Added basic email renderer

arn/EmailRenderer.go

@@ -0,0 +1,33 @@
+package arn
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/mailgun/mailgun-go/v3"
+)
+
+// HTMLEmailRenderer is the instance used for rendering emails.
+var HTMLEmailRenderer EmailRenderer
+
+// EmailRenderer is an interface for rendering HTML emails.
+type EmailRenderer interface {
+	Notification(notification *Notification) string
+}
+
+// SendEmail sends an e-mail.
+func SendEmail(email string, subject string, html string) error {
+	mg := mailgun.NewMailgun(APIKeys.Mailgun.Domain, APIKeys.Mailgun.PrivateKey)
+	sender := fmt.Sprintf("Anime Notifier <notifications@%s>", APIKeys.Mailgun.Domain)
+	message := mg.NewMessage(sender, subject, "", email)
+	message.SetHtml(html)
+
+	// Allow a 10-second timeout
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
+	defer cancel()
+
+	// Send the message
+	_, _, err := mg.Send(ctx, message)
+	return err
+}