// Gmsh - Copyright (C) 1997-2025 C. Geuzaine, J.-F. Remacle
//
// See the LICENSE.txt file in the Gmsh root directory for license information.
// Please report all issues on https://gitlab.onelab.info/gmsh/gmsh/issues.

#include <string.h>
#include "ReadImg.h"
#include "GmshMessage.h"
#include "PView.h"
#include "PViewDataList.h"
#include "GmshConfig.h"

#if defined(HAVE_FLTK)

#include <FL/Fl_JPEG_Image.H>
#include <FL/Fl_PNM_Image.H>
#include <FL/Fl_PNG_Image.H>
#include <FL/Fl_BMP_Image.H>

// from an image, we create a post-procession view

static PViewDataList *Img2Data(Fl_RGB_Image &img_init, int quads = 1,
                               int resizex = 0, int resizey = 0)
{
  img_init.desaturate(); // convert to grayscale

  // resize if necessary
  Fl_RGB_Image *img;
  if(!resizex || !resizey)
    img = (Fl_RGB_Image *)img_init.copy();
  else
    img = (Fl_RGB_Image *)img_init.copy(resizex, resizey);

  const unsigned char *data = img->array;
  int height = img->h();
  int width = img->w();
  int dim = img->d();

  if(dim != 1 && dim != 2) {
    Msg::Error("Unable to obtain one-channel image");
    return nullptr;
  }

  PViewDataList *d = new PViewDataList();

  double z = 0.;
  for(int i = 0; i < height - 1; i++) {
    const unsigned char *a = data + i * width * dim;
    const unsigned char *a1 = data + (i + 1) * width * dim;
    double y = height - i - 1;
    double y1 = height - i - 2;
    for(int j = 0; j < width - 1; j++) {
      double x = j;
      double x1 = j + 1;
      double val1 = (double)a[j * dim] / 255.;
      double val2 = (double)a1[j * dim] / 255.;
      double val3 = (double)a1[(j + 1) * dim] / 255.;
      double val4 = (double)a[(j + 1) * dim] / 255.;
      if(quads) { // generate quads
        d->SQ.push_back(x);
        d->SQ.push_back(x);
        d->SQ.push_back(x1);
        d->SQ.push_back(x1);
        d->SQ.push_back(y);
        d->SQ.push_back(y1);
        d->SQ.push_back(y1);
        d->SQ.push_back(y);
        d->SQ.push_back(z);
        d->SQ.push_back(z);
        d->SQ.push_back(z);
        d->SQ.push_back(z);
        d->SQ.push_back(val1);
        d->SQ.push_back(val2);
        d->SQ.push_back(val3);
        d->SQ.push_back(val4);
        d->NbSQ++;
      }
      else { // generate triangles
        d->ST.push_back(x);
        d->ST.push_back(x);
        d->ST.push_back(x1);
        d->ST.push_back(y);
        d->ST.push_back(y1);
        d->ST.push_back(y1);
        d->ST.push_back(z);
        d->ST.push_back(z);
        d->ST.push_back(z);
        d->ST.push_back(val1);
        d->ST.push_back(val2);
        d->ST.push_back(val3);
        d->NbST++;
        d->ST.push_back(x);
        d->ST.push_back(x1);
        d->ST.push_back(x1);
        d->ST.push_back(y);
        d->ST.push_back(y1);
        d->ST.push_back(y);
        d->ST.push_back(z);
        d->ST.push_back(z);
        d->ST.push_back(z);
        d->ST.push_back(val1);
        d->ST.push_back(val3);
        d->ST.push_back(val4);
        d->NbST++;
      }
    }
  }
  delete img;
  return d;
}

static int EndPos(const char *name, PViewData *d)
{
  if(!d) return 0;
  char name_pos[256], title[256];
  strcpy(name_pos, name);
  strcat(name_pos, ".pos");
  int i;
  for(i = strlen(name) - 1; i >= 0; i--) {
    if(name[i] == '/' || name[i] == '\\') break;
  }
  if(i <= 0)
    strcpy(title, name);
  else
    strcpy(title, &name[i + 1]);
  d->setName(title);
  d->setFileName(name_pos);
  if(d->finalize()) {
    new PView(d);
    return 1;
  }
  else {
    delete d;
    return 0;
  }
}

int read_pnm(const std::string &fileName)
{
  Fl_PNM_Image img(fileName.c_str());
  return EndPos(fileName.c_str(), Img2Data(img));
}

int read_jpeg(const std::string &fileName)
{
  Fl_JPEG_Image img(fileName.c_str());
  return EndPos(fileName.c_str(), Img2Data(img));
}

int read_png(const std::string &fileName)
{
  Fl_PNG_Image img(fileName.c_str());
  return EndPos(fileName.c_str(), Img2Data(img));
}

int read_bmp(const std::string &fileName)
{
  Fl_BMP_Image img(fileName.c_str());
  return EndPos(fileName.c_str(), Img2Data(img));
}

#else

int read_pnm(std::string fileName) { return 0; }
int read_jpeg(std::string fileName) { return 0; }
int read_png(std::string fileName) { return 0; }
int read_bmp(std::string fileName) { return 0; }

#endif
