using System;
using System.Collections.Generic;
using Indy.IL2CPU.Assembler;


using CPUx86 = Indy.IL2CPU.Assembler.X86;
using System.Reflection;
using Indy.IL2CPU.Compiler;

namespace Indy.IL2CPU.IL.X86 {
	[OpCode(OpCodeEnum.Ldsfld)]
	public class Ldsfld: Op {
		private string mDataName;
		private bool mNeedsGC;
        private string mNextLabel;
	    private string mCurLabel;
	    private uint mCurOffset;
	    private MethodInformation mMethodInformation;

			public static void ScanOp(ILReader aReader, MethodInformation aMethodInfo, SortedList<string, object> aMethodData, IServiceProvider aProvider)
			{
				FieldInfo xField = aReader.OperandValueField;
				Engine.QueueStaticField(xField);
			}

		public Ldsfld(ILReader aReader, MethodInformation aMethodInfo)
			: base(aReader, aMethodInfo) {
			mField = aReader.OperandValueField;
            // todo: improve, strings need gc?
			mNeedsGC = !mField.FieldType.IsValueType;
             mMethodInformation = aMethodInfo;
		    mCurOffset = aReader.Position;
		    mCurLabel = IL.Op.GetInstructionLabel(aReader);
            mNextLabel = IL.Op.GetInstructionLabel(aReader.NextPosition);
		}
        private FieldInfo mField;
		public override void DoAssemble() {
            var xSize = GetService<IMetaDataInfoService>().GetFieldStorageSize(mField.FieldType);
            mDataName = GetService<IMetaDataInfoService>().GetStaticFieldLabel(mField);
			
		    if (xSize >= 4) {
				for (int i = 1; i <= (xSize / 4); i++) {
					//	Pop("eax");
					//	Move(Assembler, "dword [" + mDataName + " + 0x" + (i * 4).ToString("X") + "]", "eax");
                    new CPUx86.Push { DestinationRef = ElementReference.New(mDataName), DestinationIsIndirect = true, DestinationDisplacement = (int)(xSize - (i * 4)) };
				}
				switch (xSize % 4) {
					case 1: {
                            new CPUx86.Move { DestinationReg = CPUx86.Registers.EAX, SourceValue = 0 };
                            new CPUx86.Move { DestinationReg = CPUx86.Registers.AL, SourceRef = ElementReference.New(mDataName), SourceIsIndirect = true };
                            new CPUx86.Push { DestinationReg = CPUx86.Registers.EAX };
							break;
						}
					case 2: {
                            new CPUx86.Move { DestinationReg = CPUx86.Registers.EAX, SourceValue = 0 };
                            new CPUx86.Move { DestinationReg = CPUx86.Registers.AX, SourceRef = ElementReference.New(mDataName), SourceIsIndirect = true };
							new CPUx86.Push{DestinationReg=CPUx86.Registers.EAX};
							break;
						}
					case 0: {
							break;
						}
					default:
                        EmitNotImplementedException(Assembler, GetServiceProvider(), "Ldsfld: Remainder size " + (xSize % 4) + " not supported!", mCurLabel, mMethodInformation, mCurOffset, mNextLabel);
                        break;
				}
			} else {
				switch (xSize) {
					case 1: {
                            new CPUx86.Move { DestinationReg = CPUx86.Registers.EAX, SourceValue = 0 };
                            new CPUx86.Move { DestinationReg = CPUx86.Registers.AL, SourceRef = ElementReference.New(mDataName), SourceIsIndirect = true };
                            new CPUx86.Push { DestinationReg = CPUx86.Registers.EAX };
							break;
						}
					case 2: {
                            new CPUx86.Move { DestinationReg = CPUx86.Registers.EAX, SourceValue = 0 };
                            new CPUx86.Move { DestinationReg = CPUx86.Registers.AX, SourceRef = ElementReference.New(mDataName), SourceIsIndirect = true };
							new CPUx86.Push{DestinationReg=CPUx86.Registers.EAX};
							break;
						}
					case 0: {
							break;
						}
					default:
                        EmitNotImplementedException(Assembler, GetServiceProvider(), "Ldsfld: Remainder size " + (xSize % 4) + " not supported!", mCurLabel, mMethodInformation, mCurOffset, mNextLabel);
                        break;
				}
			}
			Assembler.StackContents.Push(new StackContent((int)xSize, null));
			if (mNeedsGC) {
				new Dup(null, null) {
					Assembler = this.Assembler
				}.Assemble();
				new CPUx86.Call { DestinationLabel = MethodInfoLabelGenerator.GenerateLabelName(GCImplementationRefs.IncRefCountRef) };
				Assembler.StackContents.Pop();
			}
		}
	}
}