eventstore: boltdb (copied from lmdb)

eventstore/boltdb/replace.go

@@ -0,0 +1,47 @@
+package bolt
+
+import (
+	"fmt"
+	"iter"
+
+	"fiatjaf.com/nostr"
+	"fiatjaf.com/nostr/eventstore/internal"
+	"go.etcd.io/bbolt"
+)
+
+func (b *BoltBackend) ReplaceEvent(evt nostr.Event) error {
+	return b.DB.Update(func(txn *bbolt.Tx) error {
+		filter := nostr.Filter{Limit: 1, Kinds: []nostr.Kind{evt.Kind}, Authors: []nostr.PubKey{evt.PubKey}}
+		if evt.Kind.IsAddressable() {
+			// when addressable, add the "d" tag to the filter
+			filter.Tags = nostr.TagMap{"d": []string{evt.Tags.GetD()}}
+		}
+
+		// now we fetch the past events, whatever they are, delete them and then save the new
+		var yield_ func(nostr.Event) bool
+		var results iter.Seq[nostr.Event] = func(yield func(nostr.Event) bool) {
+			yield_ = yield
+		}
+		err := b.query(txn, filter, 10 /* in theory limit could be just 1 and this should work */, yield_)
+		if err != nil {
+			return fmt.Errorf("failed to query past events with %s: %w", filter, err)
+		}
+
+		shouldStore := true
+		for previous := range results {
+			if internal.IsOlder(previous, evt) {
+				if err := b.delete(txn, previous.ID); err != nil {
+					return fmt.Errorf("failed to delete event %s for replacing: %w", previous.ID, err)
+				}
+			} else {
+				// there is a newer event already stored, so we won't store this
+				shouldStore = false
+			}
+		}
+		if shouldStore {
+			return b.save(txn, evt)
+		}
+
+		return nil
+	})
+}