#include <string.h>
#include <unistd.h>
#include "common.h"
#include "modgmt_gsfuncs.h"

struct gs_abilities_struct gs_abilities;

static int gs_callback_out(void *caller_handle, const char *buf, int len)
{
 struct gs_runtime* r=static_cast<struct gs_runtime*>(caller_handle);
 if(0!=r->out) r->out->append(buf,len);
 return len;
}

static int gs_callback_err(void *caller_handle, const char *buf, int len)
{
 struct gs_runtime* r=static_cast<struct gs_runtime*>(caller_handle);
 if(0!=r->err) r->err->append(buf,len);
 return len;
}

static int gs_callback_in(void *caller_handle, char *buf, int len)
{
 struct gs_runtime* r=static_cast<struct gs_runtime*>(caller_handle);
 if(r->pos>=r->in->length()) return 0;
 size_t rem=r->in->length()-r->pos;
 if(rem>static_cast<size_t>(len)) rem=len;
 memcpy(buf,r->in->c_str()+r->pos,rem);
 r->pos+=rem;
 return rem;
}

struct gsworkthreadpars
{
 struct gs_runtime* r;
 gs_callback input_callback;
 int fd;
 const std::string* opts;
 int ret;
};

// This function call gs_* in separate thread, because ghostscript write to stdout
static void* gsworkthread(void* x)
{
 struct gsworkthreadpars* p=reinterpret_cast<struct gsworkthreadpars*>(x);
 WordList wl;
 if(-1==p->fd) wl=Split("-dSAFER -q -o/dev/null "+*(p->opts)+" -");
 else wl=Split("-dSAFER -dDOINTERPOLATE -q -o/dev/fd/"+ToString(p->fd)+" "+*(p->opts)+" -");
 int argc=wl.size()+1;
 char** argv;
 int i;
 void* gs;

 argv=new char*[argc];
 argv[0]=new char[2]; argv[0][0]='G'; argv[0][1]=0;
 i=1;
 for(auto& opt: wl)
 {
  argv[i]=new char[opt.length()+1];
  memcpy(argv[i],opt.c_str(),opt.length()+1);
  i++;
 }

 p->ret=gsapi_new_instance(&gs,p->r);
 if(p->ret<0) goto end;
 gsapi_set_stdio(gs,p->input_callback?p->input_callback:gs_callback_in,gs_callback_out,gs_callback_err);
 p->ret=gsapi_init_with_args(gs,argc,argv);
 if(0==p->ret || e_Quit==p->ret) p->ret=gsapi_exit(gs);
 else gsapi_exit(gs);
 if(e_Quit==p->ret) p->ret=0;
 gsapi_delete_instance(gs);

 end:
 close(p->fd);
 for(i=0;i<argc;i++) delete[] argv[i];
 delete[] argv;
 return &p->ret;
}

// Main function for prepare and run ghostscript
static int GhostRun(const std::string& opts, struct gs_runtime* r, std::string* out, gs_callback input=0)
{
 struct gsworkthreadpars wp;
 int* pret;

 wp.r=r;
 wp.input_callback=input;
 wp.opts=&opts;
 wp.ret=0;
 wp.fd=-1;

 if(0!=out)
 {
  int pipefd[2];
  pthread_t wthr;
  ssize_t br;
  char buffer[4096];

  pipe(pipefd);
  wp.fd=pipefd[1];

  out->erase();
  pthread_create(&wthr,0,&gsworkthread,&wp);
  do
  {
   br=read(pipefd[0],buffer,4096);
   out->append(buffer,br);
  } while(0!=br);
  close(pipefd[0]);
  out->shrink_to_fit();
  pthread_join(wthr,reinterpret_cast<void**>(&pret));
 }
 else pret=reinterpret_cast<int*>(gsworkthread(&wp));

 return *pret;
}


// This function run ghostscript with input data in string
int GhostRun(const std::string& opts, const std::string& input, std::string* sout, std::string* serr, std::string* out)
{
 struct gs_runtime r;

 r.in=&input;
 r.pos=0;
 r.out=sout;
 r.err=serr;
 return GhostRun(opts,&r,out);
}

// This function run ghostscript with input data provided by callback function
int GhostRun(const std::string& opts, gs_callback input, void* inputdata, std::string* sout, std::string* serr, std::string* out)
{
 struct gs_runtime r;

 r.indata=inputdata;
 r.out=sout;
 r.err=serr;
 return GhostRun(opts,&r,out,input);
}

void CheckGhostscriptAbilities()
{
 std::string out;
 gs_abilities.havepdf=gs_abilities.havebbox=gs_abilities.havepngmono=gs_abilities.havepngmonod=gs_abilities.havepng16=gs_abilities.havepng256=gs_abilities.havepnggray=gs_abilities.havepng16m=gs_abilities.havejpeg=gs_abilities.havejpeggray=false;

 if(0!=GhostRun("-sDEVICE=nullpage","devicenames ==",&out,0,0)) return;

 WordList wl=Split(out,"[]/ \t");
 for(auto& i:wl)
 {
  if("pdfwrite"==i) gs_abilities.havepdf=true;
  if("bbox"==i) gs_abilities.havebbox=true;
  if("pngmono"==i) gs_abilities.havepngmono=true;
  if("pngmonod"==i) gs_abilities.havepngmonod=true;
  if("png16"==i) gs_abilities.havepng16=true;
  if("png256"==i) gs_abilities.havepng256=true;
  if("pnggray"==i) gs_abilities.havepnggray=true;
  if("png16m"==i) gs_abilities.havepng16m=true;
  if("jpeg"==i) gs_abilities.havejpeg=true;
  if("jpeggray"==i) gs_abilities.havejpeggray=true;
 }

// gs_abilities.havepdf=(0==GhostRun("-sDEVICE=pdfwrite -dCompatibilityLevel=1.4","gsave 1 0 0 setrgbcolor 5 setlinewidth 100 100 moveto 200 200 lineto stroke grestore showpage",0,0,0));
}