#include "../buffer/imagebuffer.h"
#include <limits>
#include <algorithm>
#include <cstring>

#ifdef HAVE_AVX2
#include <immintrin.h>

// SIMD optimized implementations for x86_64 architecture using AVX2

namespace simd
{

// Add two 8-bit buffers with AVX2
void add_u8_avx2(uint8_t* a, const uint8_t* b, size_t n)
{
    size_t i = 0;

    // Process 32 elements at a time using AVX2
    if (n >= 32)
    {
        for (; i <= n - 32; i += 32)
        {
            // Load 32 bytes (256 bits)
            __m256i va = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(a + i));
            __m256i vb = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(b + i));

            // Perform saturated add (AVX2 doesn't have direct 8-bit saturated add)
            // We need to use SSE instructions via AVX2 lanes
            __m128i va_lo = _mm256_extracti128_si256(va, 0);
            __m128i va_hi = _mm256_extracti128_si256(va, 1);
            __m128i vb_lo = _mm256_extracti128_si256(vb, 0);
            __m128i vb_hi = _mm256_extracti128_si256(vb, 1);

            // Perform saturated add using SSE
            __m128i result_lo = _mm_adds_epu8(va_lo, vb_lo);
            __m128i result_hi = _mm_adds_epu8(va_hi, vb_hi);

            // Combine results back into 256-bit register
            __m256i result = _mm256_set_m128i(result_hi, result_lo);

            // Store the result
            _mm256_storeu_si256(reinterpret_cast<__m256i*>(a + i), result);
        }
    }

    // Process remaining elements
    for (; i < n; ++i)
    {
        int sum = static_cast<int>(a[i]) + static_cast<int>(b[i]);
        a[i] = static_cast<uint8_t>(std::min(255, sum));
    }
}

// Subtract two 8-bit buffers with AVX2
void subtract_u8_avx2(uint8_t* a, const uint8_t* b, size_t n)
{
    size_t i = 0;

    // Process 32 elements at a time using AVX2
    if (n >= 32)
    {
        for (; i <= n - 32; i += 32)
        {
            // Load 32 bytes (256 bits)
            __m256i va = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(a + i));
            __m256i vb = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(b + i));

            // Perform saturated subtract (AVX2 doesn't have direct 8-bit saturated subtract)
            // We need to use SSE instructions via AVX2 lanes
            __m128i va_lo = _mm256_extracti128_si256(va, 0);
            __m128i va_hi = _mm256_extracti128_si256(va, 1);
            __m128i vb_lo = _mm256_extracti128_si256(vb, 0);
            __m128i vb_hi = _mm256_extracti128_si256(vb, 1);

            // Perform saturated subtract using SSE
            __m128i result_lo = _mm_subs_epu8(va_lo, vb_lo);
            __m128i result_hi = _mm_subs_epu8(va_hi, vb_hi);

            // Combine results back into 256-bit register
            __m256i result = _mm256_set_m128i(result_hi, result_lo);

            // Store the result
            _mm256_storeu_si256(reinterpret_cast<__m256i*>(a + i), result);
        }
    }

    // Process remaining elements
    for (; i < n; ++i)
    {
        int diff = static_cast<int>(a[i]) - static_cast<int>(b[i]);
        a[i] = static_cast<uint8_t>(std::max(0, diff));
    }
}

// Multiply 8-bit buffer by a scalar with AVX2
void multiply_u8_avx2(uint8_t* a, float factor, size_t n)
{
    size_t i = 0;

    // Create a vector with the factor replicated 8 times
    __m256 vfactor = _mm256_set1_ps(factor);

    // Process 16 elements at a time using AVX2
    if (n >= 16)
    {
        for (; i <= n - 16; i += 16)
        {
            // Process 16 bytes at a time to avoid lane crossing issues
            __m128i v_int = _mm_loadu_si128(reinterpret_cast<const __m128i*>(a + i));

            // Process first 8 bytes
            __m128i v_int_lo = _mm_unpacklo_epi8(v_int, _mm_setzero_si128());

            // Convert to 32-bit integers (first 4 16-bit integers)
            __m128i v_int_lo_lo = _mm_unpacklo_epi16(v_int_lo, _mm_setzero_si128());

            // Convert to float
            __m128 v_float_lo_lo = _mm_cvtepi32_ps(v_int_lo_lo);

            // Multiply by factor
            v_float_lo_lo = _mm_mul_ps(v_float_lo_lo, _mm256_castps256_ps128(vfactor));

            // Convert back to int
            v_int_lo_lo = _mm_cvtps_epi32(v_float_lo_lo);

            // Convert to 32-bit integers (next 4 16-bit integers)
            __m128i v_int_lo_hi = _mm_unpackhi_epi16(v_int_lo, _mm_setzero_si128());

            // Convert to float
            __m128 v_float_lo_hi = _mm_cvtepi32_ps(v_int_lo_hi);

            // Multiply by factor
            v_float_lo_hi = _mm_mul_ps(v_float_lo_hi, _mm256_castps256_ps128(vfactor));

            // Convert back to int
            v_int_lo_hi = _mm_cvtps_epi32(v_float_lo_hi);

            // Process second 8 bytes
            __m128i v_int_hi = _mm_unpackhi_epi8(v_int, _mm_setzero_si128());

            // Convert to 32-bit integers (first 4 16-bit integers)
            __m128i v_int_hi_lo = _mm_unpacklo_epi16(v_int_hi, _mm_setzero_si128());

            // Convert to float
            __m128 v_float_hi_lo = _mm_cvtepi32_ps(v_int_hi_lo);

            // Multiply by factor
            v_float_hi_lo = _mm_mul_ps(v_float_hi_lo, _mm256_castps256_ps128(vfactor));

            // Convert back to int
            v_int_hi_lo = _mm_cvtps_epi32(v_float_hi_lo);

            // Convert to 32-bit integers (next 4 16-bit integers)
            __m128i v_int_hi_hi = _mm_unpackhi_epi16(v_int_hi, _mm_setzero_si128());

            // Convert to float
            __m128 v_float_hi_hi = _mm_cvtepi32_ps(v_int_hi_hi);

            // Multiply by factor
            v_float_hi_hi = _mm_mul_ps(v_float_hi_hi, _mm256_castps256_ps128(vfactor));

            // Convert back to int
            v_int_hi_hi = _mm_cvtps_epi32(v_float_hi_hi);

            // Pack back to 16-bit
            __m128i v_int_lo_16 = _mm_packus_epi32(v_int_lo_lo, v_int_lo_hi);
            __m128i v_int_hi_16 = _mm_packus_epi32(v_int_hi_lo, v_int_hi_hi);

            // Pack back to 8-bit
            __m128i v_int_result = _mm_packus_epi16(v_int_lo_16, v_int_hi_16);

            // Store the result
            _mm_storeu_si128(reinterpret_cast<__m128i*>(a + i), v_int_result);
        }
    }

    // Process remaining elements
    for (; i < n; ++i)
    {
        float result = static_cast<float>(a[i]) * factor;
        a[i] = static_cast<uint8_t>(std::min(255.0f, result));
    }
}

// Add two 16-bit buffers with AVX2
void add_u16_avx2(uint16_t* a, const uint16_t* b, size_t n)
{
    size_t i = 0;

    // Process 16 elements at a time using AVX2
    if (n >= 16)
    {
        for (; i <= n - 16; i += 16)
        {
            // Load 16 16-bit integers (256 bits)
            __m256i va = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(a + i));
            __m256i vb = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(b + i));

            // Add with saturation (AVX2 doesn't have 16-bit saturated add)
            // We need to implement it manually
            __m256i sum = _mm256_add_epi16(va, vb);

            // Check for overflow: if sum < a or sum < b, then overflow occurred
            __m256i overflow_mask = _mm256_or_si256(
                                        _mm256_cmpgt_epi16(va, sum),
                                        _mm256_cmpgt_epi16(vb, sum)
                                    );

            // Set overflowed elements to max value (0xFFFF)
            __m256i max_val = _mm256_set1_epi16(0xFFFF);
            __m256i result = _mm256_blendv_epi8(sum, max_val, overflow_mask);

            // Store the result
            _mm256_storeu_si256(reinterpret_cast<__m256i*>(a + i), result);
        }
    }

    // Process remaining elements
    for (; i < n; ++i)
    {
        int sum = static_cast<int>(a[i]) + static_cast<int>(b[i]);
        a[i] = static_cast<uint16_t>(std::min(65535, sum));
    }
}

// Subtract two 16-bit buffers with AVX2
void subtract_u16_avx2(uint16_t* a, const uint16_t* b, size_t n)
{
    size_t i = 0;

    // Process 16 elements at a time using AVX2
    if (n >= 16)
    {
        for (; i <= n - 16; i += 16)
        {
            // Load 16 16-bit integers (256 bits)
            __m256i va = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(a + i));
            __m256i vb = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(b + i));

            // Implement saturated subtraction manually
            // Create a mask where a < b
            __m256i mask = _mm256_cmpgt_epi16(vb, va);

            // Where a >= b, do normal subtraction; where a < b, set to 0
            __m256i result = _mm256_andnot_si256(
                                 mask,
                                 _mm256_sub_epi16(va, vb)
                             );

            // Store the result
            _mm256_storeu_si256(reinterpret_cast<__m256i*>(a + i), result);
        }
    }

    // Process remaining elements
    for (; i < n; ++i)
    {
        int diff = static_cast<int>(a[i]) - static_cast<int>(b[i]);
        a[i] = static_cast<uint16_t>(std::max(0, diff));
    }
}

// Multiply 16-bit buffer by a scalar with AVX2
void multiply_u16_avx2(uint16_t* a, float factor, size_t n)
{
    size_t i = 0;

    // Create a vector with the factor replicated 8 times
    __m256 vfactor = _mm256_set1_ps(factor);

    // Process 16 elements at a time using AVX2
    if (n >= 16)
    {
        for (; i <= n - 16; i += 16)
        {
            // Load 16 16-bit integers (256 bits)
            __m256i v_int = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(a + i));

            // Process first 8 16-bit integers
            __m128i v_int_lo = _mm256_extracti128_si256(v_int, 0);

            // Convert to 32-bit integers
            __m256i v_int_lo_32 = _mm256_cvtepu16_epi32(v_int_lo);

            // Convert to float
            __m256 v_float_lo = _mm256_cvtepi32_ps(v_int_lo_32);

            // Multiply by factor
            v_float_lo = _mm256_mul_ps(v_float_lo, vfactor);

            // Convert back to int
            v_int_lo_32 = _mm256_cvtps_epi32(v_float_lo);

            // Process second 8 16-bit integers
            __m128i v_int_hi = _mm256_extracti128_si256(v_int, 1);

            // Convert to 32-bit integers
            __m256i v_int_hi_32 = _mm256_cvtepu16_epi32(v_int_hi);

            // Convert to float
            __m256 v_float_hi = _mm256_cvtepi32_ps(v_int_hi_32);

            // Multiply by factor
            v_float_hi = _mm256_mul_ps(v_float_hi, vfactor);

            // Convert back to int
            v_int_hi_32 = _mm256_cvtps_epi32(v_float_hi);

            // Pack back to 16-bit with saturation
            __m256i v_int_16 = _mm256_packus_epi32(v_int_lo_32, v_int_hi_32);

            // Permute to get the correct order (AVX2 packus_epi32 has a different order than expected)
            __m256i idx = _mm256_set_epi32(7, 5, 3, 1, 6, 4, 2, 0);
            v_int_16 = _mm256_permutevar8x32_epi32(v_int_16, idx);

            // Store the result
            _mm256_storeu_si256(reinterpret_cast<__m256i*>(a + i), v_int_16);
        }
    }

    // Process remaining elements
    for (; i < n; ++i)
    {
        float result = static_cast<float>(a[i]) * factor;
        a[i] = static_cast<uint16_t>(std::min(65535.0f, result));
    }
}

// Calculate mean of 8-bit buffer with AVX2
float mean_u8_avx2(const uint8_t* data, size_t n)
{
    if (n == 0) return 0.0f;

    size_t i = 0;
    __m256i vsum = _mm256_setzero_si256();

    // Process 32 elements at a time
    if (n >= 32)
    {
        for (; i <= n - 32; i += 32)
        {
            // Load 32 bytes
            __m256i v = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(data + i));

            // Convert to 16-bit integers
            __m128i v_lo = _mm256_extracti128_si256(v, 0);
            __m128i v_hi = _mm256_extracti128_si256(v, 1);

            __m256i v_16_lo = _mm256_cvtepu8_epi16(v_lo);
            __m256i v_16_hi = _mm256_cvtepu8_epi16(v_hi);

            // Convert to 32-bit integers and accumulate
            vsum = _mm256_add_epi32(vsum, _mm256_cvtepu16_epi32(_mm256_extracti128_si256(v_16_lo, 0)));
            vsum = _mm256_add_epi32(vsum, _mm256_cvtepu16_epi32(_mm256_extracti128_si256(v_16_lo, 1)));
            vsum = _mm256_add_epi32(vsum, _mm256_cvtepu16_epi32(_mm256_extracti128_si256(v_16_hi, 0)));
            vsum = _mm256_add_epi32(vsum, _mm256_cvtepu16_epi32(_mm256_extracti128_si256(v_16_hi, 1)));
        }
    }

    // Horizontal sum of vsum
    __m128i vsum_128 = _mm_add_epi32(_mm256_extracti128_si256(vsum, 0), _mm256_extracti128_si256(vsum, 1));
    __m128i vsum_64 = _mm_add_epi32(vsum_128, _mm_srli_si128(vsum_128, 8));
    __m128i vsum_32 = _mm_add_epi32(vsum_64, _mm_srli_si128(vsum_64, 4));
    uint32_t sum = _mm_cvtsi128_si32(vsum_32);

    // Process remaining elements
    for (; i < n; ++i)
    {
        sum += data[i];
    }

    return static_cast<float>(sum) / n;
}

// Calculate mean of 16-bit buffer with AVX2
float mean_u16_avx2(const uint16_t* data, size_t n)
{
    if (n == 0) return 0.0f;

    size_t i = 0;
    __m256i vsum = _mm256_setzero_si256();

    // Process 16 elements at a time
    if (n >= 16)
    {
        for (; i <= n - 16; i += 16)
        {
            // Load 16 16-bit integers
            __m256i v = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(data + i));

            // Convert to 32-bit integers and accumulate
            __m128i v_lo = _mm256_extracti128_si256(v, 0);
            __m128i v_hi = _mm256_extracti128_si256(v, 1);

            vsum = _mm256_add_epi32(vsum, _mm256_cvtepu16_epi32(v_lo));
            vsum = _mm256_add_epi32(vsum, _mm256_cvtepu16_epi32(v_hi));
        }
    }

    // Horizontal sum of vsum
    __m128i vsum_128 = _mm_add_epi32(_mm256_extracti128_si256(vsum, 0), _mm256_extracti128_si256(vsum, 1));
    __m128i vsum_64 = _mm_add_epi32(vsum_128, _mm_srli_si128(vsum_128, 8));
    __m128i vsum_32 = _mm_add_epi32(vsum_64, _mm_srli_si128(vsum_64, 4));
    uint32_t sum = _mm_cvtsi128_si32(vsum_32);

    // Process remaining elements
    for (; i < n; ++i)
    {
        sum += data[i];
    }

    return static_cast<float>(sum) / n;
}

// Calculate variance of 8-bit buffer with AVX2
float variance_u8_avx2(const uint8_t* data, size_t n)
{
    if (n <= 1) return 0.0f;

    // Calculate mean first
    float mean_val = mean_u8_avx2(data, n);

    size_t i = 0;
    __m256 vsum_squared_diff = _mm256_setzero_ps();
    __m256 vmean = _mm256_set1_ps(mean_val);

    // Process 32 elements at a time
    if (n >= 32)
    {
        for (; i <= n - 32; i += 32)
        {
            // Load 32 bytes
            __m256i v = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(data + i));

            // Process in 8-element chunks
            for (int j = 0; j < 4; ++j)
            {
                // Extract 8 bytes and convert to 32-bit floats
                __m128i v8;
                if (j < 2)
                {
                    // Extract from low 128 bits
                    __m128i v_lo = _mm256_extracti128_si256(v, 0);
                    if (j == 0)
                        v8 = _mm_cvtsi32_si128(_mm_extract_epi32(v_lo, 0));
                    else
                        v8 = _mm_cvtsi32_si128(_mm_extract_epi32(v_lo, 1));
                }
                else
                {
                    // Extract from high 128 bits
                    __m128i v_hi = _mm256_extracti128_si256(v, 1);
                    if (j == 2)
                        v8 = _mm_cvtsi32_si128(_mm_extract_epi32(v_hi, 0));
                    else
                        v8 = _mm_cvtsi32_si128(_mm_extract_epi32(v_hi, 1));
                }
                __m256i v32 = _mm256_cvtepu8_epi32(v8);
                __m256 vf = _mm256_cvtepi32_ps(v32);

                // Calculate squared difference
                __m256 vdiff = _mm256_sub_ps(vf, vmean);
                __m256 vsquared_diff = _mm256_mul_ps(vdiff, vdiff);

                // Accumulate
                vsum_squared_diff = _mm256_add_ps(vsum_squared_diff, vsquared_diff);
            }
        }
    }

    // Horizontal sum of vsum_squared_diff
    __m128 vsum_128 = _mm_add_ps(_mm256_extractf128_ps(vsum_squared_diff, 0), _mm256_extractf128_ps(vsum_squared_diff, 1));
    __m128 vsum_64 = _mm_add_ps(vsum_128, _mm_movehl_ps(vsum_128, vsum_128));
    __m128 vsum_32 = _mm_add_ss(vsum_64, _mm_shuffle_ps(vsum_64, vsum_64, 1));
    float sum_squared_diff = _mm_cvtss_f32(vsum_32);

    // Process remaining elements
    for (; i < n; ++i)
    {
        float diff = data[i] - mean_val;
        sum_squared_diff += diff * diff;
    }

    return sum_squared_diff / (n - 1);
}

// Calculate variance of 16-bit buffer with AVX2
float variance_u16_avx2(const uint16_t* data, size_t n)
{
    if (n <= 1) return 0.0f;

    // Calculate mean first
    float mean_val = mean_u16_avx2(data, n);

    size_t i = 0;
    __m256 vsum_squared_diff = _mm256_setzero_ps();
    __m256 vmean = _mm256_set1_ps(mean_val);

    // Process 16 elements at a time
    if (n >= 16)
    {
        for (; i <= n - 16; i += 16)
        {
            // Load 16 16-bit integers
            __m256i v = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(data + i));

            // Process in 8-element chunks
            for (int j = 0; j < 2; ++j)
            {
                // Extract 8 16-bit integers and convert to 32-bit floats
                __m128i v16 = (j == 0) ? _mm256_extracti128_si256(v, 0) : _mm256_extracti128_si256(v, 1);
                __m256i v32 = _mm256_cvtepu16_epi32(v16);
                __m256 vf = _mm256_cvtepi32_ps(v32);

                // Calculate squared difference
                __m256 vdiff = _mm256_sub_ps(vf, vmean);
                __m256 vsquared_diff = _mm256_mul_ps(vdiff, vdiff);

                // Accumulate
                vsum_squared_diff = _mm256_add_ps(vsum_squared_diff, vsquared_diff);
            }
        }
    }

    // Horizontal sum of vsum_squared_diff
    __m128 vsum_128 = _mm_add_ps(_mm256_extractf128_ps(vsum_squared_diff, 0), _mm256_extractf128_ps(vsum_squared_diff, 1));
    __m128 vsum_64 = _mm_add_ps(vsum_128, _mm_movehl_ps(vsum_128, vsum_128));
    __m128 vsum_32 = _mm_add_ss(vsum_64, _mm_shuffle_ps(vsum_64, vsum_64, 1));
    float sum_squared_diff = _mm_cvtss_f32(vsum_32);

    // Process remaining elements
    for (; i < n; ++i)
    {
        float diff = data[i] - mean_val;
        sum_squared_diff += diff * diff;
    }

    return sum_squared_diff / (n - 1);
}

// Find min and max values in 8-bit buffer with AVX2
void min_max_u8_avx2(const uint8_t* data, size_t n, uint8_t &min_val, uint8_t &max_val)
{
    if (n == 0)
    {
        min_val = 0;
        max_val = 0;
        return;
    }

    size_t i = 0;
    __m256i vmin = _mm256_set1_epi8(255);
    __m256i vmax = _mm256_setzero_si256();

    // Process 32 elements at a time
    if (n >= 32)
    {
        for (; i <= n - 32; i += 32)
        {
            // Load 32 bytes
            __m256i v = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(data + i));

            // Update min and max
            vmin = _mm256_min_epu8(vmin, v);
            vmax = _mm256_max_epu8(vmax, v);
        }
    }

    // Combine results from the two 128-bit lanes
    __m128i vmin_lo = _mm256_extracti128_si256(vmin, 0);
    __m128i vmin_hi = _mm256_extracti128_si256(vmin, 1);
    __m128i vmax_lo = _mm256_extracti128_si256(vmax, 0);
    __m128i vmax_hi = _mm256_extracti128_si256(vmax, 1);

    __m128i vmin_combined = _mm_min_epu8(vmin_lo, vmin_hi);
    __m128i vmax_combined = _mm_max_epu8(vmax_lo, vmax_hi);

    // Find min and max in the 128-bit register
    min_val = 255;
    max_val = 0;

    // Extract values from the 128-bit registers
    alignas(16) uint8_t min_values[16];
    alignas(16) uint8_t max_values[16];

    _mm_store_si128(reinterpret_cast<__m128i*>(min_values), vmin_combined);
    _mm_store_si128(reinterpret_cast<__m128i*>(max_values), vmax_combined);

    for (int j = 0; j < 16; ++j)
    {
        min_val = std::min(min_val, min_values[j]);
        max_val = std::max(max_val, max_values[j]);
    }

    // Process remaining elements
    for (; i < n; ++i)
    {
        min_val = std::min(min_val, data[i]);
        max_val = std::max(max_val, data[i]);
    }
}

// Find min and max values in 16-bit buffer with AVX2
void min_max_u16_avx2(const uint16_t* data, size_t n, uint16_t &min_val, uint16_t &max_val)
{
    if (n == 0)
    {
        min_val = 0;
        max_val = 0;
        return;
    }

    size_t i = 0;
    __m256i vmin = _mm256_set1_epi16(65535);
    __m256i vmax = _mm256_setzero_si256();

    // Process 16 elements at a time
    if (n >= 16)
    {
        for (; i <= n - 16; i += 16)
        {
            // Load 16 16-bit integers
            __m256i v = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(data + i));

            // Update min and max
            vmin = _mm256_min_epi16(vmin, v);
            vmax = _mm256_max_epi16(vmax, v);
        }
    }

    // Combine results from the two 128-bit lanes
    __m128i vmin_lo = _mm256_extracti128_si256(vmin, 0);
    __m128i vmin_hi = _mm256_extracti128_si256(vmin, 1);
    __m128i vmax_lo = _mm256_extracti128_si256(vmax, 0);
    __m128i vmax_hi = _mm256_extracti128_si256(vmax, 1);

    __m128i vmin_combined = _mm_min_epi16(vmin_lo, vmin_hi);
    __m128i vmax_combined = _mm_max_epi16(vmax_lo, vmax_hi);

    // Find min and max in the 128-bit register
    min_val = 65535;
    max_val = 0;

    // Extract values from the 128-bit registers
    alignas(16) uint16_t min_values[8];
    alignas(16) uint16_t max_values[8];

    _mm_store_si128(reinterpret_cast<__m128i*>(min_values), vmin_combined);
    _mm_store_si128(reinterpret_cast<__m128i*>(max_values), vmax_combined);

    for (int j = 0; j < 8; ++j)
    {
        min_val = std::min(min_val, min_values[j]);
        max_val = std::max(max_val, max_values[j]);
    }

    // Process remaining elements
    for (; i < n; ++i)
    {
        min_val = std::min(min_val, data[i]);
        max_val = std::max(max_val, data[i]);
    }
}

// Create histogram for 8-bit buffer with AVX2
void histogram_u8_avx2(const uint8_t* data, size_t n, uint32_t* histogram, size_t bins)
{
    // Initialize histogram to zeros
    for (size_t i = 0; i < bins; ++i)
    {
        histogram[i] = 0;
    }

    // Process elements one by one
    // Note: SIMD histogram calculation is complex due to potential race conditions
    // when incrementing bins. For simplicity, we use a scalar implementation here.
    for (size_t i = 0; i < n; ++i)
    {
        histogram[data[i]]++;
    }
}

// Apply threshold to 8-bit buffer with AVX2
void threshold_u8_avx2(uint8_t* data, size_t n, uint8_t threshold, uint8_t low_value, uint8_t high_value)
{
    size_t i = 0;

    // Create vectors with threshold, low_value, and high_value replicated
    __m256i vthreshold = _mm256_set1_epi8(threshold);
    __m256i vlow = _mm256_set1_epi8(low_value);
    __m256i vhigh = _mm256_set1_epi8(high_value);

    // Process 32 elements at a time
    if (n >= 32)
    {
        for (; i <= n - 32; i += 32)
        {
            // Load 32 bytes
            __m256i v = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(data + i));

            // Compare with threshold
            __m256i mask = _mm256_cmpgt_epi8(v, vthreshold);

            // Select low or high value based on comparison
            __m256i result = _mm256_blendv_epi8(vlow, vhigh, mask);

            // Store the result
            _mm256_storeu_si256(reinterpret_cast<__m256i*>(data + i), result);
        }
    }

    // Process remaining elements
    for (; i < n; ++i)
    {
        data[i] = (data[i] > threshold) ? high_value : low_value;
    }
}

// Apply threshold to 16-bit buffer with AVX2
void threshold_u16_avx2(uint16_t* data, size_t n, uint16_t threshold, uint16_t low_value, uint16_t high_value)
{
    size_t i = 0;

    // Create vectors with threshold, low_value, and high_value replicated
    __m256i vthreshold = _mm256_set1_epi16(threshold);
    __m256i vlow = _mm256_set1_epi16(low_value);
    __m256i vhigh = _mm256_set1_epi16(high_value);

    // Process 16 elements at a time
    if (n >= 16)
    {
        for (; i <= n - 16; i += 16)
        {
            // Load 16 16-bit integers
            __m256i v = _mm256_loadu_si256(reinterpret_cast<const __m256i*>(data + i));

            // Compare with threshold
            __m256i mask = _mm256_cmpgt_epi16(v, vthreshold);

            // Select low or high value based on comparison
            __m256i result = _mm256_blendv_epi8(vlow, vhigh, mask);

            // Store the result
            _mm256_storeu_si256(reinterpret_cast<__m256i*>(data + i), result);
        }
    }

    // Process remaining elements
    for (; i < n; ++i)
    {
        data[i] = (data[i] > threshold) ? high_value : low_value;
    }
}

// Apply Gaussian blur to 8-bit buffer with AVX2
void gaussian_blur_u8_avx2(uint8_t* dst, const uint8_t* src, int width, int height, int channels, float sigma)
{
    // This is a placeholder implementation
    // In a real implementation, we would compute a Gaussian kernel and apply it
    // For now, we'll just copy the source to the destination
    std::memcpy(dst, src, width * height * channels);
}

// Apply median filter to 8-bit buffer with AVX2
void median_filter_u8_avx2(uint8_t* dst, const uint8_t* src, int width, int height, int channels, int kernel_size)
{
    // This is a placeholder implementation
    // In a real implementation, we would apply a median filter with the specified kernel size
    // For now, we'll just copy the source to the destination
    std::memcpy(dst, src, width * height * channels);
}

} // namespace simd

#endif // HAVE_AVX2
