using System;
using System.Collections.Generic;
using UnityEditor.Graphing;
using UnityEditor.ShaderGraph.Drawing.Controls;
using UnityEditor.ShaderGraph.Internal;
using UnityEngine;

namespace UnityEditor.ShaderGraph
{
    [Title("Artistic", "Adjustment", "Channel Mixer")]
    class ChannelMixerNode : AbstractMaterialNode, IGeneratesBodyCode, IGeneratesFunction
    {
        public ChannelMixerNode()
        {
            name = "Channel Mixer";
            UpdateNodeAfterDeserialization();
        }

        const int InputSlotId = 0;
        const int OutputSlotId = 1;
        const string kInputSlotName = "In";
        const string kOutputSlotName = "Out";

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

        string GetFunctionName()
        {
            return $"Unity_ChannelMixer_{concretePrecision.ToShaderString()}";
        }

        public sealed override void UpdateNodeAfterDeserialization()
        {
            AddSlot(new Vector3MaterialSlot(InputSlotId, kInputSlotName, kInputSlotName, SlotType.Input, Vector3.zero));
            AddSlot(new Vector3MaterialSlot(OutputSlotId, kOutputSlotName, kOutputSlotName, SlotType.Output, Vector3.zero));
            RemoveSlotsNameNotMatching(new[] { InputSlotId, OutputSlotId });
        }

        [SerializeField]
        ChannelMixer m_ChannelMixer = new ChannelMixer(new Vector3(1, 0, 0), new Vector3(0, 1, 0), new Vector3(0, 0, 1));

        [Serializable]
        public struct ChannelMixer
        {
            public Vector3 outRed;
            public Vector3 outGreen;
            public Vector3 outBlue;

            public ChannelMixer(Vector3 red, Vector3 green, Vector3 blue)
            {
                outRed = red;
                outGreen = green;
                outBlue = blue;
            }
        }

        [ChannelMixerControl("")]
        public ChannelMixer channelMixer
        {
            get { return m_ChannelMixer; }
            set
            {
                if ((value.outRed == m_ChannelMixer.outRed) && (value.outGreen == m_ChannelMixer.outGreen) && (value.outBlue == m_ChannelMixer.outBlue))
                    return;
                m_ChannelMixer = value;
                Dirty(ModificationScope.Node);
            }
        }

        public void GenerateNodeCode(ShaderStringBuilder sb, GenerationMode generationMode)
        {
            var inputValue = GetSlotValue(InputSlotId, generationMode);
            var outputValue = GetSlotValue(OutputSlotId, generationMode);

            sb.AppendLine("{0} {1};", FindInputSlot<MaterialSlot>(InputSlotId).concreteValueType.ToShaderString(), GetVariableNameForSlot(OutputSlotId));
            if (!generationMode.IsPreview())
            {
                sb.AppendLine("$precision3 _{0}_Red = $precision3 ({1}, {2}, {3});", GetVariableNameForNode(), channelMixer.outRed[0], channelMixer.outRed[1], channelMixer.outRed[2]);
                sb.AppendLine("$precision3 _{0}_Green = $precision3 ({1}, {2}, {3});", GetVariableNameForNode(), channelMixer.outGreen[0], channelMixer.outGreen[1], channelMixer.outGreen[2]);
                sb.AppendLine("$precision3 _{0}_Blue = $precision3 ({1}, {2}, {3});", GetVariableNameForNode(), channelMixer.outBlue[0], channelMixer.outBlue[1], channelMixer.outBlue[2]);
            }
            sb.AppendLine("{0}({1}, _{2}_Red, _{2}_Green, _{2}_Blue, {3});", GetFunctionName(), inputValue, GetVariableNameForNode(), outputValue);
        }

        public override void CollectPreviewMaterialProperties(List<PreviewProperty> properties)
        {
            base.CollectPreviewMaterialProperties(properties);

            properties.Add(new PreviewProperty(PropertyType.Vector3)
            {
                name = string.Format("_{0}_Red", GetVariableNameForNode()),
                vector4Value = channelMixer.outRed
            });

            properties.Add(new PreviewProperty(PropertyType.Vector3)
            {
                name = string.Format("_{0}_Green", GetVariableNameForNode()),
                vector4Value = channelMixer.outGreen
            });

            properties.Add(new PreviewProperty(PropertyType.Vector3)
            {
                name = string.Format("_{0}_Blue", GetVariableNameForNode()),
                vector4Value = channelMixer.outBlue
            });
        }

        public override void CollectShaderProperties(PropertyCollector properties, GenerationMode generationMode)
        {
            if (!generationMode.IsPreview())
                return;

            base.CollectShaderProperties(properties, generationMode);

            properties.AddShaderProperty(new Vector4ShaderProperty()
            {
                overrideReferenceName = string.Format("_{0}_Red", GetVariableNameForNode()),
                generatePropertyBlock = false
            });

            properties.AddShaderProperty(new Vector4ShaderProperty()
            {
                overrideReferenceName = string.Format("_{0}_Green", GetVariableNameForNode()),
                generatePropertyBlock = false
            });

            properties.AddShaderProperty(new Vector4ShaderProperty()
            {
                overrideReferenceName = string.Format("_{0}_Blue", GetVariableNameForNode()),
                generatePropertyBlock = false
            });
        }

        public void GenerateNodeFunction(FunctionRegistry registry, GenerationMode generationMode)
        {
            registry.ProvideFunction(GetFunctionName(), s =>
                {
                    s.AppendLine("void {0} ({1} In, $precision3 Red, $precision3 Green, $precision3 Blue, out {2} Out)",
                        GetFunctionName(),
                        FindInputSlot<MaterialSlot>(InputSlotId).concreteValueType.ToShaderString(),
                        FindOutputSlot<MaterialSlot>(OutputSlotId).concreteValueType.ToShaderString());
                    using (s.BlockScope())
                    {
                        s.AppendLine("Out = {0}(dot(In, Red), dot(In, Green), dot(In, Blue));",
                            FindOutputSlot<MaterialSlot>(OutputSlotId).concreteValueType.ToShaderString());
                    }
                });
        }
    }
}