allow to send html emails on mailgun

service/mailgun/mailgun.go

@@ -7,12 +7,20 @@ import (
 	"github.com/mailgun/mailgun-go/v5"
 )
 
+type mailgunMode int
+
+const (
+	mailgunModeText mailgunMode = iota
+	mailgunModeHTML
+)
+
 // Mailgun struct holds necessary data to communicate with the Mailgun API.
 type Mailgun struct {
 	client            *mailgun.Client
 	domain            string
 	senderAddress     string
 	receiverAddresses []string
+	mode              mailgunMode
 }
 
 // New returns a new instance of a Mailgun notification service.
@@ -24,6 +32,7 @@ func New(domain, apiKey, senderAddress string, opts ...Option) *Mailgun {
 		domain:            domain,
 		senderAddress:     senderAddress,
 		receiverAddresses: []string{},
+		mode:              mailgunModeText,
 	}
 
 	for _, opt := range opts {
@@ -39,10 +48,19 @@ func (m *Mailgun) AddReceivers(addresses ...string) {
 	m.receiverAddresses = append(m.receiverAddresses, addresses...)
 }
 
-// Send takes a message subject and a message body and sends them to all previously set chats. Message body supports
-// html as markup language.
+// Send takes a message subject and a message body and sends them to all previously added email receivers.
+// The body is sent as plain text by default, or as HTML when the service is configured with WithHTML().
 func (m Mailgun) Send(ctx context.Context, subject, message string) error {
-	mailMessage := mailgun.NewMessage(m.domain, m.senderAddress, subject, message, m.receiverAddresses...)
+	var mailMessage *mailgun.PlainMessage
+	switch m.mode {
+	case mailgunModeText:
+		mailMessage = mailgun.NewMessage(m.domain, m.senderAddress, subject, message, m.receiverAddresses...)
+	case mailgunModeHTML:
+		mailMessage = mailgun.NewMessage(m.domain, m.senderAddress, subject, "", m.receiverAddresses...)
+		mailMessage.SetHTML(message)
+	default:
+		return fmt.Errorf("unknown mailgun mode: %d", m.mode)
+	}
 
 	_, err := m.client.Send(ctx, mailMessage)
 	if err != nil {

service/mailgun/options.go

@@ -13,3 +13,10 @@ func WithEurope() Option {
 		_ = m.client.SetAPIBase(mailgun.APIBaseEU)
 	}
 }
+
+// WithHTML sets the message mode to HTML. By default, the message mode is text.
+func WithHTML() Option {
+	return func(m *Mailgun) {
+		m.mode = mailgunModeHTML
+	}
+}