#include <cmath></cmath>

#include <vector></vector>

#include <limits> /* std::numeric_limits */</limits>

#include "igs_ifx_common.h"

#include "igs_warp.h"

namespace {

void hori_change_(float* image, const int height, const int width,

                  const int channels,

                  const float* refer,  // same as height,width,channels

                  const int refchannels, const int refcc, const double maxlen,

                  const bool alpha_rendering_sw, const bool anti_aliasing_sw) {

  std::vector<std::vector<float>> buf_s(channels);</std::vector<float>

  for (int zz = 0; zz < channels; ++zz) {

    buf_s.at(zz).resize(width);

  }

  std::vector<double> buf_r(width);</double>

  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) {

    // buf_sにSourceのスキャンラインのピクセル値をいれる

    for (int xx = 0; xx < width; ++xx) {

      for (int zz = 0; zz < channels; ++zz) {

        buf_s.at(zz).at(xx) = image[xx * channels + zz];

      }

    }

    // buf_rに参照画像の指定チャンネルの値を入れる

    for (int xx = 0; xx < width; ++xx) {  // reference red of refer[]

      float pos = refer[xx * refchannels];

      // clamp 0.f to 1.f in case using TPixelF

      pos          = std::min(1.f, std::max(0.f, pos));

      buf_r.at(xx) = (pos - 0.5f) * maxlen;

    }

    if (anti_aliasing_sw) {

      for (int xx = 0; xx < width; ++xx) {

        float pos  = buf_r.at(xx);

        int fl_pos = xx + static_cast<int>(std::floor(pos));</int>

        int ce_pos = xx + static_cast<int>(std::ceil(pos));</int>

        float div  = pos - floor(pos);

        // clamp

        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)) {

            image[xx * channels + zz] = buf_s.at(zz).at(xx);

          } else {

            image[xx * channels + zz] = buf_s.at(zz).at(fl_pos) * (1.0 - div) +

                                        buf_s.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));</int>

        // clamp

        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)) {

            image[xx * channels + zz] = buf_s.at(zz).at(xx);

          } else {

            image[xx * channels + zz] = buf_s.at(zz).at(pos);

          }

        }

      }

    }

  }

}

}  // namespace

//--------------------------------------------------------------------

void igs::warp::hori_change(float* image, const int height, const int width,

                            const int channels,

                            const float* refer,  // by height,width,channels

                            const int refchannels, const int refcc,

                            const double maxlen, const bool alpha_rendering_sw,

                            const bool anti_aliasing_sw) {

  hori_change_(image, height, width, channels, refer, refchannels, refcc,

               maxlen, alpha_rendering_sw, anti_aliasing_sw);

}