refactor: extract smtp module

internal/tools/smtp/client.go

@@ -0,0 +1,96 @@
+package smtp
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/wneessen/go-mail"
+
+	xtls "github.com/certimate-go/certimate/pkg/utils/tls"
+)
+
+type Client struct {
+	cli *mail.Client
+}
+
+func NewClient(config *Config) (*Client, error) {
+	if config == nil {
+		return nil, fmt.Errorf("the configuration of SMTP client is nil")
+	}
+
+	client, err := createSmtpClient(config)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Client{cli: client}, nil
+}
+
+func (c *Client) Close() error {
+	return c.cli.Close()
+}
+
+func (c *Client) Send(ctx context.Context, msg *Message) error {
+	if err := c.cli.DialAndSendWithContext(ctx, msg); err != nil {
+		errShouldBeIgnored := false
+
+		// REF: https://github.com/wneessen/go-mail/issues/463
+		var sendErr *mail.SendError
+		if errors.As(err, &sendErr) {
+			if sendErr.Reason == mail.ErrSMTPReset {
+				errShouldBeIgnored = true
+			}
+		}
+
+		if !errShouldBeIgnored {
+			return fmt.Errorf("smtp: %w", err)
+		}
+	}
+
+	return nil
+}
+
+func createSmtpClient(config *Config) (*mail.Client, error) {
+	clientOptions := []mail.Option{
+		mail.WithSMTPAuth(mail.SMTPAuthAutoDiscover),
+		mail.WithUsername(config.Username),
+		mail.WithPassword(config.Password),
+		mail.WithTimeout(time.Second * 30),
+	}
+
+	if config.Port == 0 {
+		if config.UseSsl {
+			clientOptions = append(clientOptions, mail.WithPort(mail.DefaultPortSSL))
+		} else {
+			clientOptions = append(clientOptions, mail.WithPort(mail.DefaultPort))
+		}
+	} else {
+		clientOptions = append(clientOptions, mail.WithPort(config.Port))
+	}
+
+	if config.UseSsl {
+		tlsConfig := xtls.NewCompatibleConfig()
+		if config.SkipTlsVerify {
+			tlsConfig.InsecureSkipVerify = true
+		} else {
+			tlsConfig.ServerName = config.Host
+		}
+
+		clientOptions = append(clientOptions, mail.WithSSL())
+		clientOptions = append(clientOptions, mail.WithTLSConfig(tlsConfig))
+		clientOptions = append(clientOptions, mail.WithTLSPolicy(mail.TLSMandatory))
+	} else {
+		clientOptions = append(clientOptions, mail.WithTLSPolicy(mail.TLSOpportunistic))
+	}
+
+	client, err := mail.NewClient(config.Host, clientOptions...)
+	if err != nil {
+		return nil, fmt.Errorf("smtp: %w", err)
+	}
+
+	client.ErrorHandlerRegistry.RegisterHandler("smtp.qq.com", "QUIT", &wQQMailQuitErrorHandler{})
+
+	return client, nil
+}

internal/tools/smtp/config.go

@@ -0,0 +1,20 @@
+package smtp
+
+const (
+	defaultPort int = 25
+)
+
+type Config struct {
+	Host          string
+	Port          int
+	Username      string
+	Password      string
+	UseSsl        bool
+	SkipTlsVerify bool
+}
+
+func NewDefaultConfig() *Config {
+	return &Config{
+		Port: defaultPort,
+	}
+}

internal/tools/smtp/errhandler.go

@@ -1,4 +1,4 @@
-package email
+package smtp
 
 import (
 	"bytes"

internal/tools/smtp/message.go

@@ -0,0 +1,18 @@
+package smtp
+
+import (
+	"github.com/wneessen/go-mail"
+)
+
+type Message = mail.Msg
+
+func NewMessage() *Message {
+	return mail.NewMsg()
+}
+
+type MIMEType = mail.ContentType
+
+const (
+	MIMETypeTextHTML  MIMEType = mail.TypeTextHTML
+	MIMETypeTextPlain MIMEType = mail.TypeTextPlain
+)

pkg/core/notifier/providers/email/email.go

@@ -5,12 +5,9 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
-	"time"
-
-	"github.com/wneessen/go-mail"
 
+	"github.com/certimate-go/certimate/internal/tools/smtp"
 	"github.com/certimate-go/certimate/pkg/core/notifier"
-	xtls "github.com/certimate-go/certimate/pkg/utils/tls"
 )
 
 type NotifierConfig struct {
@@ -62,49 +59,23 @@ func (n *Notifier) SetLogger(logger *slog.Logger) {
 }
 
 func (n *Notifier) Notify(ctx context.Context, subject string, message string) (*notifier.NotifyResult, error) {
-	clientOptions := []mail.Option{
-		mail.WithSMTPAuth(mail.SMTPAuthAutoDiscover),
-		mail.WithUsername(n.config.Username),
-		mail.WithPassword(n.config.Password),
-		mail.WithTimeout(time.Second * 30),
-	}
-
-	if n.config.SmtpPort == 0 {
-		if n.config.SmtpTls {
-			clientOptions = append(clientOptions, mail.WithPort(mail.DefaultPortSSL))
-		} else {
-			clientOptions = append(clientOptions, mail.WithPort(mail.DefaultPort))
-		}
-	} else {
-		clientOptions = append(clientOptions, mail.WithPort(int(n.config.SmtpPort)))
-	}
-
-	if n.config.SmtpTls {
-		tlsConfig := xtls.NewCompatibleConfig()
-		if n.config.AllowInsecureConnections {
-			tlsConfig.InsecureSkipVerify = true
-		} else {
-			tlsConfig.ServerName = n.config.SmtpHost
-		}
-
-		clientOptions = append(clientOptions, mail.WithSSL())
-		clientOptions = append(clientOptions, mail.WithTLSConfig(tlsConfig))
-		clientOptions = append(clientOptions, mail.WithTLSPolicy(mail.TLSMandatory))
-	} else {
-		clientOptions = append(clientOptions, mail.WithTLSPolicy(mail.TLSOpportunistic))
-	}
-
-	client, err := mail.NewClient(n.config.SmtpHost, clientOptions...)
+	clientCfg := smtp.NewDefaultConfig()
+	clientCfg.Host = n.config.SmtpHost
+	clientCfg.Port = int(n.config.SmtpPort)
+	clientCfg.Username = n.config.Username
+	clientCfg.Password = n.config.Password
+	clientCfg.UseSsl = n.config.SmtpTls
+	clientCfg.SkipTlsVerify = n.config.AllowInsecureConnections
+	client, err := smtp.NewClient(clientCfg)
 	if err != nil {
-		return nil, fmt.Errorf("failed to create smtp client: %w", err)
+		return nil, fmt.Errorf("failed to create SMTP client: %w", err)
 	}
 
-	client.ErrorHandlerRegistry.RegisterHandler("smtp.qq.com", "QUIT", &wQQMailQuitErrorHandler{})
 	defer client.Close()
 
-	msg := mail.NewMsg()
+	msg := smtp.NewMessage()
 	msg.Subject(subject)
-	msg.SetBodyString(mail.TypeTextPlain, message)
+	msg.SetBodyString(smtp.MIMETypeTextPlain, message)
 	if n.config.SenderName == "" {
 		msg.From(n.config.SenderAddress)
 	} else {
@@ -112,20 +83,8 @@ func (n *Notifier) Notify(ctx context.Context, subject string, message string) (
 	}
 	msg.To(n.config.ReceiverAddress)
 
-	if err := client.DialAndSend(msg); err != nil {
-		errShouldBeIgnored := false
-
-		// REF: https://github.com/wneessen/go-mail/issues/463
-		var sendErr *mail.SendError
-		if errors.As(err, &sendErr) {
-			if sendErr.Reason == mail.ErrSMTPReset {
-				errShouldBeIgnored = true
-			}
-		}
-
-		if !errShouldBeIgnored {
-			return nil, fmt.Errorf("failed to send mail: %w", err)
-		}
+	if err := client.Send(ctx, msg); err != nil {
+		return nil, fmt.Errorf("failed to send mail: %w", err)
 	}
 
 	return &notifier.NotifyResult{}, nil