feat: add option to skip TLS certificate check and ability to send test email

backend/internal/service/email_service.go

@@ -2,14 +2,18 @@ package service
 
 import (
 	"bytes"
+	"crypto/tls"
 	"errors"
 	"fmt"
 	"github.com/stonith404/pocket-id/backend/internal/common"
+	"github.com/stonith404/pocket-id/backend/internal/model"
 	"github.com/stonith404/pocket-id/backend/internal/utils/email"
+	"gorm.io/gorm"
 	htemplate "html/template"
 	"io/fs"
 	"mime/multipart"
 	"mime/quotedprintable"
+	"net"
 	"net/smtp"
 	"net/textproto"
 	ttemplate "text/template"
@@ -17,11 +21,12 @@ import (
 
 type EmailService struct {
 	appConfigService *AppConfigService
+	db               *gorm.DB
 	htmlTemplates    map[string]*htemplate.Template
 	textTemplates    map[string]*ttemplate.Template
 }
 
-func NewEmailService(appConfigService *AppConfigService, templateDir fs.FS) (*EmailService, error) {
+func NewEmailService(appConfigService *AppConfigService, db *gorm.DB, templateDir fs.FS) (*EmailService, error) {
 	htmlTemplates, err := email.PrepareHTMLTemplates(templateDir, emailTemplatesPaths)
 	if err != nil {
 		return nil, fmt.Errorf("prepare html templates: %w", err)
@@ -34,11 +39,25 @@ func NewEmailService(appConfigService *AppConfigService, templateDir fs.FS) (*Em
 
 	return &EmailService{
 		appConfigService: appConfigService,
+		db:               db,
 		htmlTemplates:    htmlTemplates,
 		textTemplates:    textTemplates,
 	}, nil
 }
 
+func (srv *EmailService) SendTestEmail() error {
+	var user model.User
+	if err := srv.db.First(&user).Error; err != nil {
+		return err
+	}
+
+	return SendEmail(srv,
+		email.Address{
+			Email: user.Email,
+			Name:  user.FullName(),
+		}, TestTemplate, nil)
+}
+
 func SendEmail[V any](srv *EmailService, toEmail email.Address, template email.Template[V], tData *V) error {
 	// Check if SMTP settings are set
 	if srv.appConfigService.DbConfig.EmailEnabled.Value != "true" {
@@ -71,26 +90,100 @@ func SendEmail[V any](srv *EmailService, toEmail email.Address, template email.T
 	)
 	c.Body(body)
 
-	// Set up the authentication information.
+	// Set up the TLS configuration
+	tlsConfig := &tls.Config{
+		InsecureSkipVerify: srv.appConfigService.DbConfig.SmtpSkipCertVerify.Value == "true",
+		ServerName:         srv.appConfigService.DbConfig.SmtpHost.Value,
+	}
+
+	// Connect to the SMTP server
+	port := srv.appConfigService.DbConfig.SmtpPort.Value
+	var client *smtp.Client
+	if port == "465" {
+		client, err = srv.connectToSmtpServerUsingImplicitTLS(
+			srv.appConfigService.DbConfig.SmtpHost.Value+":"+port,
+			tlsConfig,
+		)
+	} else {
+		client, err = srv.connectToSmtpServerUsingStartTLS(
+			srv.appConfigService.DbConfig.SmtpHost.Value+":"+port,
+			tlsConfig,
+		)
+	}
+	defer client.Quit()
+	if err != nil {
+		return fmt.Errorf("failed to connect to SMTP server: %w", err)
+	}
+
+	// Set up the authentication
 	auth := smtp.PlainAuth("",
 		srv.appConfigService.DbConfig.SmtpUser.Value,
 		srv.appConfigService.DbConfig.SmtpPassword.Value,
 		srv.appConfigService.DbConfig.SmtpHost.Value,
 	)
-
-	// Send the email
-	err = smtp.SendMail(
-		srv.appConfigService.DbConfig.SmtpHost.Value+":"+srv.appConfigService.DbConfig.SmtpPort.Value,
-		auth,
-		srv.appConfigService.DbConfig.SmtpFrom.Value,
-		[]string{toEmail.Email},
-		[]byte(c.String()),
-	)
-
-	if err != nil {
-		return fmt.Errorf("failed to send email: %w", err)
+	if err := client.Auth(auth); err != nil {
+		return fmt.Errorf("failed to authenticate SMTP client: %w", err)
 	}
 
+	// Send the email
+	if err := srv.sendEmailContent(client, toEmail, c); err != nil {
+		return fmt.Errorf("send email content: %w", err)
+	}
+
+	return nil
+}
+
+func (srv *EmailService) connectToSmtpServerUsingImplicitTLS(serverAddr string, tlsConfig *tls.Config) (*smtp.Client, error) {
+	conn, err := tls.Dial("tcp", serverAddr, tlsConfig)
+	if err != nil {
+		return nil, fmt.Errorf("failed to connect to SMTP server: %w", err)
+	}
+
+	client, err := smtp.NewClient(conn, srv.appConfigService.DbConfig.SmtpHost.Value)
+	if err != nil {
+		conn.Close()
+		return nil, fmt.Errorf("failed to create SMTP client: %w", err)
+	}
+
+	return client, nil
+}
+
+func (srv *EmailService) connectToSmtpServerUsingStartTLS(serverAddr string, tlsConfig *tls.Config) (*smtp.Client, error) {
+	conn, err := net.Dial("tcp", serverAddr)
+	if err != nil {
+		return nil, fmt.Errorf("failed to connect to SMTP server: %w", err)
+	}
+
+	client, err := smtp.NewClient(conn, srv.appConfigService.DbConfig.SmtpHost.Value)
+	if err != nil {
+		conn.Close()
+		return nil, fmt.Errorf("failed to create SMTP client: %w", err)
+	}
+
+	if err := client.StartTLS(tlsConfig); err != nil {
+		return nil, fmt.Errorf("failed to start TLS: %w", err)
+	}
+	return client, nil
+}
+
+func (srv *EmailService) sendEmailContent(client *smtp.Client, toEmail email.Address, c *email.Composer) error {
+	if err := client.Mail(srv.appConfigService.DbConfig.SmtpFrom.Value); err != nil {
+		return fmt.Errorf("failed to set sender: %w", err)
+	}
+	if err := client.Rcpt(toEmail.Email); err != nil {
+		return fmt.Errorf("failed to set recipient: %w", err)
+	}
+	w, err := client.Data()
+	if err != nil {
+		return fmt.Errorf("failed to start data: %w", err)
+	}
+	_, err = w.Write([]byte(c.String()))
+	if err != nil {
+		return fmt.Errorf("failed to write email data: %w", err)
+	}
+	if err := w.Close(); err != nil {
+		return fmt.Errorf("failed to close data writer: %w", err)
+	}
 	return nil
 }