using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using BizHawk.Common;
using BizHawk.Emulation.Common;

namespace BizHawk.Emulation.Cores.Computers.Commodore64.Cartridge
{
	public abstract class CartridgeDevice : IDriveLight
	{
		public Func<int> ReadOpenBus;

		public static CartridgeDevice Load(byte[] crtFile)
		{
			using (var mem = new MemoryStream(crtFile))
			{
				var reader = new BinaryReader(mem);

				if (new string(reader.ReadChars(16)) != "C64 CARTRIDGE   ")
				{
					return null;
				}

				var chipAddress = new List<int>();
				var chipBank = new List<int>();
				var chipData = new List<int[]>();
				var chipType = new List<int>();

				var headerLength = ReadCRTInt(reader);
				var version = ReadCRTShort(reader);
				var mapper = ReadCRTShort(reader);
				var exrom = reader.ReadByte() != 0;
				var game = reader.ReadByte() != 0;

				// reserved
				reader.ReadBytes(6);

				// cartridge name
				reader.ReadBytes(0x20);

				// skip extra header bytes
				if (headerLength > 0x40)
				{
					reader.ReadBytes(headerLength - 0x40);
				}

				// read chips
				while (reader.PeekChar() >= 0)
				{
					if (new string(reader.ReadChars(4)) != "CHIP")
					{
						break;
					}

					var chipLength = ReadCRTInt(reader);
					chipType.Add(ReadCRTShort(reader));
					chipBank.Add(ReadCRTShort(reader));
					chipAddress.Add(ReadCRTShort(reader));
					var chipDataLength = ReadCRTShort(reader);
					chipData.Add(reader.ReadBytes(chipDataLength).Select(x => (int)x).ToArray());
					chipLength -= chipDataLength + 0x10;
					if (chipLength > 0)
					{
						reader.ReadBytes(chipLength);
					}
				}

				if (chipData.Count <= 0)
				{
					return null;
				}

				CartridgeDevice result;
				switch (mapper)
				{
					case 0x0000:    // Standard Cartridge
						result = new Mapper0000(chipAddress, chipData, game, exrom);
						break;
					case 0x0001:    // Action Replay (4.2 and up)
						result = new Mapper0001(chipAddress, chipBank, chipData);
						break;
					case 0x0005:    // Ocean
						result = new Mapper0005(chipAddress, chipBank, chipData);
						break;
					case 0x0007:    // Fun Play
						result = new Mapper0007(chipData, game, exrom);
						break;
					case 0x0008:    // SuperGame
						result = new Mapper0008(chipData);
						break;
					case 0x000A:    // Epyx FastLoad
						result = new Mapper000A(chipData);
						break;
					case 0x000B:    // Westermann Learning
						result = new Mapper000B(chipAddress, chipData);
						break;
					case 0x000F:    // C64 Game System / System 3
						result = new Mapper000F(chipAddress, chipBank, chipData);
						break;
					case 0x0011:    // Dinamic
						result = new Mapper0011(chipAddress, chipBank, chipData);
						break;
					case 0x0012:    // Zaxxon / Super Zaxxon
						result = new Mapper0012(chipAddress, chipBank, chipData);
						break;
					case 0x0013:    // Domark
						result = new Mapper0013(chipAddress, chipBank, chipData);
						break;
					case 0x0020:    // EasyFlash
						result = new Mapper0020(chipAddress, chipBank, chipData);
						break;
					case 0x002B:    // Prophet 64
						result = new Mapper002B(chipAddress, chipBank, chipData);
						break;
					default:
						throw new Exception("This cartridge file uses an unrecognized mapper: " + mapper);
				}
				result.HardReset();

				return result;
			}
		}

		private static int ReadCRTShort(BinaryReader reader)
		{
			return (reader.ReadByte() << 8) |
				reader.ReadByte();
		}

		private static int ReadCRTInt(BinaryReader reader)
		{
			return (reader.ReadByte() << 24) |
				(reader.ReadByte() << 16) |
				(reader.ReadByte() << 8) |
				reader.ReadByte();
		}

		protected bool pinExRom;

		protected bool pinGame;

		protected bool pinIRQ;

		protected bool pinNMI;

		protected bool pinReset;

		protected bool validCartridge;

		public virtual void ExecutePhase()
		{
		}

		public bool ExRom => pinExRom;

		public bool Game => pinGame;

		public virtual void HardReset()
		{
			pinIRQ = true;
			pinNMI = true;
			pinReset = true;
		}

		public bool IRQ => pinIRQ;

		public bool NMI => pinNMI;

		public virtual int Peek8000(int addr)
		{
			return ReadOpenBus();
		}

		public virtual int PeekA000(int addr)
		{
			return ReadOpenBus();
		}

		public virtual int PeekDE00(int addr)
		{
			return ReadOpenBus();
		}

		public virtual int PeekDF00(int addr)
		{
			return ReadOpenBus();
		}

		public virtual void Poke8000(int addr, int val)
		{
		}

		public virtual void PokeA000(int addr, int val)
		{
		}

		public virtual void PokeDE00(int addr, int val)
		{
		}

		public virtual void PokeDF00(int addr, int val)
		{
		}

		public virtual int Read8000(int addr)
		{
			return ReadOpenBus();
		}

		public virtual int ReadA000(int addr)
		{
			return ReadOpenBus();
		}

		public virtual int ReadDE00(int addr)
		{
			return ReadOpenBus();
		}

		public virtual int ReadDF00(int addr)
		{
			return ReadOpenBus();
		}

		public bool Reset => pinReset;

		protected abstract void SyncStateInternal(Serializer ser);

		public virtual void SyncState(Serializer ser)
		{
			ser.Sync(nameof(pinExRom), ref pinExRom);
			ser.Sync(nameof(pinGame), ref pinGame);
			ser.Sync(nameof(pinIRQ), ref pinIRQ);
			ser.Sync(nameof(pinNMI), ref pinNMI);
			ser.Sync(nameof(pinReset), ref pinReset);

			ser.Sync(nameof(_driveLightEnabled), ref _driveLightEnabled);
			ser.Sync(nameof(_driveLightOn), ref _driveLightOn);
		}

		public bool Valid => validCartridge;

		public virtual void Write8000(int addr, int val)
		{
		}

		public virtual void WriteA000(int addr, int val)
		{
		}

		public virtual void WriteDE00(int addr, int val)
		{
		}

		public virtual void WriteDF00(int addr, int val)
		{
		}

		private bool _driveLightEnabled;
		private bool _driveLightOn;

		public bool DriveLightEnabled
		{
			get { return _driveLightEnabled; }
			protected set { _driveLightEnabled = value; }
		}

		public bool DriveLightOn
		{
			get { return _driveLightOn; }
			protected set { _driveLightOn = value; }
		}
	}
}