using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Runtime.CompilerServices;
using UnityEngine;

namespace RMGUI.GraphView
{
	// types of port to adapt
	class PortSource<T>
	{
	}

	// attribute to declare and adapter
	class TypeAdapter : Attribute
	{
	}

	// TODO: This is a straight port from Canvas2D. I don't think that having to check for types in the assembly using reflection is the way we want to go.
	public class NodeAdapter
	{
		private static List<MethodInfo> s_TypeAdapters;
		private static Dictionary<int, MethodInfo> s_NodeAdapterDictionary;

		public bool CanAdapt(object a, object b)
		{
			if (a == b)
				return false; // self connections are not permitted

			if (a == null || b == null)
				return false;

			MethodInfo mi = GetAdapter(a, b);
			if (mi == null)
			{
				Debug.Log("adapter node not found for: " + a.GetType() + " -> " + b.GetType());
			}
			return mi != null;
		}

		public bool Connect(object a, object b)
		{
			MethodInfo mi = GetAdapter(a, b);
			if (mi == null)
			{
				Debug.LogError("Attempt to connect 2 unadaptable types: " + a.GetType() + " -> " + b.GetType());
				return false;
			}
			object retVal = mi.Invoke(this, new[] { this, a, b });
			return (bool)retVal;
		}

		IEnumerable<MethodInfo> GetExtensionMethods(Assembly assembly, Type extendedType)
		{
			return assembly.GetTypes()
						   .Where(t => t.IsSealed && !t.IsGenericType && !t.IsNested)
						   .SelectMany(t => t.GetMethods(BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic))
						   .Where(m => m.IsDefined(typeof(ExtensionAttribute), false) && m.GetParameters()[0].ParameterType == extendedType);
		}

		public MethodInfo GetAdapter(object a, object b)
		{
			if (a == null || b == null)
				return null;

			if (s_NodeAdapterDictionary == null)
			{
				s_NodeAdapterDictionary = new Dictionary<int, MethodInfo>();

				// add extension methods
				AppDomain currentDomain = AppDomain.CurrentDomain;
				foreach (Assembly assembly in currentDomain.GetAssemblies())
				{
					foreach (MethodInfo method in GetExtensionMethods(assembly, typeof(NodeAdapter)))
					{
						var methodParams = method.GetParameters();
						if (methodParams.Length == 3)
						{
							string pa = methodParams[1].ParameterType + methodParams[2].ParameterType.ToString();
							s_NodeAdapterDictionary.Add(pa.GetHashCode(), method);
						}
					}
				}
			}

			string s = a.GetType().ToString() + b.GetType();

			MethodInfo methodInfo;
			return s_NodeAdapterDictionary.TryGetValue(s.GetHashCode(), out methodInfo) ? methodInfo : null;
		}

		public MethodInfo GetTypeAdapter(Type from, Type to)
		{
			if (s_TypeAdapters == null)
			{
				s_TypeAdapters = new List<MethodInfo>();
				AppDomain currentDomain = AppDomain.CurrentDomain;
				foreach (Assembly assembly in currentDomain.GetAssemblies())
				{
					try
					{
						foreach (Type temptype in assembly.GetTypes())
						{
							MethodInfo[] methodInfos = temptype.GetMethods(BindingFlags.Public | BindingFlags.Static);
							foreach (MethodInfo i in methodInfos)
							{
								object[] allAttrs = i.GetCustomAttributes(typeof(TypeAdapter), false);
								if (allAttrs.Any())
								{
									s_TypeAdapters.Add(i);
								}
							}
						}
					}
					catch (Exception ex)
					{
						Debug.Log(ex);
					}
				}
			}


			foreach (MethodInfo i in s_TypeAdapters)
			{
				if (i.ReturnType == to)
				{
					ParameterInfo[] allParams = i.GetParameters();
					if (allParams.Length == 1)
					{
						if (allParams[0].ParameterType == from)
							return i;
					}
				}
			}
			return null;
		}
	}
}