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

using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Enumeration;
using System.Linq;
using System.Text;
using System.Text.Json;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using EpicGames.Core;
using EpicGames.UHT.Parsers;
using EpicGames.UHT.Tables;
using EpicGames.UHT.Tokenizer;
using EpicGames.UHT.Types;
using Microsoft.Extensions.Logging;

namespace EpicGames.UHT.Utils
{

	/// <summary>
	/// To support the testing framework, source files can be containing in other source files.  
	/// A source fragment represents this possibility.
	/// </summary>
	public struct UhtSourceFragment
	{

		/// <summary>
		/// When not null, this source comes from another source file
		/// </summary>
		public UhtSourceFile? SourceFile { get; set; }

		/// <summary>
		/// The file path of the source
		/// </summary>
		public string FilePath { get; set; }

		/// <summary>
		/// The line number of the fragment in the containing source file.
		/// </summary>
		public int LineNumber { get; set; }

		/// <summary>
		/// Data of the source file
		/// </summary>
		public StringView Data { get; set; }
	}

	/// <summary>
	/// A structure that represents an engine version.
	/// </summary>
	public struct EngineVersion
	{
		/// <summary>
		/// The major engine version.
		/// </summary>
		public int MajorVersion { get; set; } = 0;
		/// <summary>
		/// The minor engine version.
		/// </summary>
		public int MinorVersion { get; set; } = 0;
		/// <summary>
		/// The patch engine version.
		/// </summary>
		public int PatchVersion { get; set; } = 0;

		/// <summary>
		/// Build a default engine version (0.0.0).
		/// </summary>
		public EngineVersion() { }

		/// <summary>
		/// Build a new engine version with the given numbers.
		/// </summary>
		public EngineVersion(int major, int minor, int patch)
		{
			MajorVersion = major;
			MinorVersion = minor;
			PatchVersion = patch;
		}

		/// <summary>
		/// Compares this engine version to another one.
		/// </summary>
		/// <param name="other">The other engine version</param>
		/// <returns>Returns -1 if this version is less than the other, 1 if it is greater than the other, and 0 if they're equal</returns>
		public int CompareTo(EngineVersion other)
		{
			if (MajorVersion != other.MajorVersion)
			{
				return MajorVersion.CompareTo(other.MajorVersion);
			}
			if (MinorVersion != other.MinorVersion)
			{
				return MinorVersion.CompareTo(other.MinorVersion);
			}
			if (PatchVersion != other.PatchVersion)
			{
				return PatchVersion.CompareTo(other.PatchVersion);
			}
			return 0;
		}

		/// <summary>
		/// Generates a string representation of the engine version.
		/// </summary>
		/// <returns></returns>
		public override string ToString()
		{
			return String.Format("{0}.{1}.{2}", MajorVersion, MinorVersion, PatchVersion);
		}
	}

	/// <summary>
	/// Implementation of the export factory
	/// </summary>
	class UhtExportFactory : IUhtExportFactory
	{
		public struct Output
		{
			public string FilePath { get; set; }
			public string TempFilePath { get; set; }
			public bool Saved { get; set; }
		}

		/// <summary>
		/// UHT session
		/// </summary>
		private readonly UhtSession _session;

		/// <summary>
		/// Module associated with the plugin
		/// </summary>
		private readonly UHTManifest.Module? _pluginModule;

		/// <summary>
		/// Limiter for the number of files being saved to the reference directory.
		/// The OS can get swamped on high core systems
		/// </summary>
		private static readonly Semaphore s_writeRefSemaphore = new(32, 32);

		/// <summary>
		/// Requesting exporter
		/// </summary>
		public readonly UhtExporter Exporter;

		/// <summary>
		/// UHT Session
		/// </summary>
		public UhtSession Session => _session;

		/// <summary>
		/// Plugin module
		/// </summary>
		public UHTManifest.Module? PluginModule => _pluginModule;

		/// <summary>
		/// Collection of error from mismatches with the reference files
		/// </summary>
		public Dictionary<string, bool> ReferenceErrorMessages { get; } = new Dictionary<string, bool>();

		/// <summary>
		/// List of export outputs
		/// </summary>
		public List<Output> Outputs { get; } = new List<Output>();

		/// <summary>
		/// Directory for the reference output
		/// </summary>
		public string ReferenceDirectory { get; set; } = String.Empty;

		/// <summary>
		/// Directory for the verify output
		/// </summary>
		public string VerifyDirectory { get; set; } = String.Empty;

		/// <summary>
		/// Collection of external dependencies
		/// </summary>
		public HashSet<string> ExternalDependencies { get; } = new HashSet<string>();

		/// <summary>
		/// Create a new instance of the export factory
		/// </summary>
		/// <param name="session">UHT session</param>
		/// <param name="pluginModule">Plugin module</param>
		/// <param name="exporter">Exporter being run</param>
		public UhtExportFactory(UhtSession session, UHTManifest.Module? pluginModule, UhtExporter exporter)
		{
			_session = session;
			_pluginModule = pluginModule;
			Exporter = exporter;
			if (Session.ReferenceMode != UhtReferenceMode.None)
			{
				ReferenceDirectory = Path.Combine(Session.ReferenceDirectory, Exporter.Name);
				VerifyDirectory = Path.Combine(Session.VerifyDirectory, Exporter.Name);
				Directory.CreateDirectory(Session.ReferenceMode == UhtReferenceMode.Reference ? ReferenceDirectory : VerifyDirectory);
			}
		}

		/// <summary>
		/// Commit the contents of the string builder as the output.
		/// If you have a string builder, use this method so that a 
		/// temporary buffer can be used.
		/// </summary>
		/// <param name="filePath">Destination file path</param>
		/// <param name="builder">Source for the content</param>
		public void CommitOutput(string filePath, StringBuilder builder)
		{
			using UhtRentedPoolBuffer<char> borrowBuffer = builder.RentPoolBuffer();
			string tempFilePath = filePath + ".tmp";
			SaveIfChanged(filePath, tempFilePath, new StringView(borrowBuffer.Buffer.Memory));
		}

		/// <summary>
		/// Commit the value of the string as the output
		/// </summary>
		/// <param name="filePath">Destination file path</param>
		/// <param name="output">Output to commit</param>
		public void CommitOutput(string filePath, StringView output)
		{
			string tempFilePath = filePath + ".tmp";
			SaveIfChanged(filePath, tempFilePath, output);
		}

		/// <summary>
		/// Create a task to export two files
		/// </summary>
		/// <param name="prereqs">Tasks that must be completed prior to this task running</param>
		/// <param name="action">Action to be invoked to generate the output</param>
		/// <returns>Task object or null if the task was immediately executed.</returns>
		public Task? CreateTask(List<Task?>? prereqs, UhtExportTaskDelegate action)
		{
			if (Session.GoWide)
			{
				Task[]? prereqTasks = prereqs?.Where(x => x != null).Cast<Task>().ToArray();
				if (prereqTasks != null && prereqTasks.Length > 0)
				{
					return Task.Factory.ContinueWhenAll(prereqTasks, (Task[] tasks) => { Session.TryNoErrorCheck(null, () => action(this)); });
				}
				else
				{
					return Task.Factory.StartNew(() => { Session.TryNoErrorCheck(null, () => action(this)); }, CancellationToken.None, TaskCreationOptions.None, TaskScheduler.Default);
				}
			}
			else
			{
				Session.TryNoErrorCheck(null, () => action(this));
				return null;
			}
		}

		/// <summary>
		/// Create a task to export two files
		/// </summary>
		/// <param name="action">Action to be invoked to generate the output</param>
		/// <returns>Task object or null if the task was immediately executed.</returns>
		public Task? CreateTask(UhtExportTaskDelegate action)
		{
			return CreateTask(null, action);
		}

		/// <summary>
		/// Given a header file, generate the output file name.
		/// </summary>
		/// <param name="headerFile">Header file</param>
		/// <param name="suffix">Suffix/extension to be added to the file name.</param>
		/// <returns>Resulting file name</returns>
		public string MakePath(UhtHeaderFile headerFile, string suffix)
		{
			return MakePath(headerFile.Module.Module, headerFile.FileNameWithoutExtension, suffix);
		}

		/// <summary>
		/// Given a package file, generate the output file name
		/// </summary>
		/// <param name="module">Module</param>
		/// <param name="suffix">Suffix/extension to be added to the file name.</param>
		/// <returns>Resulting file name</returns>
		public string MakePath(UhtModule module, string suffix)
		{
			return MakePath(module.Module, module.ShortName, suffix);
		}

		/// <summary>
		/// Make a path for an output based on the package output directory.
		/// </summary>
		/// <param name="fileName">Name of the file</param>
		/// <param name="extension">Extension to add to the file</param>
		/// <returns>Output file path</returns>
		public string MakePath(string fileName, string extension)
		{
			if (PluginModule == null)
			{
				throw new UhtIceException("MakePath with just a filename and extension can not be called from non-plugin exporters");
			}
			return MakePath(PluginModule, fileName, extension);
		}

		/// <summary>
		/// Add an external dependency to the given file path
		/// </summary>
		/// <param name="filePath">External dependency to add</param>
		public void AddExternalDependency(string filePath)
		{
			ExternalDependencies.Add(filePath);
		}

		/// <inheritdoc/>
		public string GetModuleShortestIncludePath(UhtModule moduleObj, string filePath)
		{
			return GetShortestIncludePath(moduleObj.Module, filePath);
		}

		/// <inheritdoc/>
		public string GetPluginShortestIncludePath(string filePath)
		{
			if (PluginModule == null)
			{
				throw new UhtIceException("Made a request for the plugin's shortest include path but there is no plugin");
			}
			return GetShortestIncludePath(PluginModule, filePath);
		}

		public string GetShortestIncludePath(UHTManifest.Module moduleObj, string filePath)
		{
			string? relativePath = null;
			foreach (string includePath in moduleObj.IncludePaths)
			{
				if (filePath.StartsWith(includePath, StringComparison.Ordinal))
				{
					if (relativePath == null || (includePath.Length - filePath.Length - 1) < relativePath.Length)
					{
						relativePath = filePath.Substring(includePath.Length + 1);
					}
				}
			}

			// This will create a "../" path which is not great
			if (relativePath == null)
			{
				string? includePath = moduleObj.IncludePaths.Find(includePath => includePath.StartsWith(moduleObj.BaseDirectory, StringComparison.Ordinal));
				if (includePath == null)
				{
					Session.Logger.LogWarning("There are no include paths in module {ModuleName} for {FileName}. It will be included by a \"../\" path external to the module.", moduleObj.Name, filePath);
					includePath = moduleObj.IncludePaths.FirstOrDefault(".");
				}
				relativePath = Path.GetRelativePath(includePath!, filePath);
			}
			return relativePath!.Replace("\\", "/", StringComparison.Ordinal);
		}

		private string MakePath(UHTManifest.Module module, string fileName, string suffix)
		{
			if (PluginModule != null)
			{
				module = PluginModule;
			}
			return Path.Combine(module.OutputDirectory, fileName) + suffix;
		}

		/// <summary>
		/// Helper method to test to see if the output has changed.
		/// </summary>
		/// <param name="filePath">Name of the output file</param>
		/// <param name="tempFilePath">Name of the temporary file</param>
		/// <param name="exported">Exported contents of the file</param>
		internal void SaveIfChanged(string filePath, string tempFilePath, StringView exported)
		{

			ReadOnlySpan<char> exportedSpan = exported.Span;

			if (Session.ReferenceMode != UhtReferenceMode.None)
			{
				string fileName = Path.GetFileName(filePath);

				// Writing billions of files to the same directory causes issues.  Use ourselves to throttle reference writes
				try
				{
					UhtExportFactory.s_writeRefSemaphore.WaitOne();
					{
						string outPath = Path.Combine(Session.ReferenceMode == UhtReferenceMode.Reference ? ReferenceDirectory : VerifyDirectory, fileName);
						if (!Session.WriteSource(outPath, exported.Span))
						{
							new UhtSimpleFileMessageSite(Session, outPath).LogWarning($"Unable to write reference file {outPath}");
						}
					}
				}
				finally
				{
					UhtExportFactory.s_writeRefSemaphore.Release();
				}

				// If we are verifying, read the existing file and check the contents
				if (Session.ReferenceMode == UhtReferenceMode.Verify)
				{
					string message = String.Empty;
					string refPath = Path.Combine(ReferenceDirectory, fileName);
					if (Session.ReadSource(refPath, out UhtPoolBuffer<char> existingRef))
					{
						ReadOnlySpan<char> existingSpan = existingRef.Memory.Span;
						if (existingSpan.CompareTo(exportedSpan, StringComparison.Ordinal) != 0)
						{
							message = $"********************************* {fileName} has changed.";
						}
						UhtPoolBuffers.Return<char>(existingRef);
					}
					else
					{
						message = $"********************************* {fileName} appears to be a new generated file.";
					}

					if (!String.IsNullOrEmpty(message))
					{
						Session.Logger.LogInformation("{Message}", message);
						Session.SignalError();
						lock (ReferenceErrorMessages)
						{
							ReferenceErrorMessages.Add(message, true);
						}
					}
				}
			}

			// Check to see if the contents have changed
			bool save = false;
			if (Session.ReadSource(filePath, out UhtPoolBuffer<char> original))
			{
				ReadOnlySpan<char> originalSpan = original.Memory.Span;
				if (originalSpan.CompareTo(exportedSpan, StringComparison.Ordinal) != 0)
				{
					if (Session.FailIfGeneratedCodeChanges)
					{
						string conflictPath = filePath + ".conflict";
						if (!Session.WriteSource(conflictPath, exported.Span))
						{
							new UhtSimpleFileMessageSite(Session, filePath).LogError($"Changes to generated code are not allowed - conflicts written to '{conflictPath}'");
						}
					}
					save = true;
				}
				UhtPoolBuffers.Return<char>(original);
			}
			else
			{
				save = true;
			}

			// If changed of the original didn't exist, then save the new version
			if (save && !Session.NoOutput)
			{
				if (!Session.WriteSource(tempFilePath, exported.Span))
				{
					new UhtSimpleFileMessageSite(Session, filePath).LogWarning($"Failed to save export file: '{tempFilePath}'");
				}
			}
			else
			{
				save = false;
			}

			// Add this to the list of outputs
			lock (Outputs)
			{
				Outputs.Add(new Output { FilePath = filePath, TempFilePath = tempFilePath, Saved = save });
			}
		}

		/// <summary>
		/// Run the output exporter
		/// </summary>
		public void Run()
		{

			// Invoke the exported via the delegate
			Exporter.Delegate(this);

			// These outputs are used to cull old outputs from the directories
			Dictionary<string, HashSet<string>> outputsByDirectory = new(
				Session.Modules.Where(x => x.Module.SaveExportedHeaders).Select(x => new KeyValuePair<string, HashSet<string>>(x.Module.OutputDirectory, new HashSet<string>(StringComparer.OrdinalIgnoreCase))),
				StringComparer.OrdinalIgnoreCase
			);

			// If outputs were exported
			if (Outputs.Count > 0)
			{
				List<UhtExportFactory.Output> saves = new();

				// Collect information about the outputs
				foreach (UhtExportFactory.Output output in Outputs)
				{

					// Add this output to the list of expected outputs by directory
					string? fileDirectory = Path.GetDirectoryName(output.FilePath);
					if (fileDirectory != null)
					{
						if (!outputsByDirectory.TryGetValue(fileDirectory, out HashSet<string>? files))
						{
							files = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
							outputsByDirectory.Add(fileDirectory, files);
						}
						files.Add(Path.GetFileName(output.FilePath));
					}

					// Add the save task
					if (output.Saved)
					{
						saves.Add(output);
					}
				}

				// Perform the renames
				if (Session.GoWide)
				{
					Parallel.ForEach(saves, (UhtExportFactory.Output output) =>
					{
						RenameSource(output);
					});
				}
				else
				{
					foreach (UhtExportFactory.Output output in saves)
					{
						RenameSource(output);
					}
				}
			}

			// Perform the culling of the output directories
			if (Session.CullOutput && !Session.NoOutput &&
				(Exporter.CppFilters != null || Exporter.HeaderFilters != null || Exporter.OtherFilters != null))
			{
				if (Session.GoWide)
				{
					Parallel.ForEach(outputsByDirectory, (KeyValuePair<string, HashSet<string>> kvp) =>
					{
						CullOutputDirectory(kvp.Key, kvp.Value);
					});
				}
				else
				{
					foreach (KeyValuePair<string, HashSet<string>> kvp in outputsByDirectory)
					{
						CullOutputDirectory(kvp.Key, kvp.Value);
					}
				}
			}
		}

		/// <summary>
		/// Given an output, rename the output file from the temporary file name to the final file name.
		/// If there exists a current final file, it will be replaced.
		/// </summary>
		/// <param name="output">The output file to rename</param>
		private void RenameSource(UhtExportFactory.Output output)
		{
			Session.RenameSource(output.TempFilePath, output.FilePath);
		}

		/// <summary>
		/// Given a directory and a list of known files, delete any unknown file that matches of the supplied filters
		/// </summary>
		/// <param name="outputDirectory">Output directory to scan</param>
		/// <param name="knownOutputs">Collection of known output files not to be deleted</param>
		private void CullOutputDirectory(string outputDirectory, HashSet<string> knownOutputs)
		{
			foreach (string filePath in Directory.EnumerateFiles(outputDirectory))
			{
				string fileName = Path.GetFileName(filePath);
				if (knownOutputs.Contains(fileName))
				{
					continue;
				}

				if (IsFilterMatch(fileName, Exporter.CppFilters) ||
					IsFilterMatch(fileName, Exporter.HeaderFilters) ||
					IsFilterMatch(fileName, Exporter.OtherFilters))
				{
					try
					{
						File.Delete(Path.Combine(outputDirectory, filePath));
					}
					catch (Exception)
					{
					}
				}
			}
		}

		/// <summary>
		/// Test to see if the given filename (without directory), matches one of the given filters
		/// </summary>
		/// <param name="fileName">File name to test</param>
		/// <param name="filters">List of wildcard filters</param>
		/// <returns>True if there is a match</returns>
		private static bool IsFilterMatch(string fileName, IEnumerable<string> filters)
		{
			foreach (string filter in filters)
			{
				if (FileSystemName.MatchesSimpleExpression(filter, fileName, true))
				{
					return true;
				}
			}
			return false;
		}
	}

	/// <summary>
	/// UHT supports the exporting of two reference output directories for testing.  The reference version can be used to test
	/// modification to UHT and verify there are no output changes or just expected changes.
	/// </summary>
	public enum UhtReferenceMode
	{
		/// <summary>
		/// Do not export any reference output files
		/// </summary>
		None,

		/// <summary>
		/// Export the reference copy
		/// </summary>
		Reference,

		/// <summary>
		/// Export the verify copy and compare to the reference copy
		/// </summary>
		Verify,
	};

	/// <summary>
	/// Session object that represents a UHT run
	/// </summary>
	public partial class UhtSession : IUhtMessageSite, IUhtMessageSession
	{

		/// <summary>
		/// Helper class for returning a sequence of auto-incrementing indices
		/// </summary>
		private class TypeCounter
		{

			/// <summary>
			/// Current number of types
			/// </summary>
			private int _count = 0;

			/// <summary>
			/// Get the next type index
			/// </summary>
			/// <returns>Index starting at zero</returns>
			public int GetNext()
			{
				return Interlocked.Increment(ref _count) - 1;
			}

			/// <summary>
			/// The number of times GetNext was called.
			/// </summary>
			public int Count => Interlocked.Add(ref _count, 0) + 1;
		}

		/// <summary>
		/// Pair that represents a specific value for an enumeration
		/// </summary>
		private struct EnumAndValue
		{
			public UhtEnum Enum { get; set; }
			public long Value { get; set; }
		}

		/// <summary>
		/// Collection of reserved names
		/// </summary>
		private static readonly HashSet<string> s_reservedNames = new() { "none" };

		#region Configurable settings

		/// <summary>
		/// Logger interface.
		/// </summary>
		public ILogger Logger { get; }

		/// <summary>
		/// Interface used to read/write files
		/// </summary>
		public IUhtFileManager? FileManager { get; set; }

		/// <summary>
		/// Location of the engine code
		/// </summary>
		public string? EngineDirectory { get; set; }

		/// <summary>
		/// If set, the name of the project file.
		/// </summary>
		public string? ProjectFile { get; set; }

		/// <summary>
		/// Optional location of the project
		/// </summary>
		public string? ProjectDirectory { get; set; }

		/// <summary>
		/// Root directory for the engine.  This is usually just EngineDirectory without the Engine directory.
		/// </summary>
		public string? RootDirectory { get; set; }

		/// <summary>
		/// Directory to store the reference output
		/// </summary>
		public string ReferenceDirectory { get; set; } = String.Empty;

		/// <summary>
		/// Directory to store the verification output
		/// </summary>
		public string VerifyDirectory { get; set; } = String.Empty;

		/// <summary>
		/// Mode for generating and/or testing reference output
		/// </summary>
		public UhtReferenceMode ReferenceMode { get; set; } = UhtReferenceMode.None;

		/// <summary>
		/// If true, warnings are considered to be errors
		/// </summary>
		public bool WarningsAsErrors { get; set; } = false;

		/// <summary>
		/// If true, include relative file paths in the log file
		/// </summary>
		public bool RelativePathInLog { get; set; } = false;

		/// <summary>
		/// If true, use concurrent tasks to run UHT
		/// </summary>
		public bool GoWide { get; set; } = true;

		/// <summary>
		/// If any output file mismatches existing outputs, an error will be generated
		/// </summary>
		public bool FailIfGeneratedCodeChanges { get; set; } = false;

		/// <summary>
		/// If true, no output files will be saved
		/// </summary>
		public bool NoOutput { get; set; } = false;

		/// <summary>
		/// If true, cull the output for any extra files
		/// </summary>
		public bool CullOutput { get; set; } = true;

		/// <summary>
		/// If true, include extra output in code generation
		/// </summary>
		public bool IncludeDebugOutput { get; set; } = false;

		/// <summary>
		/// If true, disable all exporters which would normally be run by default
		/// </summary>
		public bool NoDefaultExporters { get; set; } = false;

		/// <summary>
		/// If true, cache any error messages until the end of processing.  This is used by the testing
		/// harness to generate more stable console output.
		/// </summary>
		public bool CacheMessages { get; set; } = false;

		/// <summary>
		/// Collection of UHT tables
		/// </summary>
		public UhtTables? Tables { get; set; }

		/// <summary>
		/// Configuration for the session
		/// </summary>
		public IUhtConfig? Config { get; set; }
		#endregion

		/// <summary>
		/// Manifest file
		/// </summary>
		public UhtManifestFile? ManifestFile { get; set; } = null;

		/// <summary>
		/// Manifest data from the manifest file
		/// </summary>
		public UHTManifest? Manifest => ManifestFile?.Manifest;

		/// <summary>
		/// Collection of modules from the manifest
		/// </summary>
		public IReadOnlyList<UhtModule> Modules => _modules;

		/// <summary>
		/// Collection of header files from the manifest.  The header files will also appear as the children 
		/// of the packages
		/// </summary>
		public IReadOnlyList<UhtHeaderFile> HeaderFiles => _headerFiles;

		/// <summary>
		/// Collection of header files topologically sorted.  This will not be populated until after header files
		/// are parsed and resolved.
		/// </summary>
		public IReadOnlyList<UhtHeaderFile> SortedHeaderFiles => _sortedHeaderFiles;

		/// <summary>
		/// Dictionary of stripped file name to the header file
		/// </summary>
		public IReadOnlyDictionary<string, UhtHeaderFile> HeaderFileDictionary => _headerFileDictionary;

		/// <summary>
		/// Gets the version of the engine this session belongs to.
		/// </summary>
		public EngineVersion EngineVersion => _engineVersion.Value;

		/// <summary>
		/// After headers are parsed, returns the UObject class.
		/// </summary>
		public UhtClass UObject
		{
			get
			{
				if (_uobject == null)
				{
					throw new UhtIceException("UObject was not defined.");
				}
				return _uobject;
			}
		}

		/// <summary>
		/// After headers are parsed, returns the UClass class.
		/// </summary>
		public UhtClass UClass
		{
			get
			{
				if (_uclass == null)
				{
					throw new UhtIceException("UClass was not defined.");
				}
				return _uclass;
			}
		}

		/// <summary>
		/// After headers are parsed, returns the UInterface class.
		/// </summary>
		public UhtClass UInterface
		{
			get
			{
				if (_uinterface == null)
				{
					throw new UhtIceException("UInterface was not defined.");
				}
				return _uinterface;
			}
		}

		/// <summary>
		/// After headers are parsed, returns the IInterface class.
		/// </summary>
		public UhtClass IInterface
		{
			get
			{
				if (_iinterface == null)
				{
					throw new UhtIceException("IInterface was not defined.");
				}
				return _iinterface;
			}
		}

		/// <summary>
		/// After headers are parsed, returns the AActor class.  Unlike such properties as "UObject", there
		/// is no requirement for AActor to be defined.  May be null.
		/// </summary>
		public UhtClass? AActor { get; set; } = null;

		/// <summary>
		/// After headers are parsed, return the INotifyFieldValueChanged interface.  There is no requirement 
		/// that this interface be defined.
		/// </summary>
		public UhtClass? INotifyFieldValueChanged { get; set; } = null;

		/// <summary>
		/// After headers are parsed, returns the FInstancedStruct script struct.  Unlike such properties as 
		/// "UObject", there is no requirement for FInstancedStruct to be defined.  May be null.
		/// </summary>
		public UhtScriptStruct? FInstancedStruct { get; set; } = null;

		/// <summary>
		/// After headers are parsed, returns the FStateTreePropertyRef script struct.
		/// There is no requirement for FStateTreePropertyRef to be defined. May be null.
		/// </summary>
		public UhtScriptStruct? FStateTreePropertyRef { get; set; } = null;

		/// <summary>
		/// After headers are parsed, returns the EVerseNativeCallResult enumeration.
		/// There is no requirement for EVerseNativeCallResult to be defined. May be null.
		/// </summary>
		public UhtEnum? EVerseNativeCallResult { get; set; } = null;

		private readonly List<UhtModule> _modules = new();
		private readonly List<UhtHeaderFile> _headerFiles = new();
		private readonly List<UhtHeaderFile> _sortedHeaderFiles = new();
		private readonly Dictionary<string, UhtHeaderFile> _headerFileDictionary = new(StringComparer.OrdinalIgnoreCase);
		private readonly Lazy<EngineVersion> _engineVersion;
		private long _errorCount = 0;
		private long _warningCount = 0;
		private readonly List<UhtMessage> _messages = new();
		private Task? _messageTask = null;
		private UhtClass? _uobject = null;
		private UhtClass? _uclass = null;
		private UhtClass? _uinterface = null;
		private UhtClass? _iinterface = null;
		private readonly TypeCounter _typeCounter = new();
		private readonly TypeCounter _packageTypeCount = new();
		private readonly TypeCounter _headerFileTypeCount = new();
		private readonly TypeCounter _objectTypeCount = new();
		private UhtSymbolTable _sourceNameSymbolTable = new(0);
		private UhtSymbolTable _engineNameSymbolTable = new(0);
		private bool _symbolTablePopulated = false;
		private Task? _referenceDeleteTask = null;
		private readonly Dictionary<string, bool> _exporterStates = new(StringComparer.OrdinalIgnoreCase);
		private readonly Dictionary<string, EnumAndValue> _fullEnumValueLookup = new();
		private readonly Dictionary<string, UhtEnum> _shortEnumValueLookup = new();
		private JsonDocument? _projectJson = null;

		/// <summary>
		/// The number of errors
		/// </summary>
		public long ErrorCount => Interlocked.Read(ref _errorCount);

		/// <summary>
		/// The number of warnings
		/// </summary>
		public long WarningCount => Interlocked.Read(ref _warningCount);

		/// <summary>
		/// True if any errors have occurred or warnings if warnings are to be treated as errors 
		/// </summary>
		public bool HasErrors => ErrorCount > 0 || (WarningsAsErrors && WarningCount > 0);

		#region IUHTMessageSession implementation
		/// <inheritdoc/>
		public IUhtMessageSession MessageSession => this;
		/// <inheritdoc/>
		public IUhtMessageSource? MessageSource => null;
		/// <inheritdoc/>
		public IUhtMessageLineNumber? MessageLineNumber => null;
		#endregion

		/// <summary>
		/// Constructor
		/// </summary>
		/// <param name="logger">Logger for the session</param>
		public UhtSession(ILogger logger)
		{
			Logger = logger;

			_engineVersion = new Lazy<EngineVersion>(() => LoadEngineVersion(), true);
		}

		/// <summary>
		/// Return the index for a newly defined type
		/// </summary>
		/// <returns>New index</returns>
		public int GetNextTypeIndex()
		{
			return _typeCounter.GetNext();
		}

		/// <summary>
		/// Return the number of types that have been defined.  This includes all types.
		/// </summary>
		public int TypeCount => _typeCounter.Count;

		/// <summary>
		/// Return the index for a newly defined packaging
		/// </summary>
		/// <returns>New index</returns>
		public int GetNextHeaderFileTypeIndex()
		{
			return _headerFileTypeCount.GetNext();
		}

		/// <summary>
		/// Return the number of headers that have been defined
		/// </summary>
		public int HeaderFileTypeCount => _headerFileTypeCount.Count;

		/// <summary>
		/// Return the index for a newly defined package
		/// </summary>
		/// <returns>New index</returns>
		public int GetNextPackageTypeIndex()
		{
			return _packageTypeCount.GetNext();
		}

		/// <summary>
		/// Return the number of UPackage types that have been defined
		/// </summary>
		public int PackageTypeCount => _packageTypeCount.Count;

		/// <summary>
		/// Return the index for a newly defined object
		/// </summary>
		/// <returns>New index</returns>
		public int GetNextObjectTypeIndex()
		{
			return _objectTypeCount.GetNext();
		}

		/// <summary>
		/// Return the total number of UObject types that have been defined
		/// </summary>
		public int ObjectTypeCount => _objectTypeCount.Count;

		/// <summary>
		/// Return the collection of exporters
		/// </summary>
		public UhtExporterTable ExporterTable => Tables!.ExporterTable;

		/// <summary>
		/// Return the keyword table for the given table name
		/// </summary>
		/// <param name="tableName">Name of the table</param>
		/// <returns>The requested table</returns>
		public UhtKeywordTable GetKeywordTable(string tableName)
		{
			return Tables!.KeywordTables.Get(tableName);
		}

		/// <summary>
		/// Return the specifier table for the given table name
		/// </summary>
		/// <param name="tableName">Name of the table</param>
		/// <returns>The requested table</returns>
		public UhtSpecifierTable GetSpecifierTable(string tableName)
		{
			return Tables!.SpecifierTables.Get(tableName);
		}

		/// <summary>
		/// Return the specifier validator table for the given table name
		/// </summary>
		/// <param name="tableName">Name of the table</param>
		/// <returns>The requested table</returns>
		public UhtSpecifierValidatorTable GetSpecifierValidatorTable(string tableName)
		{
			return Tables!.SpecifierValidatorTables.Get(tableName);
		}

		/// <summary>
		/// Generate an error for the given unhandled keyword
		/// </summary>
		/// <param name="tokenReader">Token reader</param>
		/// <param name="token">Unhandled token</param>
		public void LogUnhandledKeywordError(IUhtTokenReader tokenReader, UhtToken token)
		{
			Tables!.KeywordTables.LogUnhandledError(tokenReader, token);
		}

		/// <summary>
		/// Test to see if the given class name is a property
		/// </summary>
		/// <param name="name">Name of the class without the prefix</param>
		/// <returns>True if the class name is a property.  False if the class name isn't a property or isn't an engine class.</returns>
		public bool IsValidPropertyTypeName(StringView name)
		{
			return Tables!.EngineClassTable.IsValidPropertyTypeName(name);
		}

		/// <summary>
		/// Return the loc text default value associated with the given name
		/// </summary>
		/// <param name="name"></param>
		/// <param name="locTextDefaultValue">Loc text default value handler</param>
		/// <returns></returns>
		public bool TryGetLocTextDefaultValue(StringView name, out UhtLocTextDefaultValue locTextDefaultValue)
		{
			return Tables!.LocTextDefaultValueTable.TryGet(name, out locTextDefaultValue);
		}

		/// <summary>
		/// Return the default processor
		/// </summary>
		public UhtPropertyType DefaultPropertyType => Tables!.PropertyTypeTable.Default;

		/// <summary>
		/// Return the property type associated with the given name
		/// </summary>
		/// <param name="name"></param>
		/// <param name="propertyType">Property type if matched</param>
		/// <returns></returns>
		public bool TryGetPropertyType(StringView name, out UhtPropertyType propertyType)
		{
			return Tables!.PropertyTypeTable.TryGet(name, out propertyType);
		}

		/// <summary>
		/// Fetch the default sanitizer
		/// </summary>
		public UhtStructDefaultValue DefaultStructDefaultValue => Tables!.StructDefaultValueTable.Default;

		/// <summary>
		/// Return the structure default value associated with the given name
		/// </summary>
		/// <param name="name"></param>
		/// <param name="structDefaultValue">Structure default value handler</param>
		/// <returns></returns>
		public bool TryGetStructDefaultValue(StringView name, out UhtStructDefaultValue structDefaultValue)
		{
			return Tables!.StructDefaultValueTable.TryGet(name, out structDefaultValue);
		}

		/// <summary>
		/// Run UHT on the given manifest.  Use the bHasError property to see if process was successful.
		/// </summary>
		/// <param name="manifestFilePath">Path to the manifest file</param>
		/// <param name="arguments">Any command line arguments</param>
		public void Run(string manifestFilePath, CommandLineArguments? arguments = null)
		{
			if (FileManager == null)
			{
				SignalError();
				Logger.LogError("No file manager supplied, aborting.");
				return;
			}

			if (Config == null)
			{
				SignalError();
				Logger.LogError("No configuration supplied, aborting.");
				return;
			}

			if (Tables == null)
			{
				SignalError();
				Logger.LogError("No parsing tables supplied, aborting.");
				return;
			}

			switch (ReferenceMode)
			{
				case UhtReferenceMode.None:
					break;

				case UhtReferenceMode.Reference:
					if (String.IsNullOrEmpty(ReferenceDirectory))
					{
						Logger.LogError("WRITEREF requested but directory not set, ignoring");
						ReferenceMode = UhtReferenceMode.None;
					}
					break;

				case UhtReferenceMode.Verify:
					if (String.IsNullOrEmpty(ReferenceDirectory) || String.IsNullOrEmpty(VerifyDirectory))
					{
						Logger.LogError("VERIFYREF requested but directories not set, ignoring");
						ReferenceMode = UhtReferenceMode.None;
					}
					break;
			}

			{
				string defaultPolicyName = Config.DefaultDocumentationPolicy;
				if (!String.IsNullOrEmpty(defaultPolicyName))
				{
					if (!Config.DocumentationPolicies.TryGetValue(defaultPolicyName, out UhtDocumentationPolicy? policy))
					{
						Logger.LogError("The default documentation policy '{DefaultPolicyName}' isn't known", defaultPolicyName);
						return;
					}
				}
			}

			if (ReferenceMode != UhtReferenceMode.None)
			{
				string directoryToDelete = ReferenceMode == UhtReferenceMode.Reference ? ReferenceDirectory : VerifyDirectory;
				_referenceDeleteTask = Task.Factory.StartNew(() =>
				{
					try
					{
						Directory.Delete(directoryToDelete, true);
					}
					catch (Exception)
					{ }
				}, CancellationToken.None, TaskCreationOptions.None, TaskScheduler.Default);
			}

			StepReadManifestFile(manifestFilePath);

			if (arguments != null)
			{
				foreach (UhtExporter Exporter in ExporterTable)
				{
					if (arguments.HasOption($"-{Exporter.Name}"))
					{
						SetExporterStatus(Exporter.Name, true);
					}
					else if (arguments.HasOption($"-no{Exporter.Name}"))
					{
						SetExporterStatus(Exporter.Name, false);
					}
				}
			}

			StepPrepareModules();
			StepPrepareHeaders();
			StepParseHeaders();
			StepPopulateTypeTable();
			StepResolveInvalidCheck();
			StepBindSuperAndBases();
			RecursiveStructCheck();
			StepResolveBases();
			StepResolveProperties();
			StepResolveFinal();
			StepResolveValidate();
			StepCollectReferences();
			TopologicalSortHeaderFiles();

			// If we are deleting the reference directory, then wait for that task to complete
			if (_referenceDeleteTask != null)
			{
				Logger.LogTrace("Step - Waiting for reference output to be cleared.");
				_referenceDeleteTask.Wait();
			}

			Logger.LogTrace("Step - Starting exporters.");
			StepExport();
		}

		/// <summary>
		/// Try the given action.  If an exception occurs that doesn't have the required
		/// context, use the supplied context to generate the message.  If a previous error
		/// has occured, the action will not be executed
		/// </summary>
		/// <param name="messageSource">Message context for when the exception doesn't contain a context.</param>
		/// <param name="action">The lambda to be invoked</param>
		public void Try(IUhtMessageSource? messageSource, Action action)
		{
			if (!HasErrors)
			{
				TryNoErrorCheck(messageSource, action);
			}
		}

		/// <summary>
		/// Try the given action.  If an exception occurs that doesn't have the required
		/// context, use the supplied context to generate the message.
		/// </summary>
		/// <param name="messageSource">Message context for when the exception doesn't contain a context.</param>
		/// <param name="action">The lambda to be invoked</param>
		public void TryNoErrorCheck(IUhtMessageSource? messageSource, Action action)
		{
			try
			{
				action();
			}
			catch (Exception e)
			{
				HandleException(messageSource, e);
			}
		}

		/// <summary>
		/// Execute the given action on all the headers
		/// </summary>
		/// <param name="action">Action to be executed</param>
		/// <param name="allowGoWide">If true, go wide if enabled.  Otherwise single threaded</param>
		public void ForEachHeader(Action<UhtHeaderFile> action, bool allowGoWide)
		{
			if (!HasErrors)
			{
				ForEachHeaderNoErrorCheck(action, allowGoWide);
			}
		}

		/// <summary>
		/// Execute the given action on all the headers
		/// </summary>
		/// <param name="action">Action to be executed</param>
		/// <param name="allowGoWide">If true, go wide if enabled.  Otherwise single threaded</param>
		public void ForEachHeaderNoErrorCheck(Action<UhtHeaderFile> action, bool allowGoWide)
		{
			if (GoWide && allowGoWide)
			{
				Parallel.ForEach(_headerFiles, headerFile =>
				{
					TryHeader(action, headerFile);
				});
			}
			else
			{
				foreach (UhtHeaderFile headerFile in _headerFiles)
				{
					TryHeader(action, headerFile);
				}
			}
		}

		/// <summary>
		/// Read the given source file
		/// </summary>
		/// <param name="filePath">Full or relative file path</param>
		/// <returns>Information about the read source</returns>
		public UhtSourceFragment ReadSource(string filePath)
		{
			if (FileManager!.ReadSource(filePath, out UhtSourceFragment fragment))
			{
				return fragment;
			}
			throw new UhtException($"File not found '{filePath}'");
		}

		/// <summary>
		/// Read the given source file
		/// </summary>
		/// <param name="filePath">Full or relative file path</param>
		/// <returns>Buffer containing the read data or null if not found.  The returned buffer must be returned to the cache via a call to UhtBuffer.Return</returns>
		[Obsolete("Use the ReadSource method with the UhtPoolBuffer<char> output parameter")]
		public UhtBuffer? ReadSourceToBuffer(string filePath)
		{
			return FileManager!.ReadOutput(filePath);
		}

		/// <summary>
		/// Read the given source file
		/// </summary>
		/// <param name="filePath">Full or relative file path</param>
		/// <param name="output">Read source file</param>
		/// <returns>True if the file was read</returns>
		public bool ReadSource(string filePath, out UhtPoolBuffer<char> output)
		{
			return FileManager!.ReadOutput(filePath, out output);
		}

		/// <summary>
		/// Write the given contents to the file
		/// </summary>
		/// <param name="filePath">Path to write to</param>
		/// <param name="contents">Contents to write</param>
		/// <returns>True if the source was written</returns>
		internal bool WriteSource(string filePath, ReadOnlySpan<char> contents)
		{
			return FileManager!.WriteOutput(filePath, contents);
		}

		/// <summary>
		/// Rename the given file
		/// </summary>
		/// <param name="oldFilePath">Old file path name</param>
		/// <param name="newFilePath">New file path name</param>
		public void RenameSource(string oldFilePath, string newFilePath)
		{
			if (!FileManager!.RenameOutput(oldFilePath, newFilePath))
			{
				new UhtSimpleFileMessageSite(this, newFilePath).LogError($"Failed to rename exported file: '{oldFilePath}'");
			}
		}

		/// <summary>
		/// Given the name of a regular enum value, return the enum type
		/// </summary>
		/// <param name="name">Enum value</param>
		/// <returns>Associated regular enum type or null if not found or enum isn't a regular enum.</returns>
		public UhtEnum? FindRegularEnumValue(string name)
		{
			//COMPATIBILITY-TODO - See comment below on a more rebust version of the enum lookup
			//if (RegularEnumValueLookup.TryGetValue(name, out UhtEnum? enumObj))
			//{
			//	return enumObj;
			//}
			if (_fullEnumValueLookup.TryGetValue(name, out EnumAndValue value))
			{
				if (value.Value != -1)
				{
					return value.Enum;
				}
			}

			if (!name.Contains("::", StringComparison.Ordinal) && _shortEnumValueLookup.TryGetValue(name, out UhtEnum? enumObj))
			{
				return enumObj;
			}

			return null;
		}

		/// <summary>
		/// Find the given type in the type hierarchy
		/// </summary>
		/// <param name="startingType">Starting point for searches</param>
		/// <param name="options">Options controlling what is searched</param>
		/// <param name="name">Name of the type.</param>
		/// <param name="messageSite">If supplied, then a error message will be generated if the type can not be found</param>
		/// <param name="lineNumber">Source code line number requesting the lookup.</param>
		/// <returns>The located type of null if not found</returns>
		public UhtType? FindType(UhtType? startingType, UhtFindOptions options, string name, IUhtMessageSite? messageSite = null, int lineNumber = -1)
		{
			ValidateFindOptions(options);

			UhtType? type = FindTypeInternal(startingType, options, name);
			if (type == null && messageSite != null)
			{
				FindTypeError(messageSite, lineNumber, options, name);
			}
			return type;
		}

		/// <summary>
		/// Find the given type in the type hierarchy
		/// </summary>
		/// <param name="startingType">Starting point for searches</param>
		/// <param name="options">Options controlling what is searched</param>
		/// <param name="name">Name of the type.</param>
		/// <param name="messageSite">If supplied, then a error message will be generated if the type can not be found</param>
		/// <returns>The located type of null if not found</returns>
		public UhtType? FindType(UhtType? startingType, UhtFindOptions options, ref UhtToken name, IUhtMessageSite? messageSite = null)
		{
			ValidateFindOptions(options);

			UhtType? type = FindTypeInternal(startingType, options, name.Value.ToString());
			if (type == null && messageSite != null)
			{
				FindTypeError(messageSite, name.InputLine, options, name.Value.ToString());
			}
			return type;
		}

		/// <summary>
		/// Find the given type in the type hierarchy
		/// </summary>
		/// <param name="startingType">If specified, this represents the starting type to use when searching base/owner chain for a match</param>
		/// <param name="options">Options controlling what is searched</param>
		/// <param name="identifiers">Enumeration of identifiers.</param>
		/// <param name="messageSite">If supplied, then a error message will be generated if the type can not be found</param>
		/// <param name="lineNumber">Source code line number requesting the lookup.</param>
		/// <returns>The located type of null if not found</returns>
		public UhtType? FindType(UhtType? startingType, UhtFindOptions options, UhtTokenList identifiers, IUhtMessageSite? messageSite = null, int lineNumber = -1)
		{
			ValidateFindOptions(options);

			if (identifiers.Next != null && identifiers.Next.Next != null)
			{
				if (messageSite != null)
				{
					//messageSite.LogError(lineNumber, "UnrealHeaderTool only supports C++ identifiers of two or less identifiers");
					string fullIdentifier = identifiers.Join("::");
					FindTypeError(messageSite, lineNumber, options, fullIdentifier);
					return null;
				}
			}

			UhtType? type;
			if (identifiers.Next != null)
			{
				type = FindTypeTwoNamesInternal(startingType, options, identifiers.Token.Value.ToString(), identifiers.Next.Token.Value.ToString());
			}
			else
			{
				type = FindTypeInternal(startingType, options, identifiers.Token.Value.ToString());
			}

			if (type == null && messageSite != null)
			{
				string fullIdentifier = identifiers.Join("::");
				FindTypeError(messageSite, lineNumber, options, fullIdentifier);
			}
			return type;
		}

		/// <summary>
		/// Find the given type in the type hierarchy
		/// </summary>
		/// <param name="startingType">If specified, this represents the starting type to use when searching base/owner chain for a match</param>
		/// <param name="options">Options controlling what is searched</param>
		/// <param name="identifiers">Enumeration of identifiers.</param>
		/// <param name="messageSite">If supplied, then a error message will be generated if the type can not be found</param>
		/// <param name="lineNumber">Source code line number requesting the lookup.</param>
		/// <returns>The located type of null if not found</returns>
		public UhtType? FindType(UhtType? startingType, UhtFindOptions options, UhtToken[] identifiers, IUhtMessageSite? messageSite = null, int lineNumber = -1)
		{
			ValidateFindOptions(options);

			if (identifiers.Length == 0)
			{
				throw new UhtIceException("Empty identifier array");
			}
			if (identifiers.Length > 2)
			{
				if (messageSite != null)
				{
					//messageSite.LogError(lineNumber, "UnrealHeaderTool only supports C++ identifiers of two or less identifiers");
					string fullIdentifier = String.Join("::", identifiers);
					FindTypeError(messageSite, lineNumber, options, fullIdentifier);
					return null;
				}
			}

			UhtType? type;
			if (identifiers.Length == 0)
			{
				type = FindTypeTwoNamesInternal(startingType, options, identifiers[0].Value.ToString(), identifiers[1].Value.ToString());
			}
			else
			{
				type = FindTypeInternal(startingType, options, identifiers[0].Value.ToString());
			}

			if (type == null && messageSite != null)
			{
				string fullIdentifier = String.Join("::", identifiers);
				FindTypeError(messageSite, lineNumber, options, fullIdentifier);
			}
			return type;
		}

		/// <summary>
		/// Find the given type in the type hierarchy
		/// </summary>
		/// <param name="startingType">Starting point for searches</param>
		/// <param name="options">Options controlling what is searched</param>
		/// <param name="firstName">First name of the type.</param>
		/// <param name="secondName">Second name used by delegates in classes and namespace enumerations</param>
		/// <returns>The located type of null if not found</returns>
		private UhtType? FindTypeTwoNamesInternal(UhtType? startingType, UhtFindOptions options, string firstName, string secondName)
		{
			// If we have two names
			if (secondName.Length > 0)
			{
				if (options.HasAnyFlags(UhtFindOptions.DelegateFunction | UhtFindOptions.Enum))
				{
					UhtFindOptions subOptions = UhtFindOptions.NoParents | (options & ~UhtFindOptions.TypesMask) | (options & UhtFindOptions.Enum);
					if (options.HasAnyFlags(UhtFindOptions.DelegateFunction))
					{
						subOptions |= UhtFindOptions.Class;
					}
					UhtType? type = FindTypeInternal(startingType, subOptions, firstName);
					if (type == null)
					{
						return null;
					}
					if (type is UhtEnum)
					{
						return type;
					}
					if (type is UhtClass)
					{
						//TODO - Old UHT compatibility.  In UWidget, it references USlateAccessibleWidgetData::FGetText.  However, since UWidget has a FGetText, that 
						// is returned first.
						UhtType? compatType = FindTypeInternal(startingType, UhtFindOptions.DelegateFunction | UhtFindOptions.NoParents | (options & ~UhtFindOptions.TypesMask), secondName);
						if (compatType != null)
						{
							return compatType;
						}
						return FindTypeInternal(type, UhtFindOptions.DelegateFunction | UhtFindOptions.NoParents | (options & ~UhtFindOptions.TypesMask), secondName);
					}
				}

				// We can't match anything at this point
				return null;
			}

			// Perform the lookup for just a single name
			return FindTypeInternal(startingType, options, firstName);
		}

		/// <summary>
		/// Find the given type in the type hierarchy
		/// </summary>
		/// <param name="startingType">Starting point for searches</param>
		/// <param name="options">Options controlling what is searched</param>
		/// <param name="name">Name of the type.</param>
		/// <returns>The located type of null if not found</returns>
		public UhtType? FindTypeInternal(UhtType? startingType, UhtFindOptions options, string name)
		{
			if (options.HasAnyFlags(UhtFindOptions.EngineName))
			{
				if (options.HasAnyFlags(UhtFindOptions.CaseCompare))
				{
					return _engineNameSymbolTable.FindCasedType(startingType, options, name);
				}
				else
				{
					return _engineNameSymbolTable.FindCaselessType(startingType, options, name);
				}
			}
			else if (options.HasAnyFlags(UhtFindOptions.SourceName))
			{
				if (options.HasAnyFlags(UhtFindOptions.CaselessCompare))
				{
					return _sourceNameSymbolTable.FindCaselessType(startingType, options, name);
				}
				else
				{
					return _sourceNameSymbolTable.FindCasedType(startingType, options, name);
				}
			}
			else
			{
				throw new UhtIceException("Either EngineName or SourceName must be specified in the options");
			}
		}

		/// <summary>
		/// Verify that the options are valid.  Will also check to make sure the symbol table has been populated.
		/// </summary>
		/// <param name="options">Find options</param>
		private void ValidateFindOptions(UhtFindOptions options)
		{
			if (!options.HasAnyFlags(UhtFindOptions.EngineName | UhtFindOptions.SourceName))
			{
				throw new UhtIceException("Either EngineName or SourceName must be specified in the options");
			}

			if (options.HasAnyFlags(UhtFindOptions.CaseCompare) && options.HasAnyFlags(UhtFindOptions.CaselessCompare))
			{
				throw new UhtIceException("Both CaseCompare and CaselessCompare can't be specified as FindType options");
			}

			UhtFindOptions typeOptions = options & UhtFindOptions.TypesMask;
			if (typeOptions == 0)
			{
				throw new UhtIceException("No type options specified");
			}

			if (!_symbolTablePopulated)
			{
				throw new UhtIceException("Symbol table has not been populated, don't call FindType until headers are parsed.");
			}
		}

		/// <summary>
		/// Generate an error message for when a given symbol wasn't found.  The text will contain the list of types that the symbol must be
		/// </summary>
		/// <param name="messageSite">Destination for the message</param>
		/// <param name="lineNumber">Line number generating the error</param>
		/// <param name="options">Collection of required types</param>
		/// <param name="name">The name of the symbol</param>
		private static void FindTypeError(IUhtMessageSite messageSite, int lineNumber, UhtFindOptions options, string name)
		{
			List<string> types = new();
			if (options.HasAnyFlags(UhtFindOptions.Enum))
			{
				types.Add("'enum'");
			}
			if (options.HasAnyFlags(UhtFindOptions.ScriptStruct))
			{
				types.Add("'struct'");
			}
			if (options.HasAnyFlags(UhtFindOptions.Class))
			{
				types.Add("'class'");
			}
			if (options.HasAnyFlags(UhtFindOptions.DelegateFunction))
			{
				types.Add("'delegate'");
			}
			if (options.HasAnyFlags(UhtFindOptions.Function))
			{
				types.Add("'function'");
			}
			if (options.HasAnyFlags(UhtFindOptions.Property))
			{
				types.Add("'property'");
			}

			messageSite.LogError(lineNumber, $"Unable to find {UhtUtilities.MergeTypeNames(types, "or")} with name '{name}'");
		}

		/// <summary>
		/// Search for the given header file by just the file name
		/// </summary>
		/// <param name="name">Name to be found</param>
		/// <returns></returns>
		public UhtHeaderFile? FindHeaderFile(string name)
		{
			if (_headerFileDictionary.TryGetValue(name, out UhtHeaderFile? headerFile))
			{
				return headerFile;
			}
			return null;
		}

		#region IUHTMessageSource implementation
		/// <summary>
		/// Add a message to the collection of output messages
		/// </summary>
		/// <param name="message">Message being added</param>
		public void AddMessage(UhtMessage message)
		{
			if (message.MessageType == UhtMessageType.Deprecation && !Config!.ShowDeprecations)
			{
				return;
			}

			lock (_messages)
			{
				_messages.Add(message);

				// If we aren't caching messages and this is the first message,
				// start a task to flush the messages.
				if (!CacheMessages && _messageTask == null)
				{
					_messageTask = Task.Factory.StartNew(() => FlushMessages(), CancellationToken.None, TaskCreationOptions.None, TaskScheduler.Default);
				}
			}

			switch (message.MessageType)
			{
				case UhtMessageType.Error:
				case UhtMessageType.Ice:
					SignalError();
					break;

				case UhtMessageType.Warning:
					Interlocked.Increment(ref _warningCount);
					break;

				case UhtMessageType.Info:
				case UhtMessageType.Trace:
				case UhtMessageType.Deprecation:
					break;
			}
		}
		#endregion

		/// <summary>
		/// Register than an error has happened
		/// </summary>
		public void SignalError()
		{
			Interlocked.Increment(ref _errorCount);
		}

		/// <summary>
		/// Log all the collected messages to the log/console.  If messages aren't being
		/// cached, then this just waits until the flush task has completed.  If messages
		/// are being cached, they are sorted by file name and line number to ensure the 
		/// output is stable.
		/// </summary>
		public void LogMessages()
		{
			Task? messageTask = null;
			lock (_messages)
			{
				messageTask = _messageTask;
			}
			messageTask?.Wait();

			foreach (UhtMessage message in FetchOrderedMessages())
			{
				LogMessage(message);
			}
		}

		/// <summary>
		/// Flush all pending messages to the logger
		/// </summary>
		private void FlushMessages()
		{
			while (true)
			{
				UhtMessage[]? messageArray = null;
				lock (_messages)
				{
					messageArray = _messages.ToArray();
					_messages.Clear();
					if (messageArray.Length == 0)
					{
						_messageTask = null;
						return;
					}
				}

				foreach (UhtMessage message in messageArray)
				{
					LogMessage(message);
				}
			}
		}

		/// <summary>
		/// Log the given message
		/// </summary>
		/// <param name="msg">The message to be logged</param>
		private void LogMessage(UhtMessage msg)
		{
			LogLevel logLevel;
			switch (msg.MessageType)
			{
				default:
				case UhtMessageType.Error:
				case UhtMessageType.Ice:
					logLevel = LogLevel.Error;
					break;

				case UhtMessageType.Warning:
					logLevel = LogLevel.Warning;
					break;

				case UhtMessageType.Deprecation:
					logLevel = LogLevel.Information;
					break;

				case UhtMessageType.Info:
					logLevel = LogLevel.Information;
					break;

				case UhtMessageType.Trace:
					logLevel = LogLevel.Trace;
					break;
			}

			GetMessageParts(msg, out string filePath, out int lineNumber, out string fragmentPath, out string severity, out string message);
			(Logger??Log.Logger).Log(logLevel, KnownLogEvents.UHT, "{File}({Line}){FileFragment}: {Severity}: {Message}", 
				new FileReference(filePath), 
				new LogValue(LogValueType.LineNumber, lineNumber.ToString()), 
				fragmentPath, 
				new LogValue(LogValueType.Severity, severity), 
				new LogValue(LogValueType.Message, message));
		}

		/// <summary>
		/// Return all of the messages into a list
		/// </summary>
		/// <returns>List of all the messages</returns>
		public List<string> CollectMessages()
		{
			List<string> messages = new();
			foreach (UhtMessage msg in FetchOrderedMessages())
			{
				GetMessageParts(msg, out string filePath, out int lineNumber, out string fragmentPath, out string severity, out string message);
				messages.Add($"{filePath}({lineNumber}){fragmentPath}: {severity}: {message}");
			}
			return messages;
		}

		/// <summary>
		/// Given an existing and a new instance, replace the given type in the symbol table.
		/// This is used by the property resolution system to replace properties created during
		/// the parsing phase that couldn't be resoled until after all headers are parsed.
		/// </summary>
		/// <param name="oldType"></param>
		/// <param name="newType"></param>
		public void ReplaceTypeInSymbolTable(UhtType oldType, UhtType newType)
		{
			_sourceNameSymbolTable.Replace(oldType, newType, oldType.SourceName);
			if (oldType.EngineType.HasEngineName())
			{
				_engineNameSymbolTable.Replace(oldType, newType, oldType.EngineName);
			}
		}

		/// <summary>
		/// Hide the given type in the symbol table
		/// </summary>
		/// <param name="typeToHide"></param>
		public void HideTypeInSymbolTable(UhtType typeToHide)
		{
			_sourceNameSymbolTable.Hide(typeToHide, typeToHide.SourceName);
			if (typeToHide.EngineType.HasEngineName())
			{
				_engineNameSymbolTable.Hide(typeToHide, typeToHide.EngineName);
			}
		}

		/// <summary>
		/// Return an ordered enumeration of all messages.
		/// </summary>
		/// <returns>Enumerator</returns>
		private IOrderedEnumerable<UhtMessage> FetchOrderedMessages()
		{
			List<UhtMessage> messages = new();
			lock (_messages)
			{
				messages.AddRange(_messages);
				_messages.Clear();
			}
			return messages.OrderBy(context => context.FilePath).ThenBy(context => context.LineNumber + context.MessageSource?.MessageFragmentLineNumber);
		}

		/// <summary>
		/// Extract the part of a message
		/// </summary>
		/// <param name="msg">Message being consider</param>
		/// <param name="filePath">Full path of file where error happened</param>
		/// <param name="lineNumber">Line number where error happened</param>
		/// <param name="fragmentPath">For multi-part files (test harness), the inner file</param>
		/// <param name="severity">Severity of the error</param>
		/// <param name="message">Text of the message</param>
		private void GetMessageParts(UhtMessage msg, out string filePath, out int lineNumber, out string fragmentPath, out string severity, out string message)
		{
			fragmentPath = "";
			lineNumber = msg.LineNumber;
			if (msg.FilePath != null)
			{
				filePath = msg.FilePath;
			}
			else if (msg.MessageSource != null)
			{
				if (msg.MessageSource.MessageIsFragment)
				{
					if (RelativePathInLog)
					{
						filePath = msg.MessageSource.MessageFragmentFilePath;
					}
					else
					{
						filePath = msg.MessageSource.MessageFragmentFullFilePath;
					}
					fragmentPath = $"[{msg.MessageSource.MessageFilePath}]";
					lineNumber += msg.MessageSource.MessageFragmentLineNumber;
				}
				else
				{
					if (RelativePathInLog)
					{
						filePath = msg.MessageSource.MessageFilePath;
					}
					else
					{
						filePath = msg.MessageSource.MessageFullFilePath;
					}
				}
			}
			else
			{
				filePath = "UnknownSource";
			}

			switch (msg.MessageType)
			{
				case UhtMessageType.Error:
					severity = "Error";
					break;
				case UhtMessageType.Warning:
					severity = "Warning";
					break;
				case UhtMessageType.Info:
					severity = "Info";
					break;
				case UhtMessageType.Trace:
					severity = "Trace";
					break;
				case UhtMessageType.Deprecation:
					severity = "Deprecation";
					break;
				default:
				case UhtMessageType.Ice:
					severity = "Internal Compiler Error";
					break;
			}

			message = msg.Message;
		}

		/// <summary>
		/// Handle the given exception with the provided message context
		/// </summary>
		/// <param name="messageSource">Context for the exception.  Required to handled all exceptions other than UHTException</param>
		/// <param name="e">Exception being handled</param>
		private void HandleException(IUhtMessageSource? messageSource, Exception e)
		{
			switch (e)
			{
				case UhtException uhtException:
					UhtMessage message = uhtException.UhtMessage;
					message.MessageSource ??= messageSource;
					AddMessage(message);
					break;

				case JsonException jsonException:
					AddMessage(UhtMessage.MakeMessage(UhtMessageType.Error, messageSource, null, (int)(jsonException.LineNumber + 1 ?? 1), jsonException.Message));
					break;

				default:
					//Log.TraceInformation("{0}", E.StackTrace);
					AddMessage(UhtMessage.MakeMessage(UhtMessageType.Ice, messageSource, null, 1, $"{e.GetType()} - {e.Message}"));
					break;
			}
		}

		[GeneratedRegex(@"^\#define\s+ENGINE_(?<Name>[A-Z]+)_VERSION\s+(?<Number>\d+)\s*$")]
		private static partial Regex GetEngineVersionFragmentRegex();

		private EngineVersion LoadEngineVersion()
		{
			if (EngineDirectory == null)
			{
				throw new UhtException("Can't parse engine version without an engine directory");
			}

			string versionHeader = Path.Combine(EngineDirectory, "Source", "Runtime", "Launch", "Resources", "Version.h");
			Log.Logger.LogDebug("Reading engine version from file: {VersionHeader}", versionHeader);
			string[] lines;
			try
			{
				lines = File.ReadAllLines(versionHeader);
			}
			catch (Exception ex)
			{
				throw new UhtException(String.Format("Error reading engine version header '{0}': {1}", versionHeader, ex));
			}

			EngineVersion loadedVersion = new EngineVersion();
			bool gotMajor = false, gotMinor = false, gotPatch = false;
			Regex versionRegex = GetEngineVersionFragmentRegex();
			foreach (string line in lines)
			{
				Match match = versionRegex.Match(line);
				if (match.Success)
				{
					int matchNumber = Int32.Parse(match.Groups["Number"].Value);
					switch (match.Groups["Name"].Value)
					{
						case "MAJOR":
							loadedVersion.MajorVersion = matchNumber;
							gotMajor = true;
							break;
						case "MINOR":
							loadedVersion.MinorVersion = matchNumber;
							gotMinor = true;
							break;
						case "PATCH":
							loadedVersion.PatchVersion = matchNumber;
							gotPatch = true;
							break;
					}

					if (gotMajor && gotMinor && gotPatch)
					{
						break;
					}
				}
			}

			if (!gotMajor || !gotMinor || !gotPatch)
			{
				throw new UhtException(String.Format("Got incomplete engine version {0}", loadedVersion));
			}

			Log.Logger.LogDebug("Got engine version {EngineVersion}", loadedVersion);
			return loadedVersion;
		}

		#region Run steps
		private void StepReadManifestFile(string manifestFilePath)
		{
			ManifestFile = new UhtManifestFile(this, manifestFilePath);

			Try(ManifestFile.MessageSource, () =>
			{
				Log.Logger.LogTrace("Step - Read Manifest File");

				ManifestFile.Read();

				if (Manifest != null && Tables != null)
				{
					Tables.AddPlugins(Manifest.UhtPlugins);
				}
			});
		}

		private void StepPrepareModules()
		{
			if (ManifestFile == null || ManifestFile.Manifest == null)
			{
				return;
			}

			Try(ManifestFile.MessageSource, () =>
			{
				Log.Logger.LogTrace("Step - Prepare Modules");

				foreach (UHTManifest.Module manifestModule in ManifestFile.Manifest.Modules)
				{
					UhtModule module = new(this, manifestModule);
					_modules.Add(module);
				}
			});
		}

		private void StepPrepareHeaders()
		{
			if (ManifestFile == null)
			{
				return;
			}

			Try(ManifestFile.MessageSource, () =>
			{
				Log.Logger.LogTrace("Step - Prepare Headers");

				foreach (UhtModule module in Modules)
				{
					module.PrepareHeaders(headerFile =>
					{
						_headerFiles.Add(headerFile);
						_headerFileDictionary.Add(Path.GetFileName(headerFile.FilePath), headerFile);
					});
				}

				// Locate the NoExportTypes.h file and add it to every other header file
				if (_headerFileDictionary.TryGetValue("NoExportTypes.h", out UhtHeaderFile? noExportTypes))
				{
					foreach (UhtHeaderFile headerFile in _headerFiles)
					{
						if (headerFile != noExportTypes)
						{
							headerFile.AddReferencedHeader(noExportTypes, UhtHeaderReferenceType.Passive);
						}
					}
				}
			});
		}

		private void StepParseHeaders()
		{
			if (HasErrors)
			{
				return;
			}

			Log.Logger.LogTrace("Step - Parse Headers");
			ForEachHeader(headerFile =>
			{
				headerFile.Read();
				UhtHeaderFileParser.Parse(headerFile);
			}, true);
		}

		private void StepPopulateTypeTable()
		{
			Try(null, () =>
			{
				Log.Logger.LogTrace("Step - Populate symbol table");

				_sourceNameSymbolTable = new UhtSymbolTable(TypeCount);
				_engineNameSymbolTable = new UhtSymbolTable(TypeCount);

				PopulateSymbolTable();

				_uobject = (UhtClass?)FindType(null, UhtFindOptions.SourceName | UhtFindOptions.Class, "UObject");
				_uclass = (UhtClass?)FindType(null, UhtFindOptions.SourceName | UhtFindOptions.Class, "UClass");
				_uinterface = (UhtClass?)FindType(null, UhtFindOptions.SourceName | UhtFindOptions.Class, "UInterface");
				_iinterface = (UhtClass?)FindType(null, UhtFindOptions.SourceName | UhtFindOptions.Class, "IInterface");
				EVerseNativeCallResult = (UhtEnum?)FindType(null, UhtFindOptions.SourceName | UhtFindOptions.Enum, "EVerseNativeCallResult");
				AActor = (UhtClass?)FindType(null, UhtFindOptions.SourceName | UhtFindOptions.Class, "AActor");
				INotifyFieldValueChanged = (UhtClass?)FindType(null, UhtFindOptions.SourceName | UhtFindOptions.Class, "INotifyFieldValueChanged");
				FInstancedStruct = (UhtScriptStruct?)FindType(null, UhtFindOptions.SourceName | UhtFindOptions.ScriptStruct, "FInstancedStruct");
				FStateTreePropertyRef = (UhtScriptStruct?)FindType(null, UhtFindOptions.SourceName | UhtFindOptions.ScriptStruct, "FStateTreePropertyRef");
			});
		}

		private void StepBindSuperAndBases()
		{
			Log.Logger.LogTrace("Step - Bind super and bases");
			ForEachHeader(headerFile => headerFile.BindSuperAndBases(), true);
		}

		private void StepResolveBases()
		{
			Log.Logger.LogTrace("Step - Resolve bases");
			ResolveAllHeaders(UhtResolvePhase.Bases);
		}

		private void StepResolveInvalidCheck()
		{
			Log.Logger.LogTrace("Step - Resolve invalid check");
			ResolveAllHeaders(UhtResolvePhase.InvalidCheck);
		}

		private void StepResolveProperties()
		{
			Log.Logger.LogTrace("Step - Resolve properties");
			ResolveAllHeaders(UhtResolvePhase.Properties);
		}

		private void StepResolveFinal()
		{
			Log.Logger.LogTrace("Step - Resolve final");
			ResolveAllHeaders(UhtResolvePhase.Final);
		}

		private void StepResolveValidate()
		{
			Log.Logger.LogTrace("Step - Resolve validate");
			ForEachHeader(headerFile => headerFile.Validate(UhtValidationOptions.None), true);
		}

		private void StepCollectReferences()
		{
			Log.Logger.LogTrace("Step - Collect references");
			ForEachHeader(headerFile => headerFile.CollectReferences(), true);
		}

		private void ResolveAllHeaders(UhtResolvePhase resolvePhase)
		{
			ForEachHeader(headerFile => headerFile.Resolve(resolvePhase), resolvePhase.IsMultiThreadedResolvePhase());
			if (resolvePhase == UhtResolvePhase.InvalidCheck)
			{
				foreach (UhtModule module in Modules)
				{
					foreach (UhtPackage package in module.Packages)
					{
						package.RemoveInvalidChildren();
					}
				}
			}
		}

		private void TryHeader(Action<UhtHeaderFile> action, UhtHeaderFile headerFile)
		{
			try
			{
				action(headerFile);
			}
			catch (Exception e)
			{
				HandleException(headerFile.MessageSource, e);
			}
		}
		#endregion

		#region Symbol table initialization
		private void PopulateSymbolTable()
		{
			foreach (UhtHeaderFile headerFile in _headerFiles)
			{
				foreach (UhtType child in headerFile.Children)
				{
					if (child.Outer is UhtPackage package)
					{
						package.AddChildDirectly(child);
					}
					else
					{
						throw new UhtIceException($"Type \"{child.SourceName}\" is a root level type but does not have a package outer");
					}
					AddTypeToSymbolTable(child);
				}
			}
			_symbolTablePopulated = true;
		}

		private void AddTypeToSymbolTable(UhtType type)
		{
			UhtEngineType engineExtendedType = type.EngineType;

			if (type is UhtEnum enumObj)
			{
				//COMPATIBILITY-TODO: We can get more reliable results by only adding regular enums to the table
				// and then in the lookup code in the property system to look for the '::' and just lookup
				// the raw enum name.  In UHT we only care about the enum and not the value.
				//
				// The current algorithm has issues with two cases:
				//
				//		EnumNamespaceName::EnumTypeName::Value - Where the enum type name is included with a namespace enum
				//		EnumName::Value - Where the value is defined in terms that can't be parsed.  The -1 check causes it
				//			to be kicked out.
				//if (Enum.CppForm == UhtEnumCppForm.Regular)
				//{
				//	foreach (UhtEnumValue Value in Enum.EnumValues)
				//	{
				//		RegularEnumValueLookup.Add(Value.Name.ToString(), Enum);
				//	}
				//}
				bool addShortNames = enumObj.CppForm == UhtEnumCppForm.Namespaced || enumObj.CppForm == UhtEnumCppForm.EnumClass;
				string checkName = $"{enumObj.SourceName}::";
				foreach (UhtEnumValue value in enumObj.EnumValues)
				{
					if (!_fullEnumValueLookup.TryAdd(value.Name, new EnumAndValue { Enum = enumObj, Value = value.Value }))
					{
						//TODO - add a warning
					}
					if (addShortNames)
					{
						if (value.Name.StartsWith(checkName, StringComparison.Ordinal))
						{
							_shortEnumValueLookup.TryAdd(value.Name[checkName.Length..], enumObj);
						}
					}
				}
			}

			if (engineExtendedType.FindOptions() != 0)
			{
				if (engineExtendedType.MustNotBeReserved())
				{
					if (s_reservedNames.Contains(type.EngineName))
					{
						type.HeaderFile.LogError(type.LineNumber, $"{engineExtendedType.CapitalizedText()} '{type.EngineName}' uses a reserved type name.");
					}
				}

				if (engineExtendedType.HasEngineName() && engineExtendedType.MustBeUnique())
				{
					UhtType? existingType = _engineNameSymbolTable.FindCaselessType(null, engineExtendedType.MustBeUniqueFindOptions(), type.EngineName);
					if (existingType != null)
					{
						type.HeaderFile.LogError(type.LineNumber,
							$"{engineExtendedType.CapitalizedText()} '{type.SourceName}' shares engine name '{type.EngineName}' with " +
							$"{existingType.EngineType.LowercaseText()} '{existingType.SourceName}' in {existingType.HeaderFile.FilePath}({existingType.LineNumber})");
					}
				}

				_sourceNameSymbolTable.Add(type, type.SourceName);
				if (engineExtendedType.HasEngineName())
				{
					_engineNameSymbolTable.Add(type, type.EngineName);
				}
			}

			if (engineExtendedType.AddChildrenToSymbolTable())
			{
				foreach (UhtType child in type.Children)
				{
					AddTypeToSymbolTable(child);
				}
			}
		}
		#endregion

		#region Topological testing of headers and structs
		private enum TopologicalState
		{
			Unmarked,
			Temporary,
			Permanent,
		}

		private void TopologicalHeaderVisit(List<TopologicalState> states, UhtHeaderFile visit, List<UhtHeaderFile> headerStack)
		{
			headerStack.Add(visit);
			switch (states[visit.HeaderFileTypeIndex])
			{
				case TopologicalState.Unmarked:
					states[visit.HeaderFileTypeIndex] = TopologicalState.Temporary;
					foreach (UhtHeaderFile referenced in visit.ReferencedHeadersNoLock)
					{
						TopologicalHeaderVisit(states, referenced, headerStack);
					}
					states[visit.HeaderFileTypeIndex] = TopologicalState.Permanent;
					_sortedHeaderFiles.Add(visit);
					break;

				case TopologicalState.Temporary:
					{
						int index = headerStack.IndexOf(visit);
						if (index == -1 || index == headerStack.Count - 1)
						{
							throw new UhtIceException("Error locating include file loop");
						}
						index++;
						visit.LogError("Circular dependency detected:");
						UhtHeaderFile previous = visit;
						for (int loopIndex = index; loopIndex < headerStack.Count; loopIndex++)
						{
							UhtHeaderFile next = headerStack[loopIndex];
							previous.LogError($"includes/requires '{next.FilePath}'");
							previous = next;
						}
					}
					break;

				case TopologicalState.Permanent:
					break;

				default:
					throw new UhtIceException("Unknown topological state");
			}
			headerStack.RemoveAt(headerStack.Count - 1);
		}

		private void TopologicalSortHeaderFiles()
		{
			Try(null, () =>
			{
				Log.Logger.LogTrace("Step - Topological Sort Header Files");

				// Initialize a scratch table for topological states
				_sortedHeaderFiles.Capacity = HeaderFileTypeCount;
				List<TopologicalState> states = new(HeaderFileTypeCount);
				for (int index = 0; index < HeaderFileTypeCount; ++index)
				{
					states.Add(TopologicalState.Unmarked);
				}

				List<UhtHeaderFile> headerStack = new(32); // arbitrary capacity
				foreach (UhtHeaderFile headerFile in HeaderFiles)
				{
					if (states[headerFile.HeaderFileTypeIndex] == TopologicalState.Unmarked)
					{
						TopologicalHeaderVisit(states, headerFile, headerStack);
					}
				}
			});
		}

		private void TopologicalStructVisitChildren(List<TopologicalState> states, UhtHeaderFile visit, List<UhtStruct> structStack)
		{
			foreach (UhtType child in visit.Children)
			{
				if (child is UhtStruct childStruct)
				{
					TopologicalStructVisit(states, childStruct, structStack);
				}
			}
		}

		private void TopologicalStructVisitChildren(List<TopologicalState> states, UhtType visit, List<UhtStruct> structStack)
		{
			foreach (UhtType child in visit.Children)
			{
				if (child is UhtStruct childStruct)
				{
					TopologicalStructVisit(states, childStruct, structStack);
				}
			}
		}

		private void TopologicalStructVisit(List<TopologicalState> states, UhtStruct visit, List<UhtStruct> structStack)
		{
			structStack.Add(visit);
			switch (states[visit.ObjectTypeIndex])
			{
				case TopologicalState.Unmarked:
					states[visit.ObjectTypeIndex] = TopologicalState.Temporary;
					if (visit.Super != null)
					{
						TopologicalStructVisit(states, visit.Super, structStack);
					}
					foreach (UhtStruct baseStruct in visit.Bases)
					{
						TopologicalStructVisit(states, baseStruct, structStack);
					}
					if (visit is UhtClass classObj)
					{
						foreach (UhtStruct verseInterface in classObj.VerseInterfaces)
						{
							TopologicalStructVisit(states, verseInterface, structStack);
						}
					}
					TopologicalStructVisitChildren(states, visit, structStack);
					states[visit.ObjectTypeIndex] = TopologicalState.Permanent;
					break;

				case TopologicalState.Temporary:
					{
						int index = structStack.IndexOf(visit);
						if (index == -1 || index == structStack.Count - 1)
						{
							throw new UhtIceException("Error locating struct loop");
						}
						index++;
						visit.LogError("Recursive class/struct definition:");
						UhtStruct previous = visit;
						for (int loopIndex = index; loopIndex < structStack.Count; loopIndex++)
						{
							UhtStruct next = structStack[loopIndex];
							previous.LogError($"'{previous.SourceName}' inherits '{next.SourceName}'");
							previous = next;
						}
					}
					break;

				case TopologicalState.Permanent:
					break;

				default:
					throw new UhtIceException("Unknown topological state");
			}
			structStack.RemoveAt(structStack.Count - 1);
		}

		private void RecursiveStructCheck()
		{
			Try(null, () =>
			{
				Log.Logger.LogTrace("Step - Check for recursive structs");

				// Initialize a scratch table for topological states
				List<TopologicalState> states = new(ObjectTypeCount);
				for (int index = 0; index < ObjectTypeCount; ++index)
				{
					states.Add(TopologicalState.Unmarked);
				}

				List<UhtStruct> structStack = new(32); // arbitrary capacity
				foreach (UhtHeaderFile headerFile in HeaderFiles)
				{
					TopologicalStructVisitChildren(states, headerFile, structStack);
				}
			});
		}
		#endregion

		#region Validation helpers
		private readonly HashSet<UhtScriptStruct> _scriptStructsValidForNet = new();

		/// <summary>
		/// Validate that the given referenced script structure is valid for network operations.  If the structure
		/// is valid, then the result will be cached.  It not valid, errors will be generated each time the structure
		/// is referenced.
		/// </summary>
		/// <param name="referencingProperty">The property referencing a structure</param>
		/// <param name="referencedScriptStruct">The script structure being referenced</param>
		/// <returns></returns>
		public bool ValidateScriptStructOkForNet(UhtProperty referencingProperty, UhtScriptStruct referencedScriptStruct)
		{

			// Check for existing value
			lock (_scriptStructsValidForNet)
			{
				if (_scriptStructsValidForNet.Contains(referencedScriptStruct))
				{
					return true;
				}
			}

			bool isStructValid = true;

			// Check the super chain structure
			UhtScriptStruct? superScriptStruct = referencedScriptStruct.SuperScriptStruct;
			if (superScriptStruct != null)
			{
				if (!ValidateScriptStructOkForNet(referencingProperty, superScriptStruct))
				{
					isStructValid = false;
				}
			}

			// Check the structure properties
			foreach (UhtProperty property in referencedScriptStruct.Properties)
			{
				if (!property.ValidateStructPropertyOkForNet(referencingProperty))
				{
					isStructValid = false;
					break;
				}
			}

			// Save the results
			if (isStructValid)
			{
				lock (_scriptStructsValidForNet)
				{
					_scriptStructsValidForNet.Add(referencedScriptStruct);
				}
			}
			return isStructValid;
		}
		#endregion

		#region Exporting

		/// <summary>
		/// Enable/Disable an exporter.  This overrides the default state of the exporter.
		/// </summary>
		/// <param name="name">Name of the exporter</param>
		/// <param name="enabled">If true, the exporter is to be enabled</param>
		public void SetExporterStatus(string name, bool enabled)
		{
			_exporterStates[name] = enabled;
		}

		/// <summary>
		/// Test to see if the given exporter plugin is enabled.
		/// </summary>
		/// <param name="pluginName">Name of the plugin</param>
		/// <param name="includeTargetCheck">If true, include a target check</param>
		/// <returns>True if enabled</returns>
		public bool IsPluginEnabled(string pluginName, bool includeTargetCheck)
		{
			if (_projectJson == null && ProjectDirectory != null && ProjectFile != null)
			{
				if (ReadSource(ProjectFile, out UhtPoolBuffer<char> contents))
				{
					_projectJson = JsonDocument.Parse(contents.Memory);
					UhtPoolBuffers.Return<char>(contents);
				}
			}

			if (_projectJson == null)
			{
				return false;
			}

			JsonObject rootObject = new(_projectJson.RootElement);
			if (rootObject.TryGetObjectArrayField("Plugins", out JsonObject[]? plugins))
			{
				foreach (JsonObject plugin in plugins)
				{
					if (!plugin.TryGetStringField("Name", out string? testPluginName) || !String.Equals(pluginName, testPluginName, StringComparison.OrdinalIgnoreCase))
					{
						continue;
					}
					if (!plugin.TryGetBoolField("Enabled", out bool enabled) || !enabled)
					{
						return false;
					}
					if (includeTargetCheck && Manifest != null)
					{
						if (plugin.TryGetStringArrayField("TargetAllowList", out string[]? allowList))
						{
							if (allowList.Contains(Manifest.TargetName, StringComparer.OrdinalIgnoreCase))
							{
								return true;
							}
						}
						if (plugin.TryGetStringArrayField("TargetDenyList", out string[]? denyList))
						{
							if (denyList.Contains(Manifest.TargetName, StringComparer.OrdinalIgnoreCase))
							{
								return false;
							}
						}
					}
					return true;
				}
			}
			return false;
		}

		private void StepExport()
		{
			HashSet<string> externalDependencies = new();
			long totalWrittenFiles = 0;
			Try(null, () =>
			{
				Logger.LogDebug("Step - Exports");

				foreach (UhtExporter exporter in ExporterTable)
				{
					if (!_exporterStates.TryGetValue(exporter.Name, out bool run))
					{
						run = Config!.IsExporterEnabled(exporter.Name) ||
							(exporter.Options.HasAnyFlags(UhtExporterOptions.Default) && !NoDefaultExporters);
					}

					UHTManifest.Module? pluginModule = null;
					if (!String.IsNullOrEmpty(exporter.ModuleName))
					{
						foreach (UHTManifest.Module module in Manifest!.Modules)
						{
							if (String.Equals(module.Name, exporter.ModuleName, StringComparison.OrdinalIgnoreCase))
							{
								pluginModule = module;
								break;
							}
						}
						if (pluginModule == null)
						{
							Logger.LogWarning("Exporter \"{ExporterName}\" skipped because module \"{ModuleName}\" was not found in manifest", exporter.Name, exporter.ModuleName);
							continue;
						}
					}

					if (run)
					{
						Logger.LogDebug("       Running exporter {ExporterName}", exporter.Name);
						UhtExportFactory factory = new(this, pluginModule, exporter);
						factory.Run();
						foreach (UhtExportFactory.Output output in factory.Outputs)
						{
							if (output.Saved)
							{
								totalWrittenFiles++;
							}
						}
						foreach (string dep in factory.ExternalDependencies)
						{
							externalDependencies.Add(dep);
						}
					}
					else
					{
						Logger.LogDebug("       Exporter {ExporterName} skipped", exporter.Name);
					}
				}

				// Save the collected external dependencies
				if (!String.IsNullOrEmpty(Manifest!.ExternalDependenciesFile))
				{
					using StreamWriter output = new(Manifest!.ExternalDependenciesFile);
					foreach (string dep in externalDependencies)
					{ 
						output.WriteLine(dep);
					}
				}
			});

			Logger.LogInformation("Total of {NumFiles} written", totalWrittenFiles);
		}
		#endregion

		#region Other helper methods
		/// <summary>
		/// Test to see if the given property is an incomplete return type
		/// </summary>
		/// <param name="property"></param>
		/// <returns></returns>
		public bool IsIncompleteReturn(UhtProperty? property)
		{
			return property is UhtEnumProperty enumProperty && enumProperty.Enum == EVerseNativeCallResult;
		}
		#endregion
	}
}