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

package email

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

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

const (
	emailRateLimitingMemstoreSize = 65536
	emailRateLimitingPerHour      = 20
	emailRateLimitingMaxBurst     = 20

	TokenTypePasswordRecovery = "password_recovery"
	TokenTypeVerifyEmail      = "verify_email"
	TokenTypeTeamInvitation   = "team_invitation"
	TokenTypeGuestInvitation  = "guest_invitation"
	TokenTypeCWSAccess        = "cws_access_token"
)

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

	userService *users.UserService
	store       store.Store

	templatesContainer      *templates.Container
	perHourEmailRateLimiter *throttled.GCRARateLimiter
	perDayEmailRateLimiter  *throttled.GCRARateLimiter
	EmailBatching           *EmailBatchingJob
}

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

	TemplatesContainer *templates.Container
	UserService        *users.UserService
	Store              store.Store
}

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,
		store:              config.Store,
		userService:        config.UserService,
	}
	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.New(emailRateLimitingMemstoreSize)
	if err != nil {
		return errors.Wrap(err, "Unable to setup email rate limiting memstore.")
	}

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

	perDayQuota := throttled.RateQuota{
		MaxRate:  throttled.PerDay(1),
		MaxBurst: 0,
	}

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

	perDayRateLimiter, err := throttled.NewGCRARateLimiter(store, perDayQuota)
	if err != nil || perDayRateLimiter == nil {
		return errors.Wrap(err, "Unable to setup per day email rate limiting GCRA rate limiter.")
	}

	es.perHourEmailRateLimiter = perHourRateLimiter
	es.perDayEmailRateLimiter = perDayRateLimiter
	return nil
}

type ServiceInterface interface {
	GetPerDayEmailRateLimiter() *throttled.GCRARateLimiter
	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
	SendPasswordResetEmail(email string, token *model.Token, locale, siteURL string) (bool, error)
	SendMfaChangeEmail(email string, activated bool, locale, siteURL string) error
	SendInviteEmails(team *model.Team, senderName string, senderUserId string, invites []string, siteURL string, reminderData *model.TeamInviteReminderData, errorWhenNotSent bool, isSystemAdmin bool, isFirstAdmin bool) error
	SendGuestInviteEmails(team *model.Team, channels []*model.Channel, senderName string, senderUserId string, senderProfileImage []byte, invites []string, siteURL string, message string, errorWhenNotSent bool, isSystemAdmin bool, isFirstAdmin bool) error
	SendInviteEmailsToTeamAndChannels(team *model.Team, channels []*model.Channel, senderName string, senderUserId string, senderProfileImage []byte, invites []string, siteURL string, reminderData *model.TeamInviteReminderData, message string, errorWhenNotSent bool, isSystemAdmin bool, isFirstAdmin bool) ([]*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, name, locale, siteURL, ctaTitle, ctaLink, ctaText string, daysToExpiration int) error
	SendRemoveExpiredLicenseEmail(ctaText, ctaLink, email, locale, siteURL 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()
}

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

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

func (es *Service) GetPerDayEmailRateLimiter() *throttled.GCRARateLimiter {
	return es.perDayEmailRateLimiter
}

func (es *Service) GetPerHourEmailRateLimiter() *throttled.GCRARateLimiter {
	return es.perHourEmailRateLimiter
}