V2 alpha - initial version (#172)

Initial alpha codebase for version 2 of WireGuard Portal.
This version is considered unstable and incomplete (for example, no public REST API)! 
Use with care!


Fixes/Implements the following issues:
 - OAuth support #154, #1 
 - New Web UI with internationalisation support #98, #107, #89, #62
 - Postgres Support #49 
 - Improved Email handling #47, #119 
 - DNS Search Domain support #46 
 - Bugfixes #94, #48 

---------

Co-authored-by: Fabian Wechselberger <wechselbergerf@hotmail.com>

internal/adapters/mailer.go

@@ -0,0 +1,138 @@
+package adapters
+
+import (
+	"context"
+	"crypto/tls"
+	"errors"
+	"fmt"
+	"github.com/h44z/wg-portal/internal"
+	"github.com/h44z/wg-portal/internal/config"
+	"github.com/h44z/wg-portal/internal/domain"
+	mail "github.com/xhit/go-simple-mail/v2"
+	"io"
+	"time"
+)
+
+type MailRepo struct {
+	cfg *config.MailConfig
+}
+
+func NewSmtpMailRepo(cfg config.MailConfig) MailRepo {
+	return MailRepo{cfg: &cfg}
+}
+
+// Send sends a mail.
+func (r MailRepo) Send(_ context.Context, subject, body string, to []string, options *domain.MailOptions) error {
+	if options == nil {
+		options = &domain.MailOptions{}
+	}
+	r.setDefaultOptions(r.cfg.From, options)
+
+	if len(to) == 0 {
+		return errors.New("missing email recipient")
+	}
+
+	uniqueTo := internal.UniqueStringSlice(to)
+	email := mail.NewMSG()
+	email.SetFrom(r.cfg.From).
+		AddTo(uniqueTo...).
+		SetReplyTo(options.ReplyTo).
+		SetSubject(subject).
+		SetBody(mail.TextPlain, body)
+
+	if len(options.Cc) > 0 {
+		// the underlying mail library does not allow the same address to appear in TO and CC... so filter entries that are already included
+		// in the TO addresses
+		cc := RemoveDuplicates(internal.UniqueStringSlice(options.Cc), uniqueTo)
+		email.AddCc(cc...)
+	}
+	if len(options.Bcc) > 0 {
+		// the underlying mail library does not allow the same address to appear in TO or CC and BCC... so filter entries that are already
+		// included in the TO and CC addresses
+		bcc := RemoveDuplicates(internal.UniqueStringSlice(options.Bcc), uniqueTo)
+		bcc = RemoveDuplicates(bcc, options.Cc)
+
+		email.AddCc(internal.UniqueStringSlice(options.Bcc)...)
+	}
+	if options.HtmlBody != "" {
+		email.AddAlternative(mail.TextHTML, options.HtmlBody)
+	}
+
+	for _, attachment := range options.Attachments {
+		attachmentData, err := io.ReadAll(attachment.Data)
+		if err != nil {
+			return fmt.Errorf("failed to read attachment data for %s: %w", attachment.Name, err)
+		}
+
+		if attachment.Embedded {
+			email.AddInlineData(attachmentData, attachment.Name, attachment.ContentType)
+		} else {
+			email.AddAttachmentData(attachmentData, attachment.Name, attachment.ContentType)
+		}
+	}
+
+	// Call Send and pass the client
+	srv := r.getMailServer()
+	client, err := srv.Connect()
+	if err != nil {
+		return fmt.Errorf("failed to connect to SMTP server: %w", err)
+	}
+
+	err = email.Send(client)
+	if err != nil {
+		return fmt.Errorf("failed to send email: %w", err)
+	}
+
+	return nil
+}
+
+func (r MailRepo) setDefaultOptions(sender string, options *domain.MailOptions) {
+	if options.ReplyTo == "" {
+		options.ReplyTo = sender
+	}
+}
+
+func (r MailRepo) getMailServer() *mail.SMTPServer {
+	srv := mail.NewSMTPClient()
+
+	srv.ConnectTimeout = 30 * time.Second
+	srv.SendTimeout = 30 * time.Second
+	srv.Host = r.cfg.Host
+	srv.Port = r.cfg.Port
+	srv.Username = r.cfg.Username
+	srv.Password = r.cfg.Password
+
+	switch r.cfg.Encryption {
+	case config.MailEncryptionTLS:
+		srv.Encryption = mail.EncryptionSSLTLS
+	case config.MailEncryptionStartTLS:
+		srv.Encryption = mail.EncryptionSTARTTLS
+	default: // MailEncryptionNone
+		srv.Encryption = mail.EncryptionNone
+	}
+	srv.TLSConfig = &tls.Config{ServerName: srv.Host, InsecureSkipVerify: !r.cfg.CertValidation}
+	switch r.cfg.AuthType {
+	case config.MailAuthPlain:
+		srv.Authentication = mail.AuthPlain
+	case config.MailAuthLogin:
+		srv.Authentication = mail.AuthLogin
+	case config.MailAuthCramMD5:
+		srv.Authentication = mail.AuthCRAMMD5
+	}
+
+	return srv
+}
+
+// RemoveDuplicates removes addresses from the given string slice which are contained in the remove slice.
+func RemoveDuplicates(slice []string, remove []string) []string {
+	uniqueSlice := make([]string, 0, len(slice))
+
+	for _, i := range remove {
+		for _, j := range slice {
+			if i != j {
+				uniqueSlice = append(uniqueSlice, j)
+			}
+		}
+	}
+	return uniqueSlice
+}