use SteamKit2 to automatically fetch latest manifest

AppInfo.cs

@@ -0,0 +1,114 @@
+using SteamKit2;
+using System;
+using System.Diagnostics;
+
+namespace BeatSaberNoUpdate
+{
+    class AppInfo
+    {
+        // Beat Saber's app id
+        const uint APPID = 620980;
+
+        private static SteamClient steamClient;
+        private static SteamApps steamApps;
+        private static SteamUser steamUser;
+        private static CallbackManager manager;
+
+        private static bool isRunning;
+
+        private static JobID infoRequest = JobID.Invalid;
+        private static string manifestId = "";
+        private static bool success = false;
+
+        public (bool, string) Initialize()
+        {
+            // initialize a client and a callback manager for responding to events
+            steamClient = new SteamClient();
+            manager = new CallbackManager(steamClient);
+
+            // get a handler and register to callbacks we are interested in
+            steamUser = steamClient.GetHandler<SteamUser>();
+            steamApps = steamClient.GetHandler<SteamApps>();
+            manager.Subscribe<SteamApps.PICSProductInfoCallback>(OnProductInfo);
+            manager.Subscribe<SteamClient.ConnectedCallback>(OnConnected);
+            manager.Subscribe<SteamClient.DisconnectedCallback>(OnDisconnected);
+            manager.Subscribe<SteamUser.LoggedOnCallback>(OnLoggedOn);
+            manager.Subscribe<SteamUser.LoggedOffCallback>(OnLoggedOff);
+
+
+            isRunning = true;
+
+            Debug.WriteLine("Connecting to Steam...");
+
+            steamClient.Connect();
+
+            while (isRunning)
+            {
+                manager.RunWaitCallbacks(TimeSpan.FromSeconds(1));
+            }
+
+            return (success, manifestId);
+        }
+
+
+        static void OnConnected(SteamClient.ConnectedCallback callback)
+        {
+            Debug.WriteLine("Successfully connected to Steam");
+            // log on anonymously
+            steamUser.LogOnAnonymous();
+        }
+
+        static void OnDisconnected(SteamClient.DisconnectedCallback callback)
+        {
+            Debug.WriteLine("Disconnected from Steam");
+            isRunning = false;
+        }
+
+        static void OnLoggedOn(SteamUser.LoggedOnCallback callback)
+        {
+            if (callback.Result != EResult.OK)
+            {
+                if (callback.Result == EResult.AccountLogonDenied)
+                {
+                    // this shouldn't happen when logging in anonymously
+                    Debug.WriteLine("Unable to login to Steam");
+                    isRunning = false;
+                    return;
+                }
+                // if there is another error
+                Debug.WriteLine("Unable to login to Steam: {0} / {1}", callback.Result, callback.ExtendedResult);
+                isRunning = false;
+                return;
+            }
+
+            Debug.WriteLine("Successfully logged in to Steam");
+
+
+            // request product info
+            infoRequest = steamApps.PICSGetProductInfo(APPID, null);
+        }
+
+        private void OnProductInfo(SteamApps.PICSProductInfoCallback callback)
+        {
+            Debug.WriteLine("In OnProductInfo callback");
+            if (callback.JobID != infoRequest)
+            {
+                return;
+            }
+
+            // not sure if this is game specific or applies to other games
+            manifestId = callback.Apps[APPID].KeyValues.Children[4].Children[1].Children[1].Children[0].Value;
+
+            if (manifestId.Length == 19) success = true;
+            Debug.WriteLine(manifestId);
+            // log off after getting the manifest
+            steamUser.LogOff();
+        }
+
+        static void OnLoggedOff(SteamUser.LoggedOffCallback callback)
+        {
+            Debug.WriteLine("Logged off Steam: {0}", callback.Result);
+            isRunning = false;
+        }
+    }
+}