using Mesen.Interop;
using ReactiveUI;
using ReactiveUI.Fody.Helpers;
using System;
using System.Text;

namespace Mesen.Debugger.StatusViews
{
	public class SmsStatusViewModel : BaseConsoleStatusViewModel
	{
		[Reactive] public byte RegA { get; set; }
		[Reactive] public byte RegB { get; set; }
		[Reactive] public byte RegC { get; set; }
		[Reactive] public byte RegD { get; set; }
		[Reactive] public byte RegE { get; set; }
		[Reactive] public byte RegFlags { get; set; }

		[Reactive] public byte RegH { get; set; }
		[Reactive] public byte RegL { get; set; }
		
		[Reactive] public UInt16 RegIX { get; set; }
		[Reactive] public UInt16 RegIY { get; set; }

		[Reactive] public byte RegR { get; set; }
		[Reactive] public byte RegI { get; set; }

		[Reactive] public byte RegAltA { get; set; }
		[Reactive] public byte RegAltFlags { get; set; }
		[Reactive] public byte RegAltB { get; set; }
		[Reactive] public byte RegAltC { get; set; }
		[Reactive] public byte RegAltD { get; set; }
		[Reactive] public byte RegAltE { get; set; }
		[Reactive] public byte RegAltH { get; set; }
		[Reactive] public byte RegAltL { get; set; }

		[Reactive] public UInt16 RegSP { get; set; }
		[Reactive] public UInt16 RegPC { get; set; }

		[Reactive] public UInt16 Scanline { get; set; }
		[Reactive] public UInt16 Cycle { get; set; }

		[Reactive] public bool FlagCarry { get; set; }
		[Reactive] public bool FlagAddSub { get; set; }
		[Reactive] public bool FlagParity { get; set; }
		[Reactive] public bool FlagF3 { get; set; }
		[Reactive] public bool FlagHalf { get; set; }
		[Reactive] public bool FlagF5 { get; set; }
		[Reactive] public bool FlagZero { get; set; }
		[Reactive] public bool FlagSign { get; set; }

		[Reactive] public bool FlagIFF1 { get; set; }
		[Reactive] public bool FlagIFF2 { get; set; }
		[Reactive] public bool FlagHalted { get; set; }
		[Reactive] public byte IM { get; set; }

		[Reactive] public string StackPreview { get; private set; } = "";

		public SmsStatusViewModel()
		{
			this.WhenAnyValue(x => x.FlagCarry, x => x.FlagHalf, x => x.FlagAddSub, x => x.FlagZero).Subscribe(x => UpdateFlagsValue());

			this.WhenAnyValue(x => x.RegFlags).Subscribe(x => {
				using var delayNotifs = DelayChangeNotifications(); //don't reupdate RegFlags while updating the flags
				FlagCarry = (x & (byte)SmsCpuFlags.Carry) != 0;
				FlagAddSub = (x & (byte)SmsCpuFlags.AddSub) != 0;
				FlagParity = (x & (byte)SmsCpuFlags.Parity) != 0;
				FlagF3 = (x & (byte)SmsCpuFlags.F3) != 0;
				FlagHalf = (x & (byte)SmsCpuFlags.HalfCarry) != 0;
				FlagF5 = (x & (byte)SmsCpuFlags.F5) != 0;
				FlagZero = (x & (byte)SmsCpuFlags.Zero) != 0;
				FlagSign = (x & (byte)SmsCpuFlags.Sign) != 0;
			});
		}

		private void UpdateFlagsValue()
		{
			RegFlags = (byte)(
				(FlagCarry ? (byte)SmsCpuFlags.Carry : 0) |
				(FlagAddSub ? (byte)SmsCpuFlags.AddSub : 0) |
				(FlagParity ? (byte)SmsCpuFlags.Parity : 0) |
				(FlagF3 ? (byte)SmsCpuFlags.F3 : 0) |
				(FlagHalf ? (byte)SmsCpuFlags.HalfCarry : 0) |
				(FlagF5 ? (byte)SmsCpuFlags.F5 : 0) |
				(FlagZero ? (byte)SmsCpuFlags.Zero : 0) |
				(FlagSign ? (byte)SmsCpuFlags.Sign : 0)
			);
		}

		protected override void InternalUpdateUiState()
		{
			SmsState state = DebugApi.GetConsoleState<SmsState>(ConsoleType.Sms);

			SmsCpuState cpu = state.Cpu;
			SmsVdpState ppu = DebugApi.GetPpuState<SmsVdpState>(CpuType.Sms);

			UpdateCycleCount(state.Cpu.CycleCount);

			RegA = cpu.A;
			RegB = cpu.B;
			RegC = cpu.C;
			RegD = cpu.D;
			RegE = cpu.E;
			RegFlags = cpu.Flags;

			RegH = cpu.H;
			RegL = cpu.L;

			RegIX = (UInt16)(cpu.IXL | (cpu.IXH << 8));
			RegIY = (UInt16)(cpu.IYL | (cpu.IYH << 8));

			RegPC = cpu.PC;
			RegSP = cpu.SP;

			RegR = cpu.R;
			RegI = cpu.I;

			RegAltA = cpu.AltA;
			RegAltB = cpu.AltB;
			RegAltC = cpu.AltC;
			RegAltD = cpu.AltD;
			RegAltE = cpu.AltE;
			RegAltFlags = cpu.AltFlags;

			RegAltH = cpu.AltH;
			RegAltL = cpu.AltL;

			FlagIFF1 = cpu.IFF1;
			FlagIFF2 = cpu.IFF2;
			FlagHalted = cpu.Halted;
			IM = cpu.IM;

			Scanline = ppu.Scanline;
			Cycle = ppu.Cycle;

			StringBuilder sb = new StringBuilder();
			for(UInt32 i = (UInt32)cpu.SP; (i & 0xFF) != 0; i++) {
				sb.Append($"${DebugApi.GetMemoryValue(MemoryType.SmsMemory, i):X2} ");
			}
			StackPreview = sb.ToString();
		}

		protected override void InternalUpdateConsoleState()
		{
			SmsCpuState cpu = DebugApi.GetCpuState<SmsCpuState>(CpuType.Sms);

			cpu.A = RegA;
			cpu.B = RegB;
			cpu.C = RegC;
			cpu.D = RegD;
			cpu.E = RegE;
			cpu.Flags = RegFlags;

			cpu.H = RegH;
			cpu.L = RegL;

			cpu.IXL = (byte)(RegIX & 0xFF);
			cpu.IXH = (byte)((RegIX >> 8) & 0xFF);
			cpu.IYL = (byte)(RegIY & 0xFF);
			cpu.IYH = (byte)((RegIY >> 8) & 0xFF);

			cpu.PC = RegPC;
			cpu.SP = RegSP;

			cpu.R = RegR;
			cpu.I = RegI;

			cpu.AltA = RegAltA;
			cpu.AltB = RegAltB;
			cpu.AltC = RegAltC;
			cpu.AltD = RegAltD;
			cpu.AltE = RegAltE;
			cpu.AltFlags = RegAltFlags;

			cpu.AltH = RegAltH;
			cpu.AltL = RegAltL;

			cpu.IFF1 = FlagIFF1;
			cpu.IFF2 = FlagIFF2;
			cpu.Halted = FlagHalted;
			cpu.IM = IM;

			DebugApi.SetCpuState(cpu, CpuType.Sms);
		}
	}
}