move structs in right packages + impl sender service to build and send e-mail

mail/mail.go

@@ -0,0 +1,49 @@
+package mail
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"strings"
+)
+
+type Email struct {
+	Sender    string   `json:"sender"`
+	Receivers []string `json:"receivers"`
+	Subject   string   `json:"subject"`
+	Content   string   `json:"content"`
+}
+
+func NewEmail(sender string, receivers []string, subject, content string) Email {
+	return Email{
+		Sender:    sender,
+		Receivers: receivers,
+		Subject:   subject,
+		Content:   content,
+	}
+}
+
+func FromJSON(path string) error {
+	content, err := ioutil.ReadFile(path)
+	if err != nil {
+		return err
+	}
+
+	var mail Email
+	if err := json.Unmarshal(content, &mail); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (e Email) Generate() []byte {
+	mail := fmt.Sprintf(
+		"To: %s\nFrom: %s\nContent-Type: text/html\nSubject: %s\n\n%s",
+		strings.Join(e.Receivers, ","),
+		e.Sender,
+		e.Sender,
+		e.Content,
+	)
+	return []byte(mail)
+}