// Copyright (c) 2016 Daniel Grunwald
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection.Metadata;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

using ICSharpCode.Decompiler.CSharp.OutputVisitor;
using ICSharpCode.Decompiler.CSharp.Syntax;
using ICSharpCode.Decompiler.CSharp.Transforms;
using ICSharpCode.Decompiler.DebugInfo;
using ICSharpCode.Decompiler.Metadata;
using ICSharpCode.Decompiler.Semantics;
using ICSharpCode.Decompiler.Solution;
using ICSharpCode.Decompiler.TypeSystem;
using ICSharpCode.Decompiler.Util;

using static ICSharpCode.Decompiler.Metadata.MetadataExtensions;

namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
{
	/// <summary>
	/// Decompiles an assembly into a visual studio project file.
	/// </summary>
	public class WholeProjectDecompiler : IProjectInfoProvider
	{
		const int maxSegmentLength = 255;

		#region Settings
		/// <summary>
		/// Gets the setting this instance uses for decompiling.
		/// </summary>
		public DecompilerSettings Settings { get; }

		LanguageVersion? languageVersion;

		public LanguageVersion LanguageVersion {
			get { return languageVersion ?? Settings.GetMinimumRequiredVersion(); }
			set {
				var minVersion = Settings.GetMinimumRequiredVersion();
				if (value < minVersion)
					throw new InvalidOperationException($"The chosen settings require at least {minVersion}." +
						$" Please change the DecompilerSettings accordingly.");
				languageVersion = value;
			}
		}

		public IAssemblyResolver AssemblyResolver { get; }

		public AssemblyReferenceClassifier AssemblyReferenceClassifier { get; }

		public IDebugInfoProvider DebugInfoProvider { get; }

		/// <summary>
		/// The MSBuild ProjectGuid to use for the new project.
		/// </summary>
		public Guid ProjectGuid { get; }

		/// <summary>
		/// The target directory that the decompiled files are written to.
		/// </summary>
		/// <remarks>
		/// This property is set by DecompileProject() and protected so that overridden protected members
		/// can access it.
		/// </remarks>
		public string TargetDirectory { get; protected set; }

		/// <summary>
		/// Path to the snk file to use for signing.
		/// <c>null</c> to not sign.
		/// </summary>
		public string StrongNameKeyFile { get; set; }

		public int MaxDegreeOfParallelism { get; set; } = Environment.ProcessorCount;

		public IProgress<DecompilationProgress> ProgressIndicator { get; set; }
		#endregion

		public WholeProjectDecompiler(IAssemblyResolver assemblyResolver)
			: this(new DecompilerSettings(), assemblyResolver, projectWriter: null, assemblyReferenceClassifier: null, debugInfoProvider: null)
		{
		}

		public WholeProjectDecompiler(
			DecompilerSettings settings,
			IAssemblyResolver assemblyResolver,
			IProjectFileWriter projectWriter,
			AssemblyReferenceClassifier assemblyReferenceClassifier,
			IDebugInfoProvider debugInfoProvider)
			: this(settings, Guid.NewGuid(), assemblyResolver, projectWriter, assemblyReferenceClassifier, debugInfoProvider)
		{
		}

		protected WholeProjectDecompiler(
			DecompilerSettings settings,
			Guid projectGuid,
			IAssemblyResolver assemblyResolver,
			IProjectFileWriter projectWriter,
			AssemblyReferenceClassifier assemblyReferenceClassifier,
			IDebugInfoProvider debugInfoProvider)
		{
			Settings = settings ?? throw new ArgumentNullException(nameof(settings));
			ProjectGuid = projectGuid;
			AssemblyResolver = assemblyResolver ?? throw new ArgumentNullException(nameof(assemblyResolver));
			AssemblyReferenceClassifier = assemblyReferenceClassifier ?? new AssemblyReferenceClassifier();
			DebugInfoProvider = debugInfoProvider;
			this.projectWriter = projectWriter ?? (Settings.UseSdkStyleProjectFormat ? ProjectFileWriterSdkStyle.Create() : ProjectFileWriterDefault.Create());
		}

		// per-run members
		HashSet<string> directories = new HashSet<string>(Platform.FileNameComparer);
		readonly IProjectFileWriter projectWriter;

		public void DecompileProject(MetadataFile file, string targetDirectory, CancellationToken cancellationToken = default(CancellationToken))
		{
			string projectFileName = Path.Combine(targetDirectory, CleanUpFileName(file.Name) + ".csproj");
			using (var writer = new StreamWriter(projectFileName))
			{
				DecompileProject(file, targetDirectory, writer, cancellationToken);
			}
		}

		public ProjectId DecompileProject(MetadataFile file, string targetDirectory, TextWriter projectFileWriter, CancellationToken cancellationToken = default(CancellationToken))
		{
			if (string.IsNullOrEmpty(targetDirectory))
			{
				throw new InvalidOperationException("Must set TargetDirectory");
			}
			TargetDirectory = targetDirectory;
			directories.Clear();
			var resources = WriteResourceFilesInProject(file).ToList();
			var files = WriteCodeFilesInProject(file, resources.SelectMany(r => r.PartialTypes ?? Enumerable.Empty<PartialTypeInfo>()).ToList(), cancellationToken).ToList();
			files.AddRange(resources);
			var module = file as PEFile;
			if (module != null)
			{
				files.AddRange(WriteMiscellaneousFilesInProject(module));
			}
			if (StrongNameKeyFile != null)
			{
				File.Copy(StrongNameKeyFile, Path.Combine(targetDirectory, Path.GetFileName(StrongNameKeyFile)), overwrite: true);
			}

			projectWriter.Write(projectFileWriter, this, files, file);

			string platformName = module != null ? TargetServices.GetPlatformName(module) : "AnyCPU";
			return new ProjectId(platformName, ProjectGuid, ProjectTypeGuids.CSharpWindows);
		}

		#region WriteCodeFilesInProject
		protected virtual bool IncludeTypeWhenDecompilingProject(MetadataFile module, TypeDefinitionHandle type)
		{
			var metadata = module.Metadata;
			var typeDef = metadata.GetTypeDefinition(type);
			string name = metadata.GetString(typeDef.Name);
			string ns = metadata.GetString(typeDef.Namespace);
			if (name == "<Module>" || CSharpDecompiler.MemberIsHidden(module, type, Settings))
				return false;
			if (ns == "XamlGeneratedNamespace" && name == "GeneratedInternalTypeHelper")
				return false;
			if (!typeDef.IsNested && RemoveEmbeddedAttributes.attributeNames.Contains(ns + "." + name))
				return false;
			return true;
		}

		CSharpDecompiler CreateDecompiler(DecompilerTypeSystem ts)
		{
			var decompiler = new CSharpDecompiler(ts, Settings);
			decompiler.DebugInfoProvider = DebugInfoProvider;
			decompiler.AstTransforms.Add(new EscapeInvalidIdentifiers());
			decompiler.AstTransforms.Add(new RemoveCLSCompliantAttribute());
			return decompiler;
		}

		IEnumerable<ProjectItemInfo> WriteAssemblyInfo(DecompilerTypeSystem ts, CancellationToken cancellationToken)
		{
			var decompiler = CreateDecompiler(ts);
			decompiler.CancellationToken = cancellationToken;
			decompiler.AstTransforms.Add(new RemoveCompilerGeneratedAssemblyAttributes());
			SyntaxTree syntaxTree = decompiler.DecompileModuleAndAssemblyAttributes();

			const string prop = "Properties";
			if (directories.Add(prop))
				Directory.CreateDirectory(Path.Combine(TargetDirectory, prop));
			string assemblyInfo = Path.Combine(prop, "AssemblyInfo.cs");
			using (StreamWriter w = new StreamWriter(Path.Combine(TargetDirectory, assemblyInfo)))
			{
				syntaxTree.AcceptVisitor(new CSharpOutputVisitor(w, Settings.CSharpFormattingOptions));
			}
			return new[] { new ProjectItemInfo("Compile", assemblyInfo) };
		}

		IEnumerable<ProjectItemInfo> WriteCodeFilesInProject(MetadataFile module, IList<PartialTypeInfo> partialTypes, CancellationToken cancellationToken)
		{
			var metadata = module.Metadata;
			var files = module.Metadata.GetTopLevelTypeDefinitions().Where(td => IncludeTypeWhenDecompilingProject(module, td))
				.GroupBy(GetFileFileNameForHandle, StringComparer.OrdinalIgnoreCase).ToList();
			var progressReporter = ProgressIndicator;
			var progress = new DecompilationProgress { TotalUnits = files.Count, Title = "Exporting project..." };
			DecompilerTypeSystem ts = new DecompilerTypeSystem(module, AssemblyResolver, Settings);
			var workList = new HashSet<TypeDefinitionHandle>();
			var processedTypes = new HashSet<TypeDefinitionHandle>();
			ProcessFiles(files);
			while (workList.Count > 0)
			{
				var additionalFiles = workList
					.GroupBy(GetFileFileNameForHandle, StringComparer.OrdinalIgnoreCase).ToList();
				workList.Clear();
				ProcessFiles(additionalFiles);
				files.AddRange(additionalFiles);
				progress.TotalUnits = files.Count;
			}

			return files.Select(f => new ProjectItemInfo("Compile", f.Key)).Concat(WriteAssemblyInfo(ts, cancellationToken));

			string GetFileFileNameForHandle(TypeDefinitionHandle h)
			{
				var type = metadata.GetTypeDefinition(h);
				string file = CleanUpFileName(metadata.GetString(type.Name) + ".cs");
				string ns = metadata.GetString(type.Namespace);
				if (string.IsNullOrEmpty(ns))
				{
					return file;
				}
				else
				{
					string dir = Settings.UseNestedDirectoriesForNamespaces ? CleanUpPath(ns) : CleanUpDirectoryName(ns);
					if (directories.Add(dir))
					{
						var path = Path.Combine(TargetDirectory, dir);
						try
						{
							Directory.CreateDirectory(path);
						}
						catch (IOException)
						{
							File.Delete(path);
							Directory.CreateDirectory(path);
						}
					}
					return Path.Combine(dir, file);
				}
			}

			void ProcessFiles(List<IGrouping<string, TypeDefinitionHandle>> files)
			{
				processedTypes.AddRange(files.SelectMany(f => f));
				Parallel.ForEach(
					Partitioner.Create(files, loadBalance: true),
					new ParallelOptions {
						MaxDegreeOfParallelism = this.MaxDegreeOfParallelism,
						CancellationToken = cancellationToken
					},
					delegate (IGrouping<string, TypeDefinitionHandle> file) {
						try
						{
							using StreamWriter w = new StreamWriter(Path.Combine(TargetDirectory, file.Key));
							CSharpDecompiler decompiler = CreateDecompiler(ts);

							foreach (var partialType in partialTypes)
							{
								decompiler.AddPartialTypeDefinition(partialType);
							}

							decompiler.CancellationToken = cancellationToken;
							var declaredTypes = file.ToArray();
							var syntaxTree = decompiler.DecompileTypes(declaredTypes);

							foreach (var node in syntaxTree.Descendants)
							{
								var td = (node.GetResolveResult() as TypeResolveResult)?.Type.GetDefinition();
								if (td?.ParentModule != ts.MainModule)
									continue;
								while (td?.DeclaringTypeDefinition != null)
								{
									td = td.DeclaringTypeDefinition;
								}
								if (td != null && td.MetadataToken is { IsNil: false } token && !processedTypes.Contains((TypeDefinitionHandle)token))
								{
									lock (workList)
									{
										workList.Add((TypeDefinitionHandle)token);
									}
								}
							}

							syntaxTree.AcceptVisitor(new CSharpOutputVisitor(w, Settings.CSharpFormattingOptions));
						}
						catch (Exception innerException) when (!(innerException is OperationCanceledException || innerException is DecompilerException))
						{
							throw new DecompilerException(module, $"Error decompiling for '{file.Key}'", innerException);
						}
						progress.Status = file.Key;
						Interlocked.Increment(ref progress.UnitsCompleted);
						progressReporter?.Report(progress);
					});
			}
		}
		#endregion

		#region WriteResourceFilesInProject
		protected virtual IEnumerable<ProjectItemInfo> WriteResourceFilesInProject(MetadataFile module)
		{
			foreach (var r in module.Resources.Where(r => r.ResourceType == ResourceType.Embedded))
			{
				Stream stream = r.TryOpenStream();
				stream.Position = 0;

				if (r.Name.EndsWith(".resources", StringComparison.OrdinalIgnoreCase))
				{
					bool decodedIntoIndividualFiles;
					var individualResources = new List<ProjectItemInfo>();
					try
					{
						var resourcesFile = new ResourcesFile(stream);
						if (resourcesFile.AllEntriesAreStreams())
						{
							foreach (var (name, value) in resourcesFile)
							{
								string fileName = SanitizeFileName(name)
									.Replace('/', Path.DirectorySeparatorChar);
								string dirName = Path.GetDirectoryName(fileName);
								if (!string.IsNullOrEmpty(dirName) && directories.Add(dirName))
								{
									Directory.CreateDirectory(Path.Combine(TargetDirectory, dirName));
								}
								Stream entryStream = (Stream)value;
								entryStream.Position = 0;
								individualResources.AddRange(
									WriteResourceToFile(fileName, name, entryStream));
							}
							decodedIntoIndividualFiles = true;
						}
						else
						{
							decodedIntoIndividualFiles = false;
						}
					}
					catch (BadImageFormatException)
					{
						decodedIntoIndividualFiles = false;
					}
					catch (EndOfStreamException)
					{
						decodedIntoIndividualFiles = false;
					}
					if (decodedIntoIndividualFiles)
					{
						foreach (var entry in individualResources)
						{
							yield return entry;
						}
					}
					else
					{
						stream.Position = 0;
						string fileName = GetFileNameForResource(r.Name);
						foreach (var entry in WriteResourceToFile(fileName, r.Name, stream))
						{
							yield return entry;
						}
					}
				}
				else
				{
					string fileName = GetFileNameForResource(r.Name);
					using (FileStream fs = new FileStream(Path.Combine(TargetDirectory, fileName), FileMode.Create, FileAccess.Write))
					{
						stream.Position = 0;
						stream.CopyTo(fs);
					}
					yield return new ProjectItemInfo("EmbeddedResource", fileName).With("LogicalName", r.Name);
				}
			}
		}

		protected virtual IEnumerable<ProjectItemInfo> WriteResourceToFile(string fileName, string resourceName, Stream entryStream)
		{
			if (fileName.EndsWith(".resources", StringComparison.OrdinalIgnoreCase))
			{
				string resx = Path.ChangeExtension(fileName, ".resx");
				try
				{
					using (FileStream fs = new FileStream(Path.Combine(TargetDirectory, resx), FileMode.Create, FileAccess.Write))
					using (ResXResourceWriter writer = new ResXResourceWriter(fs))
					{
						foreach (var entry in new ResourcesFile(entryStream))
						{
							writer.AddResource(entry.Key, entry.Value);
						}
					}
					return new[] { new ProjectItemInfo("EmbeddedResource", resx).With("LogicalName", resourceName) };
				}
				catch (BadImageFormatException)
				{
					// if the .resources can't be decoded, just save them as-is
				}
				catch (EndOfStreamException)
				{
					// if the .resources can't be decoded, just save them as-is
				}
			}
			using (FileStream fs = new FileStream(Path.Combine(TargetDirectory, fileName), FileMode.Create, FileAccess.Write))
			{
				entryStream.CopyTo(fs);
			}
			return new[] { new ProjectItemInfo("EmbeddedResource", fileName).With("LogicalName", resourceName) };
		}

		string GetFileNameForResource(string fullName)
		{
			// Clean up the name first and ensure the length does not exceed the maximum length
			// supported by the OS.
			fullName = SanitizeFileName(fullName);
			// The purpose of the below algorithm is to "maximize" the directory name and "minimize" the file name.
			// That is, a full name of the form "Namespace1.Namespace2{...}.NamespaceN.ResourceName" is split such that
			// the directory part Namespace1\Namespace2\... reuses as many existing directories as
			// possible, and only the remaining name parts are used as prefix for the filename.
			// This is not affected by the UseNestedDirectoriesForNamespaces setting.
			string[] splitName = fullName.Split('\\', '/');
			string fileName = string.Join(".", splitName);
			string separator = Path.DirectorySeparatorChar.ToString();
			for (int i = splitName.Length - 1; i > 0; i--)
			{
				string ns = string.Join(separator, splitName, 0, i);
				if (directories.Contains(ns))
				{
					string name = string.Join(".", splitName, i, splitName.Length - i);
					fileName = Path.Combine(ns, name);
					break;
				}
			}
			return fileName;
		}
		#endregion

		#region WriteMiscellaneousFilesInProject
		protected virtual IEnumerable<ProjectItemInfo> WriteMiscellaneousFilesInProject(PEFile module)
		{
			var resources = module.Reader.ReadWin32Resources();
			if (resources == null)
				yield break;

			byte[] appIcon = CreateApplicationIcon(resources);
			if (appIcon != null)
			{
				File.WriteAllBytes(Path.Combine(TargetDirectory, "app.ico"), appIcon);
				yield return new ProjectItemInfo("ApplicationIcon", "app.ico");
			}

			byte[] appManifest = CreateApplicationManifest(resources);
			if (appManifest != null && !IsDefaultApplicationManifest(appManifest))
			{
				File.WriteAllBytes(Path.Combine(TargetDirectory, "app.manifest"), appManifest);
				yield return new ProjectItemInfo("ApplicationManifest", "app.manifest");
			}

			var appConfig = module.FileName + ".config";
			if (File.Exists(appConfig))
			{
				File.Copy(appConfig, Path.Combine(TargetDirectory, "app.config"), overwrite: true);
				yield return new ProjectItemInfo("ApplicationConfig", Path.GetFileName(appConfig));
			}
		}

		const int RT_ICON = 3;
		const int RT_GROUP_ICON = 14;

		unsafe static byte[] CreateApplicationIcon(Win32ResourceDirectory resources)
		{
			var iconGroup = resources.Find(new Win32ResourceName(RT_GROUP_ICON))?.FirstDirectory()?.FirstData()?.Data;
			if (iconGroup == null)
				return null;

			var iconDir = resources.Find(new Win32ResourceName(RT_ICON));
			if (iconDir == null)
				return null;

			using var outStream = new MemoryStream();
			using var writer = new BinaryWriter(outStream);
			fixed (byte* pIconGroupData = iconGroup)
			{
				var pIconGroup = (GRPICONDIR*)pIconGroupData;
				writer.Write(pIconGroup->idReserved);
				writer.Write(pIconGroup->idType);
				writer.Write(pIconGroup->idCount);

				int iconCount = pIconGroup->idCount;
				uint offset = (2 * 3) + ((uint)iconCount * 0x10);
				for (int i = 0; i < iconCount; i++)
				{
					var pIconEntry = pIconGroup->idEntries + i;
					writer.Write(pIconEntry->bWidth);
					writer.Write(pIconEntry->bHeight);
					writer.Write(pIconEntry->bColorCount);
					writer.Write(pIconEntry->bReserved);
					writer.Write(pIconEntry->wPlanes);
					writer.Write(pIconEntry->wBitCount);
					writer.Write(pIconEntry->dwBytesInRes);
					writer.Write(offset);
					offset += pIconEntry->dwBytesInRes;
				}

				for (int i = 0; i < iconCount; i++)
				{
					var icon = iconDir.FindDirectory(new Win32ResourceName(pIconGroup->idEntries[i].nID))?.FirstData()?.Data;
					if (icon == null)
						return null;
					writer.Write(icon);
				}
			}

			return outStream.ToArray();
		}

		[StructLayout(LayoutKind.Sequential, Pack = 2)]
		unsafe struct GRPICONDIR
		{
			public ushort idReserved;
			public ushort idType;
			public ushort idCount;
			private fixed byte _idEntries[1];
			[System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE1006:Naming Styles", Justification = "<Pending>")]
			public GRPICONDIRENTRY* idEntries {
				get {
					fixed (byte* p = _idEntries)
						return (GRPICONDIRENTRY*)p;
				}
			}
		};

		[StructLayout(LayoutKind.Sequential, Pack = 2)]
		struct GRPICONDIRENTRY
		{
			public byte bWidth;
			public byte bHeight;
			public byte bColorCount;
			public byte bReserved;
			public ushort wPlanes;
			public ushort wBitCount;
			public uint dwBytesInRes;
			public short nID;
		};

		const int RT_MANIFEST = 24;

		unsafe static byte[] CreateApplicationManifest(Win32ResourceDirectory resources)
		{
			return resources.Find(new Win32ResourceName(RT_MANIFEST))?.FirstDirectory()?.FirstData()?.Data;
		}

		static bool IsDefaultApplicationManifest(byte[] appManifest)
		{
			const string DEFAULT_APPMANIFEST =
				"<?xmlversion=\"1.0\"encoding=\"UTF-8\"standalone=\"yes\"?><assemblyxmlns=\"urn:schemas-microsoft-com" +
				":asm.v1\"manifestVersion=\"1.0\"><assemblyIdentityversion=\"1.0.0.0\"name=\"MyApplication.app\"/><tr" +
				"ustInfoxmlns=\"urn:schemas-microsoft-com:asm.v2\"><security><requestedPrivilegesxmlns=\"urn:schemas-" +
				"microsoft-com:asm.v3\"><requestedExecutionLevellevel=\"asInvoker\"uiAccess=\"false\"/></requestedPri" +
				"vileges></security></trustInfo></assembly>";

			string s = CleanUpApplicationManifest(appManifest);
			return s == DEFAULT_APPMANIFEST;
		}

		static string CleanUpApplicationManifest(byte[] appManifest)
		{
			bool bom = appManifest.Length >= 3 && appManifest[0] == 0xEF && appManifest[1] == 0xBB && appManifest[2] == 0xBF;
			string s = Encoding.UTF8.GetString(appManifest, bom ? 3 : 0, appManifest.Length - (bom ? 3 : 0));
			var sb = new StringBuilder(s.Length);
			for (int i = 0; i < s.Length; i++)
			{
				char c = s[i];
				switch (c)
				{
					case '\t':
					case '\n':
					case '\r':
					case ' ':
						continue;
				}
				sb.Append(c);
			}
			return sb.ToString();
		}
		#endregion

		/// <summary>
		/// Cleans up a node name for use as a file name.
		/// </summary>
		public static string CleanUpFileName(string text)
		{
			return CleanUpName(text, separateAtDots: false, treatAsFileName: false);
		}

		/// <summary>
		/// Removes invalid characters from file names and reduces their length,
		/// but keeps file extensions and path structure intact.
		/// </summary>
		public static string SanitizeFileName(string fileName)
		{
			return CleanUpName(fileName, separateAtDots: false, treatAsFileName: true);
		}

		/// <summary>
		/// Cleans up a node name for use as a file system name. If <paramref name="separateAtDots"/> is active,
		/// dots are seen as segment separators. Each segment is limited to maxSegmentLength characters.
		/// If <paramref name="treatAsFileName"/> is active, we check for file a extension and try to preserve it,
		/// if it's valid.
		/// </summary>
		static string CleanUpName(string text, bool separateAtDots, bool treatAsFileName)
		{
			// Remove anything that could be confused with a rooted path.
			int pos = text.IndexOf(':');
			if (pos > 0)
				text = text.Substring(0, pos);
			text = text.Trim();
			string extension = null;
			int currentSegmentLength = 0;
			if (treatAsFileName)
			{
				// Check if input is a file name, i.e., has a valid extension
				// If yes, preserve extension and append it at the end.
				// But only, if the extension length does not exceed maxSegmentLength,
				// if that's the case we just give up and treat the extension no different
				// from the file name.
				int lastDot = text.LastIndexOf('.');
				if (lastDot >= 0 && text.Length - lastDot < maxSegmentLength)
				{
					string originalText = text;
					extension = text.Substring(lastDot);
					text = text.Remove(lastDot);
					foreach (var c in extension)
					{
						if (!(char.IsLetterOrDigit(c) || c == '-' || c == '_' || c == '.'))
						{
							// extension contains an invalid character, therefore cannot be a valid extension.
							extension = null;
							text = originalText;
							break;
						}
					}
				}
			}
			// Remove generics
			pos = text.IndexOf('`');
			if (pos > 0)
			{
				text = text.Substring(0, pos).Trim();
			}
			// Whitelist allowed characters, replace everything else:
			StringBuilder b = new StringBuilder(text.Length + (extension?.Length ?? 0));
			foreach (var c in text)
			{
				currentSegmentLength++;
				if (char.IsLetterOrDigit(c) || c == '-' || c == '_')
				{
					// if the current segment exceeds maxSegmentLength characters,
					// skip until the end of the segment.
					if (currentSegmentLength <= maxSegmentLength)
						b.Append(c);
				}
				else if (c == '.' && b.Length > 0 && b[b.Length - 1] != '.')
				{
					// if the current segment exceeds maxSegmentLength characters,
					// skip until the end of the segment.
					if (separateAtDots || currentSegmentLength <= maxSegmentLength)
						b.Append('.'); // allow dot, but never two in a row

					// Reset length at end of segment.
					if (separateAtDots)
						currentSegmentLength = 0;
				}
				else if (treatAsFileName && (c is '/' or '\\') && currentSegmentLength > 1)
				{
					// if we treat this as a file name, we've started a new segment
					b.Append(Path.DirectorySeparatorChar);
					currentSegmentLength = 0;
				}
				else
				{
					// if the current segment exceeds maxSegmentLength characters,
					// skip until the end of the segment.
					if (currentSegmentLength <= maxSegmentLength)
						b.Append('-');
				}
			}
			if (b.Length == 0)
				b.Append('-');
			string name = b.ToString();
			if (extension != null)
			{
				// make sure that adding the extension to the filename
				// does not exceed maxSegmentLength.
				// trim the name, if necessary.
				if (name.Length + extension.Length > maxSegmentLength)
					name = name.Remove(name.Length - extension.Length);
				name += extension;
			}

			if (IsReservedFileSystemName(name))
				return name + "_";
			else if (name == ".")
				return "_";
			else
				return name;
		}

		/// <summary>
		/// Cleans up a node name for use as a directory name.
		/// </summary>
		public static string CleanUpDirectoryName(string text)
		{
			return CleanUpName(text, separateAtDots: false, treatAsFileName: false);
		}

		public static string CleanUpPath(string text)
		{
			return CleanUpName(text, separateAtDots: true, treatAsFileName: false)
				.Replace('.', Path.DirectorySeparatorChar);
		}

		static bool IsReservedFileSystemName(string name)
		{
			switch (name.ToUpperInvariant())
			{
				case "AUX":
				case "COM1":
				case "COM2":
				case "COM3":
				case "COM4":
				case "COM5":
				case "COM6":
				case "COM7":
				case "COM8":
				case "COM9":
				case "CON":
				case "LPT1":
				case "LPT2":
				case "LPT3":
				case "LPT4":
				case "LPT5":
				case "LPT6":
				case "LPT7":
				case "LPT8":
				case "LPT9":
				case "NUL":
				case "PRN":
					return true;
				default:
					return false;
			}
		}

		public static bool CanUseSdkStyleProjectFormat(MetadataFile module)
		{
			return TargetServices.DetectTargetFramework(module).Moniker != null;
		}
	}

	public record struct ProjectItemInfo(string ItemType, string FileName)
	{
		public List<PartialTypeInfo> PartialTypes { get; set; } = null;

		public Dictionary<string, string> AdditionalProperties { get; set; } = null;

		public ProjectItemInfo With(string name, string value)
		{
			AdditionalProperties ??= new Dictionary<string, string>();
			AdditionalProperties.Add(name, value);
			return this;
		}

		public ProjectItemInfo With(IEnumerable<KeyValuePair<string, string>> pairs)
		{
			AdditionalProperties ??= new Dictionary<string, string>();
			AdditionalProperties.AddRange(pairs);
			return this;
		}
	}
}