using System;
using System.Linq;
using UnityEngine;

namespace UnityEditor.Graphs.Material
{
	[Title("Generate/Color Node")]
	class ColorNode : PropertyNode, IGeneratesBodyCode
	{
		[SerializeField]
		private Color m_Color;

		private const string kOutputSlotName = "Color";

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

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

		public override void GeneratePropertyBlock(PropertyGenerator visitor, GenerationMode generationMode)
		{
			if (HasBoundProperty() || !generationMode.IsPreview ())
				return;

			visitor.AddShaderProperty (new ColorPropertyChunk (GetPropertyName (), GetPropertyName (), m_Color, true));
		}

		public override string GetOutputVariableNameForSlot(Slot s, GenerationMode generationMode)
		{
			return GetPropertyName();
		}

		public override void GeneratePropertyUsages(ShaderGenerator visitor, GenerationMode generationMode)
		{
			if (HasBoundProperty() || !generationMode.IsPreview ())
				return;
			
			visitor.AddShaderChunk("float4 " + GetPropertyName() + ";", true);
		}

		public void GenerateNodeCode(ShaderGenerator visitor, GenerationMode generationMode)
		{
			// we only need to generate node code if we are using a constant... otherwise we can just refer to the property :)
			if (HasBoundProperty() || generationMode.IsPreview ())
				return;

			visitor.AddShaderChunk (precision+"4 " + GetPropertyName () + " = "+precision+"4 (" + m_Color.r + ", " + m_Color.g + ", " + m_Color.b + ", " + m_Color.a + ");", true);
		}

		public override void NodeUI (Graphs.GraphGUI host) 
		{
			base.NodeUI(host);

			EditorGUI.BeginChangeCheck ();
			m_Color = EditorGUILayout.ColorField(m_Color);
			if (EditorGUI.EndChangeCheck())
			{
				var boundProp = boundProperty as ColorProperty;
				if (boundProp != null)
				{
					boundProp.defaultColor = m_Color;
				}
				UpdatePreviewProperties ();
			}
		}

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

			var colorProp = property as ColorProperty;
			if (colorProp)
			{
				m_Color = colorProp.defaultColor;
			}

			if (rebuildShaders)
				RegeneratePreviewShaders();
			else
				UpdatePreviewProperties();
		}

		public override PreviewProperty GetPreviewProperty ()
		{
				return new PreviewProperty {
					m_Name = GetPropertyName (),
					m_PropType = PropertyType.Color,
					m_Color = m_Color
				};
		}
	}
}