#include <cmath>
#include <vector>
#include <limits> /* std::numeric_limits */
#include "igs_ifx_common.h"
#include "igs_warp.h"

namespace {
template <class ST, class RT>
void vert_change_template_(ST *image, const int height, const int width,
                           const int channels

                           ,
                           const RT *refer  // same as height,width,channels
                           ,
                           const int refchannels, const int refcc

                           ,
                           const double offset, const double maxlen,
                           const bool alpha_rendering_sw,
                           const bool anti_aliasing_sw) {
  const double smax = std::numeric_limits<ST>::max();
  const double rmax = std::numeric_limits<RT>::max();

  std::vector<std::vector<double>> buf_s1(channels), buf_s2(channels);
  for (int zz = 0; zz < channels; ++zz) {
    buf_s1.at(zz).resize(height);
    buf_s2.at(zz).resize(height);
  }
  std::vector<double> buf_r(height);

  refer += refcc; /* 参照画像の参照色チャンネル */
  for (int xx = 0; xx < width; ++xx, image += channels, refer += refchannels) {
    for (int yy = 0; yy < height; ++yy) {
      for (int zz = 0; zz < channels; ++zz) {
        buf_s1.at(zz).at(yy) = image[yy * width * channels + zz] / smax;
      }
    }

    for (int yy = 0; yy < height; ++yy) {  // reference red of refer[]
      double pos   = static_cast<double>(refer[yy * width * refchannels]);
      buf_r.at(yy) = ((pos / rmax) - offset) * maxlen;
    }

    if (anti_aliasing_sw) {
      for (int yy = 0; yy < height; ++yy) {
        double pos = buf_r.at(yy);
        int fl_pos = yy + static_cast<int>(std::floor(pos));
        int ce_pos = yy + static_cast<int>(std::ceil(pos));
        double div = pos - floor(pos);
        if (fl_pos < 0) {
          fl_pos = 0;
        } else if (height <= fl_pos) {
          fl_pos = height - 1;
        }
        if (ce_pos < 0) {
          ce_pos = 0;
        } else if (height <= ce_pos) {
          ce_pos = height - 1;
        }
        for (int zz = 0; zz < channels; ++zz) {
          if (!alpha_rendering_sw && (igs::image::rgba::alp == zz)) {
            buf_s2.at(zz).at(yy) = buf_s1.at(zz).at(yy);
          } else {
            buf_s2.at(zz).at(yy) = buf_s1.at(zz).at(fl_pos) * (1.0 - div) +
                                   buf_s1.at(zz).at(ce_pos) * div;
          }
        }
      }
    } else {
      for (int yy = 0; yy < height; ++yy) {
        int pos = yy + static_cast<int>(floor(buf_r.at(yy) + 0.5));
        if (pos < 0) {
          pos = 0;
        } else if (height <= pos) {
          pos = height - 1;
        }
        for (int zz = 0; zz < channels; ++zz) {
          if (!alpha_rendering_sw && (igs::image::rgba::alp == zz)) {
            buf_s2.at(zz).at(yy) = buf_s1.at(zz).at(yy);
          } else {
            buf_s2.at(zz).at(yy) = buf_s1.at(zz).at(pos);
          }
        }
      }
    }

    for (int yy = 0; yy < height; ++yy) {
      for (int zz = 0; zz < channels; ++zz) {
        image[yy * width * channels + zz] =
            static_cast<ST>(buf_s2.at(zz).at(yy) * (smax + 0.999999));
      }
    }
  }
}
}
//--------------------------------------------------------------------
void igs::warp::vert_change(
    unsigned char *image, const int height, const int width, const int channels,
    const int bits

    ,
    const unsigned char *refer  // by height,width,channels
    ,
    const int refchannels, const int refcc, const int refbit

    ,
    const double offset, const double maxlen, const bool alpha_rendering_sw,
    const bool anti_aliasing_sw) {
  const int ucharb  = std::numeric_limits<unsigned char>::digits;
  const int ushortb = std::numeric_limits<unsigned short>::digits;
  if ((ushortb == bits) && (ushortb == refbit)) {
    vert_change_template_(
        reinterpret_cast<unsigned short *>(image), height, width, channels,
        reinterpret_cast<const unsigned short *>(refer), refchannels, refcc,
        offset, maxlen, alpha_rendering_sw, anti_aliasing_sw);
  } else if ((ushortb == bits) && (ucharb == refbit)) {
    vert_change_template_(reinterpret_cast<unsigned short *>(image), height,
                          width, channels, refer, refchannels, refcc, offset,
                          maxlen, alpha_rendering_sw, anti_aliasing_sw);
  } else if ((ucharb == bits) && (ushortb == refbit)) {
    vert_change_template_(image, height, width, channels,
                          reinterpret_cast<const unsigned short *>(refer),
                          refchannels, refcc, offset, maxlen,
                          alpha_rendering_sw, anti_aliasing_sw);
  } else if ((ucharb == bits) && (ucharb == refbit)) {
    vert_change_template_(image, height, width, channels, refer, refchannels,
                          refcc, offset, maxlen, alpha_rendering_sw,
                          anti_aliasing_sw);
  }
}