/* SPDX-License-Identifier: Apache-2.0
 * Copyright 2021-2022 Intel Corporation */

CCL_NAMESPACE_BEGIN

/* For oneAPI implementation we do manual lookup and interpolation. */
/* TODO: share implementation with ../cpu/image.h. */

template<typename T> ccl_device_forceinline T tex_fetch(const TextureInfo &info, int index)
{
  return reinterpret_cast<ccl_global T *>(info.data)[index];
}

ccl_device_inline int svm_image_texture_wrap_periodic(int x, int width)
{
  x %= width;
  if (x < 0)
    x += width;
  return x;
}

ccl_device_inline int svm_image_texture_wrap_clamp(int x, int width)
{
  return clamp(x, 0, width - 1);
}

ccl_device_inline float4 svm_image_texture_read(const TextureInfo &info, int x, int y, int z)
{
  const int data_offset = x + info.width * y + info.width * info.height * z;
  const int texture_type = info.data_type;

  /* Float4 */
  if (texture_type == IMAGE_DATA_TYPE_FLOAT4) {
    return tex_fetch<float4>(info, data_offset);
  }
  /* Byte4 */
  else if (texture_type == IMAGE_DATA_TYPE_BYTE4) {
    uchar4 r = tex_fetch<uchar4>(info, data_offset);
    float f = 1.0f / 255.0f;
    return make_float4(r.x * f, r.y * f, r.z * f, r.w * f);
  }
  /* Ushort4 */
  else if (texture_type == IMAGE_DATA_TYPE_USHORT4) {
    ushort4 r = tex_fetch<ushort4>(info, data_offset);
    float f = 1.0f / 65535.f;
    return make_float4(r.x * f, r.y * f, r.z * f, r.w * f);
  }
  /* Float */
  else if (texture_type == IMAGE_DATA_TYPE_FLOAT) {
    float f = tex_fetch<float>(info, data_offset);
    return make_float4(f, f, f, 1.0f);
  }
  /* UShort */
  else if (texture_type == IMAGE_DATA_TYPE_USHORT) {
    ushort r = tex_fetch<ushort>(info, data_offset);
    float f = r * (1.0f / 65535.0f);
    return make_float4(f, f, f, 1.0f);
  }
  else if (texture_type == IMAGE_DATA_TYPE_HALF) {
    float f = tex_fetch<half>(info, data_offset);
    return make_float4(f, f, f, 1.0f);
  }
  else if (texture_type == IMAGE_DATA_TYPE_HALF4) {
    half4 r = tex_fetch<half4>(info, data_offset);
    return make_float4(r.x, r.y, r.z, r.w);
  }
  /* Byte */
  else {
    uchar r = tex_fetch<uchar>(info, data_offset);
    float f = r * (1.0f / 255.0f);
    return make_float4(f, f, f, 1.0f);
  }
}

ccl_device_inline float4 svm_image_texture_read_2d(int id, int x, int y)
{
  const TextureInfo &info = kernel_data_fetch(texture_info, id);

  /* Wrap */
  if (info.extension == EXTENSION_REPEAT) {
    x = svm_image_texture_wrap_periodic(x, info.width);
    y = svm_image_texture_wrap_periodic(y, info.height);
  }
  else if (info.extension == EXTENSION_EXTEND) {
    x = svm_image_texture_wrap_clamp(x, info.width);
    y = svm_image_texture_wrap_clamp(y, info.height);
  }
  else {
    if (x < 0 || x >= info.width || y < 0 || y >= info.height) {
      return make_float4(0.0f, 0.0f, 0.0f, 0.0f);
    }
  }

  return svm_image_texture_read(info, x, y, 0);
}

ccl_device_inline float4 svm_image_texture_read_3d(int id, int x, int y, int z)
{
  const TextureInfo &info = kernel_data_fetch(texture_info, id);

  /* Wrap */
  if (info.extension == EXTENSION_REPEAT) {
    x = svm_image_texture_wrap_periodic(x, info.width);
    y = svm_image_texture_wrap_periodic(y, info.height);
    z = svm_image_texture_wrap_periodic(z, info.depth);
  }
  else if (info.extension == EXTENSION_EXTEND) {
    x = svm_image_texture_wrap_clamp(x, info.width);
    y = svm_image_texture_wrap_clamp(y, info.height);
    z = svm_image_texture_wrap_clamp(z, info.depth);
  }
  else {
    if (x < 0 || x >= info.width || y < 0 || y >= info.height || z < 0 || z >= info.depth) {
      return make_float4(0.0f, 0.0f, 0.0f, 0.0f);
    }
  }

  return svm_image_texture_read(info, x, y, z);
}

static float svm_image_texture_frac(float x, int *ix)
{
  int i = float_to_int(x) - ((x < 0.0f) ? 1 : 0);
  *ix = i;
  return x - (float)i;
}

#define SET_CUBIC_SPLINE_WEIGHTS(u, t) \
  { \
    u[0] = (((-1.0f / 6.0f) * t + 0.5f) * t - 0.5f) * t + (1.0f / 6.0f); \
    u[1] = ((0.5f * t - 1.0f) * t) * t + (2.0f / 3.0f); \
    u[2] = ((-0.5f * t + 0.5f) * t + 0.5f) * t + (1.0f / 6.0f); \
    u[3] = (1.0f / 6.0f) * t * t * t; \
  } \
  (void)0

ccl_device float4 kernel_tex_image_interp(KernelGlobals, int id, float x, float y)
{
  const TextureInfo &info = kernel_data_fetch(texture_info, id);

  if (info.interpolation == INTERPOLATION_CLOSEST) {
    /* Closest interpolation. */
    int ix, iy;
    svm_image_texture_frac(x * info.width, &ix);
    svm_image_texture_frac(y * info.height, &iy);

    return svm_image_texture_read_2d(id, ix, iy);
  }
  else if (info.interpolation == INTERPOLATION_LINEAR) {
    /* Bilinear interpolation. */
    int ix, iy;
    float tx = svm_image_texture_frac(x * info.width - 0.5f, &ix);
    float ty = svm_image_texture_frac(y * info.height - 0.5f, &iy);

    float4 r;
    r = (1.0f - ty) * (1.0f - tx) * svm_image_texture_read_2d(id, ix, iy);
    r += (1.0f - ty) * tx * svm_image_texture_read_2d(id, ix + 1, iy);
    r += ty * (1.0f - tx) * svm_image_texture_read_2d(id, ix, iy + 1);
    r += ty * tx * svm_image_texture_read_2d(id, ix + 1, iy + 1);
    return r;
  }
  else {
    /* Bicubic interpolation. */
    int ix, iy;
    float tx = svm_image_texture_frac(x * info.width - 0.5f, &ix);
    float ty = svm_image_texture_frac(y * info.height - 0.5f, &iy);

    float u[4], v[4];
    SET_CUBIC_SPLINE_WEIGHTS(u, tx);
    SET_CUBIC_SPLINE_WEIGHTS(v, ty);

    float4 r = make_float4(0.0f, 0.0f, 0.0f, 0.0f);

    for (int y = 0; y < 4; y++) {
      for (int x = 0; x < 4; x++) {
        float weight = u[x] * v[y];
        r += weight * svm_image_texture_read_2d(id, ix + x - 1, iy + y - 1);
      }
    }
    return r;
  }
}

#ifdef WITH_NANOVDB
template<typename T> struct NanoVDBInterpolator {

  typedef typename nanovdb::NanoGrid<T>::AccessorType AccessorType;

  static ccl_always_inline float4 read(float r)
  {
    return make_float4(r, r, r, 1.0f);
  }

  static ccl_always_inline float4 read(nanovdb::Vec3f r)
  {
    return make_float4(r[0], r[1], r[2], 1.0f);
  }

  static ccl_always_inline float4 interp_3d_closest(const AccessorType &acc,
                                                    float x,
                                                    float y,
                                                    float z)
  {
    const nanovdb::Vec3f xyz(x, y, z);
    return read(nanovdb::SampleFromVoxels<AccessorType, 0, false>(acc)(xyz));
  }

  static ccl_always_inline float4 interp_3d_linear(const AccessorType &acc,
                                                   float x,
                                                   float y,
                                                   float z)
  {
    const nanovdb::Vec3f xyz(x - 0.5f, y - 0.5f, z - 0.5f);
    return read(nanovdb::SampleFromVoxels<AccessorType, 1, false>(acc)(xyz));
  }

  static float4 interp_3d_cubic(const AccessorType &acc, float x, float y, float z)
  {
    int ix, iy, iz;
    int nix, niy, niz;
    int pix, piy, piz;
    int nnix, nniy, nniz;
    /* Tri-cubic b-spline interpolation. */
    const float tx = svm_image_texture_frac(x - 0.5f, &ix);
    const float ty = svm_image_texture_frac(y - 0.5f, &iy);
    const float tz = svm_image_texture_frac(z - 0.5f, &iz);
    pix = ix - 1;
    piy = iy - 1;
    piz = iz - 1;
    nix = ix + 1;
    niy = iy + 1;
    niz = iz + 1;
    nnix = ix + 2;
    nniy = iy + 2;
    nniz = iz + 2;

    const int xc[4] = {pix, ix, nix, nnix};
    const int yc[4] = {piy, iy, niy, nniy};
    const int zc[4] = {piz, iz, niz, nniz};
    float u[4], v[4], w[4];

    /* Some helper macro to keep code reasonable size,
     * let compiler to inline all the matrix multiplications.
     */
#  define DATA(x, y, z) (read(acc.getValue(nanovdb::Coord(xc[x], yc[y], zc[z]))))
#  define COL_TERM(col, row) \
    (v[col] * (u[0] * DATA(0, col, row) + u[1] * DATA(1, col, row) + u[2] * DATA(2, col, row) + \
               u[3] * DATA(3, col, row)))
#  define ROW_TERM(row) \
    (w[row] * (COL_TERM(0, row) + COL_TERM(1, row) + COL_TERM(2, row) + COL_TERM(3, row)))

    SET_CUBIC_SPLINE_WEIGHTS(u, tx);
    SET_CUBIC_SPLINE_WEIGHTS(v, ty);
    SET_CUBIC_SPLINE_WEIGHTS(w, tz);

    /* Actual interpolation. */
    return ROW_TERM(0) + ROW_TERM(1) + ROW_TERM(2) + ROW_TERM(3);

#  undef COL_TERM
#  undef ROW_TERM
#  undef DATA
  }

  static ccl_always_inline float4
  interp_3d(const TextureInfo &info, float x, float y, float z, int interp)
  {
    using namespace nanovdb;

    NanoGrid<T> *const grid = (NanoGrid<T> *)info.data;
    AccessorType acc = grid->getAccessor();

    switch ((interp == INTERPOLATION_NONE) ? info.interpolation : interp) {
      case INTERPOLATION_CLOSEST:
        return interp_3d_closest(acc, x, y, z);
      case INTERPOLATION_LINEAR:
        return interp_3d_linear(acc, x, y, z);
      default:
        return interp_3d_cubic(acc, x, y, z);
    }
  }
};
#endif /* WITH_NANOVDB */

ccl_device float4 kernel_tex_image_interp_3d(KernelGlobals, int id, float3 P, int interp)
{
  const TextureInfo &info = kernel_data_fetch(texture_info, id);

  if (info.use_transform_3d) {
    Transform tfm = info.transform_3d;
    P = transform_point(&tfm, P);
  }

  float x = P.x;
  float y = P.y;
  float z = P.z;

  uint interpolation = (interp == INTERPOLATION_NONE) ? info.interpolation : interp;

#ifdef WITH_NANOVDB
  if (info.data_type == IMAGE_DATA_TYPE_NANOVDB_FLOAT) {
    return NanoVDBInterpolator<float>::interp_3d(info, x, y, z, interpolation);
  }
  else if (info.data_type == IMAGE_DATA_TYPE_NANOVDB_FLOAT3) {
    return NanoVDBInterpolator<nanovdb::Vec3f>::interp_3d(info, x, y, z, interpolation);
  }
  else if (info.data_type == IMAGE_DATA_TYPE_NANOVDB_FPN) {
    return NanoVDBInterpolator<nanovdb::FpN>::interp_3d(info, x, y, z, interpolation);
  }
  else if (info.data_type == IMAGE_DATA_TYPE_NANOVDB_FP16) {
    return NanoVDBInterpolator<nanovdb::Fp16>::interp_3d(info, x, y, z, interpolation);
  }
#else
  if (info.data_type == IMAGE_DATA_TYPE_NANOVDB_FLOAT ||
      info.data_type == IMAGE_DATA_TYPE_NANOVDB_FLOAT3 ||
      info.data_type == IMAGE_DATA_TYPE_NANOVDB_FPN ||
      info.data_type == IMAGE_DATA_TYPE_NANOVDB_FP16) {
    return make_float4(
        TEX_IMAGE_MISSING_R, TEX_IMAGE_MISSING_G, TEX_IMAGE_MISSING_B, TEX_IMAGE_MISSING_A);
  }
#endif
  else {
    x *= info.width;
    y *= info.height;
    z *= info.depth;
  }

  if (interpolation == INTERPOLATION_CLOSEST) {
    /* Closest interpolation. */
    int ix, iy, iz;
    svm_image_texture_frac(x, &ix);
    svm_image_texture_frac(y, &iy);
    svm_image_texture_frac(z, &iz);

    return svm_image_texture_read_3d(id, ix, iy, iz);
  }
  else if (interpolation == INTERPOLATION_LINEAR) {
    /* Trilinear interpolation. */
    int ix, iy, iz;
    float tx = svm_image_texture_frac(x - 0.5f, &ix);
    float ty = svm_image_texture_frac(y - 0.5f, &iy);
    float tz = svm_image_texture_frac(z - 0.5f, &iz);

    float4 r;
    r = (1.0f - tz) * (1.0f - ty) * (1.0f - tx) * svm_image_texture_read_3d(id, ix, iy, iz);
    r += (1.0f - tz) * (1.0f - ty) * tx * svm_image_texture_read_3d(id, ix + 1, iy, iz);
    r += (1.0f - tz) * ty * (1.0f - tx) * svm_image_texture_read_3d(id, ix, iy + 1, iz);
    r += (1.0f - tz) * ty * tx * svm_image_texture_read_3d(id, ix + 1, iy + 1, iz);

    r += tz * (1.0f - ty) * (1.0f - tx) * svm_image_texture_read_3d(id, ix, iy, iz + 1);
    r += tz * (1.0f - ty) * tx * svm_image_texture_read_3d(id, ix + 1, iy, iz + 1);
    r += tz * ty * (1.0f - tx) * svm_image_texture_read_3d(id, ix, iy + 1, iz + 1);
    r += tz * ty * tx * svm_image_texture_read_3d(id, ix + 1, iy + 1, iz + 1);
    return r;
  }
  else {
    /* Tri-cubic interpolation. */
    int ix, iy, iz;
    float tx = svm_image_texture_frac(x - 0.5f, &ix);
    float ty = svm_image_texture_frac(y - 0.5f, &iy);
    float tz = svm_image_texture_frac(z - 0.5f, &iz);

    float u[4], v[4], w[4];
    SET_CUBIC_SPLINE_WEIGHTS(u, tx);
    SET_CUBIC_SPLINE_WEIGHTS(v, ty);
    SET_CUBIC_SPLINE_WEIGHTS(w, tz);

    float4 r = make_float4(0.0f, 0.0f, 0.0f, 0.0f);

    for (int z = 0; z < 4; z++) {
      for (int y = 0; y < 4; y++) {
        for (int x = 0; x < 4; x++) {
          float weight = u[x] * v[y] * w[z];
          r += weight * svm_image_texture_read_3d(id, ix + x - 1, iy + y - 1, iz + z - 1);
        }
      }
    }
    return r;
  }
}

#undef SET_CUBIC_SPLINE_WEIGHTS

CCL_NAMESPACE_END