using System;
using System.Collections.Generic;
using System.IO;
using CPU = Cosmos.IL2CPU.X86;
using CPUx86 = Cosmos.IL2CPU.X86;
using System.Reflection;
using Cosmos.IL2CPU.X86;
using Cosmos.IL2CPU.ILOpCodes;
using Cosmos.IL2CPU;
using Cosmos.IL2CPU.IL.CustomImplementations.System;

namespace Cosmos.IL2CPU.X86.IL
{
    [Cosmos.IL2CPU.OpCode( ILOpCode.Code.Unbox )]
    public class Unbox : ILOp
    {
        public Unbox( Cosmos.IL2CPU.Assembler aAsmblr )
            : base( aAsmblr )
        {
        }

        public override void Execute( MethodInfo aMethod, ILOpCode aOpCode )
        {
            OpType xType = ( OpType )aOpCode;
            string BaseLabel = GetLabel( aMethod, aOpCode ) + "__";

            string xTypeID = GetTypeIDLabel(xType.Value);


            var xTypeSize = SizeOfType( xType.Value );

            string mReturnNullLabel = BaseLabel + "_ReturnNull";
            new CPUx86.Move { DestinationReg = CPUx86.Registers.EAX, SourceReg = CPUx86.Registers.ESP, SourceIsIndirect = true };
            new CPUx86.Compare { DestinationReg = CPUx86.Registers.EAX, SourceValue = 0 };
            new CPUx86.ConditionalJump { Condition = CPUx86.ConditionalTestEnum.Zero, DestinationLabel = mReturnNullLabel };
            new CPUx86.Push { DestinationReg = CPUx86.Registers.EAX, DestinationIsIndirect = true };
            Assembler.Stack.Push( new StackContents.Item( 4, typeof( uint ) ) );
            new CPUx86.Push { DestinationRef = ElementReference.New( xTypeID ), DestinationIsIndirect = true };
            Assembler.Stack.Push( new StackContents.Item( 4, typeof( uint ) ) );
            System.Reflection.MethodBase xMethodIsInstance = ReflectionUtilities.GetMethodBase( typeof( VTablesImpl ), "IsInstance", "System.Int32", "System.Int32" );
            new Call(Assembler).Execute(aMethod, new OpMethod(ILOpCode.Code.Call, 0, 0, xMethodIsInstance, aOpCode.CurrentExceptionHandler));

            new Label( BaseLabel + "_After_IsInstance_Call" );
            new CPUx86.Pop { DestinationReg = CPUx86.Registers.EAX };
            Assembler.Stack.Pop();
            new CPUx86.Compare { DestinationReg = CPUx86.Registers.EAX, SourceValue = 0 };
            new CPUx86.ConditionalJump { Condition = CPUx86.ConditionalTestEnum.Equal, DestinationLabel = mReturnNullLabel };
            new CPUx86.Pop { DestinationReg = CPUx86.Registers.EAX };
            uint xSize = xTypeSize;
            if( xSize % 4 > 0 )
            {
                xSize += 4 - ( xSize % 4 );
            }
            int xItems = ( int )xSize / 4;
            for( int i = xItems - 1; i >= 0; i-- )
            {
                new CPUx86.Push { DestinationReg = CPUx86.Registers.EAX, DestinationIsIndirect = true, DestinationDisplacement = ( ( i * 4 ) + ObjectImpl.FieldDataOffset ) };
            }
            Assembler.Stack.Push( new StackContents.Item( ( int )xTypeSize, xType.Value ) );
            //new CPUx86.Jump { DestinationLabel = mNextOpLabel };
            new CPUx86.Jump { DestinationLabel = GetLabel(aMethod, aOpCode.NextPosition) };
            new Label( mReturnNullLabel );
            new CPUx86.Add { DestinationReg = CPUx86.Registers.ESP, SourceValue = 4 };
            new CPUx86.Push { DestinationValue = 0 };
            Assembler.Stack.Push( new StackContents.Item( 4, typeof( object ) ) );
        }

        // 	[OpCode(OpCodeEnum.Unbox)]
        // 	public class Unbox: Op {
        // 		private string mTypeIdLabel;
        // 		private string mThisLabel;
        // 		private string mNextOpLabel;
        // 		private Type mType;
        // 		private uint mCurrentILOffset;
        // 		private bool mDebugMode;
        // 		public Unbox(ILReader aReader, MethodInformation aMethodInfo)
        // 			: base(aReader, aMethodInfo) {
        // 			mType = aReader.OperandValueType;
        // 			if (mType == null) {
        // 				throw new Exception("Unable to determine Type!");
        // 			}
        // 			mThisLabel = GetInstructionLabel(aReader);
        // 			mNextOpLabel = GetInstructionLabel(aReader.NextPosition);
        // 			mCurrentILOffset = aReader.Position;
        // 			mDebugMode = aMethodInfo.DebugMode;
        // 		}
        // 		public override void DoAssemble() {
        //             mTypeIdLabel = GetService<IMetaDataInfoService>().GetTypeIdLabel(mType);
        // 			
        //             var xTypeSize = GetService<IMetaDataInfoService>().SizeOfType(mType);
        // 			
        // 			string mReturnNullLabel = mThisLabel + "_ReturnNull";
        //             new CPUx86.Move { DestinationReg = CPUx86.Registers.EAX, SourceReg = CPUx86.Registers.ESP, SourceIsIndirect = true };
        //             new CPUx86.Compare { DestinationReg = CPUx86.Registers.EAX, SourceValue = 0 };
        //             new CPUx86.ConditionalJump { Condition = CPUx86.ConditionalTestEnum.Zero, DestinationLabel = mReturnNullLabel };
        //             new CPUx86.Push { DestinationReg = CPUx86.Registers.EAX, DestinationIsIndirect = true };
        // 			Assembler.Stack.Push(new StackContent(4, typeof(uint)));
        //             new CPUx86.Push { DestinationRef = ElementReference.New(mTypeIdLabel), DestinationIsIndirect=true };
        // 			Assembler.Stack.Push(new StackContent(4, typeof(uint)));
        //             MethodBase xMethodIsInstance = ReflectionUtilities.GetMethodBase(ReflectionUtilities.GetType("", "Cosmos.IL2CPU.VTablesImpl"), "IsInstance", "System.Int32", "System.Int32");
        // 			Op xOp = new Call(xMethodIsInstance, mCurrentILOffset, mDebugMode, mThisLabel + "_After_IsInstance_Call");
        // 			xOp.Assembler = Assembler;
        //             xOp.SetServiceProvider(GetServiceProvider());
        // 			xOp.Assemble();
        // 		    new Label(mThisLabel + "_After_IsInstance_Call");
        //             new CPUx86.Pop { DestinationReg = CPUx86.Registers.EAX };
        // 			Assembler.Stack.Pop();
        //             new CPUx86.Compare { DestinationReg = CPUx86.Registers.EAX, SourceValue = 0 };
        //             new CPUx86.ConditionalJump { Condition = CPUx86.ConditionalTestEnum.Equal, DestinationLabel = mReturnNullLabel };
        //             new CPUx86.Pop { DestinationReg = CPUx86.Registers.EAX };
        // 			uint xSize = xTypeSize;
        // 			if (xSize % 4 > 0) {
        // 				xSize += 4 - (xSize % 4);
        // 			}
        // 			int xItems =(int) xSize /4;
        // 			for (int i = xItems - 1; i >= 0; i--) {
        //                 new CPUx86.Push { DestinationReg = CPUx86.Registers.EAX, DestinationIsIndirect = true, DestinationDisplacement = ((i * 4) + ObjectImpl.FieldDataOffset) };
        // 			}
        // 			Assembler.Stack.Push(new StackContent((int)xTypeSize, mType));
        //             new CPUx86.Jump { DestinationLabel = mNextOpLabel };
        // 			new Label(mReturnNullLabel);
        //             new CPUx86.Add { DestinationReg = CPUx86.Registers.ESP, SourceValue = 4 };
        //             new CPUx86.Push { DestinationValue = 0 };
        // 			Assembler.Stack.Push(new StackContent(4, typeof(object)));
        // 		}
        // 	}
        // }
    }
}