#include <vips/vips8>

#include "common.h"

using namespace std;
using namespace vips;

char *Mirror(string *type, char *BufferData, size_t BufferLength,
             ArgumentMap Arguments, size_t *DataSize) {
  bool vertical = GetArgumentWithFallback<bool>(Arguments, "vertical", false);
  bool first = GetArgumentWithFallback<bool>(Arguments, "first", false);

  VOption *options = VImage::option()->set("access", "sequential");

  VImage in =
      VImage::new_from_buffer(BufferData, BufferLength, "",
                              *type == "gif" ? options->set("n", -1) : options)
          .colourspace(VIPS_INTERPRETATION_sRGB);
  if (!in.has_alpha()) in = in.bandjoin(255);

  VImage out;

  if (vertical) {
    if (*type == "gif") {
      // once again, libvips gif handling is both a blessing and a curse
      vector<VImage> img;
      int pageHeight = vips_image_get_page_height(in.get_image());
      int nPages = vips_image_get_n_pages(in.get_image());
      bool isOdd = pageHeight % 2;
      for (int i = 0; i < nPages; i++) {
        int x = (i * pageHeight) + (first ? 0 : (pageHeight / 2));
        VImage cropped = in.crop(0, x, in.width(), pageHeight / 2);
        VImage flipped = cropped.flip(VIPS_DIRECTION_VERTICAL);
        VImage final = VImage::arrayjoin(
            {first ? cropped : flipped, first ? flipped : cropped},
            VImage::option()->set("across", 1));
        img.push_back(final);
      }
      out = VImage::arrayjoin(img, VImage::option()->set("across", 1));
      out.set(VIPS_META_PAGE_HEIGHT, pageHeight - (isOdd ? 1 : 0));
    } else {
      VImage cropped = in.extract_area(0, 0, in.width(), in.height() / 2);
      VImage flipped = cropped.flip(VIPS_DIRECTION_VERTICAL);
      out = VImage::arrayjoin({cropped, flipped},
                              VImage::option()->set("across", 1));
    }
  } else {
    if (first) {
      VImage cropped = in.extract_area(0, 0, in.width() / 2, in.height());
      VImage flipped = cropped.flip(VIPS_DIRECTION_HORIZONTAL);
      out = VImage::arrayjoin({cropped, flipped});
    } else {
      int size = in.width() / 2;
      VImage cropped = in.extract_area(size, 0, size, in.height());
      VImage flipped = cropped.flip(VIPS_DIRECTION_HORIZONTAL);
      out = VImage::arrayjoin({flipped, cropped});
    }
  }

  void *buf;
  out.write_to_buffer(("." + *type).c_str(), &buf, DataSize);

  return (char *)buf;
}