using System.Linq;
using UnityEngine;
using UnityEditor.Graphing;
using UnityEditor.ShaderGraph.Drawing.Controls;
using UnityEditor.ShaderGraph.Internal;

namespace UnityEditor.ShaderGraph
{
    [Title("Input", "Texture", "Sample Texture 2D LOD")]
    class SampleTexture2DLODNode : AbstractMaterialNode, IGeneratesBodyCode, IMayRequireMeshUV
    {
        public const int OutputSlotRGBAId = 0;
        public const int OutputSlotRId = 5;
        public const int OutputSlotGId = 6;
        public const int OutputSlotBId = 7;
        public const int OutputSlotAId = 8;

        public const int TextureInputId = 1;
        public const int UVInputId = 2;
        public const int SamplerInputId = 3;
        public const int LODInputId = 4;

        const string kOutputSlotRGBAName = "RGBA";
        const string kOutputSlotRName = "R";
        const string kOutputSlotGName = "G";
        const string kOutputSlotBName = "B";
        const string kOutputSlotAName = "A";

        const string kTextureInputName = "Texture";
        const string kUVInputName = "UV";
        const string kSamplerInputName = "Sampler";
        const string kLODInputName = "LOD";

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

        public SampleTexture2DLODNode()
        {
            name = "Sample Texture 2D LOD";
            UpdateNodeAfterDeserialization();
        }

        [SerializeField]
        private TextureType m_TextureType = TextureType.Default;

        [EnumControl("Type")]
        public TextureType textureType
        {
            get { return m_TextureType; }
            set
            {
                if (m_TextureType == value)
                    return;

                m_TextureType = value;
                Dirty(ModificationScope.Graph);

                ValidateNode();
            }
        }

        [SerializeField]
        private NormalMapSpace m_NormalMapSpace = NormalMapSpace.Tangent;

        [EnumControl("Space")]
        public NormalMapSpace normalMapSpace
        {
            get { return m_NormalMapSpace; }
            set
            {
                if (m_NormalMapSpace == value)
                    return;

                m_NormalMapSpace = value;
                Dirty(ModificationScope.Graph);
            }
        }

        public sealed override void UpdateNodeAfterDeserialization()
        {
            AddSlot(new Vector4MaterialSlot(OutputSlotRGBAId, kOutputSlotRGBAName, kOutputSlotRGBAName, SlotType.Output, Vector4.zero, ShaderStageCapability.All));
            AddSlot(new Vector1MaterialSlot(OutputSlotRId, kOutputSlotRName, kOutputSlotRName, SlotType.Output, 0, ShaderStageCapability.All));
            AddSlot(new Vector1MaterialSlot(OutputSlotGId, kOutputSlotGName, kOutputSlotGName, SlotType.Output, 0, ShaderStageCapability.All));
            AddSlot(new Vector1MaterialSlot(OutputSlotBId, kOutputSlotBName, kOutputSlotBName, SlotType.Output, 0, ShaderStageCapability.All));
            AddSlot(new Vector1MaterialSlot(OutputSlotAId, kOutputSlotAName, kOutputSlotAName, SlotType.Output, 0, ShaderStageCapability.All));
            AddSlot(new Texture2DInputMaterialSlot(TextureInputId, kTextureInputName, kTextureInputName));
            AddSlot(new UVMaterialSlot(UVInputId, kUVInputName, kUVInputName, UVChannel.UV0));
            AddSlot(new SamplerStateMaterialSlot(SamplerInputId, kSamplerInputName, kSamplerInputName, SlotType.Input));
            AddSlot(new Vector1MaterialSlot(LODInputId, kLODInputName, kLODInputName, SlotType.Input, 0));
            RemoveSlotsNameNotMatching(new[] { OutputSlotRGBAId, OutputSlotRId, OutputSlotGId, OutputSlotBId, OutputSlotAId, TextureInputId, UVInputId, SamplerInputId, LODInputId });
        }

        public override void Setup()
        {
            base.Setup();
            var textureSlot = FindInputSlot<Texture2DInputMaterialSlot>(TextureInputId);
            textureSlot.defaultType = (textureType == TextureType.Normal ? Texture2DShaderProperty.DefaultType.NormalMap : Texture2DShaderProperty.DefaultType.White);
        }

        // Node generations
        public virtual void GenerateNodeCode(ShaderStringBuilder sb, GenerationMode generationMode)
        {
            var uvName = GetSlotValue(UVInputId, generationMode);

            //Sampler input slot
            var samplerSlot = FindInputSlot<MaterialSlot>(SamplerInputId);
            var edgesSampler = owner.GetEdges(samplerSlot.slotReference);

            var lodSlot = GetSlotValue(LODInputId, generationMode);

            var id = GetSlotValue(TextureInputId, generationMode);

            // GLES2 does not always support LOD sampling
            sb.AppendLine("#if defined(SHADER_API_GLES) && (SHADER_TARGET < 30)");
            {
                sb.AppendLine("  $precision4 {0} = $precision4(0.0f, 0.0f, 0.0f, 1.0f);", GetVariableNameForSlot(OutputSlotRGBAId));
            }
            sb.AppendLine("#else");
            {
                var result = string.Format("  $precision4 {0} = SAMPLE_TEXTURE2D_LOD({1}.tex, {2}.samplerstate, {1}.GetTransformedUV({3}), {4});"
                    , GetVariableNameForSlot(OutputSlotRGBAId)
                    , id
                    , edgesSampler.Any() ? GetSlotValue(SamplerInputId, generationMode) : id
                    , uvName
                    , lodSlot);

                sb.AppendLine(result);
            }
            sb.AppendLine("#endif");

            if (textureType == TextureType.Normal)
            {
                if (normalMapSpace == NormalMapSpace.Tangent)
                {
                    sb.AppendLine(string.Format("{0}.rgb = UnpackNormal({0});", GetVariableNameForSlot(OutputSlotRGBAId)));
                }
                else
                {
                    sb.AppendLine(string.Format("{0}.rgb = UnpackNormalRGB({0});", GetVariableNameForSlot(OutputSlotRGBAId)));
                }
            }

            sb.AppendLine(string.Format("$precision {0} = {1}.r;", GetVariableNameForSlot(OutputSlotRId), GetVariableNameForSlot(OutputSlotRGBAId)));
            sb.AppendLine(string.Format("$precision {0} = {1}.g;", GetVariableNameForSlot(OutputSlotGId), GetVariableNameForSlot(OutputSlotRGBAId)));
            sb.AppendLine(string.Format("$precision {0} = {1}.b;", GetVariableNameForSlot(OutputSlotBId), GetVariableNameForSlot(OutputSlotRGBAId)));
            sb.AppendLine(string.Format("$precision {0} = {1}.a;", GetVariableNameForSlot(OutputSlotAId), GetVariableNameForSlot(OutputSlotRGBAId)));
        }

        public bool RequiresMeshUV(UVChannel channel, ShaderStageCapability stageCapability)
        {
            var result = false;
            using (var tempSlots = PooledList<MaterialSlot>.Get())
            {
                GetInputSlots(tempSlots);
                foreach (var slot in tempSlots)
                {
                    if (slot.RequiresMeshUV(channel))
                    {
                        result = true;
                        break;
                    }
                }
            }

            return result;
        }
    }
}