using static VirtualNes.MMU;
using static VirtualNes.Core.CPU;
using INT = System.Int32;
using BYTE = System.Byte;
using System;
using Codice.CM.Client.Differences;

namespace VirtualNes.Core
{
	public class Mapper100 : Mapper
	{

		BYTE[] reg = new byte[8];
		BYTE prg0, prg1, prg2, prg3;
		BYTE chr0, chr1, chr2, chr3, chr4, chr5, chr6, chr7;

		BYTE irq_enable;
		BYTE irq_counter;
		BYTE irq_latch;
		public Mapper100(NES parent) : base(parent)
		{
		}

		public override void Reset()
		{
			for (INT i = 0; i < 8; i++)
			{
				reg[i] = 0x00;
			}

			prg0 = 0;
			prg1 = 1;
			prg2 = (byte)(PROM_8K_SIZE - 2);
			prg3 = (byte)(PROM_8K_SIZE - 1);
			SetBank_CPU();

			if (VROM_1K_SIZE != 0)
			{
				chr0 = 0;
				chr1 = 1;
				chr2 = 2;
				chr3 = 3;
				chr4 = 4;
				chr5 = 5;
				chr6 = 6;
				chr7 = 7;
				SetBank_PPU();
			}
			else
			{
				chr0 = chr2 = chr4 = chr5 = chr6 = chr7 = 0;
				chr1 = chr3 = 1;
			}

			irq_enable = 0; // Disable
			irq_counter = 0;
			irq_latch = 0;
		}

		//void Mapper100::Write(WORD addr, BYTE data)
		public override void Write(ushort addr, byte data)
		{
			switch (addr & 0xE001)
			{
				case 0x8000:
					reg[0] = data;
					break;
				case 0x8001:
					reg[1] = data;

					switch (reg[0] & 0xC7)
					{
						case 0x00:
							if (VROM_1K_SIZE != 0)
							{
								chr0 = (byte)(data & 0xFE);
								chr1 = (byte)(chr0 + 1);
								SetBank_PPU();
							}
							break;
						case 0x01:
							if (VROM_1K_SIZE != 0)
							{
								chr2 = (byte)(data & 0xFE);
								chr3 = (byte)(chr2 + 1);
								SetBank_PPU();
							}
							break;
						case 0x02:
							if (VROM_1K_SIZE != 0)
							{
								chr4 = data;
								SetBank_PPU();
							}
							break;
						case 0x03:
							if (VROM_1K_SIZE != 0)
							{
								chr5 = data;
								SetBank_PPU();
							}
							break;
						case 0x04:
							if (VROM_1K_SIZE != 0)
							{
								chr6 = data;
								SetBank_PPU();
							}
							break;
						case 0x05:
							if (VROM_1K_SIZE != 0)
							{
								chr7 = data;
								SetBank_PPU();
							}
							break;

						case 0x06:
							prg0 = data;
							SetBank_CPU();
							break;
						case 0x07:
							prg1 = data;
							SetBank_CPU();
							break;
						case 0x46:
							prg2 = data;
							SetBank_CPU();
							break;
						case 0x47:
							prg3 = data;
							SetBank_CPU();
							break;

						case 0x80:
							if (VROM_1K_SIZE != 0)
							{
								chr4 = (byte)(data & 0xFE);
								chr5 = (byte)(chr4 + 1);
								SetBank_PPU();
							}
							break;
						case 0x81:
							if (VROM_1K_SIZE != 0)
							{
								chr6 = (byte)(data & 0xFE);
								chr7 = (byte)(chr6 + 1);
								SetBank_PPU();
							}
							break;
						case 0x82:
							if (VROM_1K_SIZE != 0)
							{
								chr0 = data;
								SetBank_PPU();
							}
							break;
						case 0x83:
							if (VROM_1K_SIZE != 0)
							{
								chr1 = data;
								SetBank_PPU();
							}
							break;
						case 0x84:
							if (VROM_1K_SIZE != 0)
							{
								chr2 = data;
								SetBank_PPU();
							}
							break;
						case 0x85:
							if (VROM_1K_SIZE != 0)
							{
								chr3 = data;
								SetBank_PPU();
							}
							break;

					}
					break;
				case 0xA000:
					reg[2] = data;
					if (!nes.rom.Is4SCREEN())
					{
						if ((data & 0x01) != 0) SetVRAM_Mirror(VRAM_HMIRROR);
						else SetVRAM_Mirror(VRAM_VMIRROR);
					}
					break;
				case 0xA001:
					reg[3] = data;
					break;
				case 0xC000:
					reg[4] = data;
					irq_counter = data;
					break;
				case 0xC001:
					reg[5] = data;
					irq_latch = data;
					break;
				case 0xE000:
					reg[6] = data;
					irq_enable = 0;
					nes.cpu.ClrIRQ(IRQ_MAPPER);
					break;
				case 0xE001:
					reg[7] = data;
					irq_enable = 0xFF;
					break;
			}
		}

		//void Mapper100::HSync(INT scanline)
		public override void HSync(int scanline)
		{
			if ((scanline >= 0 && scanline <= 239))
			{
				if (nes.ppu.IsDispON())
				{
					if (irq_enable != 0)
					{
						if ((irq_counter--) == 0)
						{
							irq_counter = irq_latch;
							//					nes.cpu.IRQ();
							nes.cpu.SetIRQ(IRQ_MAPPER);
						}
					}
				}
			}
		}

		void SetBank_CPU()
		{
			SetPROM_32K_Bank(prg0, prg1, prg2, prg3);
		}

		void SetBank_PPU()
		{
			if (VROM_1K_SIZE != 0)
			{
				SetVROM_8K_Bank(chr0, chr1, chr2, chr3, chr4, chr5, chr6, chr7);
			}
		}

		//void Mapper100::SaveState(LPBYTE p)
		public override void SaveState(byte[] p)
		{
			for (byte i = 0; i < 8; i++)
			{
				p[i] = reg[i];
			}
			p[8] = prg0;
			p[9] = prg1;
			p[10] = prg2;
			p[11] = prg3;
			p[12] = chr0;
			p[13] = chr1;
			p[14] = chr2;
			p[15] = chr3;
			p[16] = chr4;
			p[17] = chr5;
			p[18] = chr6;
			p[19] = chr7;
			p[20] = irq_enable;
			p[21] = irq_counter;
			p[22] = irq_latch;
		}

		//void Mapper100::LoadState(LPBYTE p)
		public override void LoadState(byte[] p)
		{
			for (byte i = 0; i < 8; i++)
			{
				reg[i] = p[i];
			}
			prg0 = p[8];
			prg1 = p[9];
			prg2 = p[10];
			prg3 = p[11];
			chr0 = p[12];
			chr1 = p[13];
			chr2 = p[14];
			chr3 = p[15];
			chr4 = p[16];
			chr5 = p[17];
			chr6 = p[18];
			chr7 = p[19];
			irq_enable = p[20];
			irq_counter = p[21];
			irq_latch = p[22];
		}


		public override bool IsStateSave()
		{
			return true;
		}

	}
}