#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 hori_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(width);
    buf_s2.at(zz).resize(width);
  }
  std::vector<double> buf_r(width);
 
  refer += refcc; /* 参照画像の参照色チャンネル */
  for (int yy = 0; yy < height;
       ++yy, image += channels * width, refer += refchannels * width) {
    for (int xx = 0; xx < width; ++xx) {
      for (int zz = 0; zz < channels; ++zz) {
        buf_s1.at(zz).at(xx) = image[xx * channels + zz] / smax;
      }
    }
 
    for (int xx = 0; xx < width; ++xx) {  // reference red of refer[]
      double pos   = static_cast<double>(refer[xx * refchannels]);
      buf_r.at(xx) = ((pos / rmax) - offset) * maxlen;
    }
 
    if (anti_aliasing_sw) {
      for (int xx = 0; xx < width; ++xx) {
        double pos = buf_r.at(xx);
        int fl_pos = xx + static_cast<int>(std::floor(pos));
        int ce_pos = xx + static_cast<int>(std::ceil(pos));
        double div = pos - floor(pos);
        if (fl_pos < 0) {
          fl_pos = 0;
        } else if (width <= fl_pos) {
          fl_pos = width - 1;
        }
        if (ce_pos < 0) {
          ce_pos = 0;
        } else if (width <= ce_pos) {
          ce_pos = width - 1;
        }
        for (int zz = 0; zz < channels; ++zz) {
          if (!alpha_rendering_sw && (igs::image::rgba::alp == zz)) {
            buf_s2.at(zz).at(xx) = buf_s1.at(zz).at(xx);
          } else {
            buf_s2.at(zz).at(xx) = buf_s1.at(zz).at(fl_pos) * (1.0 - div) +
                                   buf_s1.at(zz).at(ce_pos) * div;
          }
        }
      }
    } else {
      for (int xx = 0; xx < width; ++xx) {
        int pos = xx + static_cast<int>(floor(buf_r.at(xx) + 0.5));
        if (pos < 0) {
          pos = 0;
        } else if (width <= pos) {
          pos = width - 1;
        }
        for (int zz = 0; zz < channels; ++zz) {
          if (!alpha_rendering_sw && (igs::image::rgba::alp == zz)) {
            buf_s2.at(zz).at(xx) = buf_s1.at(zz).at(xx);
          } else {
            buf_s2.at(zz).at(xx) = buf_s1.at(zz).at(pos);
          }
        }
      }
    }
 
    for (int xx = 0; xx < width; ++xx) {
      for (int zz = 0; zz < channels; ++zz) {
        image[xx * channels + zz] =
            static_cast<ST>(buf_s2.at(zz).at(xx) * (smax + 0.999999));
      }
    }
  }
}
}
//--------------------------------------------------------------------
void igs::warp::hori_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)) {
    hori_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)) {
    hori_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)) {
    hori_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)) {
    hori_change_template_(image, height, width, channels, refer, refchannels,
                          refcc, offset, maxlen, alpha_rendering_sw,
                          anti_aliasing_sw);
  }
}