notifications: implement notification service

notifications/notification_service.go

@@ -0,0 +1,73 @@
+package notifications
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"log"
+	"net/http"
+)
+
+type NotificationService struct {
+	store Store
+}
+
+func NewNotificationService(store Store) *NotificationService {
+	return &NotificationService{
+		store: store,
+	}
+}
+
+type PaymentReceivedPayload struct {
+	Template string `json:"template" binding:"required,eq=payment_received"`
+	Data     struct {
+		PaymentHash string `json:"payment_hash" binding:"required"`
+	} `json:"data"`
+}
+
+func (s *NotificationService) Notify(
+	pubkey string,
+	paymenthash string,
+) (bool, error) {
+	registrations, err := s.store.GetRegistrations(context.Background(), pubkey)
+	if err != nil {
+		log.Printf("Failed to get notification registrations for %s: %v", pubkey, err)
+		return false, err
+	}
+
+	req := &PaymentReceivedPayload{
+		Template: "payment_received",
+		Data: struct {
+			PaymentHash string "json:\"payment_hash\" binding:\"required\""
+		}{
+			PaymentHash: paymenthash,
+		},
+	}
+
+	var buf bytes.Buffer
+	err = json.NewEncoder(&buf).Encode(req)
+	if err != nil {
+		log.Printf("Failed to encode payment notification for %s: %v", pubkey, err)
+		return false, err
+	}
+
+	notified := false
+	for _, r := range registrations {
+		resp, err := http.DefaultClient.Post(r, "application/json", &buf)
+		if err != nil {
+			log.Printf("Failed to send payment notification for %s to %s: %v", pubkey, r, err)
+			// TODO: Remove subscription?
+			continue
+		}
+
+		if resp.StatusCode != 200 {
+			log.Printf("Got non 200 status code (%s) for payment notification for %s to %s: %v", resp.Status, pubkey, r, err)
+			// TODO: Remove subscription?
+			continue
+		}
+
+		notified = true
+	}
+
+	return notified, nil
+}