/*
  Copyright (C) 2009 Jeroen Frijters

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.

  Jeroen Frijters
  jeroen@frijters.net
  
*/
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using IKVM.Reflection.Metadata;

namespace IKVM.Reflection.Reader
{
	sealed class FieldDefImpl : FieldInfo
	{
		private readonly ModuleReader module;
		private readonly TypeDefImpl declaringType;
		private readonly int index;
		private FieldSignature lazyFieldSig;

		internal FieldDefImpl(ModuleReader module, TypeDefImpl declaringType, int index)
		{
			this.module = module;
			this.declaringType = declaringType;
			this.index = index;
		}

		public override FieldAttributes Attributes
		{
			get { return (FieldAttributes)module.Field.records[index].Flags; }
		}

		public override Type DeclaringType
		{
			get { return declaringType.IsModulePseudoType ? null : declaringType; }
		}

		public override string Name
		{
			get { return module.GetString(module.Field.records[index].Name); }
		}

		public override string ToString()
		{
			return this.FieldType.Name + " " + this.Name;
		}

		public override Module Module
		{
			get { return module; }
		}

		public override int MetadataToken
		{
			get { return (FieldTable.Index << 24) + index + 1; }
		}

		public override object GetRawConstantValue()
		{
			return module.Constant.GetRawConstantValue(module, this.MetadataToken);
		}

		public override void __GetDataFromRVA(byte[] data, int offset, int length)
		{
			int rid = index + 1;
			// TODO binary search?
			for (int i = 0; i < module.FieldRVA.records.Length; i++)
			{
				if (module.FieldRVA.records[i].Field == rid)
				{
					int rva = module.FieldRVA.records[i].RVA;
					if (rva == 0)
					{
						// C++ assemblies can have fields that have an RVA that is zero
						Array.Clear(data, offset, length);
						return;
					}
					module.SeekRVA(rva);
					while (length > 0)
					{
						int read = module.stream.Read(data, offset, length);
						if (read == 0)
						{
							// C++ assemblies can have fields that have an RVA that lies outside of the file
							break;
						}
						offset += read;
						length -= read;
					}
					return;
				}
			}
			throw new InvalidOperationException();
		}

		internal override IList<CustomAttributeData> GetCustomAttributesData(Type attributeType)
		{
			List<CustomAttributeData> list = module.GetCustomAttributes(this.MetadataToken, attributeType);
			if ((this.Attributes & FieldAttributes.HasFieldMarshal) != 0
				&& (attributeType == null || attributeType.IsAssignableFrom(module.universe.System_Runtime_InteropServices_MarshalAsAttribute)))
			{
				list.Add(MarshalSpec.GetMarshalAsAttribute(module, this.MetadataToken));
			}
			if (declaringType.IsExplicitLayout
				&& (attributeType == null || attributeType.IsAssignableFrom(module.universe.System_Runtime_InteropServices_FieldOffsetAttribute)))
			{
				int rid = index + 1;
				// TODO use binary search?
				for (int i = 0; i < module.FieldLayout.records.Length; i++)
				{
					if (module.FieldLayout.records[i].Field == rid)
					{
						ConstructorInfo constructor = module.universe.System_Runtime_InteropServices_FieldOffsetAttribute.GetConstructor(new Type[] { module.universe.System_Int32 });
						list.Add(new CustomAttributeData(constructor,
							new object[] { module.FieldLayout.records[i].Offset },
							null));
						break;
					}
				}
			}
			return list;
		}

		internal override FieldSignature FieldSignature
		{
			get { return lazyFieldSig ?? (lazyFieldSig = FieldSignature.ReadSig(module, module.GetBlob(module.Field.records[index].Signature), declaringType)); }
		}

		internal override int ImportTo(Emit.ModuleBuilder module)
		{
			return module.ImportMethodOrField(declaringType, this.Name, this.FieldSignature);
		}
	}
}