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


#define DEFNAME "frame"
#define DEFEXT ".jpg"
#define DEFCNT 10




// options
int hdronly=1;
int showhdr=1;
int maxframes=DEFCNT;
int saveall=0;
int savelast=0;
int nowrite=0;
int timestamp=0;
int locts=0;
int verb=1;
int skipframes=0;
int nthframe=0;
int nthframecnt=0;

FILE*fi;
FILE*fm;



void xabort2(char*reason,char*reasonparm){
  if(verb)fprintf(stderr,reason,reasonparm);
  if(verb)fprintf(stderr,"\nAbort.\n");
  exit(1);
}

void xabort(char*reason){
  xabort2("%s",reason);
}



// espcam:
// Content-Type: image/jpeg
// Content-Length: 25594
// 

// doorcam:
// --boundarydonotcross
// Content-Type: image/jpeg
// Content-Length: 48992
// X-Timestamp: 1630358637.512000
// X-UStreamer-Device: /dev/video2
// 


// workflow:
// read header until Content-Length is found, set clen
// read until \r\n\r\n
// read and output-dump clen bytes
// repeat read-header



#include <sys/time.h>
#include <time.h>

char localts[32];
char*getlocaltimestamp(){
  int millisec;
  struct tm* tm_info;
  struct timeval tv;
  char buf[32];

  gettimeofday(&tv, NULL);
  tm_info = localtime(&tv.tv_sec);
  // 2021-09-01T00:59:31.296
  strftime(buf, 26, "%Y-%m-%dT%H:%M:%S", tm_info);
  snprintf(localts,31,"%s.%03d",buf,(tv.tv_usec)/1000);
  return localts;
}



#define MAXHDR 512
char hdr[MAXHDR];
int hdrpos=0;
int imgno=1;


int readheaderline(){
  int c=0;
  int valid=1;
  hdrpos=0;
  hdr[0]=0;
  while(c!=0x0a){
    c=fgetc(fi);
    if(feof(fi))xabort("End of file reached.");
    if(c==0x0d)continue;
    if(c==0x0a)return valid;
    if(c<' ')valid=0;
    if(c>0x7f)valid=0;
    if(hdrpos>MAXHDR-2)continue; // ignore too long lines, we're likely in image here anyway and getting garbage
    hdr[hdrpos]=c;
    hdrpos++;
    hdr[hdrpos]=0;
  }
}

void sanitizetstamp(char*s){
  int t;
  if(strstr(s,".."))s[0]=0;
  for(t=0;t<strlen(s);t++){
    if(s[t]<' ')s[t]='_';else
    if(s[t]>'z')s[t]='_';else
    if(s[t]=='/')s[t]='_';else
    if(s[t]=='|')s[t]='_';else
    if(s[t]=='\\')s[t]='_';
  }
}

void dumpframe(long clen,char*name,char*tstamp){
  long t;
  char fn[512]="";
  FILE*fo;

  sanitizetstamp(tstamp);

  if(clen<=0){if(showhdr)fprintf(fm,"image length invalid, skipping\n");return;}
  if(showhdr)fprintf(fm,"image %d data [%d]...\n",imgno,clen);

  if(tstamp[0]){
    if(savelast){if(maxframes==imgno){snprintf(fn,255,"%s-%s"DEFEXT,name,tstamp);if(name[0]==0)snprintf(fn,255,DEFNAME"-%s"DEFEXT,tstamp);}}
    if(saveall){if(name[0]==0)snprintf(fn,255,DEFNAME"%d-%s"DEFEXT,imgno,tstamp);else snprintf(fn,255,"%s%d-%s"DEFEXT,name,imgno,tstamp);}
  }
  else{
    if(savelast){if(maxframes==imgno){strncpy(fn,name,255);if(name[0]==0)strcpy(fn,DEFNAME DEFEXT);}}
    if(saveall){if(name[0]==0)snprintf(fn,255,DEFNAME"%d"DEFEXT,imgno);else snprintf(fn,255,"%s%d"DEFEXT,name,imgno);}
  }
  fn[511]=0; // sanity

  if(!skipframes)if(nthframe){
    if(nthframecnt){nthframecnt--;fn[0]=0;}
    else{nthframecnt=nthframe;}
  }

  if(skipframes){skipframes--;fn[0]=0;}

  if(fn[0])if(verb)
    if(strcmp(name,"-")){
      if(nowrite)fprintf(fm,"Would write to file '%s'.\n",fn);
      else fprintf(fm,"Writing to file '%s'.\n",fn);
    }else{
      if(nowrite)fprintf(fm,"Would write to stdout.\n");
      else fprintf(fm,"Writing to stdout.\n",fn);
    }
  if(nowrite)fn[0]=0;

  if(fn[0]){
    int c;
    if(!strcmp(name,"-"))fo=stdout;
    else fo=fopen(fn,"wb");
    if(!fo)xabort2("Cannot open output file '%s'.",fn);
    for(t=0;t<clen;t++){
      c=fgetc(fi);
      if(feof(fi))break;
      fputc(c,fo);
    }
  }
  else
    for(t=0;t<clen;t++){fgetc(fi);if(feof(fi))break;}

  imgno++;
}


void help(){
  printf("mjpegparse - MJPEG stream parser\n");
  printf("Reads MJPEG stream from a file, or from stdin (\"-\")\n\n");
  printf("Usage: mjpegparse [options] <input file>\n");
  printf("Options:\n");
  printf("   -n <frames>  stop reading after n frames (0=never stop, default=%d)\n",maxframes);
  printf("   -o <fname>   name of output file, default "DEFNAME DEFEXT"; prefix-only with numbers and timestamps, - for stdout\n");
  printf("   -q           quiet; do not show headers\n");
  printf("   -qq          quieter, do not show anything\n");
  printf("   -sa          save all frames, implies numbering of filenames\n");
  printf("   -s           save last frame, needs -n\n");
  printf("   -N           do not save any file, just output messages\n");
  printf("   -xts         use timestamps from X-Timestamp: headers\n");
  printf("   -se          output messages to stderr (implied with -o -)\n");
  printf("   -skip <n>    skip n frames in the beginning\n");
  printf("   -nth <n>     output only each n-th frame\n");
  printf("   -h           this help\n");
  printf("\n");
  printf("Example:\n");
  printf("curl http://webcam:8000/stream | parsemjpeg -n 5 -o snapsnot.jpg -s\n");
  printf("fetches MJPEG stream, saves 5th image to snapshot.jpg\n");
  exit(0);
}


int main(int argc,char*argv[]){
  long clen=0; // Content-Length
  char*fn="";
  char*fpref="";
  char tstamp[256]="";

  fm=stdout;

  for(int t=1;t<argc;t++){
    if(argv[t][0]=='-'){
      char*arg,*parm;
      arg=argv[t];
      if(arg[1]==0){fn=arg;continue;} // stdin
      if(t<argc-1)parm=argv[t+1];else parm="";
      if(!strcmp(arg,"-n")){maxframes=atoi(parm);t++;continue;}
      if(!strcmp(arg,"-nth")){nthframe=atoi(parm)-1;if(nthframe<0)nthframe=0;t++;continue;}
      if(!strcmp(arg,"-skip")){skipframes=atoi(parm);t++;continue;}
      if(!strcmp(arg,"-o")){fpref=parm;t++;if(!strcmp(fpref,"-"))fm=stderr;continue;}
      if(!strcmp(arg,"-q")){showhdr=0;continue;}
      if(!strcmp(arg,"-qq")){showhdr=0;verb=0;continue;}
      if(!strcmp(arg,"-sa")){saveall=1;continue;}
      if(!strcmp(arg,"-s")){savelast=1;continue;}
      if(!strcmp(arg,"-N")){nowrite=1;continue;}
      if(!strcmp(arg,"-xts")){timestamp=1;continue;}
      if(!strcmp(arg,"-lts")){locts=1;continue;}
      if(!strcmp(arg,"-se")){fm=stderr;continue;}
      if(!strcmp(arg,"-h")){help();}
      if(!strcmp(arg,"--help")){help();}
      printf("ERROR: unknown argument '%s'.\n",arg);
      exit(1);
    }
    fn=argv[t];
  }
  if(!fn[0])help();

  if(!strcmp(fn,"-")){
    fi=stdin;
    if(verb)fprintf(fm,"Reading from stdin...\n");
  }
  else fi=fopen(fn,"rb");
  if(!fi)xabort2("Cannot open input file '%s'.",fn);

  while(1){
    int valid=readheaderline();
    if(!valid){
      if(verb)fprintf(fm,"[invalid line]\n");
      continue;
    }
    if(showhdr)fprintf(fm,"HEADER: %s\n",hdr);

    if(!strncasecmp(hdr,"Content-Length:",15)){
      clen=atol(hdr+15);
      //printf("len: %d\n",clen);
    }
    if(timestamp){if(!strncasecmp(hdr,"X-Timestamp:",12)){
      char*sp;
      sp=hdr+13;if(sp[0]==' ')sp++;
      strncpy(tstamp,sp,255);tstamp[255]=0;
      //printf("len: %d\n",clen);
    }}
    if(strlen(hdr)==0) // empty line at header block end
      if(clen){
        if(locts){
          if(tstamp[0])strncat(tstamp,"--",255);
          strncat(tstamp,getlocaltimestamp(),255);
          tstamp[255]=0;
        }
        dumpframe(clen,fpref,tstamp);
        clen=0;
        if(maxframes)if(maxframes<imgno)break;
        tstamp[0]=0;
      }

  }



  fclose(fi);
  return 0;
}