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

namespace Mesen.Debugger.StatusViews
{
	public class SpcStatusViewModel : BaseConsoleStatusViewModel
	{
		[Reactive] public byte RegA { get; set; }
		[Reactive] public byte RegX { get; set; }
		[Reactive] public byte RegY { get; set; }
		[Reactive] public byte RegSP { get; set; }
		[Reactive] public UInt16 RegPC { get; set; }
		[Reactive] public byte RegPS { get; set; }
		
		[Reactive] public bool FlagN { get; set; }
		[Reactive] public bool FlagV { get; set; }
		[Reactive] public bool FlagP { get; set; }
		[Reactive] public bool FlagB { get; set; }
		[Reactive] public bool FlagH { get; set; }
		[Reactive] public bool FlagI { get; set; }
		[Reactive] public bool FlagZ { get; set; }
		[Reactive] public bool FlagC { get; set; }

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

		public SpcStatusViewModel()
		{
			this.WhenAnyValue(x => x.FlagC, x => x.FlagP, x => x.FlagB, x => x.FlagH).Subscribe(x => UpdatePsValue());
			this.WhenAnyValue(x => x.FlagI, x => x.FlagN, x => x.FlagV, x => x.FlagZ).Subscribe(x => UpdatePsValue());

			this.WhenAnyValue(x => x.RegPS).Subscribe(x => {
				using var delayNotifs = DelayChangeNotifications(); //don't reupdate PS while updating the flags
				FlagN = (x & (byte)SpcFlags.Negative) != 0;
				FlagV = (x & (byte)SpcFlags.Overflow) != 0;
				FlagP = (x & (byte)SpcFlags.DirectPage) != 0;
				FlagB = (x & (byte)SpcFlags.Break) != 0;
				FlagH = (x & (byte)SpcFlags.HalfCarry) != 0;
				FlagI = (x & (byte)SpcFlags.IrqEnable) != 0;
				FlagZ = (x & (byte)SpcFlags.Zero) != 0;
				FlagC = (x & (byte)SpcFlags.Carry) != 0;
			});
		}

		private void UpdatePsValue()
		{
			RegPS = (byte)(
				(FlagN ? (byte)SpcFlags.Negative : 0) |
				(FlagV ? (byte)SpcFlags.Overflow : 0) |
				(FlagP ? (byte)SpcFlags.DirectPage : 0) |
				(FlagB ? (byte)SpcFlags.Break : 0) |
				(FlagH ? (byte)SpcFlags.HalfCarry : 0) |
				(FlagI ? (byte)SpcFlags.IrqEnable : 0) |
				(FlagZ ? (byte)SpcFlags.Zero : 0) |
				(FlagC ? (byte)SpcFlags.Carry : 0)
			);
		}

		protected override void InternalUpdateUiState()
		{
			SpcState cpu = DebugApi.GetCpuState<SpcState>(CpuType.Spc);

			UpdateCycleCount(cpu.Cycle);
			
			RegA = cpu.A;
			RegX = cpu.X;
			RegY = cpu.Y;
			RegSP = cpu.SP;
			RegPC = cpu.PC;
			RegPS = (byte)cpu.PS;

			StringBuilder sb = new StringBuilder();
			for(UInt32 i = (UInt32)0x100 + cpu.SP + 1; i < 0x200; i++) {
				sb.Append($"${DebugApi.GetMemoryValue(MemoryType.SpcMemory, i):X2} ");
			}
			StackPreview = sb.ToString();
		}

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

			cpu.A = RegA;
			cpu.X = RegX;
			cpu.Y = RegY;
			cpu.SP = RegSP;
			cpu.PC = RegPC;
			cpu.PS = (SpcFlags)RegPS;

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