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

using BizHawk.Emulation.Common.IEmulatorExtensions;

namespace BizHawk.Emulation.Common
{
	public abstract class CallbackBasedTraceBuffer : ITraceable
	{
		public CallbackBasedTraceBuffer(IDebuggable debuggableCore, IMemoryDomains memoryDomains, IDisassemblable disassembler)
		{
			if (!debuggableCore.MemoryCallbacksAvailable())
			{
				throw new InvalidOperationException("Memory callbacks are required");
			}

			try
			{
				debuggableCore.GetCpuFlagsAndRegisters();
			}
			catch (NotImplementedException)
			{
				throw new InvalidOperationException("GetCpuFlagsAndRegisters is required");
			}

			Header = "Instructions";
			DebuggableCore = debuggableCore;
			MemoryDomains = memoryDomains;
			Disassembler = disassembler;
		}

		protected readonly IMemoryDomains MemoryDomains;
		protected readonly IDisassemblable Disassembler;
		protected readonly IDebuggable DebuggableCore;

		protected readonly List<TraceInfo> Buffer = new List<TraceInfo>();

		private bool _enabled;

		public abstract void TraceFromCallback();

		public bool Enabled
		{
			get
			{
				return _enabled;
			}

			set
			{
				_enabled = value;
				DebuggableCore.MemoryCallbacks.Remove(TraceFromCallback);

				if (_enabled)
				{
					DebuggableCore.MemoryCallbacks.Add(new TracingMemoryCallback(TraceFromCallback));
				}
			}
		}

		public string Header { get; set; }

		public IEnumerable<TraceInfo> Contents
		{
			get { return Buffer; }
		}

		public IEnumerable<TraceInfo> TakeContents()
		{
			var contents = Buffer.ToList();
			Buffer.Clear();
			return contents;
		}

		public void Put(TraceInfo content)
		{
			if (Enabled)
			{
				Buffer.Add(content);
			}
		}

		public class TracingMemoryCallback : IMemoryCallback
		{
			public TracingMemoryCallback(Action callback)
			{
				Callback = callback;
			}

			public MemoryCallbackType Type
			{
				get { return MemoryCallbackType.Execute; }
			}

			public string Name
			{
				get { return "Trace Logging"; }
			}

			public Action Callback { get; private set; }

			public uint? Address
			{
				get { return null; }
			}
		}
	}
}