#ifndef LUX_LIT_GBUFFER_PASS_INCLUDED
#define LUX_LIT_GBUFFER_PASS_INCLUDED

#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"
#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/UnityGBuffer.hlsl"


half4 SampleMetallicSpecGloss(float2 uv, half albedoAlpha)
{
    return 1;
}

struct Attributes
{
    float3 positionOS                   : POSITION;
    float3 normalOS                     : NORMAL;
    float4 tangentOS                    : TANGENT;
    float2 texcoord                     : TEXCOORD0;
    #ifdef LIGHTMAP_ON
        float2 staticLightmapUV         : TEXCOORD1;
    #endif
    #ifdef DYNAMICLIGHTMAP_ON
        float2 dynamicLightmapUV        : TEXCOORD2;
    #endif
    UNITY_VERTEX_INPUT_INSTANCE_ID
};

struct Varyings
{
    float2 uv                           : TEXCOORD0;
    float3 positionWS                   : TEXCOORD1;
    half3 normalWS                      : TEXCOORD2;
    #if defined(_NORMALMAP)
        half4 tangentWS                 : TEXCOORD3;
    #endif
    #ifdef _ADDITIONAL_LIGHTS_VERTEX
        half3 vertexLighting            : TEXCOORD4;
    #endif
    #if defined(REQUIRES_VERTEX_SHADOW_COORD_INTERPOLATOR)
        float4 shadowCoord              : TEXCOORD5;
    #endif
    //#if defined(REQUIRES_TANGENT_SPACE_VIEW_DIR_INTERPOLATOR)
    //    half3 viewDirTS                : TEXCOORD6;
    //#endif
    DECLARE_LIGHTMAP_OR_SH(staticLightmapUV, vertexSH, 7);
    #ifdef DYNAMICLIGHTMAP_ON
        float2  dynamicLightmapUV       : TEXCOORD8;
    #endif

    float4 positionCS                   : SV_POSITION;
        
    //UNITY_VERTEX_INPUT_INSTANCE_ID
    UNITY_VERTEX_OUTPUT_STEREO
};

// Include the surface function
#include "Includes/Lux URP FlatShaded SurfaceData.hlsl"

void InitializeInputData(Varyings input, half3 normalTS, float3 normalWS, half facing, out InputData inputData)
{
    inputData = (InputData)0;
    inputData.positionWS = input.positionWS;

    half3 viewDirWS = GetWorldSpaceNormalizeViewDir(input.positionWS);

//  We are using the passed vertexnormal normalWS here!    
    #if defined(_NORMALMAP)
        //normalTS.z *= facing; // This is incorrect?
    //  Adjust tangentWS as we have tweaked normalWS
        input.tangentWS.xyz = Orthonormalize(input.tangentWS.xyz, normalWS.xyz);
        float sgn = input.tangentWS.w;      // should be either +1 or -1
        float3 bitangent = sgn * cross(normalWS.xyz, input.tangentWS.xyz);
        inputData.normalWS = TransformTangentToWorld(normalTS, half3x3(input.tangentWS.xyz, bitangent.xyz, normalWS.xyz));
    #else
        inputData.normalWS = normalWS; // * facing; // This is incorrect?
    #endif

    inputData.normalWS = NormalizeNormalPerPixel(inputData.normalWS);
    inputData.viewDirectionWS = viewDirWS;

    #if defined(REQUIRES_VERTEX_SHADOW_COORD_INTERPOLATOR)
        inputData.shadowCoord = input.shadowCoord;
    #elif defined(MAIN_LIGHT_CALCULATE_SHADOWS)
        inputData.shadowCoord = TransformWorldToShadowCoord(inputData.positionWS);
    #else
        inputData.shadowCoord = float4(0, 0, 0, 0);
    #endif

    inputData.fogCoord = 0.0; // we don't apply fog in the guffer pass
    #ifdef _ADDITIONAL_LIGHTS_VERTEX
        inputData.vertexLighting = input.vertexLighting.xyz;
    #else
        inputData.vertexLighting = half3(0, 0, 0);
    #endif
    #if defined(DYNAMICLIGHTMAP_ON)
        inputData.bakedGI = SAMPLE_GI(input.staticLightmapUV, input.dynamicLightmapUV, input.vertexSH, inputData.normalWS);
    #else
        inputData.bakedGI = SAMPLE_GI(input.staticLightmapUV, input.vertexSH, inputData.normalWS);
    #endif
    
    inputData.normalizedScreenSpaceUV = GetNormalizedScreenSpaceUV(input.positionCS);
    inputData.shadowMask = SAMPLE_SHADOWMASK(input.staticLightmapUV);
}

// Used in Standard (Physically Based) shader
Varyings LitGBufferPassVertex(Attributes input)
{
    Varyings output = (Varyings)0;

    UNITY_SETUP_INSTANCE_ID(input);
    //UNITY_TRANSFER_INSTANCE_ID(input, output);
    UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(output);

    VertexPositionInputs vertexInput = GetVertexPositionInputs(input.positionOS.xyz);
    VertexNormalInputs normalInput = GetVertexNormalInputs(input.normalOS, input.tangentOS);

    output.uv = TRANSFORM_TEX(input.texcoord, _BaseMap);
    // already normalized from normal transform to WS.
    output.normalWS = normalInput.normalWS;

    #if defined(_NORMALMAP)
        real sign = input.tangentOS.w * GetOddNegativeScale();
        half4 tangentWS = half4(normalInput.tangentWS.xyz, sign);
        output.tangentWS = tangentWS;
    #endif

    OUTPUT_LIGHTMAP_UV(input.staticLightmapUV, unity_LightmapST, output.staticLightmapUV);
    #ifdef DYNAMICLIGHTMAP_ON
        output.dynamicLightmapUV = input.dynamicLightmapUV.xy * unity_DynamicLightmapST.xy + unity_DynamicLightmapST.zw;
    #endif
    OUTPUT_SH(output.normalWS.xyz, output.vertexSH);

    #ifdef _ADDITIONAL_LIGHTS_VERTEX
        half3 vertexLight = VertexLighting(vertexInput.positionWS, normalInput.normalWS);
        output.vertexLighting = vertexLight;
    #endif

    #if defined(REQUIRES_WORLD_SPACE_POS_INTERPOLATOR)
        output.positionWS = vertexInput.positionWS;
    #endif

    #if defined(REQUIRES_VERTEX_SHADOW_COORD_INTERPOLATOR)
        output.shadowCoord = GetShadowCoord(vertexInput);
    #endif

    output.positionCS = vertexInput.positionCS;

    return output;
}

// Used in Standard (Physically Based) shader
FragmentOutput LitGBufferPassFragment(Varyings input, half facing : VFACE)
{
    //UNITY_SETUP_INSTANCE_ID(input);
    UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(input);

    SurfaceData surfaceData;
    InitializeSurfaceData(input.uv, surfaceData);

//  Create custom per vertex normal // SafeNormalize does not work here on Android?!
    half3 tnormal = half3( normalize( cross(ddy(input.positionWS), ddx(input.positionWS)) ) );
//  TODO: Vulkan on Android here shows inverted normals?
    #if defined(SHADER_API_VULKAN)
        tnormal *= -1;
    #endif

    InputData inputData;
    InitializeInputData(input, surfaceData.normalTS, tnormal, facing, inputData);

#ifdef _DBUFFER
    #if defined(_RECEIVEDECALS)
        ApplyDecalToSurfaceData(input.positionCS, surfaceData, inputData);
    #endif
#endif

    #if defined(_RIMLIGHTING)
        half rim = saturate(1.0h - saturate( dot(inputData.normalWS, inputData.viewDirectionWS) ) );
        half power = _RimPower;
        if(_RimFrequency > 0 ) {
            half perPosition = lerp(0.0h, 1.0h, dot(1.0h, frac(UNITY_MATRIX_M._m03_m13_m23) * 2.0h - 1.0h ) * _RimPerPositionFrequency ) * 3.1416h;
            power = lerp(power, _RimMinPower, (1.0h + sin(_Time.y * _RimFrequency + perPosition) ) * 0.5h );
        }
        surfaceData.emission += pow(rim, power) * _RimColor.rgb * _RimColor.a;
    #endif

    BRDFData brdfData;
    InitializeBRDFData(surfaceData.albedo, surfaceData.metallic, surfaceData.specular, surfaceData.smoothness, surfaceData.alpha, brdfData);

    Light mainLight = GetMainLight(inputData.shadowCoord, inputData.positionWS, inputData.shadowMask);
    MixRealtimeAndBakedGI(mainLight, inputData.normalWS, inputData.bakedGI, inputData.shadowMask);
    half3 color = GlobalIllumination(brdfData, inputData.bakedGI, surfaceData.occlusion, inputData.normalWS, inputData.viewDirectionWS);

    return BRDFDataToGbuffer(brdfData, inputData, surfaceData.smoothness, surfaceData.emission + color, surfaceData.occlusion);
}

#endif