fix: move implementation to "internal" package

internal/service/mail.go

@@ -0,0 +1,55 @@
+package service
+
+import (
+	"fmt"
+	"net/smtp"
+	"spend-sparrow/internal/log"
+	"spend-sparrow/internal/types"
+)
+
+type Mail interface {
+	// Sending an email is a fire and forget operation. Thus no error handling
+	SendMail(to string, subject string, message string)
+}
+
+type MailImpl struct {
+	server *types.Settings
+}
+
+func NewMail(server *types.Settings) MailImpl {
+	return MailImpl{server: server}
+}
+
+func (m MailImpl) SendMail(to string, subject string, message string) {
+	go m.internalSendMail(to, subject, message)
+}
+
+func (m MailImpl) internalSendMail(to string, subject string, message string) {
+	if m.server.Smtp == nil {
+		return
+	}
+
+	s := m.server.Smtp
+
+	auth := smtp.PlainAuth("", s.User, s.Pass, s.Host)
+
+	msg := fmt.Sprintf(
+		`From: %v <%v>
+		To: %v
+		Subject: %v
+		MIME-version: 1.0;
+		Content-Type: text/html; charset="UTF-8";
+
+		%v`,
+		s.FromName,
+		s.FromMail,
+		to,
+		subject,
+		message)
+
+	log.Info("Sending mail to %v", to)
+	err := smtp.SendMail(s.Host+":"+s.Port, auth, s.FromMail, []string{to}, []byte(msg))
+	if err != nil {
+		log.Error("Error sending mail: %v", err)
+	}
+}