#version 450

// FFT-based circular convolution for HRR binding
// This is a simplified version - full FFT requires multiple passes
// For now, we'll use a CPU fallback for FFT operations

layout (local_size_x = 256, local_size_y = 1, local_size_z = 1) in;

layout(set = 0, binding = 0) readonly buffer VectorA {
    float a[];
};

layout(set = 0, binding = 1) readonly buffer VectorB {
    float b[];
};

layout(set = 0, binding = 2) readonly buffer FFT_A_Real {
    float fft_a_real[];
};

layout(set = 0, binding = 3) readonly buffer FFT_A_Imag {
    float fft_a_imag[];
};

layout(set = 0, binding = 4) readonly buffer FFT_B_Real {
    float fft_b_real[];
};

layout(set = 0, binding = 5) readonly buffer FFT_B_Imag {
    float fft_b_imag[];
};

layout(set = 0, binding = 6) buffer FFT_Result_Real {
    float fft_result_real[];
};

layout(set = 0, binding = 7) buffer FFT_Result_Imag {
    float fft_result_imag[];
};

layout(set = 0, binding = 8) buffer Result {
    float result[];
};

layout(push_constant) uniform PushConsts {
    uint dim;
    uint stage;  // 0 = multiply FFTs, 1 = IFFT (simplified)
};

void main() {
    uint idx = gl_GlobalInvocationID.x;
    
    if (idx >= dim) {
        return;
    }
    
    if (stage == 0) {
        // Multiply FFTs: (a_real + i*a_imag) * (b_real + i*b_imag)
        // = (a_real*b_real - a_imag*b_imag) + i*(a_real*b_imag + a_imag*b_real)
        float a_r = fft_a_real[idx];
        float a_i = fft_a_imag[idx];
        float b_r = fft_b_real[idx];
        float b_i = fft_b_imag[idx];
        
        fft_result_real[idx] = a_r * b_r - a_i * b_i;
        fft_result_imag[idx] = a_r * b_i + a_i * b_r;
    } else {
        // Simplified IFFT - in practice, use proper FFT shader
        // For now, just copy real part (this is a placeholder)
        result[idx] = fft_result_real[idx] / float(dim);
    }
}
