using System.Collections.Generic;
using UnityEngine;
using System;

namespace UnityEngine.Experimental.Rendering.HDPipeline
{
    namespace Attributes
    {
        // 0 is reserved!
        [GenerateHLSL]
        public enum DebugViewVarying
        {
            None = 0,
            Texcoord0 = 1,
            Texcoord1,
            Texcoord2,
            Texcoord3,
            VertexTangentWS,
            VertexBitangentWS,
            VertexNormalWS,
            VertexColor,
            VertexColorAlpha,
            Last,
        };

        // Number must be contiguous
        [GenerateHLSL]
        public enum DebugViewGbuffer
        {
            None = 0,
            Depth = DebugViewVarying.Last,
            BakeDiffuseLightingWithAlbedoPlusEmissive,
            BakeShadowMask0,
            BakeShadowMask1,
            BakeShadowMask2,
            BakeShadowMask3,
            Last,
        }

        // Number must be contiguous
        [GenerateHLSL]
        public enum DebugViewProperties
        {
            None = 0,
            Tessellation = DebugViewGbuffer.Last,
            PixelDisplacement,
            VertexDisplacement,
            TessellationDisplacement,
            DepthOffset,
            Lightmap,
            Instancing,
            Last,
        }
    }

    [Serializable]
    public class MaterialDebugSettings
    {
        private static bool isDebugViewMaterialInit = false;

        public static GUIContent[] debugViewMaterialStrings = null;
        public static int[] debugViewMaterialValues = null;
        public static GUIContent[] debugViewEngineStrings = null;
        public static int[] debugViewEngineValues = null;
        public static GUIContent[] debugViewMaterialVaryingStrings = null;
        public static int[] debugViewMaterialVaryingValues = null;
        public static GUIContent[] debugViewMaterialPropertiesStrings = null;
        public static int[] debugViewMaterialPropertiesValues = null;
        public static GUIContent[] debugViewMaterialTextureStrings = null;
        public static int[] debugViewMaterialTextureValues = null;
        public static GUIContent[] debugViewMaterialGBufferStrings = null;
        public static int[] debugViewMaterialGBufferValues = null;

        public MaterialDebugSettings()
        {
            BuildDebugRepresentation();
        }

        // className include the additional "/"
        void FillWithProperties(Type type, GUIContent[] debugViewMaterialStrings, int[] debugViewMaterialValues, string className, ref int index)
        {
            var attributes = type.GetCustomAttributes(true);
            // Get attribute to get the start number of the value for the enum
            var attr = attributes[0] as GenerateHLSL;

            if (!attr.needParamDebug)
            {
                return;
            }

            var fields = type.GetFields();

            var localIndex = 0;
            foreach (var field in fields)
            {
                var fieldName = field.Name;

                // Check if the display name have been override by the users
                if (Attribute.IsDefined(field, typeof(SurfaceDataAttributes)))
                {
                    var propertyAttr = (SurfaceDataAttributes[])field.GetCustomAttributes(typeof(SurfaceDataAttributes), false);
                    if (propertyAttr[0].displayName != "")
                    {
                        fieldName = propertyAttr[0].displayName;
                    }
                }

                fieldName = className + fieldName;

                debugViewMaterialStrings[index] = new GUIContent(fieldName);
                debugViewMaterialValues[index] = attr.paramDefinesStart + (int)localIndex;
                index++;
                localIndex++;
            }
        }

        void FillWithPropertiesEnum(Type type, GUIContent[] debugViewMaterialStrings, int[] debugViewMaterialValues, string prefix, ref int index)
        {
            var names = Enum.GetNames(type);

            var localIndex = 0;
            foreach (var value in Enum.GetValues(type))
            {
                var valueName = prefix + names[localIndex];

                debugViewMaterialStrings[index] = new GUIContent(valueName);
                debugViewMaterialValues[index] = (int)value;
                index++;
                localIndex++;
            }
        }

        public class MaterialItem
        {
            public String className;
            public Type surfaceDataType;
            public Type bsdfDataType;
        };

        void BuildDebugRepresentation()
        {
            if (!isDebugViewMaterialInit)
            {
                List<RenderPipelineMaterial> materialList = HDUtils.GetRenderPipelineMaterialList();

                // TODO: Share this code to retrieve deferred material with HDRenderPipeline
                // Find first material that have non 0 Gbuffer count and assign it as deferredMaterial
                Type bsdfDataDeferredType = null;
                foreach (RenderPipelineMaterial material in materialList)
                {
                    if (material.GetMaterialGBufferCount() > 0)
                    {
                        bsdfDataDeferredType = material.GetType().GetNestedType("BSDFData");
                    }
                }

                // TODO: Handle the case of no Gbuffer material
                Debug.Assert(bsdfDataDeferredType != null);

                List<MaterialItem> materialItems = new List<MaterialItem>();

                int numSurfaceDataFields = 0;
                int numBSDFDataFields = 0;
                foreach (RenderPipelineMaterial material in materialList)
                {
                    MaterialItem item = new MaterialItem();

                    item.className = material.GetType().Name + "/";

                    item.surfaceDataType = material.GetType().GetNestedType("SurfaceData");
                    numSurfaceDataFields += item.surfaceDataType.GetFields().Length;

                    item.bsdfDataType = material.GetType().GetNestedType("BSDFData");
                    numBSDFDataFields += item.bsdfDataType.GetFields().Length;

                    materialItems.Add(item);
                }

                // Material properties debug
                var num =   typeof(Builtin.BuiltinData).GetFields().Length * materialList.Count // BuildtinData are duplicated for each material
                            + numSurfaceDataFields + 1; // +1 for None case

                debugViewMaterialStrings = new GUIContent[num];
                debugViewMaterialValues = new int[num];
                // Special case for None since it cannot be inferred from SurfaceData/BuiltinData
                debugViewMaterialStrings[0] = new GUIContent("None");
                debugViewMaterialValues[0] = 0;
                var index = 1;
                // 0 is a reserved number and should not be used (allow to track error)
                foreach (MaterialItem item in materialItems)
                {
                    // BuiltinData are duplicated for each material
                    FillWithProperties(typeof(Builtin.BuiltinData), debugViewMaterialStrings, debugViewMaterialValues, item.className, ref index);
                    FillWithProperties(item.surfaceDataType, debugViewMaterialStrings, debugViewMaterialValues, item.className, ref index);
                }

                // Engine properties debug
                num = numBSDFDataFields + 1; // +1 for None case
                debugViewEngineStrings = new GUIContent[num];
                debugViewEngineValues = new int[num];
                // 0 is a reserved number and should not be used (allow to track error)
                debugViewEngineStrings[0] = new GUIContent("None");
                debugViewEngineValues[0] = 0;
                index = 1;
                foreach (MaterialItem item in materialItems)
                {
                    FillWithProperties(item.bsdfDataType, debugViewEngineStrings, debugViewEngineValues, item.className, ref index);
                }

                // Attributes debug
                var varyingNames = Enum.GetNames(typeof(Attributes.DebugViewVarying));
                debugViewMaterialVaryingStrings = new GUIContent[varyingNames.Length];
                debugViewMaterialVaryingValues = new int[varyingNames.Length];
                index = 0;
                FillWithPropertiesEnum(typeof(Attributes.DebugViewVarying), debugViewMaterialVaryingStrings, debugViewMaterialVaryingValues, "", ref index);

                // Properties debug
                var propertiesNames = Enum.GetNames(typeof(Attributes.DebugViewProperties));
                debugViewMaterialPropertiesStrings = new GUIContent[propertiesNames.Length];
                debugViewMaterialPropertiesValues = new int[propertiesNames.Length];
                index = 0;
                FillWithPropertiesEnum(typeof(Attributes.DebugViewProperties), debugViewMaterialPropertiesStrings, debugViewMaterialPropertiesValues, "", ref index);

                // Gbuffer debug
                var gbufferNames = Enum.GetNames(typeof(Attributes.DebugViewGbuffer));
                debugViewMaterialGBufferStrings = new GUIContent[gbufferNames.Length + bsdfDataDeferredType.GetFields().Length];
                debugViewMaterialGBufferValues = new int[gbufferNames.Length + bsdfDataDeferredType.GetFields().Length];
                index = 0;
                FillWithPropertiesEnum(typeof(Attributes.DebugViewGbuffer), debugViewMaterialGBufferStrings, debugViewMaterialGBufferValues, "", ref index);
                FillWithProperties(typeof(Lit.BSDFData), debugViewMaterialGBufferStrings, debugViewMaterialGBufferValues, "", ref index);

                isDebugViewMaterialInit = true;
            }
        }

        public int debugViewMaterial { get { return m_DebugViewMaterial; } }
        public int debugViewEngine { get { return m_DebugViewEngine; } }
        public Attributes.DebugViewVarying debugViewVarying { get { return m_DebugViewVarying; } }
        public Attributes.DebugViewProperties debugViewProperties { get { return m_DebugViewProperties; } }
        public int debugViewGBuffer { get { return m_DebugViewGBuffer; } }

        int                             m_DebugViewMaterial = 0; // No enum there because everything is generated from materials.
        int                             m_DebugViewEngine = 0;  // No enum there because everything is generated from BSDFData
        Attributes.DebugViewVarying     m_DebugViewVarying = Attributes.DebugViewVarying.None;
        Attributes.DebugViewProperties  m_DebugViewProperties = Attributes.DebugViewProperties.None;
        int                             m_DebugViewGBuffer = 0; // Can't use GBuffer enum here because the values are actually split between this enum and values from Lit.BSDFData

        public int GetDebugMaterialIndex()
        {
            // This value is used in the shader for the actual debug display.
            // There is only one uniform parameter for that so we just add all of them
            // They are all mutually exclusive so return the sum will return the right index.
            return m_DebugViewGBuffer + m_DebugViewMaterial + m_DebugViewEngine + (int)m_DebugViewVarying + (int)m_DebugViewProperties;
        }

        public void DisableMaterialDebug()
        {
            m_DebugViewMaterial = 0;
            m_DebugViewEngine = 0;
            m_DebugViewVarying = Attributes.DebugViewVarying.None;
            m_DebugViewProperties = Attributes.DebugViewProperties.None;
            m_DebugViewGBuffer = 0;
        }

        public void SetDebugViewMaterial(int value)
        {
            if (value != 0)
                DisableMaterialDebug();
            m_DebugViewMaterial = value;
        }

        public void SetDebugViewEngine(int value)
        {
            if (value != 0)
                DisableMaterialDebug();
            m_DebugViewEngine = value;
        }

        public void SetDebugViewVarying(Attributes.DebugViewVarying value)
        {
            if (value != 0)
                DisableMaterialDebug();
            m_DebugViewVarying = value;
        }
        public void SetDebugViewProperties(Attributes.DebugViewProperties value)
        {
            if (value != 0)
                DisableMaterialDebug();
            m_DebugViewProperties = value;
        }

        public void SetDebugViewGBuffer(int value)
        {
            if (value != 0)
                DisableMaterialDebug();
            m_DebugViewGBuffer = value;
        }


        public bool IsDebugGBufferEnabled()
        {
            return m_DebugViewGBuffer != 0;
        }

        public bool IsDebugDisplayEnabled()
        {
            return (m_DebugViewEngine != 0 || m_DebugViewMaterial != 0 || m_DebugViewVarying != Attributes.DebugViewVarying.None || m_DebugViewProperties != Attributes.DebugViewProperties.None || m_DebugViewGBuffer != 0);
        }
    }
}