// Copyright Epic Games, Inc. All Rights Reserved.

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Runtime.Serialization;
using System.Text;
using System.Threading.Tasks;
using EpicGames.Core;
using Microsoft.Extensions.Logging;
using UnrealBuildBase;

namespace UnrealBuildTool
{
	/// <summary>
	/// Stores information about a compiled rules assembly and the types it contains
	/// </summary>
	public class RulesAssembly
	{
		/// <summary>
		/// Outers scope for items created by this assembly. Used for chaining assemblies together.
		/// </summary>
		internal readonly RulesScope Scope;

		/// <summary>
		/// The compiled assembly
		/// </summary>
		private Assembly? CompiledAssembly;

		/// <summary>
		/// Returns the simple name of the assembly e.g. "UE5ProgramRules"
		/// </summary>
		/// <returns></returns>
		public string? GetSimpleAssemblyName()
		{
			if (CompiledAssembly != null)
			{
				return CompiledAssembly.GetName().Name;
			}
			else return null;
		}

		/// <summary>
		/// The base directories for this assembly
		/// </summary>
		private List<DirectoryReference> BaseDirs;

		/// <summary>
		/// All the plugins included in this assembly
		/// </summary>
		private IReadOnlyList<PluginInfo> Plugins;

		/// <summary>
		/// Maps module names to their actual xxx.Module.cs file on disk
		/// </summary>
		private Dictionary<string, FileReference> ModuleNameToModuleFile = new Dictionary<string, FileReference>(StringComparer.InvariantCultureIgnoreCase);

		/// <summary>
		/// Maps target names to their actual xxx.Target.cs file on disk
		/// </summary>
		private Dictionary<string, FileReference> TargetNameToTargetFile = new Dictionary<string, FileReference>(StringComparer.InvariantCultureIgnoreCase);

		/// <summary>
		/// Mapping from module file to its context.
		/// </summary>
		private Dictionary<FileReference, ModuleRulesContext> ModuleFileToContext;

		/// <summary>
		/// Whether this assembly contains engine modules. Used to set default values for bTreatAsEngineModule.
		/// </summary>
		private bool bContainsEngineModules;

		/// <summary>
		/// Whether to use backwards compatible default settings for module and target rules. This is enabled by default for game projects to support a simpler migration path, but
		/// is disabled for engine modules.
		/// </summary>
		private BuildSettingsVersion? DefaultBuildSettings;

		/// <summary>
		/// Whether the modules and targets in this assembly are read-only
		/// </summary>
		private bool bReadOnly;

		/// <summary>
		/// The parent rules assembly that this assembly inherits. Game assemblies inherit the engine assembly, and the engine assembly inherits nothing.
		/// </summary>
		public RulesAssembly? Parent { get; }

		/// <summary>
		/// The set of files that were compiled to create this assembly
		/// </summary>
		public HashSet<FileReference>? AssemblySourceFiles { get; }

		/// <summary>
		/// Any preprocessor defines that were set when this assembly was created
		/// </summary>
		public List<string>? PreprocessorDefines { get;  }

		/// <summary>
		/// Constructor. Compiles a rules assembly from the given source files.
		/// </summary>
		/// <param name="Scope">The scope of items created by this assembly</param>
		/// <param name="BaseDirs">The base directories for this assembly</param>
		/// <param name="Plugins">All the plugins included in this assembly</param>
		/// <param name="ModuleFileToContext">List of module files to compile</param>
		/// <param name="TargetFiles">List of target files to compile</param>
		/// <param name="AssemblyFileName">The output path for the compiled assembly</param>
		/// <param name="bContainsEngineModules">Whether this assembly contains engine modules. Used to initialize the default value for ModuleRules.bTreatAsEngineModule.</param>
		/// <param name="DefaultBuildSettings">Optional override for the default build settings version for modules created from this assembly.</param>
		/// <param name="bReadOnly">Whether the modules and targets in this assembly are installed, and should be created with the bUsePrecompiled flag set</param> 
		/// <param name="bSkipCompile">Whether to skip compiling this assembly</param>
		/// <param name="bForceCompile">Whether to always compile this assembly</param>
		/// <param name="Parent">The parent rules assembly</param>
		/// <param name="Logger"></param>
		internal RulesAssembly(RulesScope Scope, List<DirectoryReference> BaseDirs, IReadOnlyList<PluginInfo> Plugins, Dictionary<FileReference, ModuleRulesContext> ModuleFileToContext, List<FileReference> TargetFiles, FileReference AssemblyFileName, bool bContainsEngineModules, BuildSettingsVersion? DefaultBuildSettings, bool bReadOnly, bool bSkipCompile, bool bForceCompile, RulesAssembly? Parent, ILogger Logger)
		{
			this.Scope = Scope;
			this.BaseDirs = BaseDirs;
			this.Plugins = Plugins;
			this.ModuleFileToContext = ModuleFileToContext;
			this.bContainsEngineModules = bContainsEngineModules;
			this.DefaultBuildSettings = DefaultBuildSettings;
			this.bReadOnly = bReadOnly;
			this.Parent = Parent;

			// Find all the source files
			AssemblySourceFiles = new HashSet<FileReference>();
			AssemblySourceFiles.UnionWith(ModuleFileToContext.Keys);
			AssemblySourceFiles.UnionWith(TargetFiles);

			// Compile the assembly
			if (AssemblySourceFiles.Count > 0)
			{
				PreprocessorDefines = GetPreprocessorDefinitions();
				CompiledAssembly = DynamicCompilation.CompileAndLoadAssembly(AssemblyFileName, AssemblySourceFiles, Logger, PreprocessorDefines: PreprocessorDefines, DoNotCompile: bSkipCompile, ForceCompile: bForceCompile);
			}

			// Setup the module map
			foreach (FileReference ModuleFile in ModuleFileToContext.Keys)
			{
				string ModuleName = ModuleFile.GetFileNameWithoutAnyExtensions();
				if (!ModuleNameToModuleFile.ContainsKey(ModuleName))
				{
					ModuleNameToModuleFile.Add(ModuleName, ModuleFile);
				}
			}

			// Setup the target map
			foreach (FileReference TargetFile in TargetFiles)
			{
				string TargetName = TargetFile.GetFileNameWithoutAnyExtensions();
				if (!TargetNameToTargetFile.ContainsKey(TargetName))
				{
					TargetNameToTargetFile.Add(TargetName, TargetFile);
				}
			}

			// Write any deprecation warnings for methods overriden from a base with the [ObsoleteOverride] attribute. Unlike the [Obsolete] attribute, this ensures the message
			// is given because the method is implemented, not because it's called.
			if (CompiledAssembly != null)
			{
				foreach (Type CompiledType in CompiledAssembly.GetTypes())
				{
					foreach (MethodInfo Method in CompiledType.GetMethods(BindingFlags.Instance | BindingFlags.Public | BindingFlags.DeclaredOnly))
					{
						ObsoleteOverrideAttribute? Attribute = Method.GetCustomAttribute<ObsoleteOverrideAttribute>(true);
						if (Attribute != null)
						{
							FileReference? Location;
							if (!TryGetFileNameFromType(CompiledType, out Location))
							{
								Location = new FileReference(CompiledAssembly.Location);
							}
							Logger.LogWarning("{Location}: warning: {AttributeMessage}", Location, Attribute.Message);
						}
					}
					if(CompiledType.BaseType == typeof(ModuleRules))
					{
						ConstructorInfo? Constructor = CompiledType.GetConstructor(new Type[] { typeof(TargetInfo) });
						if(Constructor != null)
						{
							FileReference? Location;
							if (!TryGetFileNameFromType(CompiledType, out Location))
							{
								Location = new FileReference(CompiledAssembly.Location);
							}
							Logger.LogWarning("{Location}: warning: Module constructors should take a ReadOnlyTargetRules argument (rather than a TargetInfo argument) and pass it to the base class constructor from 4.15 onwards. Please update the method signature.", Location);
						}
					}
				}
			}
		}

		/// <summary>
		/// Determines if the given path is read-only
		/// </summary>
		/// <param name="Location">The location to check</param>
		/// <returns>True if the path is read-only, false otherwise</returns>
		public bool IsReadOnly(FileSystemReference Location)
		{
			if (BaseDirs.Any(x => Location.IsUnderDirectory(x)))
			{
				return bReadOnly;
			}
			else if (Parent != null)
			{
				return Parent.IsReadOnly(Location);
			}
			else
			{
				return false;
			}
		}

		/// <summary>
		/// Finds all the preprocessor definitions that need to be set for the current engine.
		/// </summary>
		/// <returns>List of preprocessor definitions that should be set</returns>
		public static List<string> GetPreprocessorDefinitions()
		{
			List<string> PreprocessorDefines = new List<string>();
			PreprocessorDefines.Add("WITH_FORWARDED_MODULE_RULES_CTOR");
			PreprocessorDefines.Add("WITH_FORWARDED_TARGET_RULES_CTOR");

			// Define macros for the Unreal engine version, starting with 4.17
			// Assumes the current MajorVersion is 5
			BuildVersion? Version;
			if (BuildVersion.TryRead(BuildVersion.GetDefaultFileName(), out Version))
			{
				for(int MinorVersion = 17; MinorVersion <= 30; MinorVersion++)
				{
					PreprocessorDefines.Add(String.Format("UE_4_{0}_OR_LATER", MinorVersion));
				}
				for (int MinorVersion = 0; MinorVersion <= Version.MinorVersion; MinorVersion++)
				{
					PreprocessorDefines.Add(String.Format("UE_5_{0}_OR_LATER", MinorVersion));
				}
			}
			return PreprocessorDefines;
		}

		/// <summary>
		/// Fills a list with all the module names in this assembly (or its parent)
		/// </summary>
		/// <param name="ModuleNames">List to receive the module names</param>
		public void GetAllModuleNames(List<string> ModuleNames)
		{
			if (Parent != null)
			{
				Parent.GetAllModuleNames(ModuleNames);
			}
			if (CompiledAssembly != null)
			{
				ModuleNames.AddRange(CompiledAssembly.GetTypes().Where(x => x.IsClass && x.IsSubclassOf(typeof(ModuleRules)) && ModuleNameToModuleFile.ContainsKey(x.Name)).Select(x => x.Name));
			}
		}

		/// <summary>
		/// Fills a list with all the target names in this assembly
		/// </summary>
		/// <param name="TargetNames">List to receive the target names</param>
		/// <param name="bIncludeParentAssembly">Whether to include targets in the parent assembly</param>
		public void GetAllTargetNames(List<string> TargetNames, bool bIncludeParentAssembly)
		{
			if(Parent != null && bIncludeParentAssembly)
			{
				Parent.GetAllTargetNames(TargetNames, true);
			}
			TargetNames.AddRange(TargetNameToTargetFile.Keys);
		}

		/// <summary>
		/// Tries to get the filename that declared the given type
		/// </summary>
		/// <param name="ExistingType"></param>
		/// <param name="File"></param>
		/// <returns>True if the type was found, false otherwise</returns>
		public bool TryGetFileNameFromType(Type ExistingType, [NotNullWhen(true)] out FileReference? File)
		{
			if (ExistingType.Assembly == CompiledAssembly)
			{
				string Name = ExistingType.Name;
				if (ModuleNameToModuleFile.TryGetValue(Name, out File))
				{
					return true;
				}

				string NameWithoutTarget = Name;
				if (NameWithoutTarget.EndsWith("Target"))
				{
					NameWithoutTarget = NameWithoutTarget.Substring(0, NameWithoutTarget.Length - 6);
				}
				if (TargetNameToTargetFile.TryGetValue(NameWithoutTarget, out File))
				{
					return true;
				}
			}
			else
			{
				if (Parent != null && Parent.TryGetFileNameFromType(ExistingType, out File))
				{
					return true;
				}
			}

			File = null;
			return false;
		}

		/// <summary>
		/// Gets the source file containing rules for the given module
		/// </summary>
		/// <param name="ModuleName">The name of the module</param>
		/// <returns>The filename containing rules for this module, or an empty string if not found</returns>
		public FileReference? GetModuleFileName(string ModuleName)
		{
			FileReference? ModuleFile;
			if (ModuleNameToModuleFile.TryGetValue(ModuleName, out ModuleFile))
			{
				return ModuleFile;
			}
			else
			{
				return (Parent == null) ? null : Parent.GetModuleFileName(ModuleName);
			}
		}

		/// <summary>
		/// Gets the type defining rules for the given module
		/// </summary>
		/// <param name="ModuleName">The name of the module</param>
		/// <returns>The rules type for this module, or null if not found</returns>
		public Type? GetModuleRulesType(string ModuleName)
		{
			if (ModuleNameToModuleFile.ContainsKey(ModuleName))
			{
				return GetModuleRulesTypeInternal(ModuleName);
			}
			else
			{
				return (Parent == null) ? null : Parent.GetModuleRulesType(ModuleName);
			}
		}

		/// <summary>
		/// Gets the type defining rules for the given module within this assembly
		/// </summary>
		/// <param name="ModuleName">The name of the module</param>
		/// <returns>The rules type for this module, or null if not found</returns>
		private Type? GetModuleRulesTypeInternal(string ModuleName)
		{
			// The build module must define a type named 'Rules' that derives from our 'ModuleRules' type.  
			Type? RulesObjectType = CompiledAssembly?.GetType(ModuleName);
			if (RulesObjectType == null)
			{
				// Temporary hack to avoid System namespace collisions
				// @todo projectfiles: Make rules assemblies require namespaces.
				RulesObjectType = CompiledAssembly?.GetType("UnrealBuildTool.Rules." + ModuleName);
			}
			return RulesObjectType;
		}

		/// <summary>
		/// Gets the source file containing rules for the given target
		/// </summary>
		/// <param name="TargetName">The name of the target</param>
		/// <returns>The filename containing rules for this target, or an empty string if not found</returns>
		public FileReference? GetTargetFileName(string TargetName)
		{
			FileReference? TargetFile;
			if (TargetNameToTargetFile.TryGetValue(TargetName, out TargetFile))
			{
				return TargetFile;
			}
			else
			{
				return (Parent == null) ? null : Parent.GetTargetFileName(TargetName);
			}
		}

		/// <summary>
		/// Creates an instance of a module rules descriptor object for the specified module name
		/// </summary>
		/// <param name="ModuleName">Name of the module</param>
		/// <param name="Target">Information about the target associated with this module</param>
		/// <param name="ReferenceChain">Chain of references leading to this module</param>
		/// <param name="Logger">Logger for output</param>
		/// <returns>Compiled module rule info</returns>
		public ModuleRules CreateModuleRules(string ModuleName, ReadOnlyTargetRules Target, string ReferenceChain, ILogger Logger)
		{
			if (Target.IsTestTarget && !Target.ExplicitTestsTarget)
			{
				ModuleName = TargetDescriptor.GetTestedTargetName(ModuleName);
			}

			// Currently, we expect the user's rules object type name to be the same as the module name
			string ModuleTypeName = ModuleName;

			// Make sure the base module file is known to us
			FileReference? ModuleFileName;
			if (!ModuleNameToModuleFile.TryGetValue(ModuleTypeName, out ModuleFileName))
			{
				if (Parent == null)
				{
					throw new BuildException("Could not find definition for module '{0}', (referenced via {1})", ModuleTypeName, ReferenceChain);
				}
				else
				{
					return Parent.CreateModuleRules(ModuleName, Target, ReferenceChain, Logger);
				}
			}

			// get the standard Rules object class from the assembly
			Type BaseRulesObjectType = GetModuleRulesTypeInternal(ModuleTypeName)!;

			// look around for platform/group modules that we will use instead of the basic module
			Type? PlatformRulesObjectType = GetModuleRulesTypeInternal(ModuleTypeName + "_" + Target.Platform.ToString());
			if (PlatformRulesObjectType == null)
			{
				foreach (UnrealPlatformGroup Group in UEBuildPlatform.GetPlatformGroups(Target.Platform))
				{
					// look to see if the group has an override
					Type? GroupRulesObjectType = GetModuleRulesTypeInternal(ModuleName + "_" + Group.ToString());

					// we expect only one platform group to be found in the extensions
					if (GroupRulesObjectType != null && PlatformRulesObjectType != null)
					{
						throw new BuildException("Found multiple platform group overrides ({0} and {1}) for module {2} without a platform specific override. Create a platform override with the class hierarchy as needed.", 
							GroupRulesObjectType.Name, PlatformRulesObjectType.Name, ModuleName);
					}
					// remember the platform group if we found it, but keep searching to verify there isn't more than one
					if (GroupRulesObjectType != null)
					{
						PlatformRulesObjectType = GroupRulesObjectType;
					}
				}
			}

			// verify that we aren't creating a platform module when we definitely don't want it
			if (Target.OptedInModulePlatforms != null)
			{
				// figure out what platforms/groups aren't allowed with this opted in list
				List<string> DisallowedPlatformsAndGroups = Utils.MakeListOfUnsupportedPlatforms(Target.OptedInModulePlatforms.ToList(), false, Logger);

				// check if the module file is disallowed
				if (ModuleFileName.ContainsAnyNames(DisallowedPlatformsAndGroups, Unreal.EngineDirectory) ||
					(Target.ProjectFile != null && ModuleFileName.ContainsAnyNames(DisallowedPlatformsAndGroups, Target.ProjectFile.Directory)))
				{
					throw new BuildException("Platform module file {0} is not allowed (only platforms '{1}', and their groups, are allowed. This indicates a module reference not being checked with something like IsPlatformAvailableForTarget()).",
						ModuleFileName, string.Join(",", Target.OptedInModulePlatforms));
				}
			}


			// Figure out the best rules object to use
			Type? RulesObjectType = PlatformRulesObjectType != null ? PlatformRulesObjectType : BaseRulesObjectType;
			if (RulesObjectType == null)
			{
				throw new BuildException("Expecting to find a type to be declared in a module rules named '{0}' in {1}.  This type must derive from the 'ModuleRules' type defined by Unreal Build Tool.", ModuleTypeName, CompiledAssembly?.FullName);
			}

			// Create an instance of the module's rules object
			try
			{
				// Create an uninitialized ModuleRules object and set some defaults.
				ModuleRules RulesObject = (ModuleRules)FormatterServices.GetUninitializedObject(RulesObjectType);
				// even if we created a platform-extension version of the module rules, we are pretending to be
				// the base type, so that no one else needs to manage this
				RulesObject.Name = ModuleName;
				RulesObject.File = ModuleFileName;
				RulesObject.Directory = ModuleFileName.Directory;
				RulesObject.Context = ModuleFileToContext[RulesObject.File];
				RulesObject.Plugin = RulesObject.Context.Plugin;
				RulesObject.bTreatAsEngineModule = bContainsEngineModules;
				if(DefaultBuildSettings.HasValue)
				{
					RulesObject.DefaultBuildSettings = DefaultBuildSettings.Value;
				}
				RulesObject.bPrecompile = (RulesObject.bTreatAsEngineModule || ModuleName.Equals("UnrealGame", StringComparison.OrdinalIgnoreCase)) && Target.bPrecompile;
				RulesObject.bUsePrecompiled = bReadOnly;

				// go up the type hierarchy (if there is a hierarchy), looking for any extra directories for the module
				if (RulesObjectType != BaseRulesObjectType && RulesObjectType != typeof(ModuleRules))
				{
					Type SubType = RulesObjectType;

					RulesObject.DirectoriesForModuleSubClasses = new Dictionary<Type, DirectoryReference>();
					RulesObject.SubclassRules = new List<string>();
					while (SubType != null && SubType != BaseRulesObjectType)
					{
						FileReference? SubTypeFileName;
						if (TryGetFileNameFromType(SubType, out SubTypeFileName))
						{
							RulesObject.DirectoriesForModuleSubClasses.Add(SubType, SubTypeFileName.Directory);
							RulesObject.SubclassRules.Add(SubTypeFileName.FullName);
						}
						if (SubType.BaseType == null)
						{
							throw new BuildException("{0} is not derived from {1}", RulesObjectType.Name, BaseRulesObjectType.Name);
						}
						SubType = SubType.BaseType;
					}
				}

				// Call the constructor
				ConstructorInfo? Constructor = RulesObjectType.GetConstructor(new Type[] { typeof(ReadOnlyTargetRules) });
				if(Constructor == null)
				{
					throw new BuildException("No valid constructor found for {0}.", ModuleName);
				}
				Constructor.Invoke(RulesObject, new object[] { Target });

				if (Target.IsTestTarget && !RulesObject.IsTestModule)
				{
					if (!Target.ExplicitTestsTarget)
					{
						if (Target.LaunchModuleName != null && ModuleName == TargetDescriptor.GetTestedTargetName(Target.LaunchModuleName))
						{
							RulesObject = new TestModuleRules(RulesObject);
						}
					}
					RulesObject.PrepareModuleForTests();
				}

				return RulesObject;
			}
			catch (Exception Ex)
			{
				Exception MessageEx = (Ex is TargetInvocationException && Ex.InnerException != null)? Ex.InnerException : Ex;
				throw new BuildException(Ex, "Unable to instantiate module '{0}': {1}\n(referenced via {2})", ModuleName, MessageEx.ToString(), ReferenceChain);
			}
		}

		/// <summary>
		/// Construct an instance of the given target rules
		/// </summary>
		/// <param name="TypeName">Type name of the target rules</param>
		/// <param name="TargetInfo">Target configuration information to pass to the constructor</param>
		/// <param name="Logger">Logger for output</param>
		/// <param name="IsTestTarget">If building a low level tests target</param>
		/// <returns>Instance of the corresponding TargetRules</returns>
		protected TargetRules CreateTargetRulesInstance(string TypeName, TargetInfo TargetInfo, ILogger Logger, bool IsTestTarget = false)
		{
			// The build module must define a type named '<TargetName>Target' that derives from our 'TargetRules' type.  
			Type? BaseRulesType = CompiledAssembly?.GetType(TypeName);
			if (BaseRulesType == null)
			{
				throw new BuildException("Expecting to find a type to be declared in a target rules named '{0}'.  This type must derive from the 'TargetRules' type defined by Unreal Build Tool.", TypeName);
			}

			// Look for platform/group rules that we will use instead of the base rules
			string PlatformRulesName = TargetInfo.Name + "_" + TargetInfo.Platform.ToString();
			Type? PlatformRulesType = CompiledAssembly?.GetType(TypeName + "_" + TargetInfo.Platform.ToString());
			if (PlatformRulesType == null)
			{
				foreach (UnrealPlatformGroup Group in UEBuildPlatform.GetPlatformGroups(TargetInfo.Platform))
				{
					// look to see if the group has an override
					string GroupRulesName = TargetInfo.Name + "_" + Group.ToString();
					Type? GroupRulesObjectType = CompiledAssembly?.GetType(TypeName + "_" + Group.ToString());

					// we expect only one platform group to be found in the extensions
					if (GroupRulesObjectType != null && PlatformRulesType != null)
					{
						throw new BuildException("Found multiple platform group overrides ({0} and {1}) for rules {2} without a platform specific override. Create a platform override with the class hierarchy as needed.", 
							GroupRulesObjectType.Name, PlatformRulesType.Name, TypeName);
					}
					// remember the platform group if we found it, but keep searching to verify there isn't more than one
					if (GroupRulesObjectType != null)
					{
						PlatformRulesName = GroupRulesName;
						PlatformRulesType = GroupRulesObjectType;
					}
				}
			}
			if (PlatformRulesType != null && !PlatformRulesType.IsSubclassOf(BaseRulesType))
			{
				throw new BuildException("Expecting {0} to be a specialization of {1}", PlatformRulesType, BaseRulesType);
			}

			// Create an instance of the module's rules object, and set some defaults before calling the constructor.
			Type RulesType = PlatformRulesType ?? BaseRulesType;
			FileReference BaseFile = TargetNameToTargetFile[TargetInfo.Name];
			FileReference PlatformFile = TargetNameToTargetFile.TryGetValue(PlatformRulesName, out FileReference? PlatformTargetFile) ? PlatformTargetFile : BaseFile;
			TargetRules Rules = TargetRules.Create(RulesType, TargetInfo, BaseFile, PlatformFile, DefaultBuildSettings, Logger);

			// Set the default overriddes for the configured target type
			Rules.SetOverridesForTargetType();

			// Set the final value for the link type in the target rules
			if(Rules.LinkType == TargetLinkType.Default)
			{
				throw new BuildException("TargetRules.LinkType should be inferred from TargetType");
			}

			// Set the default value for whether to use the shared build environment
			if(Rules.BuildEnvironment == TargetBuildEnvironment.Unique && Unreal.IsEngineInstalled())
			{
				throw new BuildException("Targets with a unique build environment cannot be built with an installed engine.");
			}

			// Automatically include CoreUObject
			if (Rules.bCompileAgainstEngine)
			{
				Rules.bCompileAgainstCoreUObject = true;
			}

			if (Rules.Type == TargetType.Editor)
			{
				Rules.bBuildWithEditorOnlyData = true; // Must have editor only data if building the editor.
				Rules.bCompileAgainstEditor = true;
			}

			// Apply the override to force debug info to be enabled
			if (Rules.bForceDebugInfo)
			{
				Rules.bDisableDebugInfo = false;
				Rules.bOmitPCDebugInfoInDevelopment = false;
			}

			// Setup the malloc profiler
			if (Rules.bUseMallocProfiler)
			{
				Rules.bOmitFramePointers = false;
				Rules.GlobalDefinitions.Add("USE_MALLOC_PROFILER=1");
			}

			// Set a macro if we allow using generated inis
			if (!Rules.bAllowGeneratedIniWhenCooked)
			{
				Rules.GlobalDefinitions.Add("DISABLE_GENERATED_INI_WHEN_COOKED=1");
			}

			if (!Rules.bAllowNonUFSIniWhenCooked)
			{
				Rules.GlobalDefinitions.Add("DISABLE_NONUFS_INI_WHEN_COOKED=1");
			}

			if (Rules.bDisableUnverifiedCertificates)
			{
				Rules.GlobalDefinitions.Add("DISABLE_UNVERIFIED_CERTIFICATE_LOADING=1");
			}

			// if the Target has opted in only some platforms, disable any plugins of other platforms (there may be editor, etc, modules that
			// will just add themselves, with no other reference to be able to remove them, other than disabling them here)
			if (Rules.OptedInModulePlatforms != null)
			{
				// figure out what platforms/groups aren't allowed with this opted in list
				List<string> DisallowedPlatformsAndGroups = Utils.MakeListOfUnsupportedPlatforms(Rules.OptedInModulePlatforms.ToList(), false, Logger);

				// look in all plugins' paths to see if any disallowed
				IEnumerable<PluginInfo> DisallowedPlugins = EnumeratePlugins().Where(Plugin =>
					Plugin.File.ContainsAnyNames(DisallowedPlatformsAndGroups, Unreal.EngineDirectory) ||
					(Rules.ProjectFile != null && Plugin.File.ContainsAnyNames(DisallowedPlatformsAndGroups, Rules.ProjectFile.Directory)));
				// log out the plugins we are disabling
				DisallowedPlugins.ToList().ForEach(x => Logger.LogDebug("Disallowing non-opted-in platform plugin {PluginFile}", x.File));
				// and, disable these plugins
				Rules.DisablePlugins.AddRange(DisallowedPlugins.Select(x => x.Name));
			}

			// Allow the platform to finalize the settings
			UEBuildPlatform Platform = UEBuildPlatform.GetBuildPlatform(Rules.Platform);
			Platform.ValidateTarget(Rules);

			// Some platforms may *require* monolithic compilation...
			if (Rules.LinkType != TargetLinkType.Monolithic && UEBuildPlatform.PlatformRequiresMonolithicBuilds(Rules.Platform, Rules.Configuration))
			{
				throw new BuildException(String.Format("{0}: {1} does not support modular builds", Rules.Name, Rules.Platform));
			}

			if (IsTestTarget)
			{
				Rules = new TestTargetRules(Rules, TargetInfo);
			}

			return Rules;
		}

		/// <summary>
		/// Creates a target rules object for the specified target name.
		/// </summary>
		/// <param name="TargetName">Name of the target</param>
		/// <param name="Platform">Platform being compiled</param>
		/// <param name="Configuration">Configuration being compiled</param>
		/// <param name="Architecture">Architecture being built</param>
		/// <param name="ProjectFile">Path to the project file for this target</param>
		/// <param name="Arguments">Command line arguments for this target</param>
		/// <param name="Logger"></param>
		/// <param name="IsTestTarget">If building a low level test target</param>
		/// <returns>The build target rules for the specified target</returns>
		public TargetRules CreateTargetRules(string TargetName, UnrealTargetPlatform Platform, UnrealTargetConfiguration Configuration, string Architecture, FileReference? ProjectFile, CommandLineArguments? Arguments, ILogger Logger, bool IsTestTarget = false)
		{
			if (IsTestTarget)
			{
				TargetName = TargetDescriptor.GetTestedTargetName(TargetName);
			}
			bool bFoundTargetName = TargetNameToTargetFile.ContainsKey(TargetName);
			if (bFoundTargetName == false)
			{
				if (Parent == null)
				{
					//				throw new BuildException("Couldn't find target rules file for target '{0}' in rules assembly '{1}'.", TargetName, RulesAssembly.FullName);
					string ExceptionMessage = "Couldn't find target rules file for target '";
					ExceptionMessage += TargetName;
					ExceptionMessage += "' in rules assembly '";
					ExceptionMessage += CompiledAssembly?.FullName;
					ExceptionMessage += "'." + Environment.NewLine;

					ExceptionMessage += "Location: " + CompiledAssembly?.Location + Environment.NewLine;

					ExceptionMessage += "Target rules found:" + Environment.NewLine;
					foreach (KeyValuePair<string, FileReference> entry in TargetNameToTargetFile)
					{
						ExceptionMessage += "\t" + entry.Key + " - " + entry.Value + Environment.NewLine;
					}

					throw new BuildException(ExceptionMessage);
				}
				else
				{
					return Parent.CreateTargetRules(TargetName, Platform, Configuration, Architecture, ProjectFile, Arguments, Logger, IsTestTarget);
				}
			}

			// Currently, we expect the user's rules object type name to be the same as the module name + 'Target'
			string TargetTypeName = TargetName + "Target";

			// The build module must define a type named '<TargetName>Target' that derives from our 'TargetRules' type.  
			return CreateTargetRulesInstance(TargetTypeName, new TargetInfo(TargetName, Platform, Configuration, Architecture, ProjectFile, Arguments), Logger, IsTestTarget);
		}

		/// <summary>
		/// Determines a target name based on the type of target we're trying to build
		/// </summary>
		/// <param name="Type">The type of target to look for</param>
		/// <param name="Platform">The platform being built</param>
		/// <param name="Configuration">The configuration being built</param>
		/// <param name="Architecture">The architecture being built</param>
		/// <param name="ProjectFile">Project file for the target being built</param>
		/// <param name="Logger">Logger for output</param>
		/// <returns>Name of the target for the given type</returns>
		public string GetTargetNameByType(TargetType Type, UnrealTargetPlatform Platform, UnrealTargetConfiguration Configuration, string Architecture, FileReference? ProjectFile, ILogger Logger)
		{
			// Create all the targets in this assembly 
			List<string> Matches = new List<string>();
			foreach(KeyValuePair<string, FileReference> TargetPair in TargetNameToTargetFile)
			{
				TargetRules Rules = CreateTargetRulesInstance(TargetPair.Key + "Target", new TargetInfo(TargetPair.Key, Platform, Configuration, Architecture, ProjectFile, null), Logger);
				if(Rules.Type == Type)
				{
					Matches.Add(TargetPair.Key);
				}
			}

			// If we got a result, return it. If there were multiple results, fail.
			if(Matches.Count == 0)
			{
				if(Parent == null)
				{
					throw new BuildException("Unable to find target of type '{0}' for project '{1}'", Type, ProjectFile);
				}
				else
				{
					return Parent.GetTargetNameByType(Type, Platform, Configuration, Architecture, ProjectFile, Logger);
				}
			}
			else
			{
				if (Matches.Count == 1)
				{
					return Matches[0];
				}

				// attempt to get a default target (like DefaultEditorTarget) from the Engine.ini
				string KeyName = $"Default{Type}Target";
				string? DefaultTargetName;
				// read in the engine config hierarchy and get the value
				ConfigHierarchy EngineConfig = ConfigCache.ReadHierarchy(ConfigHierarchyType.Engine, ProjectFile?.Directory, Platform);
				if (EngineConfig.GetString("/Script/BuildSettings.BuildSettings", KeyName, out DefaultTargetName))
				{
					// if a value was found, make sure that this is one of the found targets
					if (Matches.Contains(DefaultTargetName))
					{
						return DefaultTargetName;
					}
				}
				
				throw new BuildException("Found multiple targets with TargetType={0}: {1}.\nSpecify a default with a {2} entry in [/Script/BuildSettings.BuildSettings] section of your DefaultEngine.ini", Type, String.Join(", ", Matches), KeyName);
			}
		}

		/// <summary>
		/// Enumerates all the plugins that are available
		/// </summary>
		/// <returns></returns>
		public IEnumerable<PluginInfo> EnumeratePlugins()
		{
			return global::UnrealBuildTool.Plugins.FilterPlugins(EnumeratePluginsInternal());
		}

		/// <summary>
		/// Enumerates all the plugins that are available
		/// </summary>
		/// <returns></returns>
		protected IEnumerable<PluginInfo> EnumeratePluginsInternal()
		{
			if (Parent == null)
			{
				return Plugins;
			}
			else
			{
				return Plugins.Concat(Parent.EnumeratePluginsInternal());
			}
		}

		/// <summary>
		/// Tries to find the ModuleRulesContext associated with a given module file
		/// </summary>
		internal ModuleRulesContext? TryGetContextForModule(FileReference ModuleFile)
		{
			for (RulesAssembly? Assembly = this; Assembly != null; Assembly = Assembly.Parent)
			{
				if (Assembly.ModuleFileToContext.TryGetValue(ModuleFile, out var Context))
				{
					return Context;
				}
			}

			return null;
		}
	}
}