using UnityEngine.Graphing;

namespace UnityEngine.MaterialGraph
{
    [Title("Math/UVOperations/Rotator")]
    public class UVRotatorNode : Function2Input, IGeneratesFunction
    {
        private const string kUVSlotName = "UV";
        private const string kRotationSlotName = "Rotation";

        public UVRotatorNode()
        {
            name = "UVRotator";
        }

        protected override string GetFunctionName()
        {
            return "unity_uvrotator_" + precision;
        }

        protected override MaterialSlot GetInputSlot1()
        {
            return new MaterialSlot(InputSlot1Id, kUVSlotName, kUVSlotName, SlotType.Input, SlotValueType.Vector4, Vector4.zero);
        }

        protected override MaterialSlot GetInputSlot2()
        {
            return new MaterialSlot(InputSlot2Id, kRotationSlotName, kRotationSlotName, SlotType.Input, SlotValueType.Vector1, Vector4.zero);
        }

        protected override MaterialSlot GetOutputSlot()
        {
            return new MaterialSlot(OutputSlotId, kUVSlotName, kUVSlotName, SlotType.Output, SlotValueType.Vector4, Vector4.zero);
        }

        //TODO:Externalize
        //Reference code from:http://www.chilliant.com/rgb2hsv.html
        public void GenerateNodeFunction(ShaderGenerator visitor, GenerationMode generationMode)
        {
            var outputString = new ShaderGenerator();
            outputString.AddShaderChunk(GetFunctionPrototype("arg1", "arg2"), false);
            outputString.AddShaderChunk("{", false);
            outputString.Indent();

            //center texture's pivot
            outputString.AddShaderChunk("arg1.xy -= 0.5;", false);

            //rotation matrix
            outputString.AddShaderChunk(precision + " s = sin(arg2);", false);
            outputString.AddShaderChunk(precision + " c = cos(arg2);", false);
            outputString.AddShaderChunk(precision + "2x2 rMatrix = float2x2(c, -s, s, c);", false);

            //center rotation matrix
            outputString.AddShaderChunk("rMatrix *= 0.5;", false);
            outputString.AddShaderChunk("rMatrix += 0.5;", false);
            outputString.AddShaderChunk("rMatrix = rMatrix*2 - 1;", false);

            //multiply the UVs by the rotation matrix
            outputString.AddShaderChunk("arg1.xy = mul(arg1.xy, rMatrix);", false);
            outputString.AddShaderChunk("arg1.xy += 0.5;", false);

            outputString.AddShaderChunk("return " + "arg1;", false);
            outputString.Deindent();
            outputString.AddShaderChunk("}", false);

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