Implement module patch abstraction and patch loader (#250)

* Implement patch abstractions and patch loader using an interface

* remove patch loader

* rename patch class

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;
+    }
+}

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() ];
+    }
+}

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;
+    }
+}