// 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.IO;
using System.Linq;
using Mono.Cecil;
using Mono.Cecil.Cil;

namespace ICSharpCode.Decompiler
{
	/// <summary>
	/// Cecil helper methods.
	/// </summary>
	public static class CecilExtensions
	{
		#region GetPushDelta / GetPopDelta
		public static int GetPushDelta(this Instruction instruction)
		{
			OpCode code = instruction.OpCode;
			switch (code.StackBehaviourPush) {
				case StackBehaviour.Push0:
					return 0;

				case StackBehaviour.Push1:
				case StackBehaviour.Pushi:
				case StackBehaviour.Pushi8:
				case StackBehaviour.Pushr4:
				case StackBehaviour.Pushr8:
				case StackBehaviour.Pushref:
					return 1;

				case StackBehaviour.Push1_push1:
					return 2;

				case StackBehaviour.Varpush:
					if (code.FlowControl != FlowControl.Call)
						break;

					IMethodSignature method = (IMethodSignature) instruction.Operand;
					return IsVoid (method.ReturnType) ? 0 : 1;
			}

			throw new NotSupportedException ();
		}
		
		public static int GetPopDelta(this Instruction instruction, MethodDefinition current, int currentStackSize)
		{
			OpCode code = instruction.OpCode;
			switch (code.StackBehaviourPop) {
				case StackBehaviour.Pop0:
					return 0;
				case StackBehaviour.Popi:
				case StackBehaviour.Popref:
				case StackBehaviour.Pop1:
					return 1;

				case StackBehaviour.Pop1_pop1:
				case StackBehaviour.Popi_pop1:
				case StackBehaviour.Popi_popi:
				case StackBehaviour.Popi_popi8:
				case StackBehaviour.Popi_popr4:
				case StackBehaviour.Popi_popr8:
				case StackBehaviour.Popref_pop1:
				case StackBehaviour.Popref_popi:
					return 2;

				case StackBehaviour.Popi_popi_popi:
				case StackBehaviour.Popref_popi_popi:
				case StackBehaviour.Popref_popi_popi8:
				case StackBehaviour.Popref_popi_popr4:
				case StackBehaviour.Popref_popi_popr8:
				case StackBehaviour.Popref_popi_popref:
					return 3;

				case StackBehaviour.PopAll:
					return currentStackSize;

				case StackBehaviour.Varpop:
					if (code == OpCodes.Ret)
						return IsVoid (current.ReturnType) ? 0 : 1;

					if (code.FlowControl != FlowControl.Call)
						break;

					IMethodSignature method = (IMethodSignature) instruction.Operand;
					int count = method.HasParameters ? method.Parameters.Count : 0;
					if (method.HasThis && code != OpCodes.Newobj)
						++count;

					return count;
			}

			throw new NotSupportedException ();
		}
		
		public static bool IsVoid(this TypeReference type)
		{
			return type.FullName == "System.Void" && !(type is TypeSpecification);
		}
		
		public static bool IsValueTypeOrVoid(this TypeReference type)
		{
			while (type is OptionalModifierType || type is RequiredModifierType)
				type = ((TypeSpecification)type).ElementType;
			if (type is ArrayType)
				return false;
			return type.IsValueType || type.IsVoid();
		}
		#endregion
		
		public static void WriteTo(this Instruction instruction, TextWriter writer)
		{
			writer.Write(OffsetToString(instruction.Offset));
			writer.Write(": ");
			writer.Write(instruction.OpCode.Name);
			if(null != instruction.Operand) {
				writer.Write(' ');
				writer.Write(OperandToString(instruction.Operand));
			}
		}
		
		public static void WriteTo(this ExceptionHandler exceptionHandler, TextWriter writer)
		{
			writer.Write("Try IL_{0:x4}-IL_{1:x4} ", exceptionHandler.TryStart.Offset, exceptionHandler.TryEnd.Offset);
			writer.Write(exceptionHandler.HandlerType.ToString());
			if (exceptionHandler.FilterStart != null) {
				writer.Write(" IL_{0:x4}-IL_{1:x4} handler ", exceptionHandler.FilterStart.Offset, exceptionHandler.FilterEnd.Offset);
			}
			writer.Write(" IL_{0:x4}-IL_{1:x4} ", exceptionHandler.HandlerStart.Offset, exceptionHandler.HandlerEnd.Offset);
		}
		
		public static string OffsetToString(int offset)
		{
			return string.Format("IL_{0:x4}", offset);
		}
		
		public static string OperandToString(object operand)
		{
			if(null == operand) throw new ArgumentNullException("operand");
			
			Instruction targetInstruction = operand as Instruction;
			if(null != targetInstruction) {
				return OffsetToString(targetInstruction.Offset);
			}
			
			Instruction [] targetInstructions = operand as Instruction [];
			if(null != targetInstructions) {
				return string.Join(", ", targetInstructions.Select(i => OffsetToString(i.Offset)));
			}
			
			VariableReference variableRef = operand as VariableReference;
			if(null != variableRef) {
				return variableRef.Index.ToString();
			}
			
			MethodReference methodRef = operand as MethodReference;
			if(null != methodRef) {
				return methodRef.ToString();
			}
			
			string s = operand as string;
			if(null != s) {
				return "\"" + s + "\"";
			}
			
			return operand.ToString();
		}
	}
}