using System;
using System.Linq;
using Cosmos.Assembler;
using Cosmos.Assembler.x86;

namespace Cosmos.Debug.DebugStub {
	public class Init : Cosmos.Assembler.Code {

		public Init(Assembler.Assembler aAssembler) : base(aAssembler) {}

		public override void Assemble() {
			new Comment("X#: Group DebugStub");

			new Comment("Todo: Change these to a group level var");

			new Comment("X#: var .DebugBPs int[256]");
			mAssembler.DataMembers.Add(new DataMember("DebugBPs", new int[256]));

			new Comment("X#: var .DebugWaitMsg = 'Waiting for debugger connection...'");
			mAssembler.DataMembers.Add(new DataMember("DebugWaitMsg", "Waiting for debugger connection..."));

			new Comment("Called before Kernel runs. Inits debug stub, etc");

			new Comment("X#: procedure Init {");
			new Label("DebugStub_Init");

			new Comment("X#: Cls()");
			new Call { DestinationLabel = "DebugStub_Cls" };

			new Comment("Display message before even trying to init serial");

			new Comment("X#: DisplayWaitMsg()");
			new Call { DestinationLabel = "DebugStub_DisplayWaitMsg" };

			new Comment("X#: InitSerial()");
			new Call { DestinationLabel = "DebugStub_InitSerial" };

			new Comment("X#: WaitForDbgHandshake()");
			new Call { DestinationLabel = "DebugStub_WaitForDbgHandshake" };

			new Comment("X#: Cls()");
			new Call { DestinationLabel = "DebugStub_Cls" };

			new Comment("X#: }");
			new Label("DebugStub_Init_Exit");
			new Return();

			new Comment("X#: procedure WaitForSignature {");
			new Label("DebugStub_WaitForSignature");

			new Comment("X#: EBX = 0");
			new Mov{ DestinationReg = RegistersEnum.EBX, SourceValue = 0 };

			new Comment("X#: Read:");
			new Label("DebugStub_WaitForSignature_Read");

			new Comment("X#: ComReadAL()");
			new Call { DestinationLabel = "DebugStub_ComReadAL" };

			new Comment("X#: BL = AL");
			new Mov{ DestinationReg = RegistersEnum.BL, SourceReg = RegistersEnum.AL };

			new Comment("X#: EBX ~> 8");
			new LiteralAssemblerCode("ROR EBX, 8");

			new Comment("X#: if EBX != $19740807 goto Read");
			new Compare { DestinationReg = RegistersEnum.EBX, SourceValue = 0x19740807 };
			new ConditionalJump { Condition = ConditionalTestEnum.NotZero, DestinationLabel = "DebugStub_WaitForSignature_Read" };

			new Comment("X#: }");
			new Label("DebugStub_WaitForSignature_Exit");
			new Return();

			new Comment("QEMU (and possibly others) send some garbage across the serial line first.");

			new Comment("Actually they send the garbage inbound, but garbage could be inbound as well so we");

			new Comment("keep this.");

			new Comment("To work around this we send a signature. DC then discards everything before the signature.");

			new Comment("QEMU has other serial issues too, and we dont support it anymore, but this signature is a good");

			new Comment("feature so we kept it.");

			new Comment("X#: procedure WaitForDbgHandshake {");
			new Label("DebugStub_WaitForDbgHandshake");

			new Comment("\"Clear\" the UART out");

			new Comment("X#: AL = 0");
			new Mov{ DestinationReg = RegistersEnum.AL, SourceValue = 0 };

			new Comment("X#: ComWriteAL()");
			new Call { DestinationLabel = "DebugStub_ComWriteAL" };

			new Comment("Cosmos.Debug.Consts.Consts.SerialSignature");

			new Comment("X#: +$19740807");
			new Push { DestinationValue = 0x19740807, Size = 32 };

			new Comment("X#: ESI = ESP");
			new Mov{ DestinationReg = RegistersEnum.ESI, SourceReg = RegistersEnum.ESP };

			new Comment("TODO pass a count register");

			new Comment("X#: ComWrite8()");
			new Call { DestinationLabel = "DebugStub_ComWrite8" };

			new Comment("X#: ComWrite8()");
			new Call { DestinationLabel = "DebugStub_ComWrite8" };

			new Comment("X#: ComWrite8()");
			new Call { DestinationLabel = "DebugStub_ComWrite8" };

			new Comment("X#: ComWrite8()");
			new Call { DestinationLabel = "DebugStub_ComWrite8" };

			new Comment("Restore ESP, we actually dont care about EAX or the value on the stack anymore.");

			new Comment("X#: -EAX");
			new Pop { DestinationReg = RegistersEnum.EAX};

			new Comment("We could use the signature as the start signal, but I prefer");

			new Comment("to keep the logic separate, especially in DC.");

			new Comment("Send the actual started signal");

			new Comment("DsVsip.Started = 6");

			new Comment("X#: AL = 6");
			new Mov{ DestinationReg = RegistersEnum.AL, SourceValue = 6 };

			new Comment("X#: ComWriteAL()");
			new Call { DestinationLabel = "DebugStub_ComWriteAL" };

			new Comment("X#: WaitForSignature()");
			new Call { DestinationLabel = "DebugStub_WaitForSignature" };

			new Comment("X#: ProcessCommandBatch()");
			new Call { DestinationLabel = "DebugStub_ProcessCommandBatch" };

			new Comment("X#: }");
			new Label("DebugStub_WaitForDbgHandshake_Exit");
			new Return();

		}
	}
}