using UnityEngine;
using System.Collections;
using UnityEditor;
using System.Collections.Generic;
using System.Reflection;
using System;

public static class FindReferenceInScene
{
	[MenuItem("GameObject/Find Reference in Scene", false, 45)]
	static void DoFindReferenceInScene()
	{
		if (Selection.activeGameObject == null)
			return;

		bool found = false;
		var list = FindAllTransformInScene();
		foreach (var item in list)
		{
			var behaviours = item.GetComponents<MonoBehaviour>();
			//Debug.LogWarning(behaviours.Length + ":" + item.name, item);

			foreach (var b in behaviours)
			{
				Type type;
				try
				{
					type = b.GetType();
				}
				catch (System.Exception e)
				{
					Debug.LogError(item);
					Debug.LogError(e.Message);
					continue;
				}

				var fields = type.GetFields(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
				foreach (var f in fields)
				{
					bool isArray;
					Type baseType;
					if (IsUnitySerializable(f, out isArray, out baseType))
					{
						//Debug.Log(f.ToString() + ":" + isArray + ":" + baseType.ToString());
						if (isArray)
						{
							foreach (var obj in (IEnumerable)f.GetValue(b))
								found = CheckSelection(b, type, f, obj) || found;
						}
						else
						{
							object obj = f.GetValue(b);
							found = CheckSelection(b, type, f, obj) || found;
						}
					}
				}
			}
		}
		if (!found)
			Debug.Log("no reference in current scene. <color=white>" + Selection.activeGameObject + "</color>");
	}

	private static bool CheckSelection(MonoBehaviour b, Type type, FieldInfo f, object obj)
	{
		if (obj == null || obj.Equals(null))

			return false;

		if (obj is GameObject)
		{
			if ((obj as GameObject) == Selection.activeGameObject)
			{
				Debug.Log(string.Format("<color=green>{0}</color>.<color=white>{1}</color> ({2}), on <color=red>{3}</color>", type, f.Name, f.FieldType, b.gameObject.name), b.gameObject);
				return true;
			}
		}
		else if (obj is Component)
		{
			if ((obj as Component).gameObject == Selection.activeGameObject)
			{
				Debug.Log(string.Format("<color=green>{0}</color>.<color=white>{1}</color> ({2}), on <color=red>{3}</color>", type, f.Name, f.FieldType, b.gameObject.name), b.gameObject);
				return true;
			}
		}
		else
		{
			// we dont care about other types
		}

		return false;
	}

	private static List<Transform> FindAllTransformInScene()
	{
		var list = new List<Transform>();
		//var roots = new List<Transform>();

		foreach (var item in GameObject.FindObjectsOfType<Transform>())
		{
			if (item == item.root) // 自己是root結點
				list.AddRange(item.GetComponentsInChildren<Transform>(true)); // dark magic here
		}
		return list;
	}

	private static bool IsUnitySerializable(FieldInfo f, out bool isArray, out Type baseType)
	{
		var isPublicOrSerializeField = (f.IsPublic || f.GetCustomAttributes(typeof(SerializeField), true).Length > 0) &&
												(f.GetCustomAttributes(typeof(NonSerializedAttribute), true).Length == 0);
		if (!isPublicOrSerializeField)
		{
			isArray = false;
			baseType = null;
			return false;
		}

		return IsSerializable(f, out isArray, out baseType);
	}

	private static bool IsSerializable(FieldInfo f, out bool isArray, out Type baseType)
	{
		var fieldType = f.FieldType;
		if (fieldType.IsArray)
		{
			baseType = fieldType.GetElementType();
			isArray = true;
		}
		else if (fieldType.IsGenericType && fieldType.GetGenericTypeDefinition() == typeof(List<>))
		{
			baseType = fieldType.GetGenericArguments()[0];
			isArray = true;
		}
		else
		{
			baseType = fieldType;
			isArray = false;
		}

		return typeof(UnityEngine.Object).IsAssignableFrom(baseType) || baseType.GetCustomAttributes(typeof(SerializableAttribute), true).Length > 0;
	}
}