Merge branch 'develop' into stable

2 files changed, 73 insertions, 3 deletions

diff --git a/src/SMAPI.Toolkit/Framework/GameScanning/GameFolderType.cs b/src/SMAPI.Toolkit/Framework/GameScanning/GameFolderType.cs
new file mode 100644
index 00000000..d18af59b
--- /dev/null
+++ b/src/SMAPI.Toolkit/Framework/GameScanning/GameFolderType.cs
@@ -0,0 +1,21 @@
+namespace StardewModdingAPI.Toolkit.Framework.GameScanning
+{
+    /// <summary>The detected validity for a Stardew Valley game folder based on file structure heuristics.</summary>
+    public enum GameFolderType
+    {
+        /// <summary>The folder seems to contain a valid Stardew Valley 1.5.5+ install.</summary>
+        Valid,
+
+        /// <summary>The folder doesn't contain Stardew Valley.</summary>
+        NoGameFound,
+
+        /// <summary>The folder contains Stardew Valley 1.5.4 or earlier. This version uses XNA Framework and 32-bit .NET Framework 4.5.2 on Windows and Mono on Linux/macOS, and isn't compatible with current versions of SMAPI.</summary>
+        Legacy154OrEarlier,
+
+        /// <summary>The folder contains Stardew Valley from the game's legacy compatibility branch, which backports newer changes to the <see cref="Legacy154OrEarlier"/> format.</summary>
+        LegacyCompatibilityBranch,
+
+        /// <summary>The folder seems to contain Stardew Valley files, but they failed to load for unknown reasons (e.g. corrupted executable).</summary>
+        InvalidUnknown
+    }
+}
diff --git a/src/SMAPI.Toolkit/Framework/GameScanning/GameScanner.cs b/src/SMAPI.Toolkit/Framework/GameScanning/GameScanner.cs
index 7553c07f..37e4f263 100644
--- a/src/SMAPI.Toolkit/Framework/GameScanning/GameScanner.cs
+++ b/src/SMAPI.Toolkit/Framework/GameScanning/GameScanner.cs
@@ -5,6 +5,7 @@ using System.Linq;
 using System.Xml.Linq;
 using System.Xml.XPath;
 using StardewModdingAPI.Toolkit.Utilities;
+using System.Reflection;
 #if SMAPI_FOR_WINDOWS
 using Microsoft.Win32;
 #endif
@@ -54,11 +55,59 @@ namespace StardewModdingAPI.Toolkit.Framework.GameScanning
         /// <param name="dir">The folder to check.</param>
         public bool LooksLikeGameFolder(DirectoryInfo dir)
         {
-            return
-                dir.Exists
-                && dir.EnumerateFiles("Stardew Valley.dll").Any();
+            return this.GetGameFolderType(dir) == GameFolderType.Valid;
         }
 
+        /// <summary>Detect the validity of a game folder based on file structure heuristics.</summary>
+        /// <param name="dir">The folder to check.</param>
+        public GameFolderType GetGameFolderType(DirectoryInfo dir)
+        {
+            // no such folder
+            if (!dir.Exists)
+                return GameFolderType.NoGameFound;
+
+            // apparently valid
+            if (dir.EnumerateFiles("Stardew Valley.dll").Any())
+                return GameFolderType.Valid;
+
+            // doesn't contain any version of Stardew Valley
+            FileInfo executable = new(Path.Combine(dir.FullName, "Stardew Valley.exe"));
+            if (!executable.Exists)
+                executable = new(Path.Combine(dir.FullName, "StardewValley.exe")); // pre-1.5.5 Linux/macOS executable
+            if (!executable.Exists)
+                return GameFolderType.NoGameFound;
+
+            // get assembly version
+            Version version;
+            try
+            {
+                version = AssemblyName.GetAssemblyName(executable.FullName).Version;
+            }
+            catch
+            {
+                // The executable exists but it doesn't seem to be a valid assembly. This would
+                // happen with Stardew Valley 1.5.5+, but that should have been flagged as a valid
+                // folder before this point.
+                return GameFolderType.InvalidUnknown;
+            }
+
+            // ignore Stardew Valley 1.5.5+ at this point
+            if (version.Major == 1 && version.Minor == 3 && version.Build == 37)
+                return GameFolderType.InvalidUnknown;
+
+            // incompatible version
+            if (version.Major == 1 && version.Minor < 4)
+            {
+                // Stardew Valley 1.5.4 and earlier have assembly versions <= 1.3.7853.31734
+                if (version.Minor < 3 || version.Build <= 7853)
+                    return GameFolderType.Legacy154OrEarlier;
+
+                // Stardew Valley 1.5.5+ legacy compatibility branch
+                return GameFolderType.LegacyCompatibilityBranch;
+            }
+
+            return GameFolderType.InvalidUnknown;
+        }
 
         /*********
         ** Private methods