#include "utility.h"
#include "newgeo.h"

void filter_atom_type(atom_symbol)
/*============================================================================*/
/* FILENAME: FILTER_ATOM_TYPE.C (FILTER_ATOM_TYPE.O)
/* PURPOSE: TO REMOVE ALL ATOMS IN THE CURRENT GEOMETRY OF THE SPECIFIED TYPE.
/* WRITTEN: M.V.GRIESHABER
/* LAST MODIFICATION: 11 JUNE 1991 MVG
*/
   char atom_symbol[];
   {
   int i;
   int j;
   int k;
   int l;

   /* RUN THROUGH ALL THE ATOMS LOOKING FOR THE TYPE TO FILTER OUT. */
   for (i=0; i<atom_cnt; i++)
      {
      /*DEBUGprintf("looking at atom #%d (%s).\n",i,intco[i].atom_name);/**/
      /* IS THIS THE TYPE TO FILTER OUT? */
      if (strcmp(intco[i].atom_name,atom_symbol)==0)
         {
         /* YES, FILTER BY MOVING ALL LATER ATOMS DOWN ONE SLOT. */
         for (j=i+1; j<atom_cnt; j++)
            {
            intco[j-1]=intco[j];
            }
         atom_cnt--;	/* ONE LESS ATOM. */
         /*DEBUGprintf("   removing atom #%d, now total of %d atoms.\n",i,atom_cnt);/**/

         /* NOW ADJUST THE BOND LISTS TO REFLECT THE REMOVED ATOM. */
         for (j=0; j<atom_cnt; j++)	/* FOR EACH ATOM. */
            {
            for (k=0; k<intco[j].bond_cnt; k++)	/* CHECK EACH BOND. */
               {
               /* IS THIS A BOND TO THE DEFUNCT ATOM? */
               if (intco[j].bonds[k]==i)
                  {
                  /*DEBUGprintf("      removing bond to defunct atom #%d: atom #%d (%s), bond #%d.\n",i,j,intco[j].atom_name,k);/**/
                  /* YES, REMOVE BY SHIFTING ALL LATER BONDS DOWN ONE. */
                  for (l=k+1; l<intco[j].bond_cnt; l++)
                     {
                     intco[j].bonds[l-1]=intco[j].bonds[l];
                     }
                  intco[j].bond_cnt--;	/* ONE LESS BOND. */
                  k--;	/* REEXAMINE THIS SLOT; NOW OCCUPIED BY NEW (SHIFTED) BOND. */
                  }

               /* NO, IS THIS A BOND TO A JUST SHIFTED ATOM? */
               else if (intco[j].bonds[k]>i)
                  {
                  /*DEBUGprintf("      decrementing bond: atom#%d (%s), bond #%d.\n",j,intco[j].atom_name,k);/**/
                  /* YES, DECREMENT THE BOND POINTER TO CORRECT. */
                  intco[j].bonds[k]--;
                  }
               }
            }
         i--;	/* REEXAMINE THIS SLOT; NOW OCCUPIED BY NEW (SHIFTED) ATOM. */
         }
      }

   return;
   }