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

/* This program is used to convert a sp3-c file into
an older-style sp3-a file (which has <= 60 cols of
data on each line).

Author:  Steve Hilla, NGS/NOAA
Date:    28 July 2005

0211.26, SH , Creation of program SP3ASP3C.C
0507.28, SH , use sp3asp3c.c to create sp3csp3a.c
0512.28, SH , compiled for use on the PC 

*/

FILE *in, *out;


int main( int argc, char * argv[])
{
   char buff[256];
   int i,l;
   int endOfFile = 0;

   printf("\nProgram SP3cSP3a converts a sp3-c file into an older sp3-a\n");
   printf("file. It truncates any standard deviations or flags in\n");
   printf("columns 61 through 80. It assumes the sp3-c file contains\n");
   printf("only GPS satellite data. It omits any EP and EV records.\n\n");

   /* check the # arguments on the command line */
   if( argc < 3 )
   {
      printf("\n You must give two arguments: \n");
      printf(" example:  sp3csp3a  sp3cfile.sp3 sp3afile.sp3  \n");
      return (-1);
   }


   /* open both files */
   if( ( in = fopen(argv[1],"r") ) == NULL )
   {
     printf(" ERROR opening the input sp3c file: %s\n",argv[1]);
     return(-1);
   }
   if( ( out = fopen(argv[2],"w") ) == NULL )
   {
     printf(" ERROR opening the output sp3a file: %s\n",argv[2]);
     return(-1);
   }



   /* read the first line */
   fgets(buff, 85, in);
   if(buff[0] == '#' && buff[1] == 'c' )
   {
      buff[1] = 'a';
      fprintf(out,"%s",buff);
   }
   else
   {
      printf("Error reading line 1 of file %s, version symbol is not #c !\n%s\n\n",
      argv[1],buff);
      return(-1);
   }


   /* read and echo the second line */
   fgets(buff, 85, in);
   fprintf(out,"%s",buff);
   

   /* read and modify lines 3 thru 4 */
   for( l = 3; l < 5; l++ )
   {
      fgets(buff, 85, in);
      for( i = 9; i < 60; i += 3)
      {
         if( buff[i] == ' ' && buff[i+1] == ' ' && buff[i+2] == '0' )
	 {
              // do nothing
         }
         else
         {
            if( buff[i] != 'G' )
	    {
              printf("Error reading lines 3 thru 4, invalid Satellite ID, not G !\n%s\n\n",
              buff);
              return(-1);
	    };
            buff[i] = ' ';
            if( buff[i+1] == '0' ) buff[i+1] = ' ';  /* change G03 into __3 */
         }
      }
      fprintf(out,"%s",buff);
   }


   /* read and echo lines 5 thru 12 */
   for( l = 5; l < 13; l++ )
   {
     fgets(buff, 85, in);
     fprintf(out,"%s",buff);
   }

   
   /* read lines 13 thru 15 */
   for( l = 13; l < 16; l++ )
   {
     fgets(buff, 85, in);
   }
   fprintf(out,
   "%%c c  cc ccc ccc cccc cccc cccc cccc ccccc ccccc ccccc ccccc\n");
   /* In the sp3a format, this line should be all c's */
   fprintf(out,
   "%%c cc cc ccc ccc cccc cccc cccc cccc ccccc ccccc ccccc ccccc\n");
   fprintf(out,
   "%%f  0.0000000  0.000000000  0.00000000000  0.000000000000000\n");
   /* In the sp3a format, these should all be zeroes */


   /* read and echo lines 16 thru 23 */
   for( l = 16; l < 24; l++ )
   {
     fgets(buff, 85, in);
     fprintf(out,"%s",buff);
   }


   /* read and modify all of the Position and Clock Records
      (and Velocity and Clock Rate-of-Change Records)   
      Omit any EP or EV records records -- these will NOT go into the sp3a file */

   while( !endOfFile )
   {
      if( fgets(buff, 85, in) == NULL )
      {
	 printf("Error reading file %s. Previous line was:\n%s\n\n",
	 argv[1],buff);
	 printf("Check that this file ends with an EOF line.\n\n");
         endOfFile = 1;
         fclose(in);
         fclose(out);
	 return(-1);
      }

      if( buff[0] == 'P' && buff[1] == 'G' )
      {
         buff[1] = ' ';
         if( buff[2] == '0') buff[2] = ' ';  /* change PG03 into P__3 */
         fprintf(out,"%.60s\n",buff);  /* truncate to 60 columns */
      }
      else if( buff[0] == 'V' && buff[1] == 'G' )
      {
         buff[1] = ' ';
         if( buff[2] == '0') buff[2] = ' ';  /* change VG03 into V__3 */
         fprintf(out,"%.60s\n",buff);  /* truncate to 60 columns */
      }
      else if( buff[0] == 'E' && buff[1] == 'P' )
      {
         // do nothing, do NOT write these types of sp3c records to the sp3a file
      }
      else if( buff[0] == 'E' && buff[1] == 'V' )
      {
         // do nothing, do NOT write these types of sp3c records to the sp3a file
      }
      else if( buff[0] == 'E' &&  buff[1] == 'O' &&  buff[2] == 'F' )
      {
         endOfFile = 1;
         fprintf(out,"%s",buff);
      }
      else
      {
         fprintf(out,"%s",buff);  /* print out all time tag lines without changes */
      }

   }

   fclose(in);
   fclose(out);
   printf("\n\nNormal Termination for Program SP3cSP3a.\n\n");
   printf("\n\nCheck that only P (and optional V) records exist in the output sp3a file.\n\n");
   return(0);

} /* end of main */