// Copyright (c) 2011 AlphaSierraPapa for the SharpDevelop Team
// 
// 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.Generic;
using System.Linq;
using System.Reflection.Metadata;
using System.Text;
using ICSharpCode.Decompiler.Metadata;
using ICSharpCode.Decompiler.Util;
using SRM = System.Reflection.Metadata;

namespace ICSharpCode.Decompiler.Disassembler
{
	public enum ILNameSyntax
	{
		/// <summary>
		/// class/valuetype + TypeName (built-in types use keyword syntax)
		/// </summary>
		Signature,
		/// <summary>
		/// Like signature, but always refers to type parameters using their position
		/// </summary>
		SignatureNoNamedTypeParameters,
		/// <summary>
		/// [assembly]Full.Type.Name (even for built-in types)
		/// </summary>
		TypeName,
		/// <summary>
		/// Name (but built-in types use keyword syntax)
		/// </summary>
		ShortTypeName
	}

	public static class DisassemblerHelpers
	{
		public static string OffsetToString(int offset)
		{
			return string.Format("IL_{0:x4}", offset);
		}
		
		public static string OffsetToString(long offset)
		{
			return string.Format("IL_{0:x4}", offset);
		}

		public static void WriteOffsetReference(ITextOutput writer, int? offset)
		{
			if (offset == null)
				writer.Write("null");
			else
				writer.WriteReference(OffsetToString(offset.Value), offset);
		}

		public static void WriteTo(this SRM.ExceptionRegion exceptionHandler, Metadata.MethodDefinition method, ITextOutput writer)
		{
			writer.Write(".try ");
			WriteOffsetReference(writer, exceptionHandler.TryOffset);
			writer.Write('-');
			WriteOffsetReference(writer, exceptionHandler.TryOffset + exceptionHandler.TryLength);
			writer.Write(' ');
			writer.Write(exceptionHandler.Kind.ToString().ToLowerInvariant());
			if (exceptionHandler.FilterOffset != -1) {
				writer.Write(' ');
				WriteOffsetReference(writer, exceptionHandler.FilterOffset);
				writer.Write(" handler ");
			}
			if (!exceptionHandler.CatchType.IsNil) {
				writer.Write(' ');
				exceptionHandler.CatchType.WriteTo(method.Module, writer, new GenericContext(method));
			}
			writer.Write(' ');
			WriteOffsetReference(writer, exceptionHandler.HandlerOffset);
			writer.Write('-');
			WriteOffsetReference(writer, exceptionHandler.HandlerOffset + exceptionHandler.HandlerLength);
		}

		static string ToInvariantCultureString(object value)
		{
			IConvertible convertible = value as IConvertible;
			return (null != convertible)
				? convertible.ToString(System.Globalization.CultureInfo.InvariantCulture)
				: value.ToString();
		}

		static bool IsValidIdentifierCharacter(char c)
		{
			return c == '_' || c == '$' || c == '@' || c == '?' || c == '`';
		}

		static bool IsValidIdentifier(string identifier)
		{
			if (string.IsNullOrEmpty(identifier))
				return false;
			if (!(char.IsLetter(identifier[0]) || IsValidIdentifierCharacter(identifier[0]))) {
				// As a special case, .ctor and .cctor are valid despite starting with a dot
				return identifier == ".ctor" || identifier == ".cctor";
			}
			for (int i = 1; i < identifier.Length; i++) {
				if (!(char.IsLetterOrDigit(identifier[i]) || IsValidIdentifierCharacter(identifier[i]) || identifier[i] == '.'))
					return false;
			}
			return true;
		}

		public static string Escape(string identifier)
		{
			if (IsValidIdentifier(identifier) && !Metadata.ILOpCodeExtensions.ILKeywords.Contains(identifier)) {
				return identifier;
			} else {
				// The ECMA specification says that ' inside SQString should be ecaped using an octal escape sequence,
				// but we follow Microsoft's ILDasm and use \'.
				return "'" + EscapeString(identifier).Replace("'", "\\'") + "'";
			}
		}

		public static void WriteParameterReference(ITextOutput writer, Metadata.MethodDefinition method, int sequence)
		{
			var metadata = method.Module.GetMetadataReader();
			var methodDefinition = metadata.GetMethodDefinition(method.Handle);
			var signatureHeader = methodDefinition.DecodeSignature(new FullTypeNameSignatureDecoder(metadata), default(Unit)).Header;
			int index = signatureHeader.IsInstance && !signatureHeader.HasExplicitThis ? sequence - 1 : sequence;
			var parameters = methodDefinition.GetParameters();
			if (index < 0 || index >= parameters.Count) {
				writer.Write(sequence.ToString());
			} else {
				var param = metadata.GetParameter(parameters.ElementAt(index));
				if (param.Name.IsNil) {
					writer.Write(sequence.ToString());
				} else {
					writer.Write(Escape(metadata.GetString(param.Name)));
				}
			}
		}

		public static void WriteVariableReference(ITextOutput writer, Metadata.MethodDefinition method, int index)
		{
			writer.Write(index.ToString());
		}

		public static void WriteOperand(ITextOutput writer, object operand)
		{
			if (operand == null)
				throw new ArgumentNullException(nameof(operand));

			/*VariableReference variableRef = operand as VariableReference;
			if (variableRef != null) {
				writer.WriteReference(variableRef.Index.ToString(), variableRef);
				return;
			}

			ParameterReference paramRef = operand as ParameterReference;
			if (paramRef != null) {
				if (string.IsNullOrEmpty(paramRef.Name)) {
					var paramDef = paramRef.Resolve();
					writer.WriteReference((paramDef == null ? paramRef.Index : paramDef.Sequence).ToString(), paramRef);
				} else
					writer.WriteReference(Escape(paramRef.Name), paramRef);
				return;
			}*/

			string s = operand as string;
			if (s != null) {
				WriteOperand(writer, s);
			} else if (operand is char) {
				writer.Write(((int)(char)operand).ToString());
			} else if (operand is float) {
				WriteOperand(writer, (float)operand);
			} else if (operand is double) {
				WriteOperand(writer, (double)operand);
			} else if (operand is bool) {
				writer.Write((bool)operand ? "true" : "false");
			} else {
				s = ToInvariantCultureString(operand);
				writer.Write(s);
			}
		}

		public static void WriteOperand(ITextOutput writer, long val)
		{
			writer.Write(ToInvariantCultureString(val));
		}

		public static void WriteOperand(ITextOutput writer, float val)
		{
			if (val == 0) {
				if (1 / val == float.NegativeInfinity) {
					// negative zero is a special case
					writer.Write('-');
				}
				writer.Write("0.0");
			} else if (float.IsInfinity(val) || float.IsNaN(val)) {
				byte[] data = BitConverter.GetBytes(val);
				writer.Write('(');
				for (int i = 0; i < data.Length; i++) {
					if (i > 0)
						writer.Write(' ');
					writer.Write(data[i].ToString("X2"));
				}
				writer.Write(')');
			} else {
				writer.Write(val.ToString("R", System.Globalization.CultureInfo.InvariantCulture));
			}
		}

		public static void WriteOperand(ITextOutput writer, double val)
		{
			if (val == 0) {
				if (1 / val == double.NegativeInfinity) {
					// negative zero is a special case
					writer.Write('-');
				}
				writer.Write("0.0");
			} else if (double.IsInfinity(val) || double.IsNaN(val)) {
				byte[] data = BitConverter.GetBytes(val);
				writer.Write('(');
				for (int i = 0; i < data.Length; i++) {
					if (i > 0)
						writer.Write(' ');
					writer.Write(data[i].ToString("X2"));
				}
				writer.Write(')');
			} else {
				writer.Write(val.ToString("R", System.Globalization.CultureInfo.InvariantCulture));
			}
		}

		public static void WriteOperand(ITextOutput writer, string operand)
		{
			writer.Write('"');
			writer.Write(EscapeString(operand));
			writer.Write('"');
		}

		public static string EscapeString(string str)
		{
			StringBuilder sb = new StringBuilder();
			foreach (char ch in str) {
				switch (ch) {
					case '"':
						sb.Append("\\\"");
						break;
					case '\\':
						sb.Append("\\\\");
						break;
					case '\0':
						sb.Append("\\0");
						break;
					case '\a':
						sb.Append("\\a");
						break;
					case '\b':
						sb.Append("\\b");
						break;
					case '\f':
						sb.Append("\\f");
						break;
					case '\n':
						sb.Append("\\n");
						break;
					case '\r':
						sb.Append("\\r");
						break;
					case '\t':
						sb.Append("\\t");
						break;
					case '\v':
						sb.Append("\\v");
						break;
					default:
						// print control characters and uncommon white spaces as numbers
						if (char.IsControl(ch) || char.IsSurrogate(ch) || (char.IsWhiteSpace(ch) && ch != ' ')) {
							sb.Append("\\u" + ((int)ch).ToString("x4"));
						} else {
							sb.Append(ch);
						}
						break;
				}
			}
			return sb.ToString();
		}
		public static string PrimitiveTypeName(string fullName)
		{
			switch (fullName) {
				case "System.SByte":
					return "int8";
				case "System.Int16":
					return "int16";
				case "System.Int32":
					return "int32";
				case "System.Int64":
					return "int64";
				case "System.Byte":
					return "uint8";
				case "System.UInt16":
					return "uint16";
				case "System.UInt32":
					return "uint32";
				case "System.UInt64":
					return "uint64";
				case "System.Single":
					return "float32";
				case "System.Double":
					return "float64";
				case "System.Void":
					return "void";
				case "System.Boolean":
					return "bool";
				case "System.String":
					return "string";
				case "System.Char":
					return "char";
				case "System.Object":
					return "object";
				case "System.IntPtr":
					return "native int";
				default:
					return null;
			}
		}
	}
}