patch (RobustWebSocket): allow resuming when seq is nil

feat: add NullEncoder property wrapper
chore: clean up logging messages

Sources/DiscordKitCommon/Utils/NullEncodable.swift

@@ -0,0 +1,27 @@
+//
+//  NullEncoder.swift
+//  From https://stackoverflow.com/a/62312021/
+//  
+//
+//  Created by Vincent Kwok on 14/10/22.
+//
+
+import Foundation
+
+/// Explicitly include a value even when nil when encoded
+@propertyWrapper
+public struct NullEncodable<T>: Encodable where T: Encodable {
+    public let wrappedValue: T?
+
+    public init(wrappedValue: T?) {
+        self.wrappedValue = wrappedValue
+    }
+
+    public func encode(to encoder: Encoder) throws {
+        var container = encoder.singleValueContainer()
+        switch wrappedValue {
+        case .some(let value): try container.encode(value)
+        case .none: try container.encodeNil()
+        }
+    }
+}

Sources/DiscordKitCore/Gateway/GatewayIdentify.swift

@@ -48,7 +48,7 @@ public extension RobustWebSocket {
     ///
     /// - Returns: A `GatewayResume` struct, or nil if the Discord token is
     /// not present in the keychain
-    internal func getResume(seq: Int, sessionID: String) -> GatewayResume? {
+    internal func getResume(seq: Int?, sessionID: String) -> GatewayResume? {
         return GatewayResume(
             token: token,
             session_id: sessionID,

Sources/DiscordKitCore/Gateway/RobustWebSocket.swift

@@ -249,12 +249,12 @@ public class RobustWebSocket: NSObject, ObservableObject {
             onHello()
             // Start heartbeating and send identify
             guard let d = decoded.d as? GatewayHello else { return }
-            log.debug("[HELLO] heartbeat interval: \(d.heartbeat_interval, privacy: .public)s")
+            log.debug("[HELLO] heartbeat interval: \(d.heartbeat_interval, privacy: .public)")
             startHeartbeating(interval: Double(d.heartbeat_interval) / 1000.0)
 
             // Check if we're attempting to and can resume
-            if canResume, let sessionID = sessionID, let seq = seq {
-                log.info("[RESUME] Resuming session \(sessionID), seq: \(seq)")
+            if canResume, let sessionID = sessionID {
+                log.info("[RESUME] Resuming session \(sessionID, privacy: .public), seq: \(String(describing: self.seq), privacy: .public)")
                 guard let resume = getResume(seq: seq, sessionID: sessionID)
                 else { return }
                 send(op: .resume, data: resume)

Sources/DiscordKitCore/Objects/Gateway/DataStructs.swift

@@ -124,5 +124,5 @@ struct GatewayIdentify: OutgoingGatewayData {
 public struct GatewayResume: OutgoingGatewayData {
     public let token: String
     public let session_id: String
-    public let seq: Int // Last sequence number received
+    @NullEncodable public var seq: Int? // Last sequence number received
 }