/*
  hey emacs this is -*- c++ -*-

  digest -- hash digest functions for R

  Copyright 2003, 2004, 2005  Dirk Eddelbuettel <edd@debian.org>

  $Id: digest_C.c,v 1.2 2007/09/02 21:59:12 jmc Exp $

  This file is part of the digest packages for GNU R.
  It is made available under the terms of the GNU General Public
  License, version 2, or at your option, any later version,
  incorporated herein by reference.

  This program is distributed in the hope that it will be
  useful, but WITHOUT ANY WARRANTY; without even the implied
  warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
  PURPOSE.  See the GNU General Public License for more
  details.

  You should have received a copy of the GNU General Public
  License along with this program; if not, write to the Free
  Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  MA 02111-1307, USA
*/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "sha1.h"		
#include "md5.h"
#include "zlib.h"

unsigned long ZEXPORT digest_crc32(unsigned long crc,
				   const unsigned char FAR *buf,
				   unsigned len);

static char * error_message;

static char * digest_string(
			   char *txt,
			   int algo,
			   int  length,
			   char *output) {
  FILE *fp=0;
  error_message = NULL;
  int nChar = strlen(txt);
  if (length>=0 && length<nChar) nChar = length;
  
  switch (algo) {
    case 1: {			/* md5 case */
      md5_context ctx;
      unsigned char md5sum[16];
      int j;

      md5_starts( &ctx );
      md5_update( &ctx, (uint8 *) txt, nChar);
      md5_finish( &ctx, md5sum );

      for(j = 0; j < 16; j++) {
	sprintf(output + j * 2, "%02x", md5sum[j]);
      }
      break;
    }
    case 2: {			/* sha1 case */
      int j;
      sha1_context ctx;
      unsigned char sha1sum[20];

      sha1_starts( &ctx );
      sha1_update( &ctx, (uint8 *) txt, nChar);
      sha1_finish( &ctx, sha1sum );

      for( j = 0; j < 20; j++ ) {
	sprintf( output + j * 2, "%02x", sha1sum[j] );
      }
      break;
    }
    case 3: {			/* crc32 case */
      unsigned long val, l;
      l = nChar;

      val  = digest_crc32(0L, 0, 0);
      val  = digest_crc32(val, (unsigned char*) txt, (unsigned) l);
      
      sprintf(output, "%2.2x", (unsigned int) val);

      break;
    }
    case 101: {			/* md5 file case */
      int j;
      md5_context ctx;
      unsigned char buf[1024];
      unsigned char md5sum[16];

      if (!(fp = fopen(txt,"rb"))) {
        error_message = (strcat("Can not open input file: ", txt));    
        return (char *)NULL;
      }
      md5_starts( &ctx );
      if (length>=0) {  
        while( ( nChar = fread( buf, 1, sizeof( buf ), fp ) ) > 0 
	       && length>0) {
          if (nChar>length) nChar=length;
          md5_update( &ctx, buf, nChar );
          length -= nChar;
        }
      } else {
        while( ( nChar = fread( buf, 1, sizeof( buf ), fp ) ) > 0) 
          md5_update( &ctx, buf, nChar );
      }
      fclose(fp);
      md5_finish( &ctx, md5sum );
      for(j = 0; j < 16; j++) sprintf(output + j * 2, "%02x", md5sum[j]);
      break;
    }
    case 102: {			/* sha1 file case */
      int j;
      sha1_context ctx;
      unsigned char buf[1024];
      unsigned char sha1sum[20];
      
      if (!(fp = fopen(txt,"rb"))) {
        error_message = (strcat("Can not open input file: ", txt));    
        return (char *)NULL;
      }
      sha1_starts ( &ctx );
      if (length>=0) {  
        while( ( nChar = fread( buf, 1, sizeof( buf ), fp ) ) > 0 
	       && length>0) {
          if (nChar>length) nChar=length;
          sha1_update( &ctx, buf, nChar );
          length -= nChar;
        }
      } else {
        while( ( nChar = fread( buf, 1, sizeof( buf ), fp ) ) > 0) 
          sha1_update( &ctx, buf, nChar );
      }
      fclose(fp);
      sha1_finish ( &ctx, sha1sum );
      for( j = 0; j < 20; j++ ) sprintf( output + j * 2, "%02x", sha1sum[j] );
      break;
    }
    case 103: {			/* crc32 file case */
      unsigned char buf[1024];
      unsigned long val;
      
      if (!(fp = fopen(txt,"rb"))) {
        error_message = (strcat("Can not open input file: ", txt));    
        return (char *)NULL;
      }
      val  = digest_crc32(0L, 0, 0);
      if (length>=0) {  
        while( ( nChar = fread( buf, 1, sizeof( buf ), fp ) ) > 0 
	       && length>0) {
          if (nChar>length) nChar=length;
          val  = digest_crc32(val , buf, (unsigned) nChar);
          length -= nChar;
        }
      } else {
        while( ( nChar = fread( buf, 1, sizeof( buf ), fp ) ) > 0) 
          val  = digest_crc32(val , buf, (unsigned) nChar);
      }
      fclose(fp);      
      sprintf(output, "%2.2x", (unsigned int) val);
      break;
    }

    default: {
      error_message = ("Unsupported algorithm code");
      return (char *)NULL;
    }  
  }
    
  return output;

}


char *digest_error_C() {
  return error_message;
}

void R_digest_C(
          char ** Txt, 
          int * Algo, 
          int * Length, 
          char ** Output) {
  static char *output, buf[41]; 
  output = digest_string(*Txt, *Algo, *Length, buf);
  if(output == NULL && error_message != NULL)
    *Txt = error_message;
  else
    *Output = output;
}

/* now an equivalent version, using the .Call interface */

#include <R.h>
#include <Rdefines.h>
#include <Rinternals.h>

SEXP R_digest(
	    SEXP Txt, 
	    SEXP Algo, 
	    SEXP Length) {
  char *txt = (char *)STRING_VALUE(Txt);
  int algo = INTEGER_VALUE(Algo);
  int  length = INTEGER_VALUE(Length);
  SEXP result = R_NilValue;
  static char *output, buf[41]; 
  output = digest_string(txt, algo, length, buf);
  if(output == NULL) {
    error("Error in C computations of digest: %s",
	  (error_message == NULL) ? "<unspecified error>" : error_message);
    return result;
  }
     
  PROTECT(result=allocVector(STRSXP, 1));
  SET_STRING_ELT(result, 0, mkChar(output));
  UNPROTECT(1);			

  return result;
}