From 0fda28526fcfce0751b8979400e4a16f6a77df8d Mon Sep 17 00:00:00 2001
From: Cj <161484149+CJ-SPT@users.noreply.github.com>
Date: Sun, 11 May 2025 15:52:14 -0400
Subject: [PATCH] Implement module patch abstraction and patch loader (#250)

* Implement patch abstractions and patch loader using an interface

* remove patch loader

* rename patch class
---
 .../SPTarkov.Reflection/CodeWrapper/Code.cs   |  46 ++++++
 .../CodeWrapper/CodeGenerator.cs              |  76 ++++++++++
 .../CodeWrapper/CodeWithLabel.cs              |  33 +++++
 .../Patching/AbstractPatch.cs                 | 132 ++++++++++++++++++
 .../Patching/Attributes.cs                    |  27 ++++
 .../SPTarkov.Reflection.csproj                |  26 ++++
 .../SPTarkov.Server.Core.csproj               |   1 +
 .../Modding/HarmonyBootstrapper.cs            |  29 ----
 SPTarkov.Server/Program.cs                    |   2 -
 SPTarkov.Server/SPTarkov.Server.csproj        |   1 -
 server-csharp.sln                             |   7 +
 11 files changed, 348 insertions(+), 32 deletions(-)
 create mode 100644 Libraries/SPTarkov.Reflection/CodeWrapper/Code.cs
 create mode 100644 Libraries/SPTarkov.Reflection/CodeWrapper/CodeGenerator.cs
 create mode 100644 Libraries/SPTarkov.Reflection/CodeWrapper/CodeWithLabel.cs
 create mode 100644 Libraries/SPTarkov.Reflection/Patching/AbstractPatch.cs
 create mode 100644 Libraries/SPTarkov.Reflection/Patching/Attributes.cs
 create mode 100644 Libraries/SPTarkov.Reflection/SPTarkov.Reflection.csproj
 delete mode 100644 SPTarkov.Server/Modding/HarmonyBootstrapper.cs

diff --git a/Libraries/SPTarkov.Reflection/CodeWrapper/Code.cs b/Libraries/SPTarkov.Reflection/CodeWrapper/Code.cs
new file mode 100644
index 00000000..87c8d832
--- /dev/null
+++ b/Libraries/SPTarkov.Reflection/CodeWrapper/Code.cs
@@ -0,0 +1,46 @@
+using System.Reflection.Emit;
+
+namespace SPTarkov.Reflection.CodeWrapper;
+
+public class Code
+{
+    public OpCode OpCode { get; }
+    public Type? CallerType { get; }
+    public object? OperandTarget { get; }
+    public Type[]? Parameters { get; }
+    public bool HasOperand { get; }
+
+    public Code(OpCode opCode)
+    {
+        OpCode = opCode;
+        HasOperand = false;
+    }
+
+    public Code(OpCode opCode, object operandTarget)
+    {
+        OpCode = opCode;
+        OperandTarget = operandTarget;
+        HasOperand = true;
+    }
+
+    public Code(OpCode opCode, Type callerType)
+    {
+        OpCode = opCode;
+        CallerType = callerType;
+        HasOperand = true;
+    }
+
+    public Code(OpCode opCode, Type callerType, object operandTarget, Type[] parameters = null)
+    {
+        OpCode = opCode;
+        CallerType = callerType;
+        OperandTarget = operandTarget;
+        Parameters = parameters;
+        HasOperand = true;
+    }
+
+    public virtual Label? GetLabel()
+    {
+        return null;
+    }
+}
diff --git a/Libraries/SPTarkov.Reflection/CodeWrapper/CodeGenerator.cs b/Libraries/SPTarkov.Reflection/CodeWrapper/CodeGenerator.cs
new file mode 100644
index 00000000..2c68965d
--- /dev/null
+++ b/Libraries/SPTarkov.Reflection/CodeWrapper/CodeGenerator.cs
@@ -0,0 +1,76 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection.Emit;
+using HarmonyLib;
+
+namespace SPTarkov.Reflection.CodeWrapper;
+
+/// <summary>
+/// Helper class to generate IL code for transpilers
+/// </summary>
+public class CodeGenerator
+{
+    public static List<CodeInstruction> GenerateInstructions(List<Code> codes)
+    {
+        var list = new List<CodeInstruction>();
+
+        foreach (Code code in codes)
+        {
+            list.Add(ParseCode(code));
+        }
+
+        return list;
+    }
+
+    private static CodeInstruction ParseCode(Code code)
+    {
+        if (!code.HasOperand)
+        {
+            return new CodeInstruction(code.OpCode) { labels = GetLabelList(code) };
+        }
+
+        if (code.OpCode == OpCodes.Ldfld || code.OpCode == OpCodes.Ldflda || code.OpCode == OpCodes.Stfld)
+        {
+            return new CodeInstruction(code.OpCode, AccessTools.Field(code.CallerType, code.OperandTarget as string)) { labels = GetLabelList(code) };
+        }
+
+        if (code.OpCode == OpCodes.Call || code.OpCode == OpCodes.Callvirt)
+        {
+            return new CodeInstruction(code.OpCode, AccessTools.Method(code.CallerType, code.OperandTarget as string, code.Parameters)) { labels = GetLabelList(code) };
+        }
+
+        if (code.OpCode == OpCodes.Box)
+        {
+            return new CodeInstruction(code.OpCode, code.CallerType) { labels = GetLabelList(code) };
+        }
+
+        if (code.OpCode == OpCodes.Br || code.OpCode == OpCodes.Brfalse || code.OpCode == OpCodes.Brtrue || code.OpCode == OpCodes.Brtrue_S
+            || code.OpCode == OpCodes.Brfalse_S || code.OpCode == OpCodes.Br_S)
+        {
+            return new CodeInstruction(code.OpCode, code.OperandTarget) { labels = GetLabelList(code) };
+        }
+
+        if (code.OpCode == OpCodes.Ldftn)
+        {
+            return new CodeInstruction(code.OpCode, AccessTools.Method(code.CallerType, code.OperandTarget as string, code.Parameters)) { labels = GetLabelList(code) };
+        }
+
+        if (code.OpCode == OpCodes.Newobj)
+        {
+            return new CodeInstruction(code.OpCode, code.CallerType.GetConstructors().FirstOrDefault(x => x.GetParameters().Length == code.Parameters.Length)) { labels = GetLabelList(code) };
+        }
+
+        throw new ArgumentException($"Code with OpCode {code.OpCode.ToString()} is not supported.");
+    }
+
+    private static List<Label> GetLabelList(Code code)
+    {
+        if (code.GetLabel() == null)
+        {
+            return new List<Label>();
+        }
+
+        return [ (Label)code.GetLabel() ];
+    }
+}
diff --git a/Libraries/SPTarkov.Reflection/CodeWrapper/CodeWithLabel.cs b/Libraries/SPTarkov.Reflection/CodeWrapper/CodeWithLabel.cs
new file mode 100644
index 00000000..b6b7ba6a
--- /dev/null
+++ b/Libraries/SPTarkov.Reflection/CodeWrapper/CodeWithLabel.cs
@@ -0,0 +1,33 @@
+using System.Reflection.Emit;
+
+namespace SPTarkov.Reflection.CodeWrapper;
+
+public class CodeWithLabel : Code
+{
+    public Label Label { get; }
+
+    public CodeWithLabel(OpCode opCode, Label label) : base(opCode)
+    {
+        Label = label;
+    }
+
+    public CodeWithLabel(OpCode opCode, Label label, object operandTarget) : base(opCode, operandTarget)
+    {
+        Label = label;
+    }
+
+    public CodeWithLabel(OpCode opCode, Label label, Type callerType) : base(opCode, callerType)
+    {
+        Label = label;
+    }
+
+    public CodeWithLabel(OpCode opCode, Label label, Type callerType, object operandTarget, Type[] parameters = null) : base(opCode, callerType, operandTarget, parameters)
+    {
+        Label = label;
+    }
+
+    public override Label? GetLabel()
+    {
+        return Label;
+    }
+}
diff --git a/Libraries/SPTarkov.Reflection/Patching/AbstractPatch.cs b/Libraries/SPTarkov.Reflection/Patching/AbstractPatch.cs
new file mode 100644
index 00000000..13975f56
--- /dev/null
+++ b/Libraries/SPTarkov.Reflection/Patching/AbstractPatch.cs
@@ -0,0 +1,132 @@
+using System.Reflection;
+using HarmonyLib;
+
+namespace SPTarkov.Reflection.Patching;
+
+public abstract class AbstractPatch
+{
+    private readonly Harmony _harmony;
+    private readonly List<HarmonyMethod> _prefixList;
+    private readonly List<HarmonyMethod> _postfixList;
+    private readonly List<HarmonyMethod> _transpilerList;
+    private readonly List<HarmonyMethod> _finalizerList;
+    private readonly List<HarmonyMethod> _ilManipulatorList;
+
+    /// <summary>
+    /// Constructor
+    /// </summary>
+    /// <param name="name">Name</param>
+    protected AbstractPatch(string? name = null)
+    {
+        _harmony = new Harmony(name ?? GetType().Name);
+        _prefixList = GetPatchMethods(typeof(PatchPrefixAttribute));
+        _postfixList = GetPatchMethods(typeof(PatchPostfixAttribute));
+        _transpilerList = GetPatchMethods(typeof(PatchTranspilerAttribute));
+        _finalizerList = GetPatchMethods(typeof(PatchFinalizerAttribute));
+        _ilManipulatorList = GetPatchMethods(typeof(PatchIlManipulatorAttribute));
+
+        if (_prefixList.Count == 0
+            && _postfixList.Count == 0
+            && _transpilerList.Count == 0
+            && _finalizerList.Count == 0
+            && _ilManipulatorList.Count == 0)
+        {
+            throw new Exception($"{_harmony.Id}: At least one of the patch methods must be specified");
+        }
+    }
+
+    /// <summary>
+    /// Get original method
+    /// </summary>
+    /// <returns>Method</returns>
+    protected abstract MethodBase GetTargetMethod();
+
+    /// <summary>
+    /// Get HarmonyMethod from string
+    /// </summary>
+    /// <param name="attributeType">Attribute type</param>
+    /// <returns>Method</returns>
+    private List<HarmonyMethod> GetPatchMethods(Type attributeType)
+    {
+        var T = GetType();
+        var methods = new List<HarmonyMethod>();
+
+        foreach (var method in T.GetMethods(BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.Public |
+                                            BindingFlags.DeclaredOnly))
+        {
+            if (method.GetCustomAttribute(attributeType) != null)
+            {
+                methods.Add(new HarmonyMethod(method));
+            }
+        }
+
+        return methods;
+    }
+
+    /// <summary>
+    /// Apply patch to target
+    /// </summary>
+    public void Enable()
+    {
+        var target = GetTargetMethod();
+
+        if (target == null)
+        {
+            throw new InvalidOperationException($"{_harmony.Id}: TargetMethod is null");
+        }
+
+        try
+        {
+            foreach (var prefix in _prefixList)
+            {
+                _harmony.Patch(target, prefix: prefix);
+            }
+
+            foreach (var postfix in _postfixList)
+            {
+                _harmony.Patch(target, postfix: postfix);
+            }
+
+            foreach (var transpiler in _transpilerList)
+            {
+                _harmony.Patch(target, transpiler: transpiler);
+            }
+
+            foreach (var finalizer in _finalizerList)
+            {
+                _harmony.Patch(target, finalizer: finalizer);
+            }
+
+            foreach (var ilmanipulator in _ilManipulatorList)
+            {
+                _harmony.Patch(target, ilmanipulator: ilmanipulator);
+            }
+        }
+        catch (Exception ex)
+        {
+            throw new Exception($"{_harmony.Id}:", ex);
+        }
+    }
+
+    /// <summary>
+    /// Remove applied patch from target
+    /// </summary>
+    public void Disable()
+    {
+        var target = GetTargetMethod();
+
+        if (target == null)
+        {
+            throw new InvalidOperationException($"{_harmony.Id}: TargetMethod is null");
+        }
+
+        try
+        {
+            _harmony.Unpatch(target, HarmonyPatchType.All, _harmony.Id);
+        }
+        catch (Exception ex)
+        {
+            throw new Exception($"{_harmony.Id}:", ex);
+        }
+    }
+}
diff --git a/Libraries/SPTarkov.Reflection/Patching/Attributes.cs b/Libraries/SPTarkov.Reflection/Patching/Attributes.cs
new file mode 100644
index 00000000..b0d84af9
--- /dev/null
+++ b/Libraries/SPTarkov.Reflection/Patching/Attributes.cs
@@ -0,0 +1,27 @@
+namespace SPTarkov.Reflection.Patching
+{
+    [AttributeUsage(AttributeTargets.Method)]
+    public class PatchPrefixAttribute : Attribute
+    {
+    }
+
+    [AttributeUsage(AttributeTargets.Method)]
+    public class PatchPostfixAttribute : Attribute
+    {
+    }
+
+    [AttributeUsage(AttributeTargets.Method)]
+    public class PatchTranspilerAttribute : Attribute
+    {
+    }
+
+    [AttributeUsage(AttributeTargets.Method)]
+    public class PatchFinalizerAttribute : Attribute
+    {
+    }
+
+    [AttributeUsage(AttributeTargets.Method)]
+    public class PatchIlManipulatorAttribute : Attribute
+    {
+    }
+}
diff --git a/Libraries/SPTarkov.Reflection/SPTarkov.Reflection.csproj b/Libraries/SPTarkov.Reflection/SPTarkov.Reflection.csproj
new file mode 100644
index 00000000..af6045fc
--- /dev/null
+++ b/Libraries/SPTarkov.Reflection/SPTarkov.Reflection.csproj
@@ -0,0 +1,26 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <Import Project="..\..\Build.props"/>
+
+    <PropertyGroup>
+        <PackageId>SPTarkov.Reflection</PackageId>
+        <Authors>Single Player Tarkov</Authors>
+        <Description>Reflection library for the Single Player Tarkov server.</Description>
+        <Copyright>Copyright (c) Single Player Tarkov 2025</Copyright>
+        <PackageLicenseFile>LICENSE</PackageLicenseFile>
+        <PackageProjectUrl>https://sp-tarkov.com</PackageProjectUrl>
+        <RepositoryUrl>https://github.com/sp-tarkov/server-csharp</RepositoryUrl>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <OutputType>Library</OutputType>
+        <IsPackable>true</IsPackable>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <None Include="..\..\LICENSE" Pack="true" Visible="false" PackagePath=""/>
+    </ItemGroup>
+
+    <ItemGroup>
+      <PackageReference Include="HarmonyX" Version="2.14.0"/>
+    </ItemGroup>
+
+</Project>
diff --git a/Libraries/SPTarkov.Server.Core/SPTarkov.Server.Core.csproj b/Libraries/SPTarkov.Server.Core/SPTarkov.Server.Core.csproj
index 0e837571..3cd54361 100644
--- a/Libraries/SPTarkov.Server.Core/SPTarkov.Server.Core.csproj
+++ b/Libraries/SPTarkov.Server.Core/SPTarkov.Server.Core.csproj
@@ -17,6 +17,7 @@
 
   <ItemGroup>
     <ProjectReference Include="..\SPTarkov.DI\SPTarkov.DI.csproj"/>
+    <ProjectReference Include="..\SPTarkov.Reflection\SPTarkov.Reflection.csproj"/>
   </ItemGroup>
 
   <ItemGroup>
diff --git a/SPTarkov.Server/Modding/HarmonyBootstrapper.cs b/SPTarkov.Server/Modding/HarmonyBootstrapper.cs
deleted file mode 100644
index 7d5f88ea..00000000
--- a/SPTarkov.Server/Modding/HarmonyBootstrapper.cs
+++ /dev/null
@@ -1,29 +0,0 @@
-using System.Reflection;
-using HarmonyLib;
-using SPTarkov.Server.Core.Utils;
-
-namespace SPTarkov.Server.Modding;
-
-public class HarmonyBootstrapper
-{
-    public static void LoadAllPatches(List<Assembly> assemblies)
-    {
-        if (!ProgramStatics.MODS())
-        {
-            return;
-        }
-
-        var hamony = new Harmony("SPT");
-        foreach (var assembly in assemblies)
-        {
-            try
-            {
-                hamony.PatchAll(assembly);
-            }
-            catch (Exception e)
-            {
-                Console.WriteLine(e);
-            }
-        }
-    }
-}
diff --git a/SPTarkov.Server/Program.cs b/SPTarkov.Server/Program.cs
index aec5638a..07049dfa 100644
--- a/SPTarkov.Server/Program.cs
+++ b/SPTarkov.Server/Program.cs
@@ -29,8 +29,6 @@ public static class Program
 
         // validate and sort mods, this will also discard any mods that are invalid
         var sortedLoadedMods = ValidateMods(mods);
-        // for harmony, we use the original list, as some mods may only be bepinex patches only
-        HarmonyBootstrapper.LoadAllPatches(mods.SelectMany(asm => asm.Assemblies).ToList());
 
         var diHandler = new DependencyInjectionHandler(builder.Services);
         // register SPT components
diff --git a/SPTarkov.Server/SPTarkov.Server.csproj b/SPTarkov.Server/SPTarkov.Server.csproj
index 9a0764bc..1539eb6c 100644
--- a/SPTarkov.Server/SPTarkov.Server.csproj
+++ b/SPTarkov.Server/SPTarkov.Server.csproj
@@ -24,7 +24,6 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="HarmonyX" Version="2.14.0"/>
     <PackageReference Include="Microsoft.Extensions.Configuration.Binder" Version="9.0.1"/>
     <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="9.0.1"/>
     <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="9.0.1"/>
diff --git a/server-csharp.sln b/server-csharp.sln
index 55de31ea..06d36fce 100644
--- a/server-csharp.sln
+++ b/server-csharp.sln
@@ -25,6 +25,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "HideoutCraftQuestIdGenerato
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Benchmarks", "Benchmarks\Benchmarks.csproj", "{6884273A-72E9-4035-B5BE-EE101C69F5F5}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SPTarkov.Reflection", "Libraries\SPTarkov.Reflection\SPTarkov.Reflection.csproj", "{9073A593-A2F5-471E-9678-B896A7226FD4}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -67,6 +69,10 @@ Global
 		{6884273A-72E9-4035-B5BE-EE101C69F5F5}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{6884273A-72E9-4035-B5BE-EE101C69F5F5}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{6884273A-72E9-4035-B5BE-EE101C69F5F5}.Release|Any CPU.Build.0 = Release|Any CPU
+		{9073A593-A2F5-471E-9678-B896A7226FD4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{9073A593-A2F5-471E-9678-B896A7226FD4}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{9073A593-A2F5-471E-9678-B896A7226FD4}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{9073A593-A2F5-471E-9678-B896A7226FD4}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -78,5 +84,6 @@ Global
 		{DB049C81-DEC0-490D-AC06-7AF4DC8C0571} = {F084DDFD-89F3-44F9-89C3-5CA11F4CDEEF}
 		{4B973AC0-0C60-4853-9AF7-7CB69127473E} = {F084DDFD-89F3-44F9-89C3-5CA11F4CDEEF}
 		{C24B1FEB-F8AC-434E-998D-5DA4D1687295} = {587959C2-5AFA-4B77-B327-566610F9A289}
+		{9073A593-A2F5-471E-9678-B896A7226FD4} = {F084DDFD-89F3-44F9-89C3-5CA11F4CDEEF}
 	EndGlobalSection
 EndGlobal