token := model.NewToken(
				TokenTypeTeamInvitation,
				model.MapToJSON(tokenExtra),
			)

			title := i18n.T("api.templates.invite_body.title", map[string]any{"SenderName": inviteData.SenderName, "TeamDisplayName": inviteData.Team.DisplayName})
			if inviteData.ReminderData != nil {
				reminder := i18n.T("api.templates.invite_body.title.reminder")
				title = fmt.Sprintf("%s: %s", reminder, title)
				tokenProps["reminder_interval"] = inviteData.ReminderData.Interval
			}

			data.Props["Title"] = title

			tokenData := model.MapToJSON(tokenProps)

			if err := es.store.Token().Save(token); err != nil {
				mlog.Error("Failed to send invite email successfully ", mlog.Err(err))
				continue
			}

			queryString := url.Values{}
			queryString.Add("d", tokenData)
			queryString.Add("t", token.Token)
			queryString.Add("md", "email")
			queryString.Add("sbr", es.GetTrackFlowStartedByRole(inviteData.IsFirstAdmin, inviteData.IsSystemAdmin))
			data.Props["ButtonURL"] = fmt.Sprintf("%s/signup_user_complete/?%s", inviteData.SiteURL, queryString.Encode())

			body, err := es.templatesContainer.RenderToString("invite_body", data)
			if err != nil {
				mlog.Error("Failed to send invite email successfully ", mlog.Err(err))
			}

			if err := es.sendMail(invite, subject, body, "InviteEmail"); err != nil {
				mlog.Error("Failed to send invite email successfully ", mlog.Err(err))
				if inviteData.ErrorWhenNotSent {
					return SendMailError
				}
			}
		}
	}
	return nil
}

const magicLinkURL = "%s/landing#/login/one_time_link?t=%s"

func (es *Service) SendGuestInviteEmails(
	rctx request.CTX,
	team *model.Team,
	channels []*model.Channel,
	senderName string,
	senderUserId string,
	senderProfileImage []byte,
	invites []string,
	siteURL string,
	message string,
	errorWhenNotSent bool,
	isSystemAdmin bool,
	isFirstAdmin bool,
	isGuestMagicLink bool,
) error {
	if es.perHourEmailRateLimiter == nil {
		return NoRateLimiterError
	}
	rateLimited, result, err := es.perHourEmailRateLimiter.RateLimitCtx(rctx.Context(), senderUserId, len(invites))
	if err != nil {
		return SetupRateLimiterError
	}

	if rateLimited {
		mlog.Error("rate limit exceeded", mlog.Duration("retry_after", result.RetryAfter), mlog.Duration("reset_after", result.ResetAfter), mlog.String("user_id", senderUserId),
			mlog.String("team_id", team.Id), mlog.String("retry_after_secs", fmt.Sprintf("%f", result.RetryAfter.Seconds())), mlog.String("reset_after_secs", fmt.Sprintf("%f", result.ResetAfter.Seconds())))
		return RateLimitExceededError
	}

	for _, invite := range invites {
		if invite != "" {
			subject := i18n.T("api.templates.invite_guest_subject",
				map[string]any{"SenderName": senderName,
					"TeamDisplayName": team.DisplayName,
					"SiteName":        es.config().TeamSettings.SiteName})

			data := es.NewEmailTemplateData("")
			data.Props["SiteURL"] = siteURL
			data.Props["Title"] = i18n.T("api.templates.invite_body.title", map[string]any{"SenderName": senderName, "TeamDisplayName": team.DisplayName})
			data.Props["SubTitle"] = i18n.T("api.templates.invite_body_guest.subTitle")
			data.Props["Button"] = i18n.T("api.templates.invite_body.button")
			data.Props["SenderName"] = senderName
			if message != "" {
				message = bluemonday.NewPolicy().Sanitize(message)
			}
			data.Props["Message"] = message
			data.Props["InviteFooterTitle"] = i18n.T("api.templates.invite_body_footer.title")
			data.Props["InviteFooterInfo"] = i18n.T("api.templates.invite_body_footer.info")
			data.Props["InviteFooterLearnMore"] = i18n.T("api.templates.invite_body_footer.learn_more")

			channelIDs := []string{}
			for _, channel := range channels {
				channelIDs = append(channelIDs, channel.Id)
			}

			tokenType := TokenTypeGuestInvitation
			if isGuestMagicLink {
				tokenType = TokenTypeGuestMagicLinkInvitation
			}

			token := model.NewToken(
				tokenType,
				model.MapToJSON(map[string]string{
					"teamId":   team.Id,
					"channels": strings.Join(channelIDs, " "),
					"email":    invite,
					"guest":    "true",
					"senderId": senderUserId,
				}),
			)

			tokenProps := make(map[string]string)
			tokenProps["email"] = invite
			tokenProps["display_name"] = team.DisplayName
			tokenProps["name"] = team.Name
			tokenData := model.MapToJSON(tokenProps)

			if err := es.store.Token().Save(token); err != nil {
				mlog.Error("Failed to send invite email successfully ", mlog.Err(err))
				continue
			}

			if isGuestMagicLink {
				// Guest magic link uses SSO-style authentication - clicking the link sends them to the landing page and logs them in directly
				data.Props["ButtonURL"] = fmt.Sprintf(magicLinkURL, siteURL, url.QueryEscape(token.Token))
			} else {
				data.Props["ButtonURL"] = fmt.Sprintf("%s/signup_user_complete/?d=%s&t=%s&sbr=%s", siteURL, url.QueryEscape(tokenData), url.QueryEscape(token.Token), es.GetTrackFlowStartedByRole(isFirstAdmin, isSystemAdmin))
			}

			if !*es.config().EmailSettings.SendEmailNotifications {
				mlog.Info("sending invitation ", mlog.String("to", invite), mlog.String("link", data.Props["ButtonURL"].(string)))
			}

			senderPhoto := ""
			embeddedFiles := make(map[string]io.Reader)
			if message != "" {
				if senderProfileImage != nil {
					senderPhoto = "user-avatar.png"
					embeddedFiles = map[string]io.Reader{
						senderPhoto: bytes.NewReader(senderProfileImage),
					}
				}
			}

			pData := postData{
				SenderName:  senderName,
				Message:     template.HTML(message),
				SenderPhoto: senderPhoto,
			}

			data.Props["Posts"] = []postData{pData}

			body, err := es.templatesContainer.RenderToString("invite_body", data)
			if err != nil {
				mlog.Error("Failed to send invite email successfully", mlog.Err(err))
			}

			if nErr := es.SendMailWithEmbeddedFiles(invite, subject, body, embeddedFiles, "", "", "", "InviteEmail"); nErr != nil {
				mlog.Error("Failed to send invite email successfully", mlog.Err(nErr))
				if errorWhenNotSent {
					return SendMailError
				}
			}
		}
	}
	return nil
}

// SendMagicLinkEmailSelfService sends a passwordless login link to an existing guest user
// This is for self-service login requests (no sender, no team/channel context).
// For admin-initiated guest magic link invitations with team/channel assignment, use SendGuestInviteEmails with isGuestMagicLink=true.
func (es *Service) SendMagicLinkEmailSelfService(
	rctx request.CTX,
	invite string,
	siteURL string,
) error {
	if es.perHourEmailRateLimiter == nil {
		return NoRateLimiterError
	}

	// Rate limit by email address for self-service requests
	rateLimited, result, err := es.perMinuteEmailRateLimiter.RateLimitCtx(rctx.Context(), invite, 1)
	if err != nil {
		return SetupRateLimiterError
	}

	if rateLimited {
		mlog.Error("rate limit exceeded", mlog.Duration("retry_after", result.RetryAfter), mlog.Duration("reset_after", result.ResetAfter), mlog.String("email", invite),
			mlog.String("retry_after_secs", fmt.Sprintf("%f", result.RetryAfter.Seconds())), mlog.String("reset_after_secs", fmt.Sprintf("%f", result.ResetAfter.Seconds())))
		return RateLimitExceededError
	}

	if invite == "" {
		return nil
	}

	subject := i18n.T("api.templates.guest_magic_link_subject",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName})

	data := es.NewEmailTemplateData("")
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = i18n.T("api.templates.guest_magic_link_body.title")
	data.Props["SubTitle"] = i18n.T("api.templates.guest_magic_link_body.subtitle")
	data.Props["Button"] = i18n.T("api.templates.invite_body.button")
	data.Props["InviteFooterTitle"] = i18n.T("api.templates.guest_magic_link_body.footer.title")
	data.Props["InviteFooterInfo"] = i18n.T("api.templates.guest_magic_link_body.footer.info")

	// Login-only token - no team or channel info needed
	token, err := es.store.Token().GetTokenByTypeAndEmail(TokenTypeGuestMagicLink, invite)
	if err != nil || token.IsExpired() {
		// No existing token found, create a new one
		token = model.NewToken(
			TokenTypeGuestMagicLink,
			model.MapToJSON(map[string]string{
				"email": invite,
			}),
		)
	}

	if saveErr := es.store.Token().Save(token); saveErr != nil {
		mlog.Error("Failed to save guest magic link token", mlog.Err(saveErr))
		return fmt.Errorf("%w: %v", SaveTokenError, saveErr)
	}

	// Guest magic link uses SSO-style authentication - clicking the link sends them to the landing page and logs them in directly
	data.Props["ButtonURL"] = fmt.Sprintf(magicLinkURL, siteURL, url.QueryEscape(token.Token))

	if !*es.config().EmailSettings.SendEmailNotifications {
		mlog.Info("sending guest magic link", mlog.String("to", invite))
	}

	body, err := es.templatesContainer.RenderToString("invite_body", data)
	if err != nil {
		mlog.Error("Failed to send guest magic link email successfully", mlog.Err(err))
	}

	if nErr := es.SendMailWithEmbeddedFiles(invite, subject, body, nil, "", "", "", "GuestMagicLinkEmail"); nErr != nil {
		mlog.Error("Failed to send guest magic link email successfully", mlog.Err(nErr))
	}

	return nil
}

func (es *Service) SendInviteEmailsToTeamAndChannels(rctx request.CTX, inviteData InviteEmailData) ([]*model.EmailInviteWithError, error) {
	if es.perHourEmailRateLimiter == nil {
		return nil, NoRateLimiterError
	}
	rateLimited, result, err := es.perHourEmailRateLimiter.RateLimitCtx(rctx.Context(), inviteData.SenderUserID, len(inviteData.Invites))
	if err != nil {
		return nil, SetupRateLimiterError
	}

	if rateLimited {
		mlog.Error("rate limit exceeded", mlog.Duration("retry_after", result.RetryAfter), mlog.Duration("reset_after", result.ResetAfter), mlog.String("user_id", inviteData.SenderUserID),
			mlog.String("team_id", inviteData.Team.Id), mlog.String("retry_after_secs", fmt.Sprintf("%f", result.RetryAfter.Seconds())), mlog.String("reset_after_secs", fmt.Sprintf("%f", result.ResetAfter.Seconds())))
		return nil, RateLimitExceededError
	}

	channelsLen := len(inviteData.Channels)

	subject := i18n.T("api.templates.invite_team_and_channels_subject", map[string]any{
		"SenderName":      inviteData.SenderName,
		"TeamDisplayName": inviteData.Team.DisplayName,
		"ChannelsLen":     channelsLen,
		"SiteName":        es.config().TeamSettings.SiteName})

	title := i18n.T("api.templates.invite_team_and_channels_body.title", map[string]any{
		"SenderName":      inviteData.SenderName,
		"ChannelsLen":     channelsLen,
		"TeamDisplayName": inviteData.Team.DisplayName})

	if channelsLen == 1 {
		channelName := inviteData.Channels[0].DisplayName

		subject = i18n.T("api.templates.invite_team_and_channel_subject",
			map[string]any{"SenderName": inviteData.SenderName,
				"TeamDisplayName": inviteData.Team.DisplayName,
				"ChannelName":     channelName,
				"SiteName":        es.config().TeamSettings.SiteName},
		)

		title = i18n.T("api.templates.invite_team_and_channel_body.title", map[string]any{
			"SenderName":      inviteData.SenderName,
			"ChannelName":     channelName,
			"TeamDisplayName": inviteData.Team.DisplayName,
		})
	}

	var invitesWithErrors []*model.EmailInviteWithError
	for _, invite := range inviteData.Invites {
		if invite == "" {
			continue
		}
		channelIDs := []string{}
		for _, channel := range inviteData.Channels {
			channelIDs = append(channelIDs, channel.Id)
		}

		data := es.NewEmailTemplateData("")
		data.Props["SiteURL"] = inviteData.SiteURL
		data.Props["SubTitle"] = i18n.T("api.templates.invite_body.subTitle")
		data.Props["Button"] = i18n.T("api.templates.invite_body.button")
		data.Props["SenderName"] = inviteData.SenderName
		data.Props["InviteFooterTitle"] = i18n.T("api.templates.invite_body_footer.title")
		data.Props["InviteFooterInfo"] = i18n.T("api.templates.invite_body_footer.info")
		data.Props["InviteFooterLearnMore"] = i18n.T("api.templates.invite_body_footer.learn_more")

		if inviteData.Message != "" {
			inviteData.Message = bluemonday.NewPolicy().Sanitize(inviteData.Message)
		}
		data.Props["Message"] = inviteData.Message

		tokenExtra, tokenProps := buildInviteTokenData(inviteData.Team, invite, inviteData.Profiles[invite])
		tokenExtra["channels"] = strings.Join(channelIDs, " ")
		tokenExtra["senderId"] = inviteData.SenderUserID

		token := model.NewToken(
			TokenTypeTeamInvitation,
			model.MapToJSON(tokenExtra),
		)

		if inviteData.ReminderData != nil {
			reminder := i18n.T("api.templates.invite_body.title.reminder")
			title = fmt.Sprintf("%s: %s", reminder, title)
			tokenProps["reminder_interval"] = inviteData.ReminderData.Interval
		}

		data.Props["Title"] = title

		tokenData := model.MapToJSON(tokenProps)

		if err := es.store.Token().Save(token); err != nil {
			mlog.Error("Failed to send invite email successfully ", mlog.Err(err))
			continue
		}

		data.Props["ButtonURL"] = fmt.Sprintf("%s/signup_user_complete/?d=%s&t=%s&sbr=%s", inviteData.SiteURL, url.QueryEscape(tokenData), url.QueryEscape(token.Token), es.GetTrackFlowStartedByRole(inviteData.IsFirstAdmin, inviteData.IsSystemAdmin))

		senderPhoto := ""
		embeddedFiles := make(map[string]io.Reader)
		if inviteData.Message != "" {
			if inviteData.SenderProfileImage != nil {
				senderPhoto = "user-avatar.png"
				embeddedFiles = map[string]io.Reader{
					senderPhoto: bytes.NewReader(inviteData.SenderProfileImage),
				}
			}
		}
		pData := postData{
			SenderName:  inviteData.SenderName,
			Message:     template.HTML(inviteData.Message),
			SenderPhoto: senderPhoto,
		}

		data.Props["Posts"] = []postData{pData}

		body, err := es.templatesContainer.RenderToString("invite_body", data)
		if err != nil {
			mlog.Error("Failed to send invite email successfully ", mlog.Err(err))
		}

		if nErr := es.SendMailWithEmbeddedFiles(invite, subject, body, embeddedFiles, "", "", "", "InviteEmailToTeamsAndChannels"); nErr != nil {
			mlog.Error("Failed to send invite email successfully", mlog.Err(nErr))
			if inviteData.ErrorWhenNotSent {
				inviteWithError := &model.EmailInviteWithError{
					Email: invite,
					Error: &model.AppError{Message: nErr.Error()},
				}
				invitesWithErrors = append(invitesWithErrors, inviteWithError)
			}
		}
	}
	return invitesWithErrors, nil
}

func (es *Service) NewEmailTemplateData(locale string) templates.Data {
	var localT i18n.TranslateFunc
	if locale != "" {
		localT = i18n.GetUserTranslations(locale)
	} else {
		localT = i18n.T
	}
	organization := ""

	if *es.config().EmailSettings.FeedbackOrganization != "" {
		organization = localT("api.templates.email_organization") + *es.config().EmailSettings.FeedbackOrganization
	}

	return templates.Data{
		Props: map[string]any{
			"EmailInfo1": localT("api.templates.email_info1"),
			"EmailInfo2": localT("api.templates.email_info2"),
			"EmailInfo3": localT("api.templates.email_info3",
				map[string]any{"SiteName": es.config().TeamSettings.SiteName}),
			"SupportEmail": *es.config().SupportSettings.SupportEmail,
			"Footer":       localT("api.templates.email_footer"),
			"FooterV2":     localT("api.templates.email_footer_v2", map[string]any{"CurrentYear": time.Now().Year()}),
			"Organization": organization,
		},
		HTML: map[string]template.HTML{},
	}
}

func (es *Service) SendDeactivateAccountEmail(email string, locale, siteURL string) error {
	T := i18n.GetUserTranslations(locale)

	serverURL := condenseSiteURL(siteURL)

	subject := T("api.templates.deactivate_subject",
		map[string]any{"SiteName": es.config().TeamSettings.SiteName,
			"ServerURL": serverURL})

	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = T("api.templates.deactivate_body.title", map[string]any{"ServerURL": serverURL})
	data.Props["Info"] = T("api.templates.deactivate_body.info",
		map[string]any{"SiteURL": siteURL})
	data.Props["Warning"] = T("api.templates.deactivate_body.warning")

	body, err := es.templatesContainer.RenderToString("deactivate_body", data)
	if err != nil {
		return err
	}

	if err := es.sendMail(email, subject, body, "DeactivateAccountEmail"); err != nil { // this needs to receive the header options
		return err
	}

	return nil
}

func (es *Service) SendNotificationMail(to, subject, htmlBody string) error {
	if !*es.config().EmailSettings.SendEmailNotifications {
		return nil
	}
	return es.sendMail(to, subject, htmlBody, "NotificationEmail")
}

func (es *Service) sendMail(to, subject, htmlBody, category string) error {
	return es.sendMailWithCC(to, subject, htmlBody, "", category)
}

func (es *Service) sendEmailWithCustomReplyTo(to, subject, htmlBody, replyToAddress, category string) error {
	license := es.license()
	mailConfig := es.mailServiceConfig(replyToAddress)

	category = getSendGridCategory(category, license.IsCloud())

	return mail.SendMailUsingConfig(to, subject, htmlBody, mailConfig, license != nil && *license.Features.Compliance, "", "", "", "", category)
}

func (es *Service) sendMailWithCC(to, subject, htmlBody, ccMail, category string) error {
	license := es.license()
	mailConfig := es.mailServiceConfig("")

	category = getSendGridCategory(category, license.IsCloud())

	return mail.SendMailUsingConfig(to, subject, htmlBody, mailConfig, license != nil && *license.Features.Compliance, "", "", "", ccMail, category)
}

func (es *Service) SendMailWithEmbeddedFilesAndCustomReplyTo(to, subject, htmlBody, replyToAddress string, embeddedFiles map[string]io.Reader, category string) error {
	license := es.license()
	mailConfig := es.mailServiceConfig(replyToAddress)

	category = getSendGridCategory(category, license.IsCloud())

	return mail.SendMailWithEmbeddedFilesUsingConfig(to, subject, htmlBody, embeddedFiles, mailConfig, license != nil && *license.Features.Compliance, "", "", "", "", category)
}

func (es *Service) SendMailWithEmbeddedFiles(to, subject, htmlBody string, embeddedFiles map[string]io.Reader, messageID string, inReplyTo string, references string, category string) error {
	license := es.license()
	mailConfig := es.mailServiceConfig("")

	category = getSendGridCategory(category, license.IsCloud())

	return mail.SendMailWithEmbeddedFilesUsingConfig(to, subject, htmlBody, embeddedFiles, mailConfig, license != nil && *license.Features.Compliance, messageID, inReplyTo, references, "", category)
}

func (es *Service) InvalidateVerifyEmailTokensForUser(userID string) *model.AppError {
	tokens, err := es.store.Token().GetAllTokensByType(TokenTypeVerifyEmail)
	if err != nil {
		return model.NewAppError("InvalidateVerifyEmailTokensForUser", "api.user.invalidate_verify_email_tokens.error", nil, "", http.StatusInternalServerError).Wrap(err)
	}

	var appErr *model.AppError
	for _, token := range tokens {
		tokenExtra := struct {
			UserId string
			Email  string
		}{}
		if err := json.Unmarshal([]byte(token.Extra), &tokenExtra); err != nil {
			appErr = model.NewAppError("InvalidateVerifyEmailTokensForUser", "api.user.invalidate_verify_email_tokens_parse.error", nil, "", http.StatusInternalServerError).Wrap(err)
			continue
		}

		if tokenExtra.UserId != userID {
			continue
		}

		if err := es.store.Token().Delete(token.Token); err != nil {
			appErr = model.NewAppError("InvalidateVerifyEmailTokensForUser", "api.user.invalidate_verify_email_tokens_delete.error", nil, "", http.StatusInternalServerError).Wrap(err)
		}
	}

	return appErr
}

func (es *Service) CreateVerifyEmailToken(userID string, newEmail string) (*model.Token, error) {
	tokenExtra := struct {
		UserId string
		Email  string
	}{
		userID,
		newEmail,
	}

	jsonData, err := json.Marshal(tokenExtra)
	if err != nil {
		return nil, errors.Wrap(CreateEmailTokenError, err.Error())
	}

	token := model.NewToken(TokenTypeVerifyEmail, string(jsonData))

	if err := es.InvalidateVerifyEmailTokensForUser(userID); err != nil {
		return nil, err
	}

	if err = es.store.Token().Save(token); err != nil {
		return nil, err
	}

	return token, nil
}

func (es *Service) SendLicenseUpForRenewalEmail(email, locale string, daysToExpiration int) error {
	T := i18n.GetUserTranslations(locale)
	skuName := es.getLicenseSkuName()
	prefixedSkuName := es.getPrefixedLicenseSkuName()
	subject := T("api.templates.license_up_for_renewal_subject",
		map[string]any{"SkuName": prefixedSkuName})
	siteName := es.getConfigSiteName()
	siteURL := *es.config().ServiceSettings.SiteURL
	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = T("api.templates.license_up_for_renewal_title")
	data.Props["Button"] = T("api.templates.license_up_for_renewal_contact_sales")
	data.Props["ButtonURL"] = "https://mattermost.com/contact-sales/"
	data.Props["NeedHelpTitle"] = T("api.templates.license_need_help.title")
	data.Props["SubTitleTwo"] = T("api.templates.license_up_for_renewal_subtitle_two")
	data.HTML["SubTitle"] = i18n.TranslateAsHTML(T, "api.templates.license_up_for_renewal_subtitle", map[string]any{"SkuName": skuName, "SiteURL": siteURL, "SiteName": siteName, "Days": daysToExpiration})
	data.HTML["NeedHelpInfo"] = template.HTML(T("api.templates.license_need_help.info"))

	body, err := es.templatesContainer.RenderToString("license_notification", data)
	if err != nil {
		return err
	}

	if err := es.sendMail(email, subject, body, "LicenseUpForRenewal"); err != nil {
		return err
	}

	return nil
}

func (es *Service) SendRemoveExpiredLicenseEmail(email, locale string) error {
	T := i18n.GetUserTranslations(locale)
	skuName := es.getLicenseSkuName()
	prefixedSkuName := es.getPrefixedLicenseSkuName()
	subject := T("api.templates.remove_expired_license.subject",
		map[string]any{"SkuName": prefixedSkuName})
	siteName := es.getConfigSiteName()
	siteURL := *es.config().ServiceSettings.SiteURL
	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = T("api.templates.remove_expired_license.body.heading")
	data.Props["Button"] = T("api.templates.license_up_for_renewal_contact_sales")
	data.Props["ButtonURL"] = "https://mattermost.com/contact-sales/"
	data.Props["NeedHelpTitle"] = T("api.templates.license_need_help.title")
	data.Props["SubTitleTwo"] = T("api.templates.remove_expired_license.body.subtitle_two")
	data.HTML["SubTitle"] = i18n.TranslateAsHTML(T, "api.templates.remove_expired_license.body.subtitle", map[string]any{"SkuName": skuName, "SiteURL": siteURL, "SiteName": siteName})
	data.HTML["NeedHelpInfo"] = template.HTML(T("api.templates.license_need_help.info"))

	body, err := es.templatesContainer.RenderToString("license_notification", data)
	if err != nil {
		return err
	}

	if err := es.sendMail(email, subject, body, "RemoveExpiredLicense"); err != nil {
		return err
	}

	return nil
}

func (es *Service) SendIPFiltersChangedEmail(email string, initiatingUser *model.User, siteURL, portalURL, locale string, isWorkspaceOwner bool) error {
	T := i18n.GetUserTranslations(locale)

	subject := T("api.templates.ip_filters_changed.subject")

	data := es.NewEmailTemplateData(locale)
	data.Props["SiteURL"] = siteURL
	data.Props["Title"] = T("api.templates.ip_filters_changed.title")
	data.Props["SubTitle"] = T("api.templates.ip_filters_changed.subTitle", map[string]any{"InitiatingUsername": initiatingUser.Username, "SiteURL": siteURL})
	data.Props["ButtonURL"] = siteURL + "/admin_console/site_config/ip_filtering"
	data.Props["Button"] = T("api.templates.ip_filters_changed.button")
	data.Props["TroubleAccessingTitle"] = T("api.templates.ip_filters_changed_footer.title")
	data.Props["SendAnEmailTo"] = T("api.templates.ip_filters_changed_footer.send_an_email_to", map[string]any{"InitiatingUserEmail": initiatingUser.Email})
	data.Props["PortalURL"] = portalURL
	// If the email we're sending to was the one who initiated the change, we don't want to show their email address as a mailto
	if email != initiatingUser.Email {
		data.Props["ActorEmail"] = initiatingUser.Email
	}

	if isWorkspaceOwner {
		data.Props["LogInToCustomerPortal"] = T("api.templates.ip_filters_changed_footer.log_in_to_customer_portal")
	}
	data.Props["ContactSupport"] = T("api.templates.ip_filters_changed_footer.contact_support")
	data.Props["SupportEmail"] = *es.config().SupportSettings.SupportEmail

	body, err := es.templatesContainer.RenderToString("ip_filters_changed", data)
	if err != nil {
		return err
	}

	if err := es.sendMail(email, subject, body, "PasswordResetEmail"); err != nil {
		return err
	}

	return nil
}