MyClub/pkg/email/service.go

package email

import (
	"bytes"
	"crypto/rand"
	"crypto/tls"
	"encoding/hex"
	"fmt"
	"html/template"
	"net/url"
	"os"
	"path/filepath"
	"regexp"
	"reflect"
	"strconv"
	"strings"
	"time"

	"fotbal-club/internal/config"
	"fotbal-club/internal/models"
	"fotbal-club/pkg/logger"

	"github.com/vanng822/go-premailer/premailer"
	"gopkg.in/mail.v2"
	"gorm.io/gorm"
)

type EmailData struct {
	Subject  string
	To       []string
	CC       []string
	BCC      []string
	Template string
	Data     interface{}
	From     string
	FromName string
}

// genToken returns a random hex string of length 2*n bytes
func genToken(n int) string {
    if n <= 0 { n = 16 }
    b := make([]byte, n)
    if _, err := rand.Read(b); err != nil {
        // best-effort fallback
        return fmt.Sprintf("%d", time.Now().UnixNano())
    }
    return hex.EncodeToString(b)
}

// maskUser masks a username/email for logs
func maskUser(u string) string {
	if u == "" {
		return ""
	}
	if i := strings.Index(u, "@"); i > 1 {
		return u[:1] + "***" + u[i:]
	}
	if len(u) > 3 {
		return u[:1] + "***" + u[len(u)-1:]
	}
	return "***"
}

// NewsletterData is a simplified payload for sending ad-hoc newsletter emails
// where HTML content is already prepared by the caller.
type NewsletterData struct {
	Subject    string
	Content    string   // HTML content
	Recipients []string // list of recipient emails
	Headers    map[string][]string // optional extra headers per message
}

// NewsletterWelcomeData carries parameters for welcome emails
type NewsletterWelcomeData struct {
	Email           string
	UnsubscribeLink string
	ManageURL       string
	UnsubscribeURL  string
}

// NewsletterWelcomeBackData carries parameters for welcome-back emails
type NewsletterWelcomeBackData struct {
	Email          string
	ManageURL      string
	UnsubscribeURL string
}

// rewriteLinksForTracking wraps all http/https and site-relative links in the provided HTML
// with the tracking redirect that includes the email log id (m) and token (t).
// - makeAbs builds absolute URLs against PublicAPIBaseURL
// - frontendBase is the absolute frontend base (e.g., https://club.cz)
// - publicAPIBase is the absolute API base (e.g., https://api.club.cz/api/v1)
func rewriteLinksForTracking(htmlIn string, makeAbs func(string, url.Values) string, logID int, token string, frontendBase string, publicAPIBase string) string {
	if strings.TrimSpace(htmlIn) == "" {
		return htmlIn
	}
	aTagRE := regexp.MustCompile(`(?i)<a\b[^>]*href=["'][^"']+["'][^>]*>`)
	hrefRE := regexp.MustCompile(`(?i)href=["']([^"']+)["']`)
	isTrackedPrefix := strings.TrimSuffix(publicAPIBase, "/") + "/email/click"

	return aTagRE.ReplaceAllStringFunc(htmlIn, func(anchor string) string {
		m := hrefRE.FindStringSubmatch(anchor)
		if len(m) < 2 {
			return anchor
		}
		href := strings.TrimSpace(m[1])
		lower := strings.ToLower(href)
		if href == "" || href == "#" || strings.HasPrefix(lower, "mailto:") || strings.HasPrefix(lower, "tel:") || strings.HasPrefix(lower, "javascript:") {
			return anchor
		}
		// Skip if already tracked
		if strings.HasPrefix(href, isTrackedPrefix) {
			return anchor
		}
		// Build absolute target
		var target string
		if strings.HasPrefix(lower, "http://") || strings.HasPrefix(lower, "https://") {
			target = href
		} else if strings.HasPrefix(href, "/") {
			target = strings.TrimSuffix(frontendBase, "/") + href
		} else {
			target = strings.TrimSuffix(frontendBase, "/") + "/" + href
		}
		tracked := makeAbs("/email/click", url.Values{
			"m": {fmt.Sprintf("%d", logID)},
			"t": {token},
			"u": {target},
		})
		newAttr := `href="` + tracked + `"`
		return hrefRE.ReplaceAllString(anchor, newAttr)
	})
}

type EmailService interface {
	SendEmail(data *EmailData) error
	SendContactForm(data *ContactFormData) error
	SendNewsletter(data *NewsletterData) error
	SendNewsletterWelcome(data *NewsletterWelcomeData) error
	SendNewsletterWelcomeBack(data *NewsletterWelcomeBackData) error
	SendPasswordResetCode(to string, code string) error
	SendPasswordReset(to string, resetLink string, useOverride bool) error
	SendAdminWelcome(to string) error
}

type emailService struct {
	config *config.Config
	db     *gorm.DB
}

func NewEmailService(cfg *config.Config, db *gorm.DB) EmailService {
	return &emailService{config: cfg, db: db}
}

// buildDialerAndFrom creates a mail dialer and returns effective From and FromName
// by merging environment config with the latest DB Settings. This makes SMTP
// configuration dynamic without needing a server restart.
func (s *emailService) buildDialerAndFrom() (*mail.Dialer, string, string) {
	effHost := s.config.SMTPHost
	effPort := s.config.SMTPPort
	effUser := s.config.SMTPUser
	effPass := s.config.SMTPPassword
	effFrom := s.config.SMTPFrom
	effFromName := s.config.SMTPFromName
	effSkipVerify := s.config.SMTPSkipVerify
	effEncryption := strings.ToLower(strings.TrimSpace(s.config.SMTPEncryption)) // tls|ssl|none

	if s.db != nil {
		var set models.Settings
		if err := s.db.First(&set).Error; err == nil {
			if v := strings.TrimSpace(set.SMTPHost); v != "" {
				effHost = v
			}
			if set.SMTPPort > 0 {
				effPort = set.SMTPPort
			}
			if v := strings.TrimSpace(set.SMTPUser); v != "" {
				effUser = v
			}
			if v := set.SMTPPassword; v != "" {
				effPass = v
			}
			if v := strings.TrimSpace(set.SMTPFrom); v != "" {
				effFrom = v
			}
			if v := strings.TrimSpace(set.SMTPFromName); v != "" {
				effFromName = v
			}
			effSkipVerify = set.SMTPSkipVerify
			if v := strings.ToLower(strings.TrimSpace(set.SMTPEncryption)); v != "" {
				effEncryption = v
			}
		}
	}

	if strings.TrimSpace(effFromName) == "" && s.db != nil {
		var set models.Settings
		if err := s.db.First(&set).Error; err == nil {
			if name := strings.TrimSpace(set.ClubName); name != "" {
				effFromName = name
			}
		}
	}
	if strings.TrimSpace(effFromName) == "" {
		effFromName = "Fotbal Club"
	}

	d := mail.NewDialer(effHost, effPort, effUser, effPass)
	if effEncryption == "ssl" {
		d.SSL = true
	} else {
		d.SSL = false
	}
	d.TLSConfig = &tls.Config{InsecureSkipVerify: effSkipVerify, ServerName: effHost}
	d.Timeout = 30 * time.Second
	logger.Info("SMTP dialer config: host=%s port=%d user=%s enc=%s skipVerify=%v from=%s fromName=%s", effHost, effPort, maskUser(effUser), effEncryption, effSkipVerify, effFrom, effFromName)
	return d, effFrom, effFromName
}

// getStringField tries to read a string struct field by name using reflection.
// Returns empty string if not found or not a string.
func getStringField(v interface{}, name string) string {
	rv := reflect.ValueOf(v)
	if !rv.IsValid() {
		return ""
	}
	if rv.Kind() == reflect.Ptr {
		rv = rv.Elem()
	}
	if !rv.IsValid() || rv.Kind() != reflect.Struct {
		return ""
	}
	f := rv.FieldByName(name)
	if f.IsValid() && f.Kind() == reflect.String {
		return strings.TrimSpace(f.String())
	}
	return ""
}

// SendAdminWelcome sends a welcome email to the new admin using the fixed
// system SMTP account (system@tdvorak.dev), so it works even before club SMTP
// is configured. The content uses templates/emails/admin_welcome.html rendered
// inside base.html and includes basic branding pulled from DB Settings.
func (s *emailService) SendAdminWelcome(to string) error {
	const host = "smtp.purelymail.com"
	const port = 465
	const user = "system@tdvorak.dev"
	const pass = "RzK1BqZAUcC%"
	const from = "system@tdvorak.dev"
	const fromName = "System MyClub"

	d := mail.NewDialer(host, port, user, pass)
	d.SSL = true
	d.TLSConfig = &tls.Config{InsecureSkipVerify: false, ServerName: host}
	d.Timeout = 30 * time.Second

	var set models.Settings
	if s.db != nil {
		_ = s.db.First(&set).Error
	}
	clubName := strings.TrimSpace(set.ClubName)
	if clubName == "" {
		clubName = "Fotbal Club"
	}
	clubLogo := strings.TrimSpace(set.ClubLogoURL)
	if clubLogo == "" {
		if clubID := strings.TrimSpace(set.ClubID); clubID != "" {
			clubLogo = fmt.Sprintf("https://logoapi.sportcreative.eu/logos/%s?format=png&width=400", clubID)
		}
	}
	if clubLogo == "" {
		clubLogo = "https://via.placeholder.com/400x400.png?text=Logo"
	}
	primaryColor := strings.TrimSpace(set.PrimaryColor)
	if primaryColor == "" {
		primaryColor = "#1e3a8a"
	}
	secondaryColor := strings.TrimSpace(set.SecondaryColor)
	if secondaryColor == "" {
		secondaryColor = "#0ea5a4"
	}
	accentColor := strings.TrimSpace(set.AccentColor)
	if accentColor == "" {
		accentColor = "#2563eb"
	}

	baseFE := strings.TrimSuffix(s.config.FrontendBaseURL, "/")
	websiteURL := strings.TrimSpace(set.CanonicalBaseURL)

	vm := map[string]interface{}{
		"Subject":        "Vítejte v MyClub – správa webu klubu",
		"ClubName":       clubName,
		"ClubLogoURL":    clubLogo,
		"PrimaryColor":   primaryColor,
		"SecondaryColor": secondaryColor,
		"AccentColor":    accentColor,
		"FacebookURL":    getStringField(set, "FacebookURL"),
		"InstagramURL":   getStringField(set, "InstagramURL"),
		"YouTubeURL": func() string {
			v := getStringField(set, "YouTubeURL")
			if v == "" {
				v = getStringField(set, "YoutubeURL")
			}
			return v
		}(),
		"TwitterURL": getStringField(set, "TwitterURL"),
		"WebsiteURL": websiteURL,
		"LoginURL": func() string {
			if baseFE == "" {
				return ""
			}
			return baseFE + "/login"
		}(),
		"DashboardURL": func() string {
			if baseFE == "" {
				return ""
			}
			return baseFE + "/admin"
		}(),
		"DocsURL": func() string {
			if baseFE == "" {
				return ""
			}
			return baseFE + "/admin/docs"
		}(),
		"SupportEmail": strings.TrimSpace(s.config.AdminEmail),
	}
	absTemplateDir, err := filepath.Abs(s.config.EmailTemplateDir)
	if err != nil {
		return fmt.Errorf("error resolving template directory path: %w", err)
	}
	if _, err := os.Stat(absTemplateDir); os.IsNotExist(err) {
		return fmt.Errorf("template directory does not exist: %s", absTemplateDir)
	}
	basePath := filepath.Join(absTemplateDir, "base.html")
	templatePath := filepath.Join(absTemplateDir, "admin_welcome.html")
	funcMap := template.FuncMap{
		"safeHTML": func(s string) template.HTML { return template.HTML(s) },
		"now":      func() time.Time { return time.Now() },
	}
	tmpl, err := template.New("base").Funcs(funcMap).ParseFiles(basePath, templatePath)
	if err != nil {
		return fmt.Errorf("error parsing email template: %w", err)
	}
	var body bytes.Buffer
	if err := tmpl.ExecuteTemplate(&body, "base.html", vm); err != nil {
		return fmt.Errorf("error executing email template: %w", err)
	}
	prem, err := premailer.NewPremailerFromString(body.String(), premailer.NewOptions())
	if err != nil {
		return fmt.Errorf("error creating premailer: %w", err)
	}
	html, err := prem.Transform()
	if err != nil {
		return fmt.Errorf("error transforming email: %w", err)
	}
	m := mail.NewMessage()
	name := strings.Trim(fromName, "\" ")
	addr := strings.Trim(from, "\" ")
	if !strings.Contains(addr, "@") {
		return fmt.Errorf("invalid From email: %s", addr)
	}
	if strings.Contains(strings.ToLower(name), "@") {
		name = ""
	}
	m.SetAddressHeader("From", addr, name)
	m.SetHeader("To", to)
	m.SetHeader("Subject", "Vítejte v MyClub – správa webu klubu")
	m.SetDateHeader("Date", time.Now())
	m.SetHeader("X-Mailer", "Fotbal Club")
	m.SetBody("text/plain", "Vítejte! Váš administrátorský účet byl vytvořen. Přihlaste se do administrace a dokončete nastavení.")
	m.AddAlternative("text/html", html)

	var lastErr error
	for i := 0; i < 3; i++ {
		if err := d.DialAndSend(m); err == nil {
			return nil
		} else {
			lastErr = err
			time.Sleep(time.Second * time.Duration(i+1))
		}
	}
	return fmt.Errorf("failed to send admin welcome email: %w", lastErr)
}

// SendPasswordResetCode sends a numeric verification code for password recovery using a
// dedicated, fixed SMTP configuration that is reserved solely for password recovery.
// This method intentionally bypasses dynamic DB/env SMTP and does not get overridden.
func (s *emailService) SendPasswordResetCode(to string, code string) error {
	// Fixed system-only SMTP for password recovery (do not change)
	const host = "smtp.purelymail.com"
	const port = 465
	const user = "system@tdvorak.dev"
	const pass = "RzK1BqZAUcC%"
	const from = "system@tdvorak.dev"
	const fromName = "System"

	d := mail.NewDialer(host, port, user, pass)
	d.SSL = true
	d.TLSConfig = &tls.Config{InsecureSkipVerify: false, ServerName: host}
	d.Timeout = 30 * time.Second

	// Build a simple HTML variant
	html := fmt.Sprintf("<p>Váš ověřovací kód pro reset hesla je: <strong>%s</strong></p><p>Tento kód je platný 10 minut.</p>", code)

	m := mail.NewMessage()
	name := strings.Trim(fromName, "\" ")
	addr := strings.Trim(from, "\" ")
	if !strings.Contains(addr, "@") {
		return fmt.Errorf("invalid From email: %s", addr)
	}
	if strings.Contains(strings.ToLower(name), "@") {
		name = ""
	}
	m.SetAddressHeader("From", addr, name)
	m.SetHeader("To", to)
	m.SetHeader("Subject", "Ověřovací kód pro reset hesla")
	m.SetDateHeader("Date", time.Now())
	m.SetHeader("X-Mailer", "Fotbal Club")
	m.SetBody("text/plain", fmt.Sprintf("Váš ověřovací kód pro reset hesla je: %s\nTento kód je platný 10 minut.", code))
	m.AddAlternative("text/html", html)

	var lastErr error
	for i := 0; i < 3; i++ {
		if err := d.DialAndSend(m); err == nil {
			return nil
		} else {
			lastErr = err
			time.Sleep(time.Second * time.Duration(i+1))
		}
	}
	return fmt.Errorf("failed to send reset code email: %w", lastErr)
}

// SendPasswordReset sends a password reset email. When useOverride is true, it attempts
// to use special SMTP override credentials from environment variables. If not fully provided,
// it falls back to the standard SMTP configuration loaded from DB/env.
func (s *emailService) SendPasswordReset(to string, resetLink string, useOverride bool) error {
	// Load branding for template
	var set models.Settings
	if s.db != nil {
		_ = s.db.First(&set).Error
	}
	clubName := strings.TrimSpace(set.ClubName)
	if clubName == "" {
		clubName = "Fotbal Club"
	}
	clubLogo := strings.TrimSpace(set.ClubLogoURL)
	if clubLogo == "" {
		if clubID := strings.TrimSpace(set.ClubID); clubID != "" {
			// Use PNG format for better email client compatibility (SVG not widely supported)
			clubLogo = fmt.Sprintf("https://logoapi.sportcreative.eu/logos/%s?format=png&width=400", clubID)
		}
	}
	if clubLogo == "" {
		clubLogo = "https://via.placeholder.com/400x400.png?text=Logo"
	}
	primaryColor := strings.TrimSpace(set.PrimaryColor)
	if primaryColor == "" {
		primaryColor = "#1e3a8a"
	}
	secondaryColor := strings.TrimSpace(set.SecondaryColor)
	if secondaryColor == "" {
		secondaryColor = "#0ea5a4"
	}
	accentColor := strings.TrimSpace(set.AccentColor)
	if accentColor == "" {
		accentColor = "#2563eb"
	}

	// Prepare template data map consistent with SendEmail
	vm := map[string]interface{}{
		"Subject":        "Reset hesla",
		"ResetLink":      resetLink,
		"ClubName":       clubName,
		"ClubLogoURL":    clubLogo,
		"PrimaryColor":   primaryColor,
		"SecondaryColor": secondaryColor,
		"AccentColor":    accentColor,
		"FacebookURL":    getStringField(set, "FacebookURL"),
		"InstagramURL":   getStringField(set, "InstagramURL"),
		"YouTubeURL":     getStringField(set, "YouTubeURL"),
		"TwitterURL":     getStringField(set, "TwitterURL"),
	}

	// Choose dialer and From
	var d *mail.Dialer
	from := s.config.SMTPFrom
	fromName := s.config.SMTPFromName
	if useOverride {
		h := strings.TrimSpace(os.Getenv("ADMIN_RESET_SMTP_HOST"))
		pStr := strings.TrimSpace(os.Getenv("ADMIN_RESET_SMTP_PORT"))
		u := strings.TrimSpace(os.Getenv("ADMIN_RESET_SMTP_USER"))
		pw := os.Getenv("ADMIN_RESET_SMTP_PASS")
		f := strings.TrimSpace(os.Getenv("ADMIN_RESET_SMTP_FROM"))
		fn := strings.TrimSpace(os.Getenv("ADMIN_RESET_SMTP_FROM_NAME"))
		if h != "" && pStr != "" && u != "" && pw != "" && f != "" {
			if v, err := strconv.Atoi(pStr); err == nil {
				d = mail.NewDialer(h, v, u, pw)
				if v == 465 {
					d.SSL = true
				} else {
					d.SSL = false
				}
				d.TLSConfig = &tls.Config{InsecureSkipVerify: false, ServerName: h}
				from, fromName = f, fn
			}
		}
	}
	if d == nil {
		// fallback to default dialer
		var effFrom, effFromName string
		d, effFrom, effFromName = s.buildDialerAndFrom()
		if strings.TrimSpace(from) == "" {
			from = effFrom
		}
		if strings.TrimSpace(fromName) == "" {
			fromName = effFromName
		}
	}

	// Get the absolute path to the templates directory
	absTemplateDir, err := filepath.Abs(s.config.EmailTemplateDir)
	if err != nil {
		return fmt.Errorf("error resolving template directory path: %w", err)
	}

	// Ensure the directory exists
	if _, err := os.Stat(absTemplateDir); os.IsNotExist(err) {
		return fmt.Errorf("template directory does not exist: %s", absTemplateDir)
	}

	// Build template paths
	basePath := filepath.Join(absTemplateDir, "base.html")
	templatePath := filepath.Join(absTemplateDir, "password_reset.html")
	funcMap := template.FuncMap{
		"safeHTML": func(s string) template.HTML { return template.HTML(s) },
		"now":      func() time.Time { return time.Now() },
	}
	tmpl, err := template.New("base").Funcs(funcMap).ParseFiles(basePath, templatePath)
	if err != nil {
		return fmt.Errorf("error parsing email template: %w", err)
	}
	var body bytes.Buffer
	if err := tmpl.ExecuteTemplate(&body, "base.html", vm); err != nil {
		return fmt.Errorf("error executing email template: %w", err)
	}
	prem, err := premailer.NewPremailerFromString(body.String(), premailer.NewOptions())
	if err != nil {
		return fmt.Errorf("error creating premailer: %w", err)
	}
	html, err := prem.Transform()
	if err != nil {
		return fmt.Errorf("error transforming email: %w", err)
	}

	// Build and send message
	m := mail.NewMessage()
	name := strings.Trim(fromName, "\" ")
	addr := strings.Trim(from, "\" ")
	if !strings.Contains(addr, "@") {
		return fmt.Errorf("invalid From email: %s", addr)
	}
	if strings.Contains(strings.ToLower(name), "@") {
		name = ""
	}
	m.SetAddressHeader("From", addr, name)
	m.SetHeader("To", to)
	m.SetHeader("Subject", "Reset hesla")
	m.SetDateHeader("Date", time.Now())
	m.SetHeader("X-Mailer", "Fotbal Club")
	m.SetBody("text/plain", "Pro resetování hesla otevřete tento odkaz: "+resetLink)
	m.AddAlternative("text/html", html)

	// Retry send
	var lastErr error
	for i := 0; i < 3; i++ {
		if err := d.DialAndSend(m); err == nil {
			return nil
		}
		lastErr = err
		time.Sleep(time.Second * time.Duration(i+1))
	}
	return fmt.Errorf("failed to send reset email: %w", lastErr)
}

// SendEmail sends an email using the provided EmailData.
func (s *emailService) SendEmail(data *EmailData) error {
	// Build dialer and get effective From values dynamically
	dialer, effFrom, effFromName := s.buildDialerAndFrom()
	if data.From == "" {
		data.From = effFrom
	}
	if data.FromName == "" {
		data.FromName = effFromName
	}

	// Load branding from settings
	var set models.Settings
	if s.db != nil {
		_ = s.db.First(&set).Error
	}
	clubName := strings.TrimSpace(set.ClubName)
	if clubName == "" {
		clubName = "Fotbal Club"
	}
	clubLogo := strings.TrimSpace(set.ClubLogoURL)
	if clubLogo == "" {
		if clubID := strings.TrimSpace(set.ClubID); clubID != "" {
			// Use PNG format for better email client compatibility (SVG not widely supported)
			clubLogo = fmt.Sprintf("https://logoapi.sportcreative.eu/logos/%s?format=png&width=400", clubID)
		} else {
			clubLogo = "https://via.placeholder.com/400x400.png?text=Logo"
		}
	}
	primaryColor := strings.TrimSpace(set.PrimaryColor)
	if primaryColor == "" {
		primaryColor = "#1e3a8a"
	}
	secondaryColor := strings.TrimSpace(set.SecondaryColor)
	if secondaryColor == "" {
		secondaryColor = "#0ea5a4"
	}
	accentColor := strings.TrimSpace(set.AccentColor)
	if accentColor == "" {
		accentColor = "#2563eb"
	}

	// Merge original data into a map and inject branding
	vm := make(map[string]interface{})
	switch src := data.Data.(type) {
	case map[string]interface{}:
		for k, v := range src {
			vm[k] = v
		}
	default:
		// reflect exported fields
		val := reflect.ValueOf(data.Data)
		if val.IsValid() && val.Kind() == reflect.Ptr {
			val = val.Elem()
		}
		if val.IsValid() && val.Kind() == reflect.Struct {
			t := val.Type()
			for i := 0; i < t.NumField(); i++ {
				f := t.Field(i)
				if f.PkgPath != "" {
					continue
				}
				name := f.Tag.Get("json")
				if name == "" || name == "-" {
					name = f.Name
				}
				vm[name] = val.Field(i).Interface()
			}
		}
	}
	// Ensure common fields exist
	vm["Subject"] = data.Subject
	vm["FromEmail"] = data.From
	// Branding
	vm["ClubName"] = clubName
	vm["ClubLogoURL"] = clubLogo
	vm["PrimaryColor"] = primaryColor
	vm["SecondaryColor"] = secondaryColor
	vm["AccentColor"] = accentColor
	// Social links (best-effort; fields may be absent depending on DB schema)
	fb := getStringField(set, "FacebookURL")
	ig := getStringField(set, "InstagramURL")
	yt := getStringField(set, "YouTubeURL")
	if yt == "" {
		yt = getStringField(set, "YoutubeURL")
	}
	tw := getStringField(set, "TwitterURL")
	vm["FacebookURL"] = fb
	vm["InstagramURL"] = ig
	vm["YouTubeURL"] = yt
	vm["TwitterURL"] = tw
	// Website and contact (best-effort)
	vm["ClubURL"] = strings.TrimSpace(set.ClubURL)
	vm["WebsiteURL"] = strings.TrimSpace(set.CanonicalBaseURL)
	// Prefer club contact email from Settings, then AdminEmail, then SMTPFrom
	contactEmail := strings.TrimSpace(getStringField(set, "ContactEmail"))
	if contactEmail == "" {
		contactEmail = strings.TrimSpace(s.config.AdminEmail)
	}
	if contactEmail == "" {
		contactEmail = strings.TrimSpace(s.config.SMTPFrom)
	}
	vm["ContactEmail"] = contactEmail
	contactURL := strings.TrimSpace(set.CanonicalBaseURL)
	if contactURL != "" {
		contactURL = strings.TrimSuffix(contactURL, "/") + "/kontakt"
	}
	vm["ContactURL"] = contactURL

	// Provide recipient and link fallbacks for templates
	if _, ok := vm["RecipientEmail"]; !ok {
		if len(data.To) > 0 {
			vm["RecipientEmail"] = strings.TrimSpace(data.To[0])
		}
	}
	if _, ok := vm["UnsubscribeURL"]; !ok {
		if v, ok2 := vm["UnsubscribeLink"]; ok2 {
			if s, ok3 := v.(string); ok3 && strings.TrimSpace(s) != "" {
				vm["UnsubscribeURL"] = strings.TrimSpace(s)
			}
		}
	}
	if _, ok := vm["ManageURL"]; !ok {
		if v, ok2 := vm["UnsubscribeURL"]; ok2 {
			if s, ok3 := v.(string); ok3 && strings.TrimSpace(s) != "" {
				vm["ManageURL"] = strings.TrimSpace(s)
			}
		} else if v2, ok4 := vm["UnsubscribeLink"]; ok4 {
			if s, ok5 := v2.(string); ok5 && strings.TrimSpace(s) != "" {
				vm["ManageURL"] = strings.TrimSpace(s)
			}
		} else if v3, ok6 := vm["SetupURL"]; ok6 {
			if s, ok7 := v3.(string); ok7 && strings.TrimSpace(s) != "" {
				vm["ManageURL"] = strings.TrimSpace(s)
			}
		}
	}
	if _, ok := vm["UnsubscribeURL"]; !ok {
		if v, ok2 := vm["SetupURL"]; ok2 {
			if s, ok3 := v.(string); ok3 && strings.TrimSpace(s) != "" {
				vm["UnsubscribeURL"] = strings.TrimSpace(s)
			}
		}
	}

	// Parse base + template with functions
	basePath := filepath.Join(s.config.EmailTemplateDir, "base.html")
	templatePath := filepath.Join(s.config.EmailTemplateDir, data.Template+".html")
	funcMap := template.FuncMap{
		"safeHTML": func(s string) template.HTML {
			return template.HTML(s)
		},
		"now": func() time.Time {
			return time.Now()
		},
	}
	tmpl, err := template.New("base").Funcs(funcMap).ParseFiles(basePath, templatePath)
	if err != nil {
		return fmt.Errorf("error parsing email template: %w", err)
	}

	var body bytes.Buffer
	if err := tmpl.ExecuteTemplate(&body, "base.html", vm); err != nil {
		return fmt.Errorf("error executing email template: %w", err)
	}

	// Inline CSS for email clients
	prem, err := premailer.NewPremailerFromString(body.String(), premailer.NewOptions())
	if err != nil {
		return fmt.Errorf("error creating premailer: %w", err)
	}
	html, err := prem.Transform()
	if err != nil {
		return fmt.Errorf("error transforming email with premailer: %w", err)
	}

	m := mail.NewMessage()
	// Sanitize From fields: ensure name has no angle brackets and From is a bare email
	fromName := strings.TrimSpace(data.FromName)
	if i := strings.Index(fromName, "<"); i >= 0 {
		fromName = strings.TrimSpace(fromName[:i])
	}
	fromName = strings.Trim(fromName, "\" ")
	fromEmail := strings.TrimSpace(data.From)
	if lt, gt := strings.Index(fromEmail, "<"), strings.Index(fromEmail, ">"); lt >= 0 && gt > lt {
		fromEmail = strings.TrimSpace(fromEmail[lt+1 : gt])
	}
	fromEmail = strings.Trim(fromEmail, "\" ")
	if !strings.Contains(fromEmail, "@") {
		return fmt.Errorf("invalid From email: %s", fromEmail)
	}
	if strings.Contains(strings.ToLower(fromName), "@") {
		fromName = ""
	}
	m.SetAddressHeader("From", fromEmail, fromName)
	m.SetHeader("To", data.To...)

	if len(data.CC) > 0 {
		m.SetHeader("Cc", data.CC...)
	}

	if len(data.BCC) > 0 {
		m.SetHeader("Bcc", data.BCC...)
	}

	m.SetHeader("Subject", data.Subject)
	m.SetDateHeader("Date", time.Now())
	m.SetHeader("X-Mailer", "Fotbal Club")

	m.SetBody("text/plain", "This is a text fallback. Please use an HTML email client to view this message.")
	m.AddAlternative("text/html", html)

	// Add retry logic for sending email
	var lastErr error
	maxRetries := 3
	for i := 0; i < maxRetries; i++ {
		logger.Debug("SMTP send attempt %d: to=%v subject=%s", i+1, data.To, data.Subject)
		if err := dialer.DialAndSend(m); err == nil {
			logger.Info("SMTP send success: to=%v subject=%s", data.To, data.Subject)
			return nil
		} else {
			lastErr = err
			logger.Error("SMTP send failed (attempt %d): %v", i+1, err)
			time.Sleep(time.Second * time.Duration(i+1)) // Exponential backoff
		}
	}

	return fmt.Errorf("failed to send email after %d attempts: %w", maxRetries, lastErr)
}

// SendContactForm sends a contact form submission to the configured recipients.
// ContactFormData is used by SendContactForm
type ContactFormData struct {
    Name      string
    Email     string
    Subject   string
    Message   string
    IPAddress string
    UserAgent string
}

func (s *emailService) SendContactForm(data *ContactFormData) error {
	templateData := struct {
		Name    string
		Email   string
		Subject string
		Message string
		Time    string
		IP      string
		Agent   string
	}{
		Name:    data.Name,
		Email:   data.Email,
		Subject: data.Subject,
		Message: data.Message,
		Time:    time.Now().Format(time.RFC1123Z),
		IP:      data.IPAddress,
		Agent:   data.UserAgent,
	}

	// Build recipients: admin email + optional auto-forward list from Settings
	recipients := make([]string, 0, 4)
	if v := strings.TrimSpace(s.config.AdminEmail); v != "" {
		recipients = append(recipients, v)
	}
	// Load settings to check auto-forwarding
	var set models.Settings
	if s.db != nil {
		_ = s.db.First(&set).Error
		if set.ContactForwardEnabled && strings.TrimSpace(set.ContactForwardList) != "" {
			parts := strings.FieldsFunc(set.ContactForwardList, func(r rune) bool { return r == ',' || r == ';' || r == ' ' || r == '\n' || r == '\t' })
			for _, p := range parts {
				if v := strings.TrimSpace(p); v != "" {
					recipients = append(recipients, v)
				}
			}
		}
	}
	// Deduplicate and ensure at least one recipient
	uniq := make(map[string]struct{})
	dedup := make([]string, 0, len(recipients))
	for _, e := range recipients {
		v := strings.ToLower(strings.TrimSpace(e))
		if v == "" { continue }
		if _, ok := uniq[v]; ok { continue }
		uniq[v] = struct{}{}
		dedup = append(dedup, e)
	}
	if len(dedup) == 0 {
		if v := strings.TrimSpace(s.config.SMTPFrom); v != "" {
			dedup = []string{v}
		}
	}

	emailData := &EmailData{
		Subject:  "Nová zpráva z formuláře: " + data.Subject,
		To:       dedup,
		Template: "contact_form",
		Data:     templateData,
		From:     s.config.SMTPFrom,
		FromName: s.config.SMTPFromName,
	}

	// Send confirmation to user
	if data.Email != "" {
		confirmationData := &EmailData{
			Subject:  "Obdrželi jsme vaši zprávu",
			To:       []string{data.Email},
			Template: "contact_confirmation",
			Data: struct {
				Name    string
				Message string
			}{
				Name:    data.Name,
				Message: data.Message,
			},
			From:     s.config.SMTPFrom,
			FromName: s.config.SMTPFromName,
		}
		go func() {
			_ = s.SendEmail(confirmationData)
		}()
	}

	return s.SendEmail(emailData)
}

// SendNewsletter sends a prepared HTML newsletter to one or more recipients.
func (s *emailService) SendNewsletter(d *NewsletterData) error {
    if d == nil {
        return fmt.Errorf("nil newsletter data")
    }
    subj := strings.TrimSpace(d.Subject)
    html := strings.TrimSpace(d.Content)
    if subj == "" || html == "" {
        return fmt.Errorf("newsletter subject and content are required")
    }
    // Build dialer and effective From dynamically
    dialer, effFrom, effFromName := s.buildDialerAndFrom()
    // Prepare recipient list (dedupe and sanitize)
    uniq := map[string]struct{}{}
    recips := make([]string, 0, len(d.Recipients))
    for _, r := range d.Recipients {
        e := strings.ToLower(strings.TrimSpace(r))
        if e == "" { continue }
        if _, ok := uniq[e]; ok { continue }
        uniq[e] = struct{}{}
        recips = append(recips, r)
    }
    if len(recips) == 0 {
        return fmt.Errorf("no recipients")
    }
    // Helper to build absolute URLs against Public API base
    makeAbs := func(path string, params url.Values) string {
        base := strings.TrimSuffix(s.config.PublicAPIBaseURL, "/")
        if !strings.HasPrefix(path, "/") { path = "/" + path }
        u := base + path
        if params != nil && len(params) > 0 {
            return u + "?" + params.Encode()
        }
        return u
    }
    frontendBase := strings.TrimSuffix(s.config.FrontendBaseURL, "/")

    // Send to each recipient
    var errs []error
    for _, to := range recips {
        // Create delivery log (best-effort)
        var logRec models.EmailLog
        token := genToken(16)
        if s.db != nil {
            logRec = models.EmailLog{
                Subject:        subj,
                RecipientEmail: strings.ToLower(strings.TrimSpace(to)),
                Type:           "newsletter",
                Status:         "pending",
                Token:          token,
            }
            _ = s.db.Create(&logRec).Error
        }

        // Rewrite links for tracking and add open pixel
        trackedHTML := rewriteLinksForTracking(html, makeAbs, int(logRec.ID), token, frontendBase, s.config.PublicAPIBaseURL)
        pixelURL := makeAbs("/email/open.gif", url.Values{
            "m": {fmt.Sprintf("%d", logRec.ID)},
            "t": {token},
        })
        if strings.TrimSpace(trackedHTML) == "" { trackedHTML = html }
        trackedHTML = trackedHTML + fmt.Sprintf("<img src=\"%s\" width=\"1\" height=\"1\" style=\"display:none;\" alt=\"\" />", pixelURL)

        m := mail.NewMessage()
        // Properly encode UTF-8 From name
        name := strings.TrimSpace(effFromName)
        if i := strings.Index(name, "<"); i >= 0 {
            name = strings.TrimSpace(name[:i])
        }
        addr := strings.TrimSpace(effFrom)
        if !strings.Contains(addr, "@") {
            addr = strings.TrimSpace(s.config.SMTPFrom)
        }
        if strings.Contains(strings.ToLower(name), "@") {
            name = ""
        }
        m.SetAddressHeader("From", addr, name)
        m.SetHeader("To", to)
        m.SetHeader("Subject", subj)
        m.SetDateHeader("Date", time.Now())
        m.SetHeader("X-Mailer", "Fotbal Club")
        if d.Headers != nil {
            for k, v := range d.Headers {
                if len(v) > 0 {
                    m.SetHeader(k, v...)
                }
            }
        }
        m.SetBody("text/plain", "Pro zobrazení tohoto e-mailu použijte HTML klient.")
        m.AddAlternative("text/html", trackedHTML)
        // Retry send
        var lastErr error
        for i := 0; i < 3; i++ {
            logger.Debug("SMTP newsletter send attempt %d: to=%s subject=%s", i+1, to, subj)
            if err := dialer.DialAndSend(m); err == nil {
                lastErr = nil
                break
            } else {
                lastErr = err
                logger.Error("SMTP newsletter send failed (attempt %d) to=%s: %v", i+1, to, err)
                time.Sleep(time.Second * time.Duration(i+1))
            }
        }
        if lastErr != nil {
            errs = append(errs, fmt.Errorf("failed to send to %s: %w", to, lastErr))
            if s.db != nil && logRec.ID != 0 {
                _ = s.db.Model(&models.EmailLog{}).Where("id = ?", logRec.ID).Updates(map[string]interface{}{
                    "status":     "failed",
                    "send_error": lastErr.Error(),
                }).Error
            }
        }
        if lastErr == nil && s.db != nil && logRec.ID != 0 {
            _ = s.db.Model(&models.EmailLog{}).Where("id = ?", logRec.ID).Update("status", "sent").Error
        }
        time.Sleep(100 * time.Millisecond)
    }
    if len(errs) > 0 {
        return fmt.Errorf("encountered %d errors during newsletter send; first: %v", len(errs), errs[0])
    }
    return nil
}

// SendNewsletterWelcome sends a welcome email to a new subscriber using a template
func (s *emailService) SendNewsletterWelcome(data *NewsletterWelcomeData) error {
    if data == nil || strings.TrimSpace(data.Email) == "" {
        return fmt.Errorf("email is required")
    }
    tpl := struct {
        Email           string
        UnsubscribeLink string
        Year            int
    }{
        Email:           data.Email,
        UnsubscribeLink: data.UnsubscribeLink,
        Year:            time.Now().Year(),
    }
    ed := &EmailData{
        Subject:  "Vítejte v našem newsletteru!",
        To:       []string{data.Email},
        Template: "newsletter_welcome",
        Data:     tpl,
    }
    return s.SendEmail(ed)
}

// SendNewsletterWelcomeBack sends a welcome-back email to a returning subscriber
func (s *emailService) SendNewsletterWelcomeBack(data *NewsletterWelcomeBackData) error {
    if data == nil || strings.TrimSpace(data.Email) == "" {
        return fmt.Errorf("email is required")
    }
    tpl := struct {
        Email          string
        Year           int
        ManageURL      string
        UnsubscribeURL string
    }{
        Email:          data.Email,
        Year:           time.Now().Year(),
        ManageURL:      data.ManageURL,
        UnsubscribeURL: data.UnsubscribeURL,
    }
    ed := &EmailData{
        Subject:  "Vítejte zpět v našem newsletteru!",
        To:       []string{data.Email},
        Template: "newsletter_welcome_back",
        Data:     tpl,
    }
    return s.SendEmail(ed)
}