#include <stdio.h>
#include <stdlib.h>
#include <string.h>


void dumpchunk(int cc1,int cc2,FILE*fi,FILE*fo){
  int c1,c2;
  c1=fgetc(fi);c2=fgetc(fi);
  int l=(c1<<8)+c2;
  fprintf(stderr,"chunk: %02x%02x  (%d)\n",cc1,cc2,l);
  fputc(cc1,fo);fputc(cc2,fo);
  fputc(c1,fo);fputc(c2,fo);
  for(int t=0;t<l-2;t++){fputc(fgetc(fi),fo);}
}

void skipchunk(int cc1,int cc2,FILE*fi){
  int c1,c2;
  c1=fgetc(fi);c2=fgetc(fi);
  int l=(c1<<8)+c2;
  fprintf(stderr," SKIP: %02x%02x  (%d)\n",cc1,cc2,l);
  for(int t=0;t<l-2;t++){fgetc(fi);}
}

void dumpall(FILE*fi,FILE*fo,char*cmt){
  int c;
  fprintf(stderr,"(%s)\n",cmt);
  while(!feof(fi)){
    c=fgetc(fi);
    if(feof(fi))break;
    fputc(c,fo);
  }
}

void dumpchunkhdr(int c1,int c2,FILE*fo){
  fprintf(stderr,"chunk: %02x%02x  ",c1,c2);
  fputc(c1,fo);fputc(c2,fo);
}




int main(int argc,char*argv[]){
  FILE*fi,*fo,*ft;
  char*fn;
  int c,oldc;
  int ischunk=0;
  int isdata=0;
  int chunklen=0;
  int chunkpos=0;
  int readoffs=0;

  int insertbefore=-1;
  int insertafter=0xe0;
  int skipexif=0;

  int fnnum=0;

  for(int t=1;t<argc;t++){
    if(argv[t][0]!='-')
     {fnnum++;
      if(fnnum==1)fn=argv[t];
     }
    else if(!strcmp(argv[t],"-stripexif"))skipexif=1;
    else {fprintf(stderr,"ERR: unknown option '%s', aborting.\n",argv[t]);return 1;}
  }

//  fn=argv[1];
  fi=fopen(fn,"rb");
  if(!fi){fprintf(stderr,"ERR: cannot open '%s', aborting.\n",fn);return 2;}
  ft=stdin;
  fo=stdout;
  ischunk=0;

  oldc=fgetc(fi);
  c=fgetc(fi);
  readoffs=2;

  if((oldc!=0xff)||(c!=0xd8)){
    fprintf(stderr,"ERR: beginning not 0xFFD8, is %02X%02X.\n",oldc,c);
    return 1;
  }
  fputc(oldc,fo);fputc(c,fo);


  while(!feof(fi)){
    oldc=c;
    c=fgetc(fi);readoffs++;

//    fprintf(stderr,"[%02x]",c);
    if(oldc==0xff){
      if(c==0xe1)if(skipexif){skipchunk(oldc,c,fi);continue;} // remove existing EXIF

      if(c==insertbefore){dumpall(ft,fo,"stdin data");continue;} // insert chunk from stdin after APP0 chunk

      if(c==0xda){dumpchunkhdr(oldc,c,fo);dumpall(fi,fo,"to the end");break;}   // data begin; passthrough everything to the end
      else dumpchunk(oldc,c,fi,fo);

      if(c==insertafter){dumpall(ft,fo,"stdin data");continue;} // insert chunk from stdin after APP0 chunk
//      if(c==0xe0){dumpall(ft,fo,"stdin data");dumpall(fi,fo,"image data");break;} // insert chunk from stdin after APP0 chunk
    }

/*

      if(c==0xd8){fprintf(stderr," [START]");ischunk=0;chunkpos=0;}
      if(c==0xe0){fprintf(stderr," [APP0] ");ischunk=0;chunkpos=0;}
      if(c==0xe1){fprintf(stderr," [EXIF] ");ischunk=0;chunkpos=0;}
      if(c==0xdb){fprintf(stderr," [QUANT]");ischunk=0;chunkpos=0;}
      if(c==0xc0){fprintf(stderr," [SOF]  ");ischunk=0;chunkpos=0;}
      if(c==0xc4){fprintf(stderr," [HUFFT]");ischunk=0;chunkpos=0;}
      if(c==0xda){fprintf(stderr," [data] ");isdata=1;}
*/
  }
  fprintf(stderr,"\n");
  fclose(fi);fclose(fo);fclose(ft);
  return 0;
}