using System;
using System.Collections.Generic;
using UnityEngine;

namespace UnityEditor.Graphs.Material
{
	public enum TextureType
	{
		White,
		Gray,
		Black,
		Bump
	}

	[Title("Input/Texture Node")]
	public class TextureNode : PropertyNode, IGeneratesBodyCode, IGeneratesVertexShaderBlock, IGeneratesVertexToFragmentBlock
	{
		protected const string kOutputSlotName = "Output";
		protected const string kUVSlotName = "UV";

		[SerializeField]
		public Texture2D m_DefaultTexture;

		[SerializeField]
		public TextureType m_TextureType;

		private List<string> m_TextureTypeNames;

		public override bool hasPreview { get { return false; } }

		public override void Init ()
		{
			name = "Texture";
			base.Init ();
			AddSlot (new Slot (SlotType.OutputSlot, kOutputSlotName));
			AddSlot (new Slot (SlotType.InputSlot, kUVSlotName));
			
			LoadTextureTypes();
		}

		private void LoadTextureTypes ()
		{
			if (m_TextureTypeNames == null)
				m_TextureTypeNames = new List<string> (Enum.GetNames (typeof(TextureType)));
		}

		// Node generations
		public virtual void GenerateNodeCode (ShaderGenerator visitor, GenerationMode generationMode)
		{
			var outputSlot = FindOutputSlot (kOutputSlotName);
			if (outputSlot == null)
				return;

			var uvSlot = FindInputSlot (kUVSlotName);
			if (uvSlot == null)
				return;

			var uvName = "IN.meshUV0";
			if (uvSlot.edges.Count > 0)
			{
				var fromNode = uvSlot.edges[0].fromSlot.node as BaseMaterialNode;
				uvName = fromNode.GetOutputVariableNameForSlot(uvSlot.edges[0].fromSlot, generationMode);
			}

			string body = "tex2D (" + GetPropertyName () + ", " + uvName + ".xy)";
			if (m_TextureType == TextureType.Bump)
				body = precision+"4(UnpackNormal(" + body + "), 0)";
			visitor.AddShaderChunk("float4 " + GetOutputVariableNameForSlot(outputSlot, generationMode) + " = " + body + ";", true);			
		}

		public void GenerateVertexToFragmentBlock (ShaderGenerator visitor, GenerationMode generationMode)
		{
			var uvSlot = FindInputSlot(kUVSlotName);
			if (uvSlot == null)
				return;

			if (uvSlot.edges.Count == 0)
				UVNode.GenerateVertexToFragmentBlock (visitor);
		}

		public void GenerateVertexShaderBlock (ShaderGenerator visitor, GenerationMode generationMode)
		{
			var uvSlot = FindInputSlot(kUVSlotName);
			if (uvSlot == null)
				return;

			if (uvSlot.edges.Count == 0)
				UVNode.GenerateVertexShaderBlock (visitor);
		}

		// Properties
		public override void GeneratePropertyBlock(PropertyGenerator visitor, GenerationMode generationMode)
		{
			if (HasBoundProperty())
				return;

			visitor.AddShaderProperty (new TexturePropertyChunk (GetPropertyName (), GetPropertyName (), m_DefaultTexture, m_TextureType, true));
		}

		public override void GeneratePropertyUsages(ShaderGenerator visitor, GenerationMode generationMode)
		{
			if (HasBoundProperty())
				return;

			visitor.AddShaderChunk ("sampler2D " + GetPropertyName () + ";", true);
		}


		// UI Shizz
		public override void NodeUI(GraphGUI host)
		{
			LoadTextureTypes();

			base.NodeUI (host);

			EditorGUI.BeginChangeCheck ();
			m_DefaultTexture = EditorGUILayout.ObjectField (GUIContent.none, m_DefaultTexture, typeof(Texture2D), false) as Texture2D;
			m_TextureType = (TextureType)EditorGUILayout.Popup((int)m_TextureType, m_TextureTypeNames.ToArray(), EditorStyles.popup);
			if (EditorGUI.EndChangeCheck())
			{
				var boundProp = boundProperty as TextureProperty; 
				if (boundProp != null)
				{
					boundProp.defaultTexture = m_DefaultTexture;
					boundProp.defaultTextureType = m_TextureType;
				}
				UpdatePreviewProperties ();
			}
		}

		public override void BindProperty(ShaderProperty property, bool rebuildShaders)
		{
			base.BindProperty (property, rebuildShaders);

			var texProp = property as TextureProperty;
			if (texProp)
			{
				m_DefaultTexture = texProp.defaultTexture;
				m_TextureType = texProp.defaultTextureType;
			}
			if (rebuildShaders)
				RegeneratePreviewShaders ();
			else
				UpdatePreviewProperties ();
		}

		public override PreviewProperty GetPreviewProperty ()
		{
			MaterialWindow.DebugMaterialGraph ("Returning: " + GetPropertyName () + " " + m_DefaultTexture);
			return new PreviewProperty {
					m_Name = GetPropertyName (),
					m_PropType = PropertyType.Texture2D,
					m_Texture = m_DefaultTexture
				};
		}

		public override PropertyType propertyType { get { return PropertyType.Texture2D; } }
	}
}