Add sqlite backend

sqlite/replace.go

@@ -0,0 +1,37 @@
+package sqlite
+
+import (
+	"fmt"
+
+	"fiatjaf.com/nostr"
+	"fiatjaf.com/nostr/eventstore"
+)
+
+func (s *SqliteBackend) ReplaceEvent(evt nostr.Event) error {
+	s.Lock()
+	defer s.Unlock()
+
+	filter := nostr.Filter{Kinds: []nostr.Kind{evt.Kind}, Authors: []nostr.PubKey{evt.PubKey}}
+	if evt.Kind.IsAddressable() {
+		filter.Tags = nostr.TagMap{"d": []string{evt.Tags.GetD()}}
+	}
+
+	shouldStore := true
+	for previous := range s.QueryEvents(filter, 1) {
+		if previous.CreatedAt <= evt.CreatedAt {
+			if err := s.DeleteEvent(previous.ID); err != nil {
+				return fmt.Errorf("failed to delete event for replacing: %w", err)
+			}
+		} else {
+			shouldStore = false
+		}
+	}
+
+	if shouldStore {
+		if err := s.SaveEvent(evt); err != nil && err != eventstore.ErrDupEvent {
+			return fmt.Errorf("failed to save: %w", err)
+		}
+	}
+
+	return nil
+}