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

using LuaInterface;
using BizHawk.Emulation.Common.IEmulatorExtensions;


namespace BizHawk.Client.Common
{
	public sealed class MemorySavestateEmuLuaLibrary : LuaLibraryBase
	{
		public MemorySavestateEmuLuaLibrary(Lua lua)
			: base(lua) { }

		public MemorySavestateEmuLuaLibrary(Lua lua, Action<string> logOutputCallback)
			: base(lua, logOutputCallback) { }

		public override string Name { get { return "memorysavestate"; } }

		private readonly Dictionary<Guid, byte[]> MemorySavestates = new Dictionary<Guid, byte[]>();

		[LuaMethodAttributes(
			"savecorestate",
			"creates a core savestate and stores it in memory.  Note: a core savestate is only the raw data from the core, and not extras such as movie input logs, or framebuffers. Returns a unique identifer for the savestate"
		)]
		public Guid SaveCoreStateToMemory()
		{
			if (Global.Emulator.HasSavestates())
			{
				var guid = Guid.NewGuid();
				var bytes = Global.Emulator.AsStatable().SaveStateBinary();

				MemorySavestates.Add(guid, bytes);

				return guid;
			}
			else
			{
				Log("Savestates not supported on this core");
				return Guid.Empty;
			}
		}

		[LuaMethodAttributes(
			"loadcorestate",
			"loads an in memory state with the given identifier"
		)]
		public void LoadCoreStateFromMemory(string identifier)
		{
			var guid = new Guid(identifier);

			if (Global.Emulator.HasSavestates())
			{
				try
				{
					var statableCore = Global.Emulator.AsStatable();
					var state = MemorySavestates[guid];

					using (MemoryStream ms = new MemoryStream(state))
					using (BinaryReader br = new BinaryReader(ms))
					{
						statableCore.LoadStateBinary(br);
					}
				}
				catch
				{
					Log("Unable to find the given savestate in memory");
				}
			}
			else
			{
				Log("Savestates not supported on this core");
			}
		}

		[LuaMethodAttributes(
			"removestate",
			"removes the savestate with the given identifier from memory"
		)]
		public void DeleteState(string identifier)
		{
			var guid = new Guid(identifier);
			MemorySavestates.Remove(guid);
		}

		[LuaMethodAttributes(
			"clearstatesfrommemory",
			"clears all savestates stored in memory"
		)]
		public void ClearInMemoryStates()
		{
			MemorySavestates.Clear();
		}
	}
}