using System;
using System.Linq;
using System.IO;
using System.Reflection;

using BizHawk.Emulation.Common;
using BizHawk.Emulation.Cores.Nintendo.SNES;

namespace BizHawk.Client.Common
{
	public static class PathManager
	{
		public static string GetExeDirectoryAbsolute()
		{
			var path = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location);
			if (path.EndsWith(Path.DirectorySeparatorChar.ToString()))
			{
				path = path.Remove(path.Length - 1, 1);
			}

			return path;
		}

		/// <summary>
		/// Makes a path relative to the %exe% dir
		/// </summary>
		public static string MakeProgramRelativePath(string path) { return MakeAbsolutePath("%exe%/" + path, null); }

		/// <summary>
		/// The location of the default INI file
		/// </summary>
		public static string DefaultIniPath
		{
			get 
			{
				return MakeProgramRelativePath("config.ini");
			} 
		}

		/// <summary>
		/// Gets absolute base as derived from EXE
		/// </summary>
		/// <returns></returns>
		public static string GetBasePathAbsolute()
		{
			if (Global.Config.PathEntries.GlobalBaseFragment.Length < 1) // If empty, then EXE path
			{
				return GetExeDirectoryAbsolute();
			}

			if (Global.Config.PathEntries.GlobalBaseFragment.Length >= 5
			    && Global.Config.PathEntries.GlobalBaseFragment.Substring(0, 5) == "%exe%")
			{
				return GetExeDirectoryAbsolute();
			}

			if (Global.Config.PathEntries.GlobalBaseFragment[0] == '.')
			{
				if (Global.Config.PathEntries.GlobalBaseFragment.Length == 1)
				{
					return GetExeDirectoryAbsolute();
				}

				if (Global.Config.PathEntries.GlobalBaseFragment.Length == 2 &&
				    Global.Config.PathEntries.GlobalBaseFragment == ".\\")
				{
					return GetExeDirectoryAbsolute();
				}
				
				var tmp = Global.Config.PathEntries.GlobalBaseFragment.Remove(0, 1);
				tmp = tmp.Insert(0, GetExeDirectoryAbsolute());
				return tmp;
			}

			if (Global.Config.PathEntries.GlobalBaseFragment.Substring(0, 2) == "..")
			{
				return RemoveParents(Global.Config.PathEntries.GlobalBaseFragment, GetExeDirectoryAbsolute());
			}

			// In case of error, return EXE path
			return GetExeDirectoryAbsolute();
		}

		public static string GetPlatformBase(string system)
		{
			return Global.Config.PathEntries[system, "Base"].Path;
		}

		public static string StandardFirmwareName(string name)
		{
			return Path.Combine(MakeAbsolutePath(Global.Config.PathEntries.FirmwaresPathFragment, null), name);
		}

		public static string MakeAbsolutePath(string path, string system)
		{
			// Hack
			if (system == "Global")
			{
				system = null;
			}

			// This function translates relative path and special identifiers in absolute paths

			if (path.Length < 1)
			{
				return GetBasePathAbsolute();
			}

			if (path == "%recent%")
			{
				return Environment.SpecialFolder.Recent.ToString();
			}

			if (path.Length >= 5 && path.Substring(0, 5) == "%exe%")
			{
				if (path.Length == 5)
				{
					return GetExeDirectoryAbsolute();
				}
				
				var tmp = path.Remove(0, 5);
				tmp = tmp.Insert(0, GetExeDirectoryAbsolute());
				return tmp;
			}

			if (path[0] == '.')
			{
				if (!string.IsNullOrWhiteSpace(system))
				{
					path = path.Remove(0, 1);
					path = path.Insert(0, GetPlatformBase(system));
				}

				if (path.Length == 1)
				{
					return GetBasePathAbsolute();
				}
				
				if (path[0] == '.')
				{
					path = path.Remove(0, 1);
					path = path.Insert(0, GetBasePathAbsolute());
				}

				return path;
			}

			// If begins wtih .. do alorithm to determine how many ..\.. combos and deal with accordingly, return drive letter only if too many ..
			if ((path[0] > 'A' && path[0] < 'Z') || (path[0] > 'a' && path[0] < 'z'))
			{
				// C:\
				if (path.Length > 2 && path[1] == ':' && path[2] == '\\')
				{
					return path;
				}
				
				// file:\ is an acceptable path as well, and what FileBrowserDialog returns
				if (path.Length >= 6 && path.Substring(0, 6) == "file:\\")
				{
					return path;
				}

				return GetExeDirectoryAbsolute(); // bad path
			}

			// all pad paths default to EXE
			return GetExeDirectoryAbsolute();
		}

		public static string RemoveParents(string path, string workingpath)
		{
			// determines number of parents, then removes directories from working path, return absolute path result
			// Ex: "..\..\Bob\", "C:\Projects\Emulators\Bizhawk" will return "C:\Projects\Bob\" 
			int x = NumParentDirectories(path);
			if (x > 0)
			{
				int y = StringHelpers.HowMany(path, "..\\");
				int z = StringHelpers.HowMany(workingpath, "\\");
				if (y >= z)
				{
					//Return drive letter only, working path must be absolute?
				}

				return string.Empty;
			}

			return path;
		}

		public static int NumParentDirectories(string path)
		{
			// determine the number of parent directories in path and return result
			int x = StringHelpers.HowMany(path, '\\');
			if (x > 0)
			{
				return StringHelpers.HowMany(path, "..\\");
			}

			return 0;
		}

		public static bool IsRecent(string path)
		{
			return path == "%recent%";
		}

		public static string GetLuaPath()
		{
			return MakeAbsolutePath(Global.Config.PathEntries.LuaPathFragment, null);
		}

		public static string GetRomsPath(string sysID)
		{
			if (Global.Config.UseRecentForROMs)
			{
				return Environment.SpecialFolder.Recent.ToString();
			}

			var path = Global.Config.PathEntries[sysID, "ROM"] ?? Global.Config.PathEntries[sysID, "Base"];

			return MakeAbsolutePath(path.Path, sysID);
		}

		public static string RemoveInvalidFileSystemChars(string name)
		{
			var newStr = name;
			var chars = Path.GetInvalidFileNameChars();
			return chars.Aggregate(newStr, (current, c) => current.Replace(c.ToString(), string.Empty));
		}

		public static string FilesystemSafeName(GameInfo game)
		{
			var filesystemSafeName = game.Name.Replace("|", "+");
			filesystemSafeName = RemoveInvalidFileSystemChars(filesystemSafeName);

			// zero 22-jul-2012 - i dont think this is used the same way it used to. game.Name shouldnt be a path, so this stuff is illogical.
			// if game.Name is a path, then someone shouldve made it not-a-path already.
			// return Path.Combine(Path.GetDirectoryName(filesystemSafeName), Path.GetFileNameWithoutExtension(filesystemSafeName));
			return filesystemSafeName;
		}

		public static string SaveRamPath(GameInfo game)
		{
			var name = FilesystemSafeName(game);
			if (Global.MovieSession.Movie.IsActive)
			{
				name += "." + Path.GetFileNameWithoutExtension(Global.MovieSession.Movie.Filename);
			}

			var pathEntry = Global.Config.PathEntries[game.System, "Save RAM"] ??
			                Global.Config.PathEntries[game.System, "Base"];

			return Path.Combine(MakeAbsolutePath(pathEntry.Path, game.System), name) + ".SaveRAM";
		}

		public static string GetSaveStatePath(GameInfo game)
		{
			var pathEntry = Global.Config.PathEntries[game.System, "Savestates"] ??
			                Global.Config.PathEntries[game.System, "Base"];

			return MakeAbsolutePath(pathEntry.Path, game.System);
		}

		public static string SaveStatePrefix(GameInfo game)
		{
			var name = FilesystemSafeName(game);

			// Neshawk and Quicknes have incompatible savestates, store the name to keep them separate
			if (Global.Emulator.SystemId == "NES")
			{
				name += "." + Global.Emulator.Attributes().CoreName;
			}

			// Bsnes profiles have incompatible savestates so save the profile name
			if (Global.Emulator is LibsnesCore)
			{
				name += "." + ((LibsnesCore.SnesSyncSettings)Global.Emulator.GetSyncSettings()).Profile;
			}

			if (Global.MovieSession.Movie.IsActive)
			{
				name += "." + Path.GetFileNameWithoutExtension(Global.MovieSession.Movie.Filename);
			}

			var pathEntry = Global.Config.PathEntries[game.System, "Savestates"] ??
			                Global.Config.PathEntries[game.System, "Base"];

			return Path.Combine(MakeAbsolutePath(pathEntry.Path, game.System), name);
		}

		public static string GetCheatsPath(GameInfo game)
		{
			var pathEntry = Global.Config.PathEntries[game.System, "Cheats"] ??
			                Global.Config.PathEntries[game.System, "Base"];

			return MakeAbsolutePath(pathEntry.Path, game.System);
		}

		public static string ScreenshotPrefix(GameInfo game)
		{
			var name = FilesystemSafeName(game);

			var pathEntry = Global.Config.PathEntries[game.System, "Screenshots"] ??
			                Global.Config.PathEntries[game.System, "Base"];

			return Path.Combine(MakeAbsolutePath(pathEntry.Path, game.System), name);
		}

		/// <summary>
		/// Takes an absolute path and attempts to convert it to a relative, based on the system, 
		/// or global base if no system is supplied, if it is not a subfolder of the base, it will return the path unaltered
		/// </summary>
		/// <param name="absolutePath"></param>
		/// <param name="system"></param>
		/// <returns></returns>
		public static string TryMakeRelative(string absolutePath, string system = null)
		{
			var parentPath = string.IsNullOrWhiteSpace(system) ?
				GetBasePathAbsolute() :
				MakeAbsolutePath(GetPlatformBase(system), system);

			if (IsSubfolder(parentPath, absolutePath))
			{
				return absolutePath.Replace(parentPath, ".");
			}
			
			return absolutePath;
		}

		//http://stackoverflow.com/questions/3525775/how-to-check-if-directory-1-is-a-subdirectory-of-dir2-and-vice-versa
		public static bool IsSubfolder(string parentPath, string childPath)
		{
			var parentUri = new Uri(parentPath);

			var childUri = new DirectoryInfo(childPath).Parent;

			while (childUri != null)
			{
				if (new Uri(childUri.FullName) == parentUri)
				{
					return true;
				}

				childUri = childUri.Parent;
			}

			return false;
		}
	}
}