//
// MethodBody.cs
//
// Author:
//   Jb Evain (jbevain@gmail.com)
//
// Copyright (c) 2008 - 2011 Jb Evain
//
// 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.Threading;

using Mono.Collections.Generic;

namespace Mono.Cecil.Cil {

	public sealed class MethodBody : IVariableDefinitionProvider
	{

		readonly internal MethodDefinition method;

		internal ParameterDefinition this_parameter;
		internal int max_stack_size;
		internal int code_size;
		internal bool init_locals;
		internal MetadataToken local_var_token;
		internal BlobReader code_reader;

		internal Collection<Instruction> instructions;
		internal Collection<ExceptionHandler> exceptions;
		internal Collection<VariableDefinition> variables;
		Scope scope;

		public MethodDefinition Method
		{
			get { return method; }
		}

		public int MaxStackSize
		{
			get { return max_stack_size; }
			set { max_stack_size = value; }
		}

		public int CodeSize
		{
			get { return code_size; }
		}

		public bool InitLocals
		{
			get { return init_locals; }
			set { init_locals = value; }
		}

		public MetadataToken LocalVarToken
		{
			get { return local_var_token; }
			set { local_var_token = value; }
		}

		public Collection<Instruction> Instructions
		{
			get { return instructions ?? (instructions = new InstructionCollection()); }
		}

		public bool HasExceptionHandlers
		{
			get { return !exceptions.IsNullOrEmpty(); }
		}

		public Collection<ExceptionHandler> ExceptionHandlers
		{
			get { return exceptions ?? (exceptions = new Collection<ExceptionHandler>()); }
		}

		public bool HasVariables
		{
			get { return !variables.IsNullOrEmpty(); }
		}

		public Collection<VariableDefinition> Variables
		{
			get { return variables ?? (variables = new VariableDefinitionCollection()); }
		}

		public Scope Scope
		{
			get { return scope; }
			set { scope = value; }
		}

		public ParameterDefinition ThisParameter
		{
			get
			{
				if (method == null || method.DeclaringType == null)
					throw new NotSupportedException();

				if (!method.HasThis)
					return null;

				if (this_parameter == null)
					Interlocked.CompareExchange(ref this_parameter, ThisParameterFor(method), null);

				return this_parameter;
			}
		}

		static ParameterDefinition ThisParameterFor(MethodDefinition method)
		{
			var declaring_type = method.DeclaringType;
			var type = declaring_type.IsValueType || declaring_type.IsPrimitive
				? new ByReferenceType(declaring_type)
				: declaring_type as TypeReference;

			return new ParameterDefinition(type, method);
		}

		public MethodBody(MethodDefinition method)
		{
			this.method = method;
		}

		public ILProcessor GetILProcessor()
		{
			return new ILProcessor(this);
		}

		public BlobReader GetILReader()
		{
			return code_reader;
		}

		public IMetadataTokenProvider LookupToken(MetadataToken token)
		{
			return method.Module.Read(token, (t, reader) => {
				reader.context = method;
				return reader.LookupToken(t);
			});
		}

		public string LookupStringToken(MetadataToken token)
		{
			return method.Module.Image.UserStringHeap.Read(token.RID);
		}
	}

	public interface IVariableDefinitionProvider {
		bool HasVariables { get; }
		Collection<VariableDefinition> Variables { get; }
	}

	class VariableDefinitionCollection : Collection<VariableDefinition> {

		internal VariableDefinitionCollection ()
		{
		}

		internal VariableDefinitionCollection (int capacity)
			: base (capacity)
		{
		}

		protected override void OnAdd (VariableDefinition item, int index)
		{
			item.index = index;
		}

		protected override void OnInsert (VariableDefinition item, int index)
		{
			item.index = index;

			for (int i = index; i < size; i++)
				items [i].index = i + 1;
		}

		protected override void OnSet (VariableDefinition item, int index)
		{
			item.index = index;
		}

		protected override void OnRemove (VariableDefinition item, int index)
		{
			item.index = -1;

			for (int i = index + 1; i < size; i++)
				items [i].index = i - 1;
		}
	}

	class InstructionCollection : Collection<Instruction> {

		internal InstructionCollection ()
		{
		}

		internal InstructionCollection (int capacity)
			: base (capacity)
		{
		}

		protected override void OnAdd (Instruction item, int index)
		{
			if (index == 0)
				return;

			var previous = items [index - 1];
			previous.next = item;
			item.previous = previous;
		}

		protected override void OnInsert (Instruction item, int index)
		{
			if (size == 0)
				return;

			var current = items [index];
			if (current == null) {
				var last = items [index - 1];
				last.next = item;
				item.previous = last;
				return;
			}

			var previous = current.previous;
			if (previous != null) {
				previous.next = item;
				item.previous = previous;
			}

			current.previous = item;
			item.next = current;
		}

		protected override void OnSet (Instruction item, int index)
		{
			var current = items [index];

			item.previous = current.previous;
			item.next = current.next;

			current.previous = null;
			current.next = null;
		}

		protected override void OnRemove (Instruction item, int index)
		{
			var previous = item.previous;
			if (previous != null)
				previous.next = item.next;

			var next = item.next;
			if (next != null)
				next.previous = item.previous;

			item.previous = null;
			item.next = null;
		}
	}
}