remove DiscordBM dependency

Sources/DiscordKit/GatewayClient.swift

@@ -3,40 +3,30 @@ import Foundation
 import FoundationNetworking
 #endif
 
-struct GatewayClient {
-    let gatewayURL: URL
+class GatewayClient {
     let ws: URLSessionWebSocketTask
+    var sequenceNum: Int? = nil
 
     init(gatewayURL: URL) {
-        self.gatewayURL = gatewayURL
         ws = URLSession.shared.webSocketTask(with: gatewayURL.appending(component: "?v=10&encoding=json"))
     }
 
-    func openConnection() {
-        listen()
+    func openConnection() async throws {
         ws.resume()
-        RunLoop.current.run()
+        guard case .hello(let helloMessage) = try await getMessage().d else { throw GatewayError.mismatchedOpcode }
+        dump(helloMessage)
+        Timer.scheduledTimer(withTimeInterval: (helloMessage.heartbeat_interval / 1000.0), repeats: true) {
+            
+        }
     }
 
-    func listen() {
-        ws.receive { result in
-            defer { listen() }
-            do {
-                if case .failure(let err) = result { throw err }
-                guard case .success(let message) = result else { return }
-                guard case .string(let str) = message else { throw GatewayError.invalidMessage }
-                let json = JSONDecoder()
-                let gwMessage = try json.decode(GatewayMessage.self, from: Data(str.utf8))
-                switch gwMessage.d {
-                    case .hello(let hello):
-                        dump(hello)
-                    case .none:
-                        return
-                }
-            } catch {
-                print(error)
-            }
-        }
+    func getMessage() async throws -> GatewayMessage {
+        let wsMessage = try await ws.receive()
+        guard case .string(let str) = wsMessage else { throw GatewayError.invalidMessage }
+        let json = JSONDecoder()
+        let gwMessage = try json.decode(GatewayMessage.self, from: Data(str.utf8))
+        sequenceNum = gwMessage.s ?? sequenceNum
+        return gwMessage
     }
 
 }
@@ -44,4 +34,5 @@ struct GatewayClient {
 public enum GatewayError: Error {
     case invalidMessage
     case invalidOpcode
+    case mismatchedOpcode
 }