using UnityEngine.Graphing;
using System.Linq;
using System.Collections;

namespace UnityEngine.MaterialGraph
{
    [Title("Art/ChannelBlend")]
    public class ChannelBlend : FunctionNInNOut, IGeneratesFunction
    {

        public ChannelBlend()
        {
            name = "ChannelBlend";
            AddSlot("Mask", "mask", Graphing.SlotType.Input, SlotValueType.Vector4, Vector4.zero);
            AddSlot("RColor", "rCol", Graphing.SlotType.Input, SlotValueType.Vector4, Vector4.zero);
            AddSlot("GColor", "gCol", Graphing.SlotType.Input, SlotValueType.Vector4, Vector4.zero);
            AddSlot("BColor", "bCol", Graphing.SlotType.Input, SlotValueType.Vector4, Vector4.zero);
            AddSlot("AColor", "aCol", Graphing.SlotType.Input, SlotValueType.Vector4, Vector4.zero);
            AddSlot("BGColor", "bgCol", Graphing.SlotType.Input, SlotValueType.Vector4, Vector4.zero);

            AddSlot("BlendedColor", "blendCol", Graphing.SlotType.Output, SlotValueType.Vector4, Vector4.zero);
        }

        protected override string GetFunctionName()
        {
            return "unity_ChannelBlend";
        }

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

        public void GenerateNodeFunction(ShaderGenerator visitor, GenerationMode generationMode)
        {
            var outputString = new ShaderGenerator();
            outputString.AddShaderChunk(GetFunctionPrototype(), false);
            outputString.AddShaderChunk("{", false);
            outputString.AddShaderChunk("float4 background = step(max(mask.r,max(mask.g,mask.b)), 0.001) * bgCol;", false);
            outputString.AddShaderChunk("blendCol = mask.r * rCol + mask.g * gCol + mask.b * bCol + mask.a * aCol + background;", false);
            outputString.AddShaderChunk("}", false);

            visitor.AddShaderChunk(outputString.GetShaderString(0), true);
        }
    }
}