// g++ -m32 -O2 -fvisibility=hidden -fPIC -shared -Wl,-Bsymbolic -o anomalyhack.so anomalyhack.cpp -ldl

// Warning: this a quick'n'dirty hack to renumber uniform locations to prevent
// Anomaly: Warzone Earth from segfaulting; not a good libGL wrapping example

#include <dlfcn.h>
#include <cstring>
#include <map>
#pragma GCC visibility push(default)
#define GLX_GLXEXT_PROTOTYPES
#define GL_GLEXT_PROTOTYPES
#include <GL/glx.h>
#pragma GCC visibility pop

static std::map<std::pair<GLuint, GLint>, GLint> revmap;

GLint glGetUniformLocation(GLuint program, const GLchar *name)
{
  static PFNGLGETUNIFORMLOCATIONPROC realfn = (PFNGLGETUNIFORMLOCATIONPROC) dlsym(RTLD_NEXT, "glGetUniformLocation");
  GLint nun, un, origloc = realfn(program, name);
  if (origloc == -1)
    return -1;

  glGetProgramiv(program, GL_ACTIVE_UNIFORMS, &nun);
  for (un = 0; un < nun; un++)
    {
      GLsizei len;
      GLint size;
      GLenum type;
      GLchar uname[256];
      glGetActiveUniform(program, un, 256, &len, &size, &type, uname);
      if (!strcmp(uname, name))
	break;
    }
  revmap[std::make_pair(program, un)] = origloc;

  return un;
}

void glUniform1i(GLint location, GLint v0)
{
  static PFNGLUNIFORM1IPROC realfn = (PFNGLUNIFORM1IPROC) dlsym(RTLD_NEXT, "glUniform1i");
  GLuint program;
  glGetIntegerv(GL_CURRENT_PROGRAM, (GLint*)&program);
  realfn(revmap[std::make_pair(program, location)], v0);
}

void glUniform4fv(GLint location, GLsizei count, const GLfloat *value)
{
  static PFNGLUNIFORM4FVPROC realfn = (PFNGLUNIFORM4FVPROC) dlsym(RTLD_NEXT, "glUniform4fv");
  GLuint program;
  glGetIntegerv(GL_CURRENT_PROGRAM, (GLint*)&program);
  realfn(revmap[std::make_pair(program, location)], count, value);
}

void glUniformMatrix4fv(GLint location, GLsizei count, GLboolean transpose, const GLfloat *value)
{
  static PFNGLUNIFORMMATRIX4FVPROC realfn = (PFNGLUNIFORMMATRIX4FVPROC) dlsym(RTLD_NEXT, "glUniformMatrix4fv");
  GLuint program;
  glGetIntegerv(GL_CURRENT_PROGRAM, (GLint*)&program);
  realfn(revmap[std::make_pair(program, location)], count, transpose, value);
}

__GLXextFuncPtr glXGetProcAddressARB(const GLubyte *procName)
{
  static const char * const redefined_names[] = {
    "glGetUniformLocation", "glUniform1i", "glUniform4fv", "glUniformMatrix4fv"
  };
  static const __GLXextFuncPtr redefined_fns[] = {
    (__GLXextFuncPtr) glGetUniformLocation, (__GLXextFuncPtr) glUniform1i, (__GLXextFuncPtr) glUniform4fv, (__GLXextFuncPtr) glUniformMatrix4fv
  };
  enum {n_redefined = sizeof(redefined_fns) / sizeof(redefined_fns[0])};
  for (int i = 0; i < n_redefined; i++)
    if (!strcmp((const char *)procName, redefined_names[i]))
      return redefined_fns[i];

  static PFNGLXGETPROCADDRESSPROC realgpa = (PFNGLXGETPROCADDRESSPROC) dlsym(RTLD_NEXT, "glXGetProcAddressARB");
  return realgpa(procName);
}