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

package email

import (
	"io"
	"net/url"
	"path"
	"strings"

	"github.com/pkg/errors"
	"github.com/throttled/throttled/v2"
	"github.com/throttled/throttled/v2/store/memstore"

	"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/channels/app/users"
	"github.com/mattermost/mattermost/server/v8/channels/store"
	"github.com/mattermost/mattermost/server/v8/platform/shared/templates"
)

const (
	emailRateLimitingMemstoreSize = 65536
	emailRateLimitingPerMinute    = 60
	emailRateLimitingPerHour      = 20
	emailRateLimitingMaxBurst     = 20

	TokenTypePasswordRecovery         = "password_recovery"
	TokenTypeVerifyEmail              = "verify_email"
	TokenTypeTeamInvitation           = "team_invitation"
	TokenTypeGuestInvitation          = "guest_invitation"
	TokenTypeCWSAccess                = "cws_access_token"
	TokenTypeGuestMagicLinkInvitation = "guest_magic_link_invitation"
	TokenTypeGuestMagicLink           = "guest_magic_link"
)

func condenseSiteURL(siteURL string) string {
	parsedSiteURL, _ := url.Parse(siteURL)
	if parsedSiteURL.Path == "" || parsedSiteURL.Path == "/" {
		return parsedSiteURL.Host
	}

	return path.Join(parsedSiteURL.Host, parsedSiteURL.Path)
}

type Service struct {
	config  func() *model.Config
	license func() *model.License
	logger  mlog.LoggerIFace

	userService *users.UserService
	store       store.Store

	templatesContainer        *templates.Container
	perMinuteEmailRateLimiter *throttled.GCRARateLimiterCtx
	perHourEmailRateLimiter   *throttled.GCRARateLimiterCtx
	EmailBatching             *EmailBatchingJob

	postDeliveryRecorder func(userID string, post *model.Post)
}

type ServiceConfig struct {
	ConfigFn  func() *model.Config
	LicenseFn func() *model.License

	TemplatesContainer     *templates.Container
	UserService            *users.UserService
	Store                  store.Store
	Logger                 mlog.LoggerIFace
	PostDeliveryRecorderFn func(userID string, post *model.Post)
}

func NewService(config ServiceConfig) (*Service, error) {
	if err := config.validate(); err != nil {
		return nil, err
	}
	service := &Service{
		config:               config.ConfigFn,
		templatesContainer:   config.TemplatesContainer,
		license:              config.LicenseFn,
		logger:               config.Logger,
		store:                config.Store,
		userService:          config.UserService,
		postDeliveryRecorder: config.PostDeliveryRecorderFn,
	}
	if err := service.setUpRateLimiters(); err != nil {
		return nil, err
	}
	service.InitEmailBatching()
	return service, nil
}

func (es *Service) Stop() {
	mlog.Info("Shutting down Email batching service...")
	if es.EmailBatching != nil {
		es.EmailBatching.Stop()
	}
}

func (c *ServiceConfig) validate() error {
	if c.ConfigFn == nil || c.Store == nil || c.LicenseFn == nil || c.TemplatesContainer == nil {
		return errors.New("invalid service config")
	}
	return nil
}

func (es *Service) setUpRateLimiters() error {
	store, err := memstore.NewCtx(emailRateLimitingMemstoreSize)
	if err != nil {
		return errors.Wrap(err, "Unable to setup email rate limiting memstore.")
	}

	perMinuteQuota := throttled.RateQuota{
		MaxRate:  throttled.PerMin(emailRateLimitingPerMinute),
		MaxBurst: emailRateLimitingMaxBurst,
	}

	perHourQuota := throttled.RateQuota{
		MaxRate:  throttled.PerHour(emailRateLimitingPerHour),
		MaxBurst: emailRateLimitingMaxBurst,
	}

	perMinuteRateLimiter, err := throttled.NewGCRARateLimiterCtx(store, perMinuteQuota)
	if err != nil {
		return errors.Wrap(err, "Unable to setup email rate limiting GCRA rate limiter.")
	}

	perHourRateLimiter, err := throttled.NewGCRARateLimiterCtx(store, perHourQuota)
	if err != nil {
		return errors.Wrap(err, "Unable to setup email rate limiting GCRA rate limiter.")
	}

	es.perMinuteEmailRateLimiter = perMinuteRateLimiter
	es.perHourEmailRateLimiter = perHourRateLimiter
	return nil
}

type InviteEmailData struct {
	Team               *model.Team
	Channels           []*model.Channel
	SenderName         string
	SenderUserID       string
	SenderProfileImage []byte
	Invites            []string
	Profiles           map[string]*model.MemberInviteProfile
	SiteURL            string
	ReminderData       *model.TeamInviteReminderData
	Message            string
	ErrorWhenNotSent   bool
	IsSystemAdmin      bool
	IsFirstAdmin       bool
}

type ServiceInterface interface {
	NewEmailTemplateData(locale string) templates.Data
	SendEmailChangeVerifyEmail(newUserEmail, locale, siteURL, token string) error
	SendEmailChangeEmail(oldEmail, newEmail, locale, siteURL string) error
	SendVerifyEmail(userEmail, locale, siteURL, token, redirect string) error
	SendSignInChangeEmail(email, method, locale, siteURL string) error
	SendWelcomeEmail(userID string, email string, verified bool, disableWelcomeEmail bool, locale, siteURL, redirect string) error
	SendCloudWelcomeEmail(userEmail, locale, teamInviteID, workSpaceName, dns, siteURL string) error
	SendPasswordChangeEmail(email, method, locale, siteURL string) error
	SendUserAccessTokenAddedEmail(email, locale, siteURL string) error
	SendUserAccessTokenRotatedEmail(email, locale, siteURL string) error
	SendPasswordResetEmail(email string, token *model.Token, locale, siteURL string) (bool, error)
	SendMfaChangeEmail(email string, activated bool, locale, siteURL string) error
	SendInviteEmails(rctx request.CTX, inviteData InviteEmailData) error
	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
	SendMagicLinkEmailSelfService(rctx request.CTX, invite string, siteURL string) error
	SendInviteEmailsToTeamAndChannels(rctx request.CTX, inviteData InviteEmailData) ([]*model.EmailInviteWithError, error)
	SendDeactivateAccountEmail(email string, locale, siteURL string) error
	SendNotificationMail(to, subject, htmlBody string) error
	SendMailWithEmbeddedFiles(to, subject, htmlBody string, embeddedFiles map[string]io.Reader, messageID string, inReplyTo string, references string, category string) error
	SendLicenseUpForRenewalEmail(email, locale string, daysToExpiration int) error
	SendRemoveExpiredLicenseEmail(email, locale string) error
	AddNotificationEmailToBatch(user *model.User, post *model.Post, team *model.Team) *model.AppError
	GetMessageForNotification(post *model.Post, teamName, siteUrl string, translateFunc i18n.TranslateFunc) string
	GenerateHyperlinkForChannels(postMessage, teamName, teamURL string) (string, error)
	InitEmailBatching()
	SendChangeUsernameEmail(newUsername, email, locale, siteURL string) error
	CreateVerifyEmailToken(userID string, newEmail string) (*model.Token, error)
	SendIPFiltersChangedEmail(email string, userWhoChangedFilter *model.User, siteURL, portalURL, locale string, isWorkspaceOwner bool) error
	SetStore(st store.Store)
	Stop()
}

// getLicenseSkuName returns the license tier descriptor (e.g. "Professional",
// "Entry", "E20"), stripping the "Mattermost " prefix if the license server
// included it. Falls back to "Mattermost" when the SKU name is absent so
// that body text like "Your {{.SkuName}} license..." still reads naturally.
func (es *Service) getLicenseSkuName() string {
	if license := es.license(); license != nil && license.SkuName != "" {
		return strings.TrimPrefix(license.SkuName, "Mattermost ")
	}
	return "Mattermost"
}

// getPrefixedLicenseSkuName returns the full product name including "Mattermost"
// (e.g. "Mattermost Professional"), suitable for email subjects. Falls back
// to "Mattermost" when no license exists or the SKU name is empty.
func (es *Service) getPrefixedLicenseSkuName() string {
	skuName := es.getLicenseSkuName()
	if skuName == "Mattermost" {
		return "Mattermost"
	}
	return "Mattermost " + skuName
}

func (es *Service) getConfigSiteName() string {
	if siteName := *es.config().TeamSettings.SiteName; siteName != "" {
		return siteName
	}
	return "Mattermost"
}

func (es *Service) Store() store.Store {
	return es.store
}

func (es *Service) SetStore(st store.Store) {
	es.store = st
}