#region license
// Copyright (c) 2004, Rodrigo B. de Oliveira (rbo@acm.org)
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
// 
//     * Redistributions of source code must retain the above copyright notice,
//     this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above copyright notice,
//     this list of conditions and the following disclaimer in the documentation
//     and/or other materials provided with the distribution.
//     * Neither the name of Rodrigo B. de Oliveira nor the names of its
//     contributors may be used to endorse or promote products derived from this
//     software without specific prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#endregion

namespace Boo.Lang.Compiler.TypeSystem
{
	using System;
	using System.Text;

	public class CallableSignature
	{
		IParameter[] _parameters;
		IType _returnType;
		int _hashCode;
		bool _acceptVarArgs;

		public CallableSignature(IMethod method)
		{
			if (null == method)
			{
				throw new ArgumentNullException("method");
			}
			Initialize(method.GetParameters(), method.ReturnType, method.AcceptVarArgs);
		}

		public CallableSignature(IParameter[] parameters, IType returnType)
		{
			Initialize(parameters, returnType, false);
		}
		
		public CallableSignature(IParameter[] parameters, IType returnType, bool acceptVarArgs)
		{
			Initialize(parameters, returnType, acceptVarArgs);
		}

		private void Initialize(IParameter[] parameters, IType returnType, bool acceptVarArgs)
		{
			if (null == parameters)
			{
				throw new ArgumentNullException("parameters");
			}
			if (null == returnType)
			{
				throw new ArgumentNullException("returnType");
			}
			_parameters = parameters;
			_returnType = returnType;
			_acceptVarArgs = acceptVarArgs;
			InitializeHashCode();
		}
		
		public IParameter[] Parameters
		{
			get
			{
				return _parameters;
			}
		}
		
		public IType ReturnType
		{
			get
			{
				return _returnType;
			}
		}

		public bool AcceptVarArgs
		{
			get
			{
				return _acceptVarArgs;
			}
		}
		
		override public int GetHashCode()
		{
			return _hashCode;
		}
		
		override public bool Equals(object other)
		{
			CallableSignature rhs = other as CallableSignature;
			if (null == rhs
				|| _returnType != rhs._returnType
				|| _acceptVarArgs != rhs._acceptVarArgs)
			{
				return false;
			}
			return AreSameParameters(_parameters, rhs._parameters);
		}
		
		override public string ToString()
		{
			StringBuilder buffer = new StringBuilder("callable(");
			for (int i=0; i<_parameters.Length; ++i)
			{
				if (i > 0) { buffer.Append(", "); }
				if (_parameters[i].IsByRef) buffer.Append("ref ");
				if (_acceptVarArgs && i == _parameters.Length-1) buffer.Append('*');
				buffer.Append(_parameters[i].Type.ToString());
			}
			buffer.Append(") as ");
			buffer.Append(_returnType.ToString());
			return buffer.ToString();
		}
		
		static public bool AreSameParameters(IParameter[] lhs, IParameter[] rhs)
		{
			if (lhs.Length != rhs.Length)
			{
				return false;
			}
			for (int i=0; i<lhs.Length; ++i)
			{
				if (lhs[i].Type != rhs[i].Type)
				{
					return false;
				}
				if (lhs[i].IsByRef != rhs[i].IsByRef)
				{
					return false;
				}
			}
			return true;
		}
		
		void InitializeHashCode()
		{
			_hashCode = _acceptVarArgs ? 1 : 2;
			foreach (IParameter parameter in _parameters)
			{
				_hashCode ^= parameter.Type.GetHashCode();
			}
			_hashCode ^= _returnType.GetHashCode();
		}
	}
}
