using System;
using System.IO;


using CPU = Indy.IL2CPU.Assembler;
using CPUx86 = Indy.IL2CPU.Assembler.X86;

namespace Indy.IL2CPU.IL.X86 {
	[OpCode(OpCodeEnum.Blt)]
	public class Blt: Op {
		public readonly string TargetLabel;
		public readonly string CurInstructionLabel;
		public readonly string NextInstructionLabel;
        private string mNextLabel;
	    private string mCurLabel;
	    private uint mCurOffset;
	    private MethodInformation mMethodInformation;
		public Blt(ILReader aReader, MethodInformation aMethodInfo)
			: base(aReader, aMethodInfo) {
			TargetLabel = GetInstructionLabel(aReader.OperandValueBranchPosition);
			CurInstructionLabel = GetInstructionLabel(aReader);
			NextInstructionLabel = GetInstructionLabel(aReader.NextPosition);
             mMethodInformation = aMethodInfo;
		    mCurOffset = aReader.Position;
		    mCurLabel = IL.Op.GetInstructionLabel(aReader);
            mNextLabel = IL.Op.GetInstructionLabel(aReader.NextPosition);
		}
		public override void DoAssemble() {
			if (Assembler.StackContents.Peek().IsFloat) {
                EmitNotImplementedException(Assembler, GetServiceProvider(), "Blt: Float support not yet implemented!", mCurLabel, mMethodInformation, mCurOffset, mNextLabel);
                return;
			}
			var right = Assembler.StackContents.Pop();
			var left = Assembler.StackContents.Pop();
            if (right.Size != left.Size)
            {
                if (right.Size > 4 || left.Size > 4)
                {
                    EmitNotImplementedException(Assembler, GetServiceProvider(), "Blt: mixed size operations are not implemented! (" + left.Size + "/" + right.Size + ")", mCurLabel, mMethodInformation, mCurOffset, mNextLabel);
                    return;                   
                }
            }

			int xSize = right.Size;

            if (xSize > 8)
            {
                EmitNotImplementedException(Assembler, GetServiceProvider(), "Blt: StackSize>8 not supported yet", mCurLabel, mMethodInformation, mCurOffset, mNextLabel);
                return;
            }

			string BaseLabel = CurInstructionLabel + "__";
			string LabelTrue = BaseLabel + "True";
			string LabelFalse = BaseLabel + "False";

            switch (xSize)
            {
                case 4:
                    new CPUx86.Pop { DestinationReg = CPUx86.Registers.ECX };
                    new CPUx86.Pop { DestinationReg = CPUx86.Registers.EAX };

                    new CPUx86.Push { DestinationReg = CPUx86.Registers.ECX };
                    new CPUx86.Compare { DestinationReg = CPUx86.Registers.EAX, SourceReg = CPUx86.Registers.ESP, SourceIsIndirect = true };
                    new CPUx86.ConditionalJump { Condition = CPUx86.ConditionalTestEnum.LessThan, DestinationLabel = LabelTrue };
                    new CPUx86.Jump { DestinationLabel = LabelFalse };
                    new CPU.Label(LabelTrue);
                    new CPUx86.Add { DestinationReg = CPUx86.Registers.ESP, SourceValue = 4 };
                    new CPUx86.Jump { DestinationLabel = TargetLabel };
                    new CPU.Label(LabelFalse);
                    new CPUx86.Add { DestinationReg = CPUx86.Registers.ESP, SourceValue = 4 };
                    break;
                case 8:
                    new CPUx86.Pop { DestinationReg = CPUx86.Registers.EAX };
                    new CPUx86.Pop { DestinationReg = CPUx86.Registers.EDX };
                    //value2: EDX:EAX
                    new CPUx86.Pop { DestinationReg = CPUx86.Registers.EBX };
                    new CPUx86.Pop { DestinationReg = CPUx86.Registers.ECX };
                    //value1: ECX:EBX
                    new CPUx86.Sub { DestinationReg = CPUx86.Registers.EBX, SourceReg = CPUx86.Registers.EAX };
                    new CPUx86.SubWithCarry { DestinationReg = CPUx86.Registers.ECX, SourceReg = CPUx86.Registers.EDX };
                    //result = value1 - value2
                    new CPUx86.ConditionalJump { Condition = CPUx86.ConditionalTestEnum.LessThan, DestinationLabel = TargetLabel };
                    break;
                default:
                    EmitNotImplementedException(Assembler, GetServiceProvider(), "Blt: Comparison of " + xSize + "Not supported", mCurLabel, mMethodInformation, mCurOffset, mNextLabel);
                    return;
            }
		}
	}
}