email

type Attachment struct {
	Filename string // Filename to display for the attachment.
	Data     []byte // Raw file data.
}

type Client interface {
	Mail(from string) error
	Rcpt(to string) error
	Data() (io.WriteCloser, error)
	Close() error
	StartTLS(config *tls.Config) error
	Auth(auth smtp.Auth) error
}

type DefaultDialer struct{}

type Dialer interface {
	// Dial connects to the SMTP server at the specified address.
	//
	// Parameters:
	//   - addr: The address of the SMTP server (e.g. "smtp.example.com:587").
	//
	// Returns:
	//   - Client: An established SMTP client.
	//   - error: If the connection cannot be established.
	Dial(addr string) (Client, error)
}

type MailClient struct {
	SMTPConfig SMTPConfig // SMTPConfig holds connection and authentication settings.
	Dialer     Dialer     // Dialer provides SMTP connections.
}

type Message struct {
	To          []string     `yaml:"to,omitempty"`          // Recipient email addresses.
	Cc          []string     `yaml:"cc,omitempty"`          // CC recipient email addresses.
	Bcc         []string     `yaml:"bcc,omitempty"`         // BCC recipient email addresses.
	IsHTML      bool         `yaml:"is_html,omitempty"`     // Whether the body is HTML formatted.
	Subject     string       `yaml:"subject,omitempty"`     // Subject of the email.
	Body        string       `yaml:"body,omitempty"`        // Body content of the email.
	Attachments []Attachment `yaml:"attachments,omitempty"` // Optional file attachments.
}

type SMTPConfig struct {
	Host               string `yaml:"host,omitempty"`                 // SMTP server hostname.
	Port               int    `yaml:"port,omitempty"`                 // SMTP server port.
	From               string `yaml:"from,omitempty"`                 // Sender email address.
	Username           string `yaml:"username,omitempty"`             // SMTP username.
	Password           string `yaml:"password,omitempty"`             // SMTP password.
	StartTLS           *bool  `yaml:"start_tls,omitempty"`            // Whether to initiate STARTTLS.
	SkipInsecureVerify *bool  `yaml:"skip_insecure_verify,omitempty"` // Whether to skip TLS certificate verification.
}

type Sender interface {
	// Send sends the given message using the SMTP protocol.
	//
	// Parameters:
	//   - ctx: The context used to control timeout or cancellation.
	//   - msg: The Message to be sent.
	//
	// Returns:
	//   - error: If sending the message fails.
	Send(ctx context.Context, msg Message) error
}