bamort/backend/mail/smtp.go

package mail

import (
	"crypto/tls"
	"fmt"
	"net/smtp"

	"bamort/config"
	"bamort/logger"
)

// Client represents an SMTP mail client
type Client struct {
	host     string
	port     int
	username string
	password string
	from     string
}

// Message represents an email message
type Message struct {
	To      string
	Subject string
	Body    string
}

// NewClient creates a new SMTP mail client from config
func NewClient() *Client {
	cfg := config.Cfg
	return &Client{
		host:     cfg.MailHost,
		port:     cfg.MailPort,
		username: cfg.MailUsername,
		password: cfg.MailPassword,
		from:     cfg.MailFrom,
	}
}

// Send sends an email message via SMTP
func (c *Client) Send(msg Message) error {
	if c.host == "" {
		logger.Warn("SMTP Host nicht konfiguriert - E-Mail-Versand übersprungen")
		return fmt.Errorf("SMTP host not configured")
	}

	logger.Debug("Sende E-Mail an %s via SMTP %s:%d", msg.To, c.host, c.port)

	// Prepare email headers and body
	headers := make(map[string]string)
	headers["From"] = c.from
	headers["To"] = msg.To
	headers["Subject"] = msg.Subject
	headers["MIME-Version"] = "1.0"
	headers["Content-Type"] = "text/html; charset=\"UTF-8\""

	// Build message
	message := ""
	for key, value := range headers {
		message += fmt.Sprintf("%s: %s\r\n", key, value)
	}
	message += "\r\n" + msg.Body

	// Connect to SMTP server
	serverAddr := fmt.Sprintf("%s:%d", c.host, c.port)

	// Create TLS config
	tlsConfig := &tls.Config{
		ServerName:         c.host,
		InsecureSkipVerify: false,
	}

	var err error
	var client *smtp.Client

	// Port 465 requires direct TLS connection, port 587 uses STARTTLS
	if c.port == 465 {
		// Direct TLS connection (implicit SSL)
		conn, err := tls.Dial("tcp", serverAddr, tlsConfig)
		if err != nil {
			logger.Error("Fehler beim Verbinden mit SMTP-Server (TLS): %s", err.Error())
			return fmt.Errorf("failed to connect to SMTP server: %w", err)
		}
		defer conn.Close()

		client, err = smtp.NewClient(conn, c.host)
		if err != nil {
			logger.Error("Fehler beim Erstellen des SMTP-Clients: %s", err.Error())
			return fmt.Errorf("failed to create SMTP client: %w", err)
		}
	} else {
		// Port 587 or other - use STARTTLS
		client, err = smtp.Dial(serverAddr)
		if err != nil {
			logger.Error("Fehler beim Verbinden mit SMTP-Server: %s", err.Error())
			return fmt.Errorf("failed to dial SMTP server: %w", err)
		}
		defer client.Close()

		// Start TLS if available
		if ok, _ := client.Extension("STARTTLS"); ok {
			if err = client.StartTLS(tlsConfig); err != nil {
				logger.Error("Fehler beim STARTTLS: %s", err.Error())
				return fmt.Errorf("failed to start TLS: %w", err)
			}
		}
	}

	// Authenticate
	if c.username != "" && c.password != "" {
		auth := smtp.PlainAuth("", c.username, c.password, c.host)
		if err = client.Auth(auth); err != nil {
			logger.Error("Fehler bei der SMTP-Authentifizierung: %s", err.Error())
			return fmt.Errorf("failed to authenticate: %w", err)
		}
	}

	// Set sender
	if err = client.Mail(c.from); err != nil {
		logger.Error("Fehler beim Setzen des Absenders: %s", err.Error())
		return fmt.Errorf("failed to set sender: %w", err)
	}

	// Set recipient
	if err = client.Rcpt(msg.To); err != nil {
		logger.Error("Fehler beim Setzen des Empfängers: %s", err.Error())
		return fmt.Errorf("failed to set recipient: %w", err)
	}

	// Send message body
	writer, err := client.Data()
	if err != nil {
		logger.Error("Fehler beim Öffnen des Data-Writers: %s", err.Error())
		return fmt.Errorf("failed to open data writer: %w", err)
	}

	_, err = writer.Write([]byte(message))
	if err != nil {
		logger.Error("Fehler beim Schreiben der Nachricht: %s", err.Error())
		writer.Close()
		return fmt.Errorf("failed to write message: %w", err)
	}

	err = writer.Close()
	if err != nil {
		logger.Error("Fehler beim Schließen des Data-Writers: %s", err.Error())
		return fmt.Errorf("failed to close data writer: %w", err)
	}

	// Quit
	if err = client.Quit(); err != nil {
		logger.Error("Fehler beim Beenden der SMTP-Verbindung: %s", err.Error())
		return fmt.Errorf("failed to quit SMTP connection: %w", err)
	}

	logger.Info("E-Mail erfolgreich an %s versendet", msg.To)
	return nil
}

// IsConfigured returns true if the mail client is properly configured
func (c *Client) IsConfigured() bool {
	return c.host != "" && c.port > 0 && c.from != ""
}