#ifndef COOKBOOK_CH10_MINIMAL_LIT_INPUT_INCLUDED
#define COOKBOOK_CH10_MINIMAL_LIT_INPUT_INCLUDED

// “最小 Lit”的材质输入。（GLSL 版，对应 Ch10/MinimalLitInput.hlsl）
// 三个 Pass（ForwardLit / ShadowCaster / DepthOnly）共用这一份，
// 保证 UnityPerMaterial 布局完全一致 —— 这是 SRP Batcher 兼容的前提。
// HLSL 版 include 了 SurfaceInput.hlsl（声明 _BaseMap / _BumpMap / _EmissionMap 以及 SampleAlbedoAlpha、SampleNormal、Alpha）；
// GLSL 没有 TEXTURE2D_ARGS 这种“贴图 + 采样器”参数宏，下面直接写出这几个函数，采样固定的那张贴图。

uniform vec4  _BaseMap_ST;
uniform vec4  _BaseColor;
uniform vec4  _EmissionColor;
uniform float _Cutoff;        // ShadowCasterPass / DepthOnlyPass 在 _ALPHATEST_ON 时会用到
uniform float _Metallic;
uniform float _Smoothness;
uniform float _BumpScale;

// ---- SurfaceInput.hlsl ----
uniform sampler2D _BaseMap;
uniform sampler2D _BumpMap;
uniform sampler2D _EmissionMap;

vec4 SampleAlbedoAlpha(vec2 uv) { return texture(_BaseMap, uv); }

float Alpha(float albedoAlpha, vec4 color, float cutoff)
{
    float alpha = albedoAlpha * color.a;
#ifdef _ALPHATEST_ON
    if (alpha - cutoff < 0.0) discard;
#endif
    return alpha;
}

vec3 SampleNormal(vec2 uv, float scale)
{
#ifdef _NORMALMAP
    return UnpackNormalScale(texture(_BumpMap, uv), scale);
#else
    return vec3(0.0, 0.0, 1.0);
#endif
}

#endif

// 材质关键字：有法线贴图才开（脚本创建材质时要自己 EnableKeyword）
#pragma shader_feature_local _NORMALMAP
// 管线关键字（主光阴影、附加光、软阴影、SSAO、雾）：网页版引擎始终提供，不用声明；
// 反射探针混合/盒体投影、Forward+、GPU Instancing 网页版没有

SurfaceData BuildSurfaceData(vec2 uv)
{
    SurfaceData s = InitSurfaceData();
    vec4 albedoAlpha = SampleAlbedoAlpha(uv);
    s.albedo     = albedoAlpha.rgb * _BaseColor.rgb;
    s.alpha      = 1.0;                      // 不透明
    s.metallic   = _Metallic;                // 金属度工作流：specular 留 0
    s.specular   = vec3(0.0);
    s.smoothness = _Smoothness;
    s.normalTS   = SampleNormal(uv, _BumpScale);
    s.occlusion  = 1.0;
    s.emission   = _EmissionColor.rgb;
    s.clearCoatMask = 0.0;
    s.clearCoatSmoothness = 0.0;
    return s;
}

InputData BuildInputData(vec3 normalTS)
{
    InputData d = InitInputData();
    d.positionWS = positionWS;
    d.positionCS = gl_FragCoord;

#if defined(_NORMALMAP)
    vec3 bitangent = tangentWS.w * cross(normalWS, tangentWS.xyz);
    d.tangentToWorld = mat3(tangentWS.xyz, bitangent, normalWS);   // GLSL 的 mat3 按列构造：列 = T、B、N
    d.normalWS = TransformTangentToWorld(normalTS, d.tangentToWorld);
#else
    d.normalWS = normalWS;
#endif
    d.normalWS = NormalizeNormalPerPixel(d.normalWS);
    d.viewDirectionWS = GetWorldSpaceNormalizeViewDir(positionWS);

    d.shadowCoord = TransformWorldToShadowCoord(positionWS);   // 逐像素算级联，省一个插值器
    d.fogCoord = fogFactor;
    d.vertexLighting = vec3(0.0);
    d.bakedGI = SampleSH(d.normalWS);                          // 无光照贴图：逐像素 SH
    d.normalizedScreenSpaceUV = GetNormalizedScreenSpaceUV(gl_FragCoord);
    d.shadowMask = vec4(1.0);
    return d;
}

void main()
{
    SurfaceData surfaceData = BuildSurfaceData(uv);
    InputData inputData = BuildInputData(surfaceData.normalTS);

    vec4 color = UniversalFragmentPBR(inputData, surfaceData);
    color.rgb = MixFog(color.rgb, inputData.fogCoord);
    fragColor = color;
}

Pass
{
    Name "ShadowCaster"
    Tags { "LightMode"="ShadowCaster" }
    ZWrite On ZTest LEqual ColorMask 0

    GLSLPROGRAM
    // 先 include 自己的输入（uniform 与 ForwardLit 相同），再复用 URP 的阴影投射 Pass（ShadowCasterPass.hlsl 的 GLSL 写法）
    #include "Ch10/MinimalLitInput.glsl"
    VARYING vec2 uv;
    #ifdef VERTEX
    void main()   // ShadowPassVertex
    {
        uv = TransformTex(texcoord0.xy, _BaseMap_ST);
        gl_Position = GetShadowPositionHClip(positionOS.xyz, normalOS);
    }
    #endif
    #ifdef FRAGMENT
    void main()   // ShadowPassFragment
    {
        Alpha(SampleAlbedoAlpha(uv).a, _BaseColor, _Cutoff);
        fragColor = vec4(0.0);
    }
    #endif
    ENDGLSL
}

Pass
{
    Name "DepthOnly"
    Tags { "LightMode"="DepthOnly" }
    ZWrite On ColorMask R

    GLSLPROGRAM
    #include "Ch10/MinimalLitInput.glsl"
    VARYING vec2 uv;
    #ifdef VERTEX
    void main()   // DepthOnlyVertex
    {
        uv = TransformTex(texcoord0.xy, _BaseMap_ST);
        gl_Position = TransformObjectToHClip(positionOS.xyz);
    }
    #endif
    #ifdef FRAGMENT
    void main()   // DepthOnlyFragment
    {
        Alpha(SampleAlbedoAlpha(uv).a, _BaseColor, _Cutoff);
        fragColor = vec4(gl_FragCoord.z);
    }
    #endif
    ENDGLSL
}

Pass
{
    // 开了 SSAO（Depth Normals 模式）或其他需要 _CameraNormalsTexture 的功能时会用到
    Name "DepthNormals"
    Tags { "LightMode"="DepthNormals" }
    ZWrite On

    GLSLPROGRAM
    #pragma shader_feature_local _NORMALMAP
    #include "Ch10/MinimalLitInput.glsl"
    VARYING vec2 uv;
    VARYING vec3 normalWS;
    VARYING vec4 tangentWS;
    #ifdef VERTEX
    void main()   // DepthNormalsVertex（LitDepthNormalsPass.hlsl）
    {
        uv = TransformTex(texcoord0.xy, _BaseMap_ST);
        VertexNormalInputs n = GetVertexNormalInputs(normalOS, tangentOS);
        normalWS = n.normalWS;
        tangentWS = vec4(n.tangentWS, tangentOS.w * GetOddNegativeScale());
        gl_Position = TransformObjectToHClip(positionOS.xyz);
    }
    #endif
    #ifdef FRAGMENT
    void main()   // DepthNormalsFragment
    {
        Alpha(SampleAlbedoAlpha(uv).a, _BaseColor, _Cutoff);
    #ifdef _NORMALMAP
        vec3 nTS = SampleNormal(uv, _BumpScale);
        vec3 b = tangentWS.w * cross(normalWS, tangentWS.xyz);
        vec3 n = normalize(mat3(tangentWS.xyz, b, normalWS) * nTS);
    #else
        vec3 n = normalize(normalWS);
    #endif
        fragColor = vec4(n, 0.0);
    }
    #endif
    ENDGLSL
}