using System;
using UnityEngine;
using System.Reflection;

namespace UnityEditor.Graphs.Material
{
	abstract class BaseMaterialGraphGUI : GraphGUI
	{
		internal const int kDefaultNodeWidth = 50;
		internal const int kDefaultNodeHeight = 80;

		public override void OnGraphGUI()
		{
			m_Host.BeginWindows();

			// Process all nodes in the graph
			foreach (var n in graph.nodes)
			{
				var n2 = n;
				bool isSelected = selection.Contains(n2);
				n.position = GUILayout.Window(n.GetInstanceID(), n.position, delegate { NodeGUI(n2); }, n.title, Styles.GetNodeStyle(n.style, n.color, isSelected), GUILayout.Width(kDefaultNodeWidth), GUILayout.Height(kDefaultNodeHeight));
				if (n2 is BaseMaterialNode)
					((BaseMaterialNode)n2).isSelected = isSelected;
			}

			m_Host.EndWindows();

			edgeGUI.DoEdges();

			edgeGUI.DoDraggedEdge ();

			DragSelection(new Rect(-5000, -5000, 10000, 10000));
			HandleMenuEvents ();

			Event evt = Event.current;
			if (evt.type == EventType.MouseDown)
			{
				if (evt.button == 1)
				{
					DoAddNodeMenu(Event.current.mousePosition);
					evt.Use();
				}
			}
		}

		private class AddNodeCreationObject : object
		{
			public Vector2 m_Pos;
			public readonly Type m_Type;

			public AddNodeCreationObject(Type t, Vector2 p) { m_Type = t; m_Pos = p; }
		};

		private void AddNode(object obj)
		{
			var posObj = obj as AddNodeCreationObject;
			if (posObj == null)
				return;

			var node = (BaseMaterialNode)CreateInstance(posObj.m_Type);
			node.Init ();
			node.position = new Rect(posObj.m_Pos.x, posObj.m_Pos.y, node.position.width, node.position.height);
			graph.AddNode(node);
		}

		public virtual bool CanAddToNodeMenu(Type type) { return true; }

		protected void DoAddNodeMenu (Vector2 pos)
		{
			var gm = new GenericMenu();
			foreach (Type type in Assembly.GetAssembly(typeof(BaseMaterialNode)).GetTypes())
			{
				if(type.IsClass && !type.IsAbstract && (type.IsSubclassOf(typeof(BaseMaterialNode)) || type.IsSubclassOf(typeof(PropertyNode))))
				{
					var attrs = type.GetCustomAttributes(typeof(TitleAttribute), false) as TitleAttribute[];
					if(attrs != null && attrs.Length > 0 && CanAddToNodeMenu(type))
					{
						gm.AddItem(new GUIContent(attrs[0].m_Title), false, AddNode, new AddNodeCreationObject(type, pos));
					}
				}
			}
			gm.ShowAsContext ();
		}
	}
}