Add AuthenticationEvent.Builder to deprecate equivalent function in E…

…ventCreating (#183)

Sources/NostrSDK/Events/AuthenticationEvent.swift

@@ -52,14 +52,33 @@ public final class AuthenticationEvent: NostrEvent, RelayProviding {
 
 public extension EventCreating {
 
+    @available(*, deprecated, message: "Deprecated in favor of AuthenticationEvent.Builder.")
     func authenticate(relayURL: URL, challenge: String, signedBy keypair: Keypair) throws -> AuthenticationEvent {
-        let validatedRelayURL = try RelayURLValidator.shared.validateRelayURL(relayURL)
+        try AuthenticationEvent.Builder()
+            .relayURL(relayURL)
+            .challenge(challenge)
+            .build(signedBy: keypair)
+    }
+}
+
+public extension AuthenticationEvent {
+    /// Builder of a ``AuthenticationEvent``.
+    final class Builder: NostrEvent.Builder<AuthenticationEvent> {
+        public init() {
+            super.init(kind: .authentication)
+        }
 
-        let tags: [Tag] = [
-            Tag(name: "relay", value: validatedRelayURL.absoluteString),
-            Tag(name: "challenge", value: challenge)
-        ]
+        /// The relay URL this event authenticates to.
+        @discardableResult
+        public final func relayURL(_ relayURL: URL) throws -> Self {
+            let validatedRelayURL = try RelayURLValidator.shared.validateRelayURL(relayURL)
+            return appendTags(Tag(name: "relay", value: validatedRelayURL.absoluteString))
+        }
 
-        return try AuthenticationEvent(content: "", tags: tags, signedBy: keypair)
+        /// The challenge string as received from the relay.
+        @discardableResult
+        public final func challenge(_ challenge: String) throws -> Self {
+            appendTags(Tag(name: "challenge", value: challenge))
+        }
     }
 }

Tests/NostrSDKTests/Events/AuthenticationEventTests.swift

@@ -11,6 +11,20 @@ import XCTest
 final class AuthenticationEventTests: XCTestCase, EventCreating, EventVerifying, FixtureLoading {
 
     func testCreateAuthenticationEvent() throws {
+        let relayURL = try XCTUnwrap(URL(string: "wss://relay.example.com/"))
+        let event = try AuthenticationEvent.Builder()
+            .relayURL(relayURL)
+            .challenge("some-challenge-string")
+            .build(signedBy: Keypair.test)
+
+        XCTAssertEqual(event.kind, .authentication)
+        XCTAssertEqual(event.relayURL, relayURL)
+        XCTAssertEqual(event.challenge, "some-challenge-string")
+
+        try verifyEvent(event)
+    }
+
+    func testCreateAuthenticationEventDeprecated() throws {
         let relayURL = try XCTUnwrap(URL(string: "wss://relay.example.com/"))
         let event = try authenticate(relayURL: relayURL, challenge: "some-challenge-string", signedBy: Keypair.test)