using System;
using System.Collections.Generic;
using System.IO;

using ICSharpCode.SharpZipLib.Zip;

namespace BizHawk.Client.Common
{
	public enum BinaryStateLump
	{
		Versiontag,
		Corestate,
		Framebuffer,
		Input,
		CorestateText,
		Movieheader
	}

	public class BinaryStateFileNames
	{
		/*
		public const string Versiontag = "BizState 1.0";
		public const string Corestate = "Core";
		public const string Framebuffer = "Framebuffer";
		public const string Input = "Input Log";
		public const string CorestateText = "CoreText";
		public const string Movieheader = "Header";
		*/

		private static readonly Dictionary<BinaryStateLump, string> LumpNames;

		static BinaryStateFileNames()
		{
			LumpNames = new Dictionary<BinaryStateLump, string>();
			LumpNames[BinaryStateLump.Versiontag] = "BizState 1.0";
			LumpNames[BinaryStateLump.Corestate] = "Core";
			LumpNames[BinaryStateLump.Framebuffer] = "Framebuffer";
			LumpNames[BinaryStateLump.Input] = "Input Log";
			LumpNames[BinaryStateLump.CorestateText] = "CoreText";
			LumpNames[BinaryStateLump.Movieheader] = "Header";
		}

		public static string Get(BinaryStateLump lump)
		{
			return LumpNames[lump];
		}
	}

	/// <summary>
	/// more accurately should be called ZipStateLoader, as it supports both text and binary core data
	/// </summary>
	public class BinaryStateLoader : IDisposable
	{
		private ZipFile _zip;
		private Version _ver;
		private bool _isDisposed;

		private BinaryStateLoader()
		{
		}

		public void Dispose()
		{
			Dispose(true);
			GC.SuppressFinalize(this);
		}

		protected virtual void Dispose(bool disposing)
		{
			if (!_isDisposed)
			{
				_isDisposed = true;

				if (disposing)
				{
					_zip.Close();
				}
			}
		}

		private void ReadVersion(Stream s)
		{
			// the "BizState 1.0" tag contains an integer in it describing the sub version.
			if (s.Length == 0)
			{
				_ver = new Version(1, 0, 0); // except for the first release, which doesn't
			}
			else
			{
				var sr = new StreamReader(s);
				_ver = new Version(1, 0, int.Parse(sr.ReadLine()));
			}

			Console.WriteLine("Read a zipstate of version {0}", _ver);
		}

		public static BinaryStateLoader LoadAndDetect(string filename)
		{
			var ret = new BinaryStateLoader();

			// PORTABLE TODO - SKIP THIS.. FOR NOW
			// check whether its an archive before we try opening it
			bool isArchive;
			using (var archiveChecker = new SevenZipSharpArchiveHandler())
			{
				int offset;
				bool isExecutable;
				isArchive = archiveChecker.CheckSignature(filename, out offset, out isExecutable);
			}

			if (!isArchive)
			{
				return null;
			}

			try
			{
				ret._zip = new ZipFile(filename);
				if (!ret.GetLump(BinaryStateLump.Versiontag, false, ret.ReadVersion))
				{
					ret._zip.Close();
					return null;
				}

				return ret;
			}
			catch (ZipException)
			{
				return null;
			}
		}

		/// <summary>
		/// Gets a lump
		/// </summary>
		/// <param name="lump">lump to retriever</param>
		/// <param name="abort">true to throw exception on failure</param>
		/// <param name="callback">function to call with the desired stream</param>
		/// <returns>true if callback was called and stream was loaded</returns>
		public bool GetLump(BinaryStateLump lump, bool abort, Action<Stream> callback)
		{
			var name = BinaryStateFileNames.Get(lump);
			var e = _zip.GetEntry(name);
			if (e != null)
			{
				using (var zs = _zip.GetInputStream(e))
				{
					callback(zs);
				}

				return true;
			}
			
			if (abort)
			{
				throw new Exception("Essential zip section not found: " + name);
			}
			
			return false;
		}

		public bool GetLump(BinaryStateLump lump, bool abort, Action<BinaryReader> callback)
		{
			return GetLump(lump, abort, delegate(Stream s)
			{
				var br = new BinaryReader(s);
				callback(br);
			});
		}

		public bool GetLump(BinaryStateLump lump, bool abort, Action<TextReader> callback)
		{
			return GetLump(lump, abort, delegate(Stream s)
			{
				var tr = new StreamReader(s);
				callback(tr);
			});
		}

		/// <summary>
		/// load binary state, or text state if binary state lump doesn't exist
		/// </summary>
		public void GetCoreState(Action<Stream> callbackBinary, Action<Stream> callbackText)
		{
			if (!GetLump(BinaryStateLump.Corestate, false, callbackBinary)
			    && !GetLump(BinaryStateLump.CorestateText, false, callbackText))
			{
				throw new Exception("Couldn't find Binary or Text savestate");
			}
		}

		public void GetCoreState(Action<BinaryReader> callbackBinary, Action<TextReader> callbackText)
		{
			if (!GetLump(BinaryStateLump.Corestate, false, callbackBinary)
			    && !GetLump(BinaryStateLump.CorestateText, false, callbackText))
			{
				throw new Exception("Couldn't find Binary or Text savestate");
			}
		}
	}

	public class BinaryStateSaver : IDisposable
	{
		private readonly ZipOutputStream _zip;
		private bool _isDisposed;

		private static void WriteVersion(Stream s)
		{
			var sw = new StreamWriter(s);
			sw.WriteLine("1"); // version 1.0.1
			sw.Flush();
		}

		/// <summary>
		/// 
		/// </summary>
		/// <param name="s">not closed when finished!</param>
		public BinaryStateSaver(Stream s)
		{
			_zip = new ZipOutputStream(s)
				{
					IsStreamOwner = false,
					UseZip64 = UseZip64.Off
				};
			_zip.SetLevel(5);

			PutLump(BinaryStateLump.Versiontag, WriteVersion);	
		}

		public void PutLump(BinaryStateLump lump, Action<Stream> callback)
		{
			var name = BinaryStateFileNames.Get(lump);
			var e = new ZipEntry(name) {CompressionMethod = CompressionMethod.Deflated};
			_zip.PutNextEntry(e);
			callback(_zip);
			_zip.CloseEntry();
		}

		public void PutLump(BinaryStateLump lump, Action<BinaryWriter> callback)
		{
			PutLump(lump, delegate(Stream s)
			{
				var bw = new BinaryWriter(s);
				callback(bw);
				bw.Flush();
			});
		}

		public void PutLump(BinaryStateLump lump, Action<TextWriter> callback)
		{
			PutLump(lump, delegate(Stream s)
			{
				TextWriter tw = new StreamWriter(s);
				callback(tw);
				tw.Flush();
			});
		}

		public void Dispose()
		{
			Dispose(true);
			GC.SuppressFinalize(this);
		}

		protected virtual void Dispose(bool disposing)
		{
			if (!_isDisposed)
			{
				_isDisposed = true;

				if (disposing)
				{
					_zip.Close();
				}
			}
		}
	}
}