// Global parameters
SamplerState gShadowSampler : ShadowSampler;
SamplerState gShadowSampler2 : ShadowSampler {
    Filter = MIN_MAG_MIP_POINT;
    AddressU = CLAMP;
    AddressV = CLAMP;
    ComparisonFunc = LESS_EQUAL;
};
texture2D gShadowMap : ShadowMap;
float4x4 gLightViewProj : LightViewProjection;

DepthStencilState ShadowDepthStencilState
{
    DepthEnable = true;
    DepthWriteMask = ALL;       // Write depth to the shadow map
    DepthFunc = LESS_EQUAL;     // Compare depth in the shadow map
    StencilEnable = false;      // We don't need stencil operations here
};

SamplerState gSampleState : SampleState;
RasterizerState gRasterizerState : RastState;

float4x4 gWorldViewProj : WorldViewProjection;
float4x4 gWorldMatrix : WorldMatrix;

texture2D gDiffuseMap : DiffuseMap;
texture2D gNormalMap : Normal;
texture2D gSpecularMap : Specular;
texture2D gGlossMap : Gloss;

float3 gLightDirection : LightDirection;
float3 gLightColor : LightColor;
float3 gCameraPosition : CameraPosition;
bool gUseNormal : UseNormal;

static const float3 gAmbient = float3(.03f, .03f, .03f);

// Input output structures
struct VS_INPUT {
    float3 Position : POSITION;
    float2 TexCoord : TEXCOORD;
    float3 Normal : NORMAL;
    float3 Tangent : TANGENT;
};

struct VS_OUTPUT {
    float4 Position : SV_POSITION;
    float4 WorldPosition : WORLDPOSITION;
    float2 TexCoord : TEXCOORD;
    float3 Normal : NORMAL;
    float3 Tangent : TANGENT;
    float4 ShadowCoord : SHADOWCOORD;  // Add this to store shadow map coordinates
};

// Vertex shader
VS_OUTPUT VS(VS_INPUT input) {
    VS_OUTPUT output = (VS_OUTPUT)0;

    output.WorldPosition = mul(float4(input.Position, 1.f), gWorldMatrix);
    output.Position = mul(float4(input.Position, 1.f), gWorldViewProj);


    output.TexCoord = input.TexCoord;
    output.Normal = mul(input.Normal, (float3x3) gWorldMatrix);
    output.Tangent = mul(input.Tangent, (float3x3) gWorldMatrix);

    // Calculate shadow map coordinates
    // lightSpaceMatrix * vec4(vs_out.FragPos, 1.0);
    output.ShadowCoord = mul(float4(input.Position, 1.f) , gLightViewProj);
    return output;
}

// Shadow sampling function
float ShadowCalculation(float4 shadowCoord) {
    // Normalize the depth by dividing by the w component
    float3 projCoord = shadowCoord.xyz / shadowCoord.w;

    // Convert from [-1, 1] to [0, 1]
    float2 UVCoords;
    UVCoords.x = 0.5f * projCoord.x + 0.5f;
    UVCoords.y = -0.5f * projCoord.y + 0.5f;
//     float z = 0.5 * projCoord.z + 0.5;
    float z = projCoord.z;
    // Sample the shadow map
    float shadowDepth = gShadowMap.Sample(gShadowSampler2, UVCoords.xy).r;

    float bias = 0.0025f;

//     float bias = max(0.05 * (1.0 - dot(normal, lightDir)), 0.005);

//     return gShadowMap.Sample(gShadowSampler2, UVCoords.xy).r;
    // Check if the current fragment is in shadow
    if (shadowDepth + bias < z)
        return 0.5f;
    else
        return 1.0f;

}

// Pixel shader
float4 PS(VS_OUTPUT input) : SV_TARGET {
    // Check if gDiffuseMap sample has a valid value, otherwise render red
//     if (gDiffuseMap.Sample(gSampleState, input.TexCoord).a == 0.f)
//         return float4(1.f, 0.f, 0.f, 1.f);

//     return float4(Shade(input), 1.0f);  // Use the shading function with shadow

//     return gShadowMap.Sample(gShadowSampler, input.ShadowCoord.xy / input.ShadowCoord.w);  // Sample shadow map

    float shadowFactor = ShadowCalculation(input.ShadowCoord);

    float3 diffuseColor = gDiffuseMap.Sample(gSampleState, input.TexCoord).rgb;

    float3 finalColor = float3(1.f, 1.f, 1.f) * shadowFactor;
    finalColor += gAmbient;


//     return float4(shadowDepth,shadowDepth,shadowDepth, 1.0f);
    return float4(finalColor, 1.0f);
//     return gShadowMap.Sample(gShadowSampler, input.TexCoord);  // Sample shadow map
}

// DepthStencilState
DepthStencilState gDepthStencilState
{
    DepthEnable = true;
    DepthWriteMask = ALL;
    DepthFunc = LESS;
    StencilEnable = true;
};

// Technique
technique11 DefaultTechnique {
    pass P0 {
        SetDepthStencilState(ShadowDepthStencilState, 0);
        SetRasterizerState(gRasterizerState);
        SetVertexShader(CompileShader(vs_5_0, VS()));
        SetGeometryShader(NULL);
        SetPixelShader(CompileShader(ps_5_0, PS()));
    }
}