using System;
using System.Linq;
using System.ComponentModel;

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

using BizHawk.Emulation.Cores.Nintendo.N64;

namespace BizHawk.Client.Common
{
	[Description("A library for registering lua functions to emulator events.\n All events support multiple registered methods.\nAll registered event methods can be named and return a Guid when registered")]
	public sealed class EventLuaLibrary : LuaLibraryBase
	{
		[OptionalService]
		private IInputPollable InputPollableCore { get; set; }

		[OptionalService]
		private IDebuggable DebuggableCore { get; set; }

		[RequiredService]
		private IEmulator Emulator { get; set; }

		private readonly LuaFunctionList _luaFunctions = new LuaFunctionList();

		public EventLuaLibrary(Lua lua)
			: base(lua) { }

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

		public override string Name => "event";

		#region Events Library Helpers

		public void CallExitEvent(Lua thread)
		{
			var exitCallbacks = _luaFunctions.Where(l => l.Lua == thread && l.Event == "OnExit");
			foreach (var exitCallback in exitCallbacks)
			{
				exitCallback.Call();
			}
		}

		public LuaFunctionList RegisteredFunctions => _luaFunctions;

		public void CallSaveStateEvent(string name)
		{
			var lfs = _luaFunctions.Where(l => l.Event == "OnSavestateSave").ToList();
			if (lfs.Any())
			{
				try
				{
					foreach (var lf in lfs)
					{
						lf.Call(name);
					}
				}
				catch (Exception e)
				{
					Log(
						"error running function attached by lua function event.onsavestate" +
						"\nError message: " +
						e.Message);
				}
			}
		}

		public void CallLoadStateEvent(string name)
		{
			var lfs = _luaFunctions.Where(l => l.Event == "OnSavestateLoad").ToList();
			if (lfs.Any())
			{
				try
				{
					foreach (var lf in lfs)
					{
						lf.Call(name);
					}
				}
				catch (Exception e)
				{
					Log(
						"error running function attached by lua function event.onloadstate" +
						"\nError message: " +
						e.Message);
				}
			}
		}

		public void CallFrameBeforeEvent()
		{
			var lfs = _luaFunctions.Where(l => l.Event == "OnFrameStart").ToList();
			if (lfs.Any())
			{
				try
				{
					foreach (var lf in lfs)
					{
						lf.Call();
					}
				}
				catch (Exception e)
				{
					Log(
						"error running function attached by lua function event.onframestart" +
						"\nError message: " +
						e.Message);
				}
			}
		}

		public void CallFrameAfterEvent()
		{
			var lfs = _luaFunctions.Where(l => l.Event == "OnFrameEnd").ToList();
			if (lfs.Any())
			{
				try
				{
					foreach (var lf in lfs)
					{
						lf.Call();
					}
				}
				catch (Exception e)
				{
					Log(
						"error running function attached by lua function event.onframeend" +
						"\nError message: " +
						e.Message);
				}
			}
		}

		private bool N64CoreTypeDynarec()
		{
			if ((Emulator as N64)?.GetSyncSettings().Core == N64SyncSettings.CoreType.Dynarec)
			{
				Log("N64 Error: Memory callbacks are not implemented for Dynamic Recompiler core type\nUse Interpreter or Pure Interpreter\n");
				return true;
			}

			return false;
		}

		private void LogMemoryCallbacksNotImplemented()
		{
			Log($"{Emulator.Attributes().CoreName} does not implement memory callbacks");
		}

		private void LogMemoryExecuteCallbacksNotImplemented()
		{
			Log($"{Emulator.Attributes().CoreName} does not implement memory execute callbacks");
		}

		#endregion

		[LuaMethodAttributes(
			"onframeend", "Calls the given lua function at the end of each frame, after all emulation and drawing has completed. Note: this is the default behavior of lua scripts")]
		public string OnFrameEnd(LuaFunction luaf, string name = null)
		{
			var nlf = new NamedLuaFunction(luaf, "OnFrameEnd", LogOutputCallback, CurrentThread, name);
			_luaFunctions.Add(nlf);
			return nlf.Guid.ToString();
		}

		[LuaMethodAttributes(
			"onframestart", "Calls the given lua function at the beginning of each frame before any emulation and drawing occurs")]
		public string OnFrameStart(LuaFunction luaf, string name = null)
		{
			var nlf = new NamedLuaFunction(luaf, "OnFrameStart", LogOutputCallback, CurrentThread, name);
			_luaFunctions.Add(nlf);
			return nlf.Guid.ToString();
		}

		[LuaMethodAttributes(
			"oninputpoll", "Calls the given lua function after each time the emulator core polls for input")]
		public string OnInputPoll(LuaFunction luaf, string name = null)
		{
			var nlf = new NamedLuaFunction(luaf, "OnInputPoll", LogOutputCallback, CurrentThread, name);
			_luaFunctions.Add(nlf);

			if (InputPollableCore != null)
			{
				try
				{
					InputPollableCore.InputCallbacks.Add(nlf.Callback);
					return nlf.Guid.ToString();
				}
				catch (NotImplementedException)
				{
					LogNotImplemented();
					return Guid.Empty.ToString();
				}
			}

			LogNotImplemented();
			return Guid.Empty.ToString();
		}

		private void LogNotImplemented()
		{
			Log($"Error: {Emulator.Attributes().CoreName} does not yet implement input polling callbacks");
		}

		[LuaMethodAttributes(
			"onloadstate", "Fires after a state is loaded. Receives a lua function name, and registers it to the event immediately following a successful savestate event")]
		public string OnLoadState(LuaFunction luaf, string name = null)
		{
			var nlf = new NamedLuaFunction(luaf, "OnSavestateLoad", LogOutputCallback, CurrentThread, name);
			_luaFunctions.Add(nlf);
			return nlf.Guid.ToString();
		}

		[LuaMethodAttributes("onmemoryexecute", "Fires after the given address is executed by the core")]
		public string OnMemoryExecute(LuaFunction luaf, uint address, string name = null)
		{
			try
			{
				if (DebuggableCore != null && DebuggableCore.MemoryCallbacksAvailable() &&
					DebuggableCore.MemoryCallbacks.ExecuteCallbacksAvailable)
				{
					if (N64CoreTypeDynarec())
					{
						return Guid.Empty.ToString();
					}

					var nlf = new NamedLuaFunction(luaf, "OnMemoryExecute", LogOutputCallback, CurrentThread, name);
					_luaFunctions.Add(nlf);

					DebuggableCore.MemoryCallbacks.Add(
						new MemoryCallback(MemoryCallbackType.Execute, "Lua Hook", nlf.Callback, address, null));
					return nlf.Guid.ToString();
				}
			}
			catch (NotImplementedException)
			{
				LogMemoryExecuteCallbacksNotImplemented();
				return Guid.Empty.ToString();
			}

			LogMemoryExecuteCallbacksNotImplemented();
			return Guid.Empty.ToString();
		}

		[LuaMethodAttributes(
			"onmemoryread", "Fires after the given address is read by the core. If no address is given, it will attach to every memory read")]
		public string OnMemoryRead(LuaFunction luaf, uint? address = null, string name = null)
		{
			try
			{
				if (DebuggableCore != null && DebuggableCore.MemoryCallbacksAvailable())
				{
					if (N64CoreTypeDynarec())
					{
						return Guid.Empty.ToString();
					}

					var nlf = new NamedLuaFunction(luaf, "OnMemoryRead", LogOutputCallback, CurrentThread, name);
					_luaFunctions.Add(nlf);

					DebuggableCore.MemoryCallbacks.Add(
						new MemoryCallback(MemoryCallbackType.Read, "Lua Hook", nlf.Callback, address, null));
					return nlf.Guid.ToString();
				}
			}
			catch (NotImplementedException)
			{
				LogMemoryCallbacksNotImplemented();
				return Guid.Empty.ToString();
			}

			LogMemoryCallbacksNotImplemented();
			return Guid.Empty.ToString();
		}

		[LuaMethodAttributes(
			"onmemorywrite", "Fires after the given address is written by the core. If no address is given, it will attach to every memory write")]
		public string OnMemoryWrite(LuaFunction luaf, uint? address = null, string name = null)
		{
			try
			{
				if (DebuggableCore != null && DebuggableCore.MemoryCallbacksAvailable())
				{
					if (N64CoreTypeDynarec())
					{
						return Guid.Empty.ToString();
					}

					var nlf = new NamedLuaFunction(luaf, "OnMemoryWrite", LogOutputCallback, CurrentThread, name);
					_luaFunctions.Add(nlf);

					DebuggableCore.MemoryCallbacks.Add(
						new MemoryCallback(MemoryCallbackType.Write, "Lua Hook", nlf.Callback, address, null));
					return nlf.Guid.ToString();
				}
			}
			catch (NotImplementedException)
			{
				LogMemoryCallbacksNotImplemented();
				return Guid.Empty.ToString();
			}

			LogMemoryCallbacksNotImplemented();
			return Guid.Empty.ToString();
		}

		[LuaMethodAttributes("onsavestate", "Fires after a state is saved")]
		public string OnSaveState(LuaFunction luaf, string name = null)
		{
			var nlf = new NamedLuaFunction(luaf, "OnSavestateSave", LogOutputCallback, CurrentThread, name);
			_luaFunctions.Add(nlf);
			return nlf.Guid.ToString();
		}

		[LuaMethodAttributes("onexit", "Fires after the calling script has stopped")]
		public string OnExit(LuaFunction luaf, string name = null)
		{
			var nlf = new NamedLuaFunction(luaf, "OnExit", LogOutputCallback, CurrentThread, name);
			_luaFunctions.Add(nlf);
			return nlf.Guid.ToString();
		}

		[LuaMethodAttributes(
			"unregisterbyid", "Removes the registered function that matches the guid. If a function is found and remove the function will return true. If unable to find a match, the function will return false.")]
		public bool UnregisterById(string guid)
		{
			foreach (var nlf in _luaFunctions.Where(nlf => nlf.Guid.ToString() == guid.ToString()))
			{
				_luaFunctions.Remove(nlf);
				return true;
			}

			return false;
		}

		[LuaMethodAttributes(
			"unregisterbyname", "Removes the first registered function that matches Name. If a function is found and remove the function will return true. If unable to find a match, the function will return false.")]
		public bool UnregisterByName(string name)
		{
			foreach (var nlf in _luaFunctions.Where(nlf => nlf.Name == name))
			{
				_luaFunctions.Remove(nlf);
				return true;
			}

			return false;
		}
	}
}