/******************************************************************
         *                            cvarc.c                             *
         *                                                                *
         *   This program converts Y2K format fpfit messages to		  *
         *   pre-Y2K format.                                              *
         *                                                                *
         *   This is a filter program, ie the input mec message is read   *
         *   from stdin, and the output mec message is written to stdout. *
         *                                                                *
         *   If the length of an input line exceeds 255 characters, the   *
         *   program will print a message to stderr and then exit.        *
         *                                                                *
         *   Otherwise, the program rearranges the fields of each line    *
         *   without checking for errors.                                 *
         *                                                                *
         *   The only difference between the Y2K format and the pre-Y2K   *
         *   format is that the Y2K format has the century in the first   *
         *   2 columns, and therefore the line is 2 characters longer.    *
         *                                                                *
         *   Written by Doug Neuhauser, NCEDC, modelled after cvarc.c     *
         *                                                                *
         ******************************************************************/

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

#define MAXCHR 256                  /* Max number of characters per line */


void cvmec( char *line_in, char *line_out )
{
    int  len       = strlen( line_in );
    char firstChar = line_in[0];

    if (len != 141)
    {
	fprintf( stderr, "Mec line wrong length - expected 141, found %d.\n", len );
	exit( -1 );
    }
    memcpy( line_out, line_in+2,  len-2 );
    line_out[len-2] = '\0';
    return;
}


/**********************************************************************
 *  The following is a filter program that calls the cvmec function.  *
 **********************************************************************/

int main( int argc, char *argv[] )
{
   char line_in[MAXCHR];      /* Unconverted line */
   char line_out[MAXCHR];     /* Converted line */

/* Read one line from the mec message into line_in
   ***********************************************/
   while ( fgets( line_in, MAXCHR, stdin ) != NULL )
   {
      int len = strlen( line_in );

/* Make sure we didn't overflow the input line
   *******************************************/
      if ( (len == MAXCHR-1) && (line_in[len-1] != '\n') )
      {
         fprintf( stderr, "Input line length exceeds max value of %d. Exiting.\n",
                 MAXCHR-1 );
         return -1;
      }

/* Remove the trailing newline character
   *************************************/
      line_in[len-1] = '\0';

/* Convert the line to pre-Y2K format
   **********************************/
      cvmec( line_in, line_out );

/* Write the convert line to standard output
   *****************************************/
      puts( line_out );
   }
   return 0;
}