//
// Author:
//   Jb Evain (jbevain@gmail.com)
//
// Copyright (c) 2008 - 2015 Jb Evain
// Copyright (c) 2008 - 2011 Novell, Inc.
//
// Licensed under the MIT/X11 license.
//

using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Compression;
using System.Security.Cryptography;
using Mono.Cecil.Metadata;
using Mono.Cecil.PE;

namespace Mono.Cecil.Cil {

	public sealed class PortablePdbReaderProvider : ISymbolReaderProvider {

		public ISymbolReader GetSymbolReader (ModuleDefinition module, string fileName)
		{
			Mixin.CheckModule (module);
			Mixin.CheckFileName (fileName);

			var file = File.OpenRead (Mixin.GetPdbFileName (fileName));
			return GetSymbolReader (module, Disposable.Owned (file as Stream), file.Name);
		}

		public ISymbolReader GetSymbolReader (ModuleDefinition module, Stream symbolStream)
		{
			Mixin.CheckModule (module);
			Mixin.CheckStream (symbolStream);

			return GetSymbolReader (module, Disposable.NotOwned (symbolStream), symbolStream.GetFileName ());
		}

		ISymbolReader GetSymbolReader (ModuleDefinition module, Disposable<Stream> symbolStream, string fileName)
		{
			return new PortablePdbReader (ImageReader.ReadPortablePdb (symbolStream, fileName, out _), module);
		}
	}

	public sealed class PortablePdbReader : ISymbolReader {

		readonly Image image;
		readonly ModuleDefinition module;
		readonly MetadataReader reader;
		readonly MetadataReader debug_reader;

		bool IsEmbedded { get { return reader.image == debug_reader.image; } }

		internal PortablePdbReader (Image image, ModuleDefinition module)
		{
			this.image = image;
			this.module = module;
			this.reader = module.reader;
			this.debug_reader = new MetadataReader (image, module, this.reader);
		}

		public ISymbolWriterProvider GetWriterProvider ()
		{
			return new PortablePdbWriterProvider ();
		}

		public bool ProcessDebugHeader (ImageDebugHeader header)
		{
			if (image == module.Image)
				return true;

			foreach (var entry in header.Entries) {
				if (!IsMatchingEntry (image.PdbHeap, entry))
					continue;

				ReadModule ();
				return true;
			}

			return false;
		}

		static bool IsMatchingEntry (PdbHeap heap, ImageDebugHeaderEntry entry)
		{
			if (entry.Directory.Type != ImageDebugType.CodeView)
				return false;

			var data = entry.Data;

			if (data.Length < 24)
				return false;

			var magic = ReadInt32 (data, 0);
			if (magic != 0x53445352)
				return false;

			var buffer = new byte [16];
			Buffer.BlockCopy (data, 4, buffer, 0, 16);

			var module_guid = new Guid (buffer);

			Buffer.BlockCopy (heap.Id, 0, buffer, 0, 16);

			var pdb_guid = new Guid (buffer);

			return module_guid == pdb_guid;
		}

		static int ReadInt32 (byte [] bytes, int start)
		{
			return (bytes [start]
				| (bytes [start + 1] << 8)
				| (bytes [start + 2] << 16)
				| (bytes [start + 3] << 24));
		}

		void ReadModule ()
		{
			module.custom_infos = debug_reader.GetCustomDebugInformation (module);
		}

		public MethodDebugInformation Read (MethodDefinition method)
		{
			var info = new MethodDebugInformation (method);
			ReadSequencePoints (info);
			ReadScope (info);
			ReadStateMachineKickOffMethod (info);
			ReadCustomDebugInformations (info);
			return info;
		}

		void ReadSequencePoints (MethodDebugInformation method_info)
		{
			method_info.sequence_points = debug_reader.ReadSequencePoints (method_info.method);
		}

		void ReadScope (MethodDebugInformation method_info)
		{
			method_info.scope = debug_reader.ReadScope (method_info.method);
		}

		void ReadStateMachineKickOffMethod (MethodDebugInformation method_info)
		{
			method_info.kickoff_method = debug_reader.ReadStateMachineKickoffMethod (method_info.method);
		}

		void ReadCustomDebugInformations (MethodDebugInformation info)
		{
			info.method.custom_infos = debug_reader.GetCustomDebugInformation (info.method);
		}

		public void Dispose ()
		{
			if (IsEmbedded)
				return;

			image.Dispose ();
		}
	}

	public sealed class EmbeddedPortablePdbReaderProvider : ISymbolReaderProvider {

		public ISymbolReader GetSymbolReader (ModuleDefinition module, string fileName)
		{
			Mixin.CheckModule (module);

			var header = module.GetDebugHeader ();
			var entry = header.GetEmbeddedPortablePdbEntry ();
			if (entry == null)
				throw new InvalidOperationException ();

			return new EmbeddedPortablePdbReader (
				(PortablePdbReader) new PortablePdbReaderProvider ().GetSymbolReader (module, GetPortablePdbStream (entry)));
		}

		static Stream GetPortablePdbStream (ImageDebugHeaderEntry entry)
		{
			var compressed_stream = new MemoryStream (entry.Data);
			var reader = new BinaryStreamReader (compressed_stream);
			reader.ReadInt32 (); // signature
			var length = reader.ReadInt32 ();
			var decompressed_stream = new MemoryStream (length);

			using (var deflate_stream = new DeflateStream (compressed_stream, CompressionMode.Decompress, leaveOpen: true))
				deflate_stream.CopyTo (decompressed_stream);

			return decompressed_stream;
		}

		public ISymbolReader GetSymbolReader (ModuleDefinition module, Stream symbolStream)
		{
			throw new NotSupportedException ();
		}
	}

	public sealed class EmbeddedPortablePdbReader : ISymbolReader
	{
		private readonly PortablePdbReader reader;

		internal EmbeddedPortablePdbReader (PortablePdbReader reader)
		{
			if (reader == null)
				throw new ArgumentNullException ();

			this.reader = reader;
		}

		public ISymbolWriterProvider GetWriterProvider ()
		{
			return new EmbeddedPortablePdbWriterProvider ();
		}

		public bool ProcessDebugHeader (ImageDebugHeader header)
		{
			return reader.ProcessDebugHeader (header);
		}

		public MethodDebugInformation Read (MethodDefinition method)
		{
			return reader.Read (method);
		}

		public void Dispose ()
		{
			reader.Dispose ();
		}
	}

	public sealed class PortablePdbWriterProvider : ISymbolWriterProvider
	{
		public ISymbolWriter GetSymbolWriter (ModuleDefinition module, string fileName)
		{
			Mixin.CheckModule (module);
			Mixin.CheckFileName (fileName);

			var file = File.Open (Mixin.GetPdbFileName (fileName), FileMode.OpenOrCreate, FileAccess.ReadWrite);
			return GetSymbolWriter (module, Disposable.Owned (file as Stream), Disposable.NotOwned ((Stream)null));
		}

		public ISymbolWriter GetSymbolWriter (ModuleDefinition module, Stream symbolStream)
		{
			Mixin.CheckModule (module);
			Mixin.CheckStream (symbolStream);

			// In order to compute the PDB checksum, the stream we're writing to needs to be able to
			// seek and read as well. We can't assume this about a stream provided by the user.
			// So in this case, create a memory stream to cache the PDB.
			return GetSymbolWriter (module, Disposable.Owned (new MemoryStream() as Stream), Disposable.NotOwned (symbolStream));
		}

		ISymbolWriter GetSymbolWriter (ModuleDefinition module, Disposable<Stream> stream, Disposable<Stream> final_stream)
		{
			var metadata = new MetadataBuilder (module, this);
			var writer = ImageWriter.CreateDebugWriter (module, metadata, stream);

			return new PortablePdbWriter (metadata, module, writer, final_stream);
		}
	}

	public sealed class PortablePdbWriter : ISymbolWriter {

		readonly MetadataBuilder pdb_metadata;
		readonly ModuleDefinition module;
		readonly ImageWriter writer;
		readonly Disposable<Stream> final_stream;

		MetadataBuilder module_metadata;

		internal byte [] pdb_checksum;
		internal Guid pdb_id_guid;
		internal uint pdb_id_stamp;

		bool IsEmbedded { get { return writer == null; } }

		internal PortablePdbWriter (MetadataBuilder pdb_metadata, ModuleDefinition module)
		{
			this.pdb_metadata = pdb_metadata;
			this.module = module;

			this.module_metadata = module.metadata_builder;

			if (module_metadata != pdb_metadata)
				this.pdb_metadata.metadata_builder = this.module_metadata;

			pdb_metadata.AddCustomDebugInformations (module);
		}

		internal PortablePdbWriter (MetadataBuilder pdb_metadata, ModuleDefinition module, ImageWriter writer, Disposable<Stream> final_stream)
			: this (pdb_metadata, module)
		{
			this.writer = writer;
			this.final_stream = final_stream;
		}

		public ISymbolReaderProvider GetReaderProvider ()
		{
			return new PortablePdbReaderProvider ();
		}

		public void Write (MethodDebugInformation info)
		{
			CheckMethodDebugInformationTable ();

			pdb_metadata.AddMethodDebugInformation (info);
		}

		public void Write ()
		{
			if (IsEmbedded)
				return;

			WritePdbFile ();

			if (final_stream.value != null) {
				writer.BaseStream.Seek (0, SeekOrigin.Begin);
				var buffer = new byte [8192];
				CryptoService.CopyStreamChunk (writer.BaseStream, final_stream.value, buffer, (int)writer.BaseStream.Length);
			}
		}

		public ImageDebugHeader GetDebugHeader ()
		{
			if (IsEmbedded)
				return new ImageDebugHeader ();

			ImageDebugHeaderEntry codeViewEntry;
			{
				var codeViewDirectory = new ImageDebugDirectory () {
					MajorVersion = 256,
					MinorVersion = 20557,
					Type = ImageDebugType.CodeView,
					TimeDateStamp = (int)pdb_id_stamp,
				};

				var buffer = new ByteBuffer ();
				// RSDS
				buffer.WriteUInt32 (0x53445352);
				// Module ID
				buffer.WriteBytes (pdb_id_guid.ToByteArray ());
				// PDB Age
				buffer.WriteUInt32 (1);
				// PDB Path
				var fileName = writer.BaseStream.GetFileName ();
				if (string.IsNullOrEmpty (fileName)) {
					fileName = module.Assembly.Name.Name + ".pdb";
				}
				buffer.WriteBytes (System.Text.Encoding.UTF8.GetBytes (fileName));
				buffer.WriteByte (0);

				var data = new byte [buffer.length];
				Buffer.BlockCopy (buffer.buffer, 0, data, 0, buffer.length);
				codeViewDirectory.SizeOfData = data.Length;

				codeViewEntry = new ImageDebugHeaderEntry (codeViewDirectory, data);
			}

			ImageDebugHeaderEntry pdbChecksumEntry;
			{
				var pdbChecksumDirectory = new ImageDebugDirectory () {
					MajorVersion = 1,
					MinorVersion = 0,
					Type = ImageDebugType.PdbChecksum,
					TimeDateStamp = 0
				};

				var buffer = new ByteBuffer ();
				// SHA256 - Algorithm name
				buffer.WriteBytes (System.Text.Encoding.UTF8.GetBytes ("SHA256"));
				buffer.WriteByte (0);

				// Checksum - 32 bytes
				buffer.WriteBytes (pdb_checksum);

				var data = new byte [buffer.length];
				Buffer.BlockCopy (buffer.buffer, 0, data, 0, buffer.length);
				pdbChecksumDirectory.SizeOfData = data.Length;

				pdbChecksumEntry = new ImageDebugHeaderEntry (pdbChecksumDirectory, data);
			}

			return new ImageDebugHeader (new ImageDebugHeaderEntry [] { codeViewEntry, pdbChecksumEntry });
		}

		void CheckMethodDebugInformationTable ()
		{
			var mdi = pdb_metadata.table_heap.GetTable<MethodDebugInformationTable> (Table.MethodDebugInformation);
			if (mdi.length > 0)
				return;

			// The MethodDebugInformation table has the same length as the Method table
			mdi.rows = new Row<uint, uint> [module_metadata.method_rid - 1];
			mdi.length = mdi.rows.Length;
		}

		public void Dispose ()
		{
			writer.stream.Dispose ();
			final_stream.Dispose ();
		}

		void WritePdbFile ()
		{
			WritePdbHeap ();

			WriteTableHeap ();

			writer.BuildMetadataTextMap ();
			writer.WriteMetadataHeader ();
			writer.WriteMetadata ();

			writer.Flush ();

			ComputeChecksumAndPdbId ();

			WritePdbId ();
		}

		void WritePdbHeap ()
		{
			var pdb_heap = pdb_metadata.pdb_heap;

			// PDB ID ( GUID + TimeStamp ) are left zeroed out for now. Will be filled at the end with a hash.
			pdb_heap.WriteBytes (20);

			pdb_heap.WriteUInt32 (module_metadata.entry_point.ToUInt32 ());

			var table_heap = module_metadata.table_heap;
			var tables = table_heap.tables;

			ulong valid = 0;
			for (int i = 0; i < tables.Length; i++) {
				if (tables [i] == null || tables [i].Length == 0)
					continue;

				valid |= (1UL << i);
			}

			pdb_heap.WriteUInt64 (valid);

			for (int i = 0; i < tables.Length; i++) {
				if (tables [i] == null || tables [i].Length == 0)
					continue;

				pdb_heap.WriteUInt32 ((uint) tables [i].Length);
			}
		}

		void WriteTableHeap ()
		{
			pdb_metadata.table_heap.string_offsets = pdb_metadata.string_heap.WriteStrings ();
			pdb_metadata.table_heap.ComputeTableInformations ();
			pdb_metadata.table_heap.WriteTableHeap ();
		}

		void ComputeChecksumAndPdbId ()
		{
			var buffer = new byte [8192];

			// Compute the has of the entire file - PDB ID is zeroes still
			writer.BaseStream.Seek (0, SeekOrigin.Begin);
			var sha256 = SHA256.Create ();
			using (var crypto_stream = new CryptoStream (Stream.Null, sha256, CryptoStreamMode.Write)) {
				CryptoService.CopyStreamChunk (writer.BaseStream, crypto_stream, buffer, (int)writer.BaseStream.Length);
			}

			pdb_checksum = sha256.Hash;

			var hashBytes = new ByteBuffer (pdb_checksum);
			pdb_id_guid = new Guid (hashBytes.ReadBytes (16));
			pdb_id_stamp = hashBytes.ReadUInt32 ();
		}

		void WritePdbId ()
		{
			// PDB ID is the first 20 bytes of the PdbHeap
			writer.MoveToRVA (TextSegment.PdbHeap);
			writer.WriteBytes (pdb_id_guid.ToByteArray ());
			writer.WriteUInt32 (pdb_id_stamp);
		}
	}

	public sealed class EmbeddedPortablePdbWriterProvider : ISymbolWriterProvider {

		public ISymbolWriter GetSymbolWriter (ModuleDefinition module, string fileName)
		{
			Mixin.CheckModule (module);
			Mixin.CheckFileName (fileName);

			var stream = new MemoryStream ();
			var pdb_writer = (PortablePdbWriter) new PortablePdbWriterProvider ().GetSymbolWriter (module, stream);
			return new EmbeddedPortablePdbWriter (stream, pdb_writer);
		}

		public ISymbolWriter GetSymbolWriter (ModuleDefinition module, Stream symbolStream)
		{
			throw new NotSupportedException ();
		}
	}

	public sealed class EmbeddedPortablePdbWriter : ISymbolWriter {

		readonly Stream stream;
		readonly PortablePdbWriter writer;

		internal EmbeddedPortablePdbWriter (Stream stream, PortablePdbWriter writer)
		{
			this.stream = stream;
			this.writer = writer;
		}

		public ISymbolReaderProvider GetReaderProvider ()
		{
			return new EmbeddedPortablePdbReaderProvider ();
		}

		public void Write (MethodDebugInformation info)
		{
			writer.Write (info);
		}

		public ImageDebugHeader GetDebugHeader ()
		{
			ImageDebugHeader pdbDebugHeader = writer.GetDebugHeader ();

			var directory = new ImageDebugDirectory {
				Type = ImageDebugType.EmbeddedPortablePdb,
				MajorVersion = 0x0100,
				MinorVersion = 0x0100,
			};

			var data = new MemoryStream ();

			var w = new BinaryStreamWriter (data);
			w.WriteByte (0x4d);
			w.WriteByte (0x50);
			w.WriteByte (0x44);
			w.WriteByte (0x42);

			w.WriteInt32 ((int) stream.Length);

			stream.Position = 0;

			using (var compress_stream = new DeflateStream (data, CompressionMode.Compress, leaveOpen: true))
				stream.CopyTo (compress_stream);

			directory.SizeOfData = (int) data.Length;

			var debugHeaderEntries = new ImageDebugHeaderEntry [pdbDebugHeader.Entries.Length + 1];
			for (int i = 0; i < pdbDebugHeader.Entries.Length; i++)
				debugHeaderEntries [i] = pdbDebugHeader.Entries [i];
			debugHeaderEntries [debugHeaderEntries.Length - 1] = new ImageDebugHeaderEntry (directory, data.ToArray ());

			return new ImageDebugHeader (debugHeaderEntries);
		}

		public void Write ()
		{
			writer.Write ();
		}

		public void Dispose ()
		{
			writer.Dispose ();
		}
	}

	static class PdbGuidMapping {

		static readonly Dictionary<Guid, DocumentLanguage> guid_language = new Dictionary<Guid, DocumentLanguage> ();
		static readonly Dictionary<DocumentLanguage, Guid> language_guid = new Dictionary<DocumentLanguage, Guid> ();

		static PdbGuidMapping ()
		{
			AddMapping (DocumentLanguage.C, new Guid ("63a08714-fc37-11d2-904c-00c04fa302a1"));
			AddMapping (DocumentLanguage.Cpp, new Guid ("3a12d0b7-c26c-11d0-b442-00a0244a1dd2"));
			AddMapping (DocumentLanguage.CSharp, new Guid ("3f5162f8-07c6-11d3-9053-00c04fa302a1"));
			AddMapping (DocumentLanguage.Basic, new Guid ("3a12d0b8-c26c-11d0-b442-00a0244a1dd2"));
			AddMapping (DocumentLanguage.Java, new Guid ("3a12d0b4-c26c-11d0-b442-00a0244a1dd2"));
			AddMapping (DocumentLanguage.Cobol, new Guid ("af046cd1-d0e1-11d2-977c-00a0c9b4d50c"));
			AddMapping (DocumentLanguage.Pascal, new Guid ("af046cd2-d0e1-11d2-977c-00a0c9b4d50c"));
			AddMapping (DocumentLanguage.Cil, new Guid ("af046cd3-d0e1-11d2-977c-00a0c9b4d50c"));
			AddMapping (DocumentLanguage.JScript, new Guid ("3a12d0b6-c26c-11d0-b442-00a0244a1dd2"));
			AddMapping (DocumentLanguage.Smc, new Guid ("0d9b9f7b-6611-11d3-bd2a-0000f80849bd"));
			AddMapping (DocumentLanguage.MCpp, new Guid ("4b35fde8-07c6-11d3-9053-00c04fa302a1"));
			AddMapping (DocumentLanguage.FSharp, new Guid ("ab4f38c9-b6e6-43ba-be3b-58080b2ccce3"));
		}

		static void AddMapping (DocumentLanguage language, Guid guid)
		{
			guid_language.Add (guid, language);
			language_guid.Add (language, guid);
		}

		static readonly Guid type_text = new Guid ("5a869d0b-6611-11d3-bd2a-0000f80849bd");

		public static DocumentType ToType (this Guid guid)
		{
			if (guid == type_text)
				return DocumentType.Text;

			return DocumentType.Other;
		}

		public static Guid ToGuid (this DocumentType type)
		{
			if (type == DocumentType.Text)
				return type_text;

			return new Guid ();
		}

		static readonly Guid hash_md5 = new Guid ("406ea660-64cf-4c82-b6f0-42d48172a799");
		static readonly Guid hash_sha1 = new Guid ("ff1816ec-aa5e-4d10-87f7-6f4963833460");
		static readonly Guid hash_sha256 = new Guid ("8829d00f-11b8-4213-878b-770e8597ac16");

		public static DocumentHashAlgorithm ToHashAlgorithm (this Guid guid)
		{
			if (guid == hash_md5)
				return DocumentHashAlgorithm.MD5;

			if (guid == hash_sha1)
				return DocumentHashAlgorithm.SHA1;

			if (guid == hash_sha256)
				return DocumentHashAlgorithm.SHA256;

			return DocumentHashAlgorithm.None;
		}

		public static Guid ToGuid (this DocumentHashAlgorithm hash_algo)
		{
			if (hash_algo == DocumentHashAlgorithm.MD5)
				return hash_md5;

			if (hash_algo == DocumentHashAlgorithm.SHA1)
				return hash_sha1;

			if (hash_algo == DocumentHashAlgorithm.SHA256)
				return hash_sha256;

			return new Guid ();
		}

		public static DocumentLanguage ToLanguage (this Guid guid)
		{
			DocumentLanguage language;
			if (!guid_language.TryGetValue (guid, out language))
				return DocumentLanguage.Other;

			return language;
		}

		public static Guid ToGuid (this DocumentLanguage language)
		{
			Guid guid;
			if (!language_guid.TryGetValue (language, out guid))
				return new Guid ();

			return guid;
		}

		static readonly Guid vendor_ms = new Guid ("994b45c4-e6e9-11d2-903f-00c04fa302a1");

		public static DocumentLanguageVendor ToVendor (this Guid guid)
		{
			if (guid == vendor_ms)
				return DocumentLanguageVendor.Microsoft;

			return DocumentLanguageVendor.Other;
		}

		public static Guid ToGuid (this DocumentLanguageVendor vendor)
		{
			if (vendor == DocumentLanguageVendor.Microsoft)
				return vendor_ms;

			return new Guid ();
		}
	}
}