using System.IO;

namespace MyNes.Core;

[BoardInfo("Tengen RAMBO-1", 64, true, true)]
internal class Mapper064 : Board
{
	private bool flag_c;

	private bool flag_p;

	private bool flag_k;

	private int address_8001;

	private int[] chr_reg;

	private int[] prg_reg;

	private bool irq_enabled;

	private byte irq_counter;

	private byte irq_reload;

	private bool irq_mode;

	private bool irq_clear;

	private int irq_prescaler;

	internal override void HardReset()
	{
		base.HardReset();
		flag_c = (flag_p = (flag_k = false));
		address_8001 = 0;
		prg_reg = new int[3];
		prg_reg[0] = 0;
		prg_reg[1] = 1;
		prg_reg[2] = 2;
		Switch08KPRG(PRG_ROM_08KB_Mask, PRGArea.AreaE000);
		SetupPRG();
		chr_reg = new int[8];
		for (int i = 0; i < 8; i++)
		{
			chr_reg[i] = i;
		}
		SetupCHR();
		irq_enabled = false;
		irq_counter = 0;
		irq_prescaler = 0;
		irq_mode = false;
		irq_reload = byte.MaxValue;
		irq_clear = false;
	}

	internal override void WritePRG(ref ushort address, ref byte data)
	{
		switch (address & 0xE001)
		{
		case 32768:
			address_8001 = data & 0xF;
			flag_c = (data & 0x80) != 0;
			flag_p = (data & 0x40) != 0;
			flag_k = (data & 0x20) != 0;
			SetupCHR();
			SetupPRG();
			break;
		case 32769:
			switch (address_8001)
			{
			case 0:
			case 1:
			case 2:
			case 3:
			case 4:
			case 5:
				chr_reg[address_8001] = data;
				SetupCHR();
				break;
			case 6:
			case 7:
				prg_reg[address_8001 - 6] = data;
				SetupPRG();
				break;
			case 8:
				chr_reg[6] = data;
				SetupCHR();
				break;
			case 9:
				chr_reg[7] = data;
				SetupCHR();
				break;
			case 15:
				prg_reg[2] = data;
				SetupPRG();
				break;
			case 10:
			case 11:
			case 12:
			case 13:
			case 14:
				break;
			}
			break;
		case 40960:
			if (NMT_DEFAULT_MIRROR != Mirroring.Full)
			{
				Switch01KNMTFromMirroring(((data & 1) == 1) ? Mirroring.Horz : Mirroring.Vert);
			}
			break;
		case 49152:
			irq_reload = data;
			break;
		case 49153:
			irq_mode = (data & 1) == 1;
			irq_clear = true;
			irq_prescaler = 0;
			break;
		case 57344:
			irq_enabled = false;
			NesEmu.IRQFlags &= -9;
			break;
		case 57345:
			irq_enabled = true;
			break;
		}
	}

	private void SetupCHR()
	{
		if (!flag_c)
		{
			if (!flag_k)
			{
				Switch02KCHR(chr_reg[0] >> 1, CHRArea.Area0000);
				Switch02KCHR(chr_reg[1] >> 1, CHRArea.Area0800);
			}
			else
			{
				Switch01KCHR(chr_reg[0], CHRArea.Area0000);
				Switch01KCHR(chr_reg[6], CHRArea.Area0400);
				Switch01KCHR(chr_reg[1], CHRArea.Area0800);
				Switch01KCHR(chr_reg[7], CHRArea.Area0C00);
			}
			Switch01KCHR(chr_reg[2], CHRArea.Area1000);
			Switch01KCHR(chr_reg[3], CHRArea.Area1400);
			Switch01KCHR(chr_reg[4], CHRArea.Area1800);
			Switch01KCHR(chr_reg[5], CHRArea.Area1C00);
		}
		else
		{
			if (!flag_k)
			{
				Switch02KCHR(chr_reg[0] >> 1, CHRArea.Area1000);
				Switch02KCHR(chr_reg[1] >> 1, CHRArea.Area1800);
			}
			else
			{
				Switch01KCHR(chr_reg[0], CHRArea.Area1000);
				Switch01KCHR(chr_reg[6], CHRArea.Area1400);
				Switch01KCHR(chr_reg[1], CHRArea.Area1800);
				Switch01KCHR(chr_reg[7], CHRArea.Area1C00);
			}
			Switch01KCHR(chr_reg[2], CHRArea.Area0000);
			Switch01KCHR(chr_reg[3], CHRArea.Area0400);
			Switch01KCHR(chr_reg[4], CHRArea.Area0800);
			Switch01KCHR(chr_reg[5], CHRArea.Area0C00);
		}
	}

	private void SetupPRG()
	{
		Switch08KPRG(prg_reg[flag_p ? 2 : 0], PRGArea.Area8000);
		Switch08KPRG(prg_reg[(!flag_p) ? 1u : 0u], PRGArea.AreaA000);
		Switch08KPRG(prg_reg[flag_p ? 1 : 2], PRGArea.AreaC000);
	}

	internal override void OnPPUA12RaisingEdge()
	{
		ClockIRQ();
	}

	internal override void OnCPUClock()
	{
		if (irq_mode)
		{
			irq_prescaler++;
			if (irq_prescaler == 4)
			{
				irq_prescaler = 0;
				ClockIRQ();
			}
		}
	}

	private void ClockIRQ()
	{
		if (irq_clear)
		{
			irq_counter = (byte)(irq_reload + 1);
			irq_clear = false;
		}
		else if (irq_counter == 0)
		{
			irq_counter = irq_reload;
		}
		else if (--irq_counter == 0 && irq_enabled)
		{
			NesEmu.IRQFlags |= 8;
		}
	}

	internal override void WriteStateData(ref BinaryWriter stream)
	{
		base.WriteStateData(ref stream);
		stream.Write(flag_c);
		stream.Write(flag_p);
		stream.Write(address_8001);
		for (int i = 0; i < chr_reg.Length; i++)
		{
			stream.Write(chr_reg[i]);
		}
		for (int j = 0; j < prg_reg.Length; j++)
		{
			stream.Write(prg_reg[j]);
		}
		stream.Write(irq_enabled);
		stream.Write(irq_counter);
		stream.Write(irq_reload);
		stream.Write(irq_clear);
		stream.Write(irq_prescaler);
		stream.Write(irq_mode);
	}

	internal override void ReadStateData(ref BinaryReader stream)
	{
		base.ReadStateData(ref stream);
		flag_c = stream.ReadBoolean();
		flag_p = stream.ReadBoolean();
		address_8001 = stream.ReadInt32();
		for (int i = 0; i < chr_reg.Length; i++)
		{
			chr_reg[i] = stream.ReadInt32();
		}
		for (int j = 0; j < prg_reg.Length; j++)
		{
			prg_reg[j] = stream.ReadInt32();
		}
		irq_enabled = stream.ReadBoolean();
		irq_counter = stream.ReadByte();
		irq_reload = stream.ReadByte();
		irq_clear = stream.ReadBoolean();
		irq_prescaler = stream.ReadInt32();
		irq_mode = stream.ReadBoolean();
	}
}