GetInstallDirectory(appId) for any SteamApp

OpenCS2hock/Installer.cs

@@ -0,0 +1,32 @@
+using Microsoft.Win32;
+
+namespace OpenCS2hock;
+
+public static class Installer
+{
+     public static string? GetInstallDirectory(int appId = 730)
+     {
+          string steamInstallation =
+#pragma warning disable CA1416 //Registry only available on Windows
+               (string)(Registry.GetValue(@"HKEY_CURRENT_USER\SOFTWARE\Valve\Steam", "SteamPath", null) ??
+#pragma warning restore CA1416
+                        throw new DirectoryNotFoundException("No Steam Installation found."));
+          string libraryFolderFilepath = Path.Combine(steamInstallation, "steamapps\\libraryfolders.vdf");
+          string? libraryPath = null;
+          string? appManifestFolderPath = null;
+          foreach (string line in File.ReadAllLines(libraryFolderFilepath))
+               if (line.Contains("path"))
+                    libraryPath = line.Split("\"").Last(split => split.Length > 0);
+               else if (line.Contains($"\"{appId}\""))
+                    appManifestFolderPath = Path.Combine(libraryPath!, $"steamapps\\appmanifest_{appId}.acf");
+
+          string installationPath = "";
+          if (appManifestFolderPath is null)
+               throw new DirectoryNotFoundException($"No {appId} Installation found.");
+          foreach(string line in File.ReadAllLines(appManifestFolderPath))
+               if (line.Contains("installdir"))
+                    installationPath = Path.Combine(libraryPath!, "steamapps\\common", line.Split("\"").Last(split => split.Length > 0));
+          
+          return installationPath;
+     }
+}