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

//  Structs
struct Attributes
{
    float4 positionOS               : POSITION;
    float3 normalOS                 : NORMAL;
    float4 tangentOS                : TANGENT;
    float2 texcoord                 : TEXCOORD0;
    #if defined(LIGHTMAP_ON)
        float2 staticLightmapUV     : TEXCOORD1;
    #endif
    #if defined(DYNAMICLIGHTMAP_ON)
        float2 dynamicLightmapUV    : TEXCOORD2;
    #endif
    #if defined(_USEVERTEXCOLORS)
        half4 color                 : COLOR;
    #endif
    UNITY_VERTEX_INPUT_INSTANCE_ID
};

struct Varyings
{
    float2 uv                           : TEXCOORD0;

    //#if defined(REQUIRES_WORLD_SPACE_POS_INTERPOLATOR)
        float3 positionWS               : TEXCOORD1;
    //#endif

    half3 normalWS                      : TEXCOORD2;

    //#if defined(REQUIRES_WORLD_SPACE_TANGENT_INTERPOLATOR)
    #ifdef _NORMALMAP
        half4 tangentWS                 : TEXCOORD3;    
    #endif

    #ifdef _ADDITIONAL_LIGHTS_VERTEX
        half3 vertexLighting            : TEXCOORD4;    // xyz: vertex lighting
    #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

    #if defined(_USEVERTEXCOLORS)
        half4 color                     : COLOR;
    #endif

    float4 positionCS                   : SV_POSITION;

    //UNITY_VERTEX_INPUT_INSTANCE_ID
    UNITY_VERTEX_OUTPUT_STEREO
};


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

Varyings vert (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 = input.texcoord; //TRANSFORM_TEX(input.texcoord, _BaseMap);

    //  Already normalized from normal transform to WS.
    output.normalWS = normalInput.normalWS;

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

    //#if defined(REQUIRES_TANGENT_SPACE_VIEW_DIR_INTERPOLATOR)
    //    half3 viewDirWS = GetWorldSpaceNormalizeViewDir(vertexInput.positionWS);
    //    half3 viewDirTS = GetViewDirectionTangentSpace(tangentWS, output.normalWS, viewDirWS);
    //    output.viewDirTS = viewDirTS;
    //#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

    #if defined(_USEVERTEXCOLORS)
        output.color = input.color;
    #endif

    output.positionCS = vertexInput.positionCS;

    return output;
}

FragmentOutput frag(Varyings input)
{
    //UNITY_SETUP_INSTANCE_ID(input);
    UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(input);

    SurfaceData surfaceData;
    half3 topdownNormal;
    half topnormalstrength;

//  Get the surface description
    InitializeStandardLitSurfaceData(input, surfaceData, topdownNormal);

//  Transfer all to world space 
    InputData inputData = (InputData)0;
    inputData.positionWS = input.positionWS;

    half3 viewDirWS = GetWorldSpaceNormalizeViewDir(input.positionWS);
    #ifdef _NORMALMAP
        #if !defined(_TOPDOWNPROJECTION)
            float sgn = input.tangentWS.w;      // should be either +1 or -1
            float3 bitangent = sgn * cross(input.normalWS.xyz, input.tangentWS.xyz);
            inputData.normalWS = TransformTangentToWorld(surfaceData.normalTS, half3x3(input.tangentWS.xyz, bitangent.xyz, input.normalWS.xyz));
        #else
            inputData.normalWS = surfaceData.normalTS;
        #endif
    #else
        inputData.normalWS = input.normalWS;
    #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);

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

}