using System;
using System.Collections.Generic;
using System.Linq;

using BizHawk.Common;
using BizHawk.Emulation.Common;
using BizHawk.Emulation.DiscSystem;
using System.IO;
using BizHawk.Emulation.Cores.Consoles.Sega.gpgx;
using BizHawk.Emulation.Cores.Sega.Saturn;
using BizHawk.Emulation.Cores.Sony.PSP;
using BizHawk.Emulation.Cores.Sony.PSX;
using BizHawk.Emulation.Cores.PCEngine;
using BizHawk.Emulation.Cores.Nintendo.Gameboy;
using BizHawk.Emulation.Cores.Nintendo.SNES;
using BizHawk.Emulation.Cores.Sega.MasterSystem;
using BizHawk.Emulation.Cores.Nintendo.NES;
using BizHawk.Emulation.Cores.Intellivision;
using BizHawk.Emulation.Cores.ColecoVision;
using BizHawk.Emulation.Cores.Nintendo.GBA;
using BizHawk.Emulation.Cores.Atari.Atari7800;
using BizHawk.Emulation.Cores.Computers.Commodore64;
using BizHawk.Emulation.Cores.Calculators;
using BizHawk.Emulation.Cores.Atari.Atari2600;
using BizHawk.Emulation.Cores.Nintendo.N64;

namespace BizHawk.Client.Common
{
	public class RomLoader
	{
		// helper methods for the settings events
		
		object GetCoreSettings<T>()
			where T : IEmulator
		{
			var e = new SettingsLoadArgs(typeof(T));
			if (OnLoadSettings != null)
				OnLoadSettings(this, e);
			return e.Settings;
		}

		object GetCoreSyncSettings<T>()
			where T : IEmulator
		{
			var e = new SettingsLoadArgs(typeof(T));
			if (OnLoadSyncSettings != null)
				OnLoadSyncSettings(this, e);
			return e.Settings;
		}

		public RomLoader()
		{
			Deterministic = true;
		}

		// TODO: reconsider the need for exposing these;
		public IEmulator LoadedEmulator { get; private set; }
		public CoreComm NextComm { get; private set; }
		public GameInfo Game { get; private set; }
		public RomGame Rom { get; private set; }
		public string CanonicalFullPath { get; private set; }

		public bool Deterministic { get; private set; }

		public class RomErrorArgs
		{
			// TODO: think about naming here, what to pass, a lot of potential good information about what went wrong could go here!
			public RomErrorArgs(string message, string systemId)
			{
				Message = message;
				AttemptedCoreLoad = systemId;
			}

			public string Message { get; private set; }
			public string AttemptedCoreLoad { get; private set; }
		}

		public class SettingsLoadArgs
		{
			public object Settings { get; set; }
			public Type Core { get; private set; }
			public SettingsLoadArgs(Type t)
			{
				Core = t;
				Settings = null;
			}
		}
		public delegate void SettingsLoadEventHandler(object sender, SettingsLoadArgs e);
		public event SettingsLoadEventHandler OnLoadSettings;
		public event SettingsLoadEventHandler OnLoadSyncSettings;


		public delegate void LoadErrorEventHandler(object sener, RomErrorArgs e);
		public event LoadErrorEventHandler OnLoadError;

		public Func<HawkFile, int?> ChooseArchive;

		public Action<string> CoreCommMessageCallback; // TODO: eww, do we have to do this?

		private int? HandleArchive(HawkFile file)
		{
			if (ChooseArchive != null)
			{
				return ChooseArchive(file);
			}

			return null;
		}

		private void ThrowLoadError(string message, string systemId)
		{
			if (OnLoadError != null)
			{
				OnLoadError(this, new RomErrorArgs(message, systemId));
			}
		}

		// TODO I'm in mainform.cs and here, move me to a common place that both can call, static method on the config object?
		private void CommitCoreSettingsToConfig()
		{
			// save settings object
			Type t = Global.Emulator.GetType();
			Global.Config.PutCoreSettings(Global.Emulator.GetSettings(), t);
			
			// don't trample config with loaded-from-movie settings
			if (!Global.MovieSession.Movie.IsActive)
			{
				Global.Config.PutCoreSyncSettings(Global.Emulator.GetSyncSettings(), t);
			}
		}

		// TODO: the hasMovie hack should be obsoleted by the standardized movie sync setting saving/loading
		public bool LoadRom(string path, bool hasmovie = false)
		{
			if (path == null)
			{
				return false;
			}

			using (var file = new HawkFile())
			{
				var romExtensions = new[] { "SMS", "SMC", "SFC", "PCE", "SGX", "GG", "SG", "BIN", "GEN", "MD", "SMD", "GB", "NES", "FDS", "ROM", "INT", "GBC", "UNF", "A78", "CRT", "COL", "XML", "Z64", "V64", "N64" };

				// lets not use this unless we need to
				// file.NonArchiveExtensions = romExtensions;
				file.Open(path);

				// if the provided file doesnt even exist, give up!
				if (!file.Exists)
				{
					return false;
				}

				// try binding normal rom extensions first
				if (!file.IsBound)
				{
					file.BindSoleItemOf(romExtensions);
				}

				// if we have an archive and need to bind something, then pop the dialog
				if (file.IsArchive && !file.IsBound)
				{
					var result = ChooseArchive(file);
					if (result.HasValue)
					{
						file.BindArchiveMember(result.Value);
					}
					else
					{
						return false;
					}
				}

				IEmulator nextEmulator = null;
				RomGame rom = null;
				GameInfo game = null;
				var nextComm = new CoreComm(CoreCommMessageCallback);
				CoreFileProvider.SyncCoreCommInputSignals(nextComm);

				// this also happens in CloseGame().  but it needs to happen here since if we're restarting with the same core,
				// any settings changes that we made need to make it back to config before we try to instantiate that core with
				// the new settings objects
				CommitCoreSettingsToConfig();

				try
				{
					var ext = file.Extension.ToLower();
					if (ext == ".iso" || ext == ".cue")
					{
						var disc = ext == ".iso" ? Disc.FromIsoPath(path) : Disc.FromCuePath(path, new CueBinPrefs());
						var hash = disc.GetHash();
						game = Database.CheckDatabase(hash);
						if (game == null)
						{
							// try to use our wizard methods
							game = new GameInfo { Name = Path.GetFileNameWithoutExtension(file.Name), Hash = hash };

							switch (disc.DetectDiscType())
							{
								case DiscType.SegaSaturn:
									game.System = "SAT";
									break;
								case DiscType.SonyPSP:
									game.System = "PSP";
									break;
								case DiscType.SonyPSX:
									game.System = "PSX";
									break;
								case DiscType.MegaCD:
									game.System = "GEN";
									break;
								case DiscType.TurboCD:
								case DiscType.UnknownCDFS:
								case DiscType.UnknownFormat:
								default: // PCECD was bizhawk's first CD core,
									// and during that time, all CDs were blindly sent to it
									// so this prevents regressions
									game.System = "PCECD";
									break;
							}
						}

						switch (game.System)
						{
							case "GEN":
								{
									var genesis = new GPGX(
										nextComm, null, disc, "GEN", GetCoreSettings<GPGX>());
									nextEmulator = genesis;
								}
								break;
							case "SAT":
								{
									var saturn = new Yabause(nextComm, disc, GetCoreSyncSettings<Yabause>());
									nextEmulator = saturn;
								}
								break;
							case "PSP":
								{
									var psp = new PSP(nextComm, file.Name);
									nextEmulator = psp;
								}
								break;
							case "PSX":
								{
									var psx = new Octoshock(nextComm);
									nextEmulator = psx;
									psx.LoadCuePath(file.CanonicalFullPath);
									nextEmulator.CoreComm.RomStatusDetails = "PSX etc.";
								}
								break;
							case "PCE":
							case "PCECD":
								{
									var biosPath = Global.FirmwareManager.Request("PCECD", "Bios");
									if (File.Exists(biosPath) == false)
									{
										ThrowLoadError("PCE-CD System Card not found. Please check the BIOS path in Config->Paths->PC Engine."
											, game.System);
										return false;
									}

									rom = new RomGame(new HawkFile(biosPath));

									if (rom.GameInfo.Status == RomStatus.BadDump)
									{
										ThrowLoadError(
											"The PCE-CD System Card you have selected is known to be a bad dump. This may cause problems playing PCE-CD games.\n\n"
											+ "It is recommended that you find a good dump of the system card. Sorry to be the bearer of bad news!"
											, game.System);
									}
									else if (rom.GameInfo.NotInDatabase)
									{
										ThrowLoadError(
											"The PCE-CD System Card you have selected is not recognized in our database. That might mean it's a bad dump, or isn't the correct rom."
											, game.System);
									}
									else if (rom.GameInfo["BIOS"] == false)
									{
										ThrowLoadError(
											"The PCE-CD System Card you have selected is not a BIOS image. You may have selected the wrong rom."
											, game.System);
									}

									if (rom.GameInfo["SuperSysCard"])
									{
										game.AddOption("SuperSysCard");
									}

									if (game["NeedSuperSysCard"] && game["SuperSysCard"] == false)
									{
										ThrowLoadError(
											"This game requires a version 3.0 System card and won't run with the system card you've selected. Try selecting a 3.0 System Card in Config->Paths->PC Engine."
											, game.System);
									}

									game.FirmwareHash = Util.Hash_SHA1(rom.RomData);
									nextEmulator = new PCEngine(nextComm, game, disc, rom.RomData, GetCoreSettings<PCEngine>());
									break;
								}
						}
					}
					else if (file.Extension.ToLower() == ".xml")
					{
						try
						{
							var XMLG = XmlGame.Create(file); // if load fails, are we supposed to retry as a bsnes XML????????
							game = XMLG.GI;

							switch (game.System)
							{
								case "DGB":

									var L = Database.GetGameInfo(XMLG.Assets["LeftRom"], "left.gb");
									var R = Database.GetGameInfo(XMLG.Assets["RightRom"], "right.gb");

									var gbl = new GambatteLink(nextComm, L, XMLG.Assets["LeftRom"], R, XMLG.Assets["RightRom"],
										GetCoreSettings<GambatteLink>(),
										GetCoreSyncSettings<GambatteLink>());
									nextEmulator = gbl;

									// other stuff todo
									break;

								default:
									return false;
							}
						}
						catch (Exception ex)
						{
							ThrowLoadError(ex.ToString(), "XMLGame Load Error"); // TODO: don't pass in XMLGame Load Error as a system ID
						}
					}
					else // most extensions
					{
						rom = new RomGame(file);
						game = rom.GameInfo;

						bool isXml = false;

						// other xml has already been handled
						if (file.Extension.ToLower() == ".xml")
						{
							game.System = "SNES";
							isXml = true;
						}

						switch (game.System)
						{
							case "SNES":
								{
									// need to get rid of this hack at some point
									((CoreFileProvider)nextComm.CoreFileProvider).SubfileDirectory = Path.GetDirectoryName(path.Replace("|", string.Empty)); //Dirty hack to get around archive filenames (since we are just getting the directory path, it is safe to mangle the filename

									var snes = new LibsnesCore(nextComm, GetCoreSettings<LibsnesCore>(), GetCoreSyncSettings<LibsnesCore>());
									nextEmulator = snes;
									byte[] romData = isXml ? null : rom.FileData;
									byte[] xmlData = isXml ? rom.FileData : null;
									snes.Load(game, romData, Deterministic, xmlData);
								}
								break;
							case "SMS":
							case "SG":
							case "GG":
								nextEmulator = new SMS(nextComm, game, rom.RomData, GetCoreSettings<SMS>(), GetCoreSyncSettings<SMS>());
								break;
							case "A26":
								nextEmulator = new Atari2600(nextComm, game, rom.FileData,
									GetCoreSettings<Atari2600>(),
									GetCoreSyncSettings<Atari2600>());
								break;
							case "PCE":
							case "PCECD":
							case "SGX":
								nextEmulator = new PCEngine(nextComm, game, rom.RomData, GetCoreSettings<PCEngine>());
								break;
							case "GEN":
								{
									// nextEmulator = new Genesis(nextComm, game, rom.RomData);
									nextEmulator = new GPGX(nextComm, rom.RomData, null, "GEN", GetCoreSyncSettings<GPGX>());
									break;
								}
							case "TI83":
								nextEmulator = new TI83(nextComm, game, rom.RomData);
								break;
							case "NES":
								nextEmulator = new NES(nextComm, game, rom.FileData,
									GetCoreSettings<NES>(),
									Global.MovieSession.Movie.Header.BoardProperties);
								break;
							case "GB":
							case "GBC":
								if (!Global.Config.GB_AsSGB)
								{
									var gb = new Gameboy(nextComm, game, rom.FileData,
										GetCoreSettings<Gameboy>(),
										GetCoreSyncSettings<Gameboy>());
									nextEmulator = gb;
								}
								else
								{
									try
									{
										game.System = "SNES";
										game.AddOption("SGB");
										var snes = new LibsnesCore(nextComm, GetCoreSettings<LibsnesCore>(), GetCoreSyncSettings<LibsnesCore>());
										nextEmulator = snes;
										snes.Load(game, rom.FileData, Deterministic, null);
									}
									catch
									{
										// failed to load SGB bios.  to avoid catch-22, disable SGB mode
										ThrowLoadError("Failed to load a GB rom in SGB mode.  Disabling SGB Mode."
											, game.System);
										Global.Config.GB_AsSGB = false;
										throw;
									}
								}
								break;
							case "Coleco":
								{
									var c = new ColecoVision(nextComm, game, rom.RomData, GetCoreSyncSettings<ColecoVision>());
									nextEmulator = c;
								}
								break;
							case "INTV":
								{
									var intv = new Intellivision(nextComm, game, rom.RomData);
									nextEmulator = intv;
								}
								break;
							case "A78":
								var gamedbpath = Path.Combine(PathManager.GetExeDirectoryAbsolute(), "gamedb", "EMU7800.csv");
								var a78 = new Atari7800(nextComm, game, rom.RomData, gamedbpath);
								nextEmulator = a78;
								break;
							case "C64":
								C64 c64 = new C64(nextComm, game, rom.RomData, rom.Extension);
								c64.HardReset();
								nextEmulator = c64;
								break;
							case "GBA":
								if (VersionInfo.INTERIM)
								{
									GBA gba = new GBA(nextComm);
									gba.Load(rom.RomData);
									nextEmulator = gba;
								}
								break;
							case "N64":
								Global.Game = game;
								nextEmulator = new N64(nextComm, game, rom.RomData, GetCoreSyncSettings<N64>());
								break;

							case "DEBUG":
								if (VersionInfo.INTERIM)
								{
									nextEmulator = LibRetroEmulator.CreateDebug(nextComm, rom.RomData);
								}
								break;
						}
					}

					if (nextEmulator == null)
					{
						ThrowLoadError("No core could load the rom.", "NULL");
						return false;
					}
				}
				catch (Exception ex)
				{
					ThrowLoadError("Exception during loadgame:\n\n" + ex, "NULL");
					return false;
				}
				Rom = rom;
				LoadedEmulator = nextEmulator;
				NextComm = nextComm;
				Game = game;
				CanonicalFullPath = file.CanonicalFullPath;
				return true;
			}
		}
	}
}