/*
   SAMPLE:  Routine to generate sample listings of ASCII datasets

   Format:

      % sample [-r count | -e count] <input file> [<output file>]

   This routine generates an output listing with the file name, number of
   records, maximum and minimum record lengths, and sample lines with column
   numbers.  By default the first and last 25 records are displayed.  The 
   user may specify a different number of records using the "-r" option, or
   can indicate that every N records should be selected by using the "-e"
   option.

   23 Mar 1994, acr: creation

*/

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

#define  MAX_RECORD_LENGTH  10000
#define  DEFAULT_LINES         25


/*=========================================================================*/

main (argc,argv)
  int   argc;
  char *argv[];

{ char   inptline[MAX_RECORD_LENGTH];   /* input record */
  char  *string;                        /* for error checking */
  int    i,j,k;                         /* loop/subscript */
  int    count;                         /* record count */
  int    headtail;        /* true if first/last records are shown */
  FILE  *ifp, *ofp;                     /* file pointers */
  char   filename[1000];                /* input file name */
  int    length;                        /* record length */

  /* Display totals: */

  int    maxlength, minlength;          /* extrema */
  int    records;                       /* record count */

  /*-----------------------------------------------------------------*/
  /* Arguments */

  if (argc < 2  ||  argc > 5)
    { fprintf (stderr, 
       "Usage: sample [-r count | -e count] <input file> [<output file>]\n");
      exit(0);
    }

  i        = 1;
  ifp      = NULL;
  ofp      = stdout;
  count    = 0;
  headtail = 1;

  while (i < argc)
    { if (!strcmp(argv[i],"-r"))
        { ++i;
          if ((count=atoi(argv[i])) < 1)
            { fprintf (stderr,"sample: Invalid record count (%s)\n",argv[i]);
              exit(11);
            }
          ++i;
        }

      else if (!strcmp(argv[i],"-e"))
        { ++i;
          if ((count=atoi(argv[i])) < 1)
            { fprintf (stderr,"sample: Invalid record count (%s)\n",argv[i]);
              exit(11);
            }
          ++i;
          headtail = 0;
        }

      else if (ifp == NULL)
        { if ((ifp=fopen(argv[i],"r")) == NULL)
            { fprintf (stderr,"sample: Unable to open \"%s\" for reading.\n",
                               argv[i]);
              exit(12);
            }
          strcpy(filename,argv[i]);   /* save filename for display */
          ++i;
        }

      else
        { if ((ofp=fopen(argv[i],"w")) == NULL)
            { fprintf (stderr,"sample: Unable to open \"%s\" for writing.\n",
                               argv[i]);
              exit(13);
            }
          ++i;
        }
    }

  if (count==0) count = DEFAULT_LINES;

  /*------------------------------------------------------------------*/

  /* First pass through the file to determine extreme record lengths
     and total record count:
  */

  maxlength = 0;
  minlength = MAX_RECORD_LENGTH;
  records   = 0;

  while ((string = fgets(inptline,MAX_RECORD_LENGTH,ifp)) != NULL)
    { length = strlen(inptline);
      maxlength = (length > maxlength) ? length : maxlength;
      minlength = (length < minlength) ? length : minlength;
      ++records;
    }

  /* Check record length: */

  if (maxlength == MAX_RECORD_LENGTH)
    { fprintf (stderr,"sample: Maximum record length (%d) exceeded.\n",
               MAX_RECORD_LENGTH - 1);
      exit(21);
    }

  /*-------------------------------------------------------------------*/

  /* Second pass; rewind file and print header:
  */

  rewind(ifp);
  fprintf(ofp," File: %s\n",filename);
  fprintf(ofp,"     Number of records: %d\n",records);
  fprintf(ofp," Maximum record length: %d      Minimum record length %d\n",
                maxlength, minlength);
  fprintf(ofp,"\n");

  /* Print separator and byte count headers, based on maximum record length: */

  for (i=0; i<maxlength; ++i) fprintf(ofp,"=");
  fprintf(ofp,"\n");

  if (headtail) 
    { if (records < 2*count)
          fprintf (ofp,"Complete file listing.\n");
      else
        { if (count == 1)
              fprintf(ofp,"Sample: the first and last record.\n");
            else
              fprintf(ofp,"Sample: the first and last %d records.\n",count);
        }
    }
  else
    { if (count == 1)
          fprintf (ofp,"Complete file listing.\n");
      else
          fprintf(ofp,"Sample: every %d records.\n",count);
    }
  fprintf(ofp,"\n");

  if (maxlength > 9999) 
    { for (i=1; i<=maxlength; ++i) fprintf(ofp,"%1d",(i/10000)%10);
      fprintf(ofp,"\n");
    }

  if (maxlength >  999)
    { for (i=1; i<=maxlength; ++i) fprintf(ofp,"%1d",(i/1000)%10);
      fprintf(ofp,"\n");
    }

  if (maxlength >   99)
    { for (i=1; i<=maxlength; ++i) fprintf(ofp,"%1d",(i/100)%10);
      fprintf(ofp,"\n");
    }

  if (maxlength >    9)
    { for (i=1; i<=maxlength; ++i) fprintf(ofp,"%1d",(i/10)%10);
      fprintf(ofp,"\n");
    }

  for (i=1; i<=maxlength; ++i) fprintf(ofp,"%1d",i%10);
  fprintf(ofp,"\n");

              /*-------------------------------------*/

  /* Loop through records again, printing those requested: */

  /* If we're printing the first and last records: */

  if (headtail)
    {
      /* First, make sure there are more records in the file than we expect
         to print out.  If not, just dump the whole file:
      */

      if (records <= 2*count)
        { while (fgets(inptline,MAX_RECORD_LENGTH,ifp) != NULL)
              fputs(inptline,ofp);
        }

      else
        { for (i=0; i<count; ++i)       /* print first 'count' records */
            { fgets(inptline,MAX_RECORD_LENGTH,ifp);
              fputs(inptline,ofp);
            }
          for (i=count; i<records-count; ++i)   /* skip middle records */
            { fgets(inptline,MAX_RECORD_LENGTH,ifp);
            }
          for (i=0; i<maxlength; ++i) fprintf(ofp,".");
          fprintf(ofp,"\n");
          for (i=records-count; i<records; ++i) /* print last records  */
            { fgets(inptline,MAX_RECORD_LENGTH,ifp);
              fputs(inptline,ofp);
            }
        }
    }


  /* If we're printing every N records: */

  else
    { for (i=0; i<records; ++i)
        { fgets(inptline,MAX_RECORD_LENGTH,ifp);
          if (!(i%count)) fputs(inptline,ofp);     /* i.e., i%count = 0 */
        }
    }

  /*-----------------------------------------------------------------------*/

  /* Close the files and say goodnight: */

  fclose(ifp);
  fclose(ofp);
          
  exit(0);
}