/* PossibleSites.c

Prints out all possible sites that can match a string of IUB codes

January 22, 1997 - R.F. Murphy */

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

void PossibleSites(char SiteString[], int Index);
short Test1(char SiteString[], int Index);
short Test2(char SiteString[], int Index);
short Test3(char SiteString[], int Index);
short Test4(char SiteString[], int Index);

void main(void)
{ char Site[10];
  
  do 
  {
    printf("Enter a string of IUB codes (up to 10 characters): ");
    scanf("%s", Site);
    PossibleSites(Site,0);
  } while (0==0);
}

void PossibleSites(char SiteString[], int Index)
{
  if (Index>=strlen(SiteString))
  {
    printf("%s\n",SiteString);
    return;
  }
  else
  {
/*    printf(" strlen %d, Index %d, SiteString[Index] %c\n",
      strlen(SiteString), Index, SiteString[Index]); */
    if (Test1(SiteString, Index)) ;
    else if (Test2(SiteString, Index)) ;
    else if (Test3(SiteString, Index)) ;
    else if (Test4(SiteString, Index)) ;
    else
    {
      printf("Illegal character (%c) encountered\n",SiteString[Index]) ;
      PossibleSites(SiteString,Index+1);
    }
  }
  return;
}

short Test1(char SiteString[], int Index)
{
/*  printf("In Test1: Index %d, SiteString[Index] %c\n",Index,SiteString[Index]); */
  switch (SiteString[Index])
  {
    case 'A':
    case 'C':
    case 'G':
    case 'T':
      break;
    default:
      return false;
  }
  PossibleSites(SiteString,Index+1);
  return true;
}
short Test2(char SiteString[], int Index)
{
  char Save;

/*  printf("In Test2: Index %d, SiteString[Index] %c\n",Index,SiteString[Index]); */

  Save = SiteString[Index];
  switch (SiteString[Index])
  {
    case 'R':
      SiteString[Index]='A';
      PossibleSites(SiteString, Index);
      SiteString[Index]='G';
      PossibleSites(SiteString, Index);
      break;
    case 'Y':
      SiteString[Index]='C';
      PossibleSites(SiteString, Index);
      SiteString[Index]='T';
      PossibleSites(SiteString, Index);
      break;
    case 'S':
      SiteString[Index]='G';
      PossibleSites(SiteString, Index);
      SiteString[Index]='C';
      PossibleSites(SiteString, Index);
      break;
    case 'W':
      SiteString[Index]='A';
      PossibleSites(SiteString, Index);
      SiteString[Index]='T';
      PossibleSites(SiteString, Index);
      break;
    case 'M':
      SiteString[Index]='A';
      PossibleSites(SiteString, Index);
      SiteString[Index]='C';
      PossibleSites(SiteString, Index);
      break;
    case 'K':
      SiteString[Index]='G';
      PossibleSites(SiteString, Index);
      SiteString[Index]='T';
      PossibleSites(SiteString, Index);
      break;
    default:
      return false;
  }
  SiteString[Index] = Save;
  return true;
}

short Test3(char SiteString[], int Index)
{
  char Save;

/*  printf("In Test3: Index %d, SiteString[Index] %c\n",Index,SiteString[Index]); */

  Save = SiteString[Index];
  switch (SiteString[Index])
  {
    case 'B': /* not A */
      SiteString[Index]='C';
      PossibleSites(SiteString, Index);
      SiteString[Index]='G';
      PossibleSites(SiteString, Index);
      SiteString[Index]='T';
      PossibleSites(SiteString, Index);
      break;
    case 'D': /* not C */
      SiteString[Index]='A';
      PossibleSites(SiteString, Index);
      SiteString[Index]='G';
      PossibleSites(SiteString, Index);
      SiteString[Index]='T';
      PossibleSites(SiteString, Index);
      break;
    case 'H': /* not G */
      SiteString[Index]='A';
      PossibleSites(SiteString, Index);
      SiteString[Index]='C';
      PossibleSites(SiteString, Index);
      SiteString[Index]='T';
      PossibleSites(SiteString, Index);
      break;
    case 'V': /* not T/U */
      SiteString[Index]='A';
      PossibleSites(SiteString, Index);
      SiteString[Index]='C';
      PossibleSites(SiteString, Index);
      SiteString[Index]='G';
      PossibleSites(SiteString, Index);
      break;
    default:
      return false;
  }
  SiteString[Index] = Save;
  return true;
}
short Test4(char SiteString[], int Index)
{
  char Save;

/*  printf("In Test4: Index %d, SiteString[Index] %c\n",Index,SiteString[Index]); */

  Save = SiteString[Index];
  switch (SiteString[Index])
  {
    case 'N': /* A,C,G,T/U (iNdeterminate) */
    case 'X': /* alternate for N */
      SiteString[Index]='A';
      PossibleSites(SiteString, Index);
      SiteString[Index]='C';
      PossibleSites(SiteString, Index);
      SiteString[Index]='G';
      PossibleSites(SiteString, Index);
      SiteString[Index]='T';
      PossibleSites(SiteString, Index);
      break;
    default:
      return false;
  }
  SiteString[Index] = Save;
  return true;
}