move nostr-sdk repository into here because why not?

sdk/relays.go

@@ -0,0 +1,41 @@
+package sdk
+
+import (
+	"github.com/nbd-wtf/go-nostr"
+)
+
+type RelayList = GenericList[Relay]
+
+type Relay struct {
+	URL    string
+	Inbox  bool
+	Outbox bool
+}
+
+func (r Relay) Value() string { return r.URL }
+
+func parseRelayFromKind10002(tag nostr.Tag) (rl Relay, ok bool) {
+	if u := tag.Value(); u != "" && tag[0] == "r" {
+		if !nostr.IsValidRelayURL(u) {
+			return rl, false
+		}
+		u := nostr.NormalizeURL(u)
+
+		relay := Relay{
+			URL: u,
+		}
+
+		if len(tag) == 2 {
+			relay.Inbox = true
+			relay.Outbox = true
+		} else if tag[2] == "write" {
+			relay.Outbox = true
+		} else if tag[2] == "read" {
+			relay.Inbox = true
+		}
+
+		return relay, true
+	}
+
+	return rl, false
+}