/* CSV_Utility.java
** Java class containing several static methods that are useful in 
** processing CSV-formatted character strings.  Such a string is one that
** is interpreted to be a sequence of "fields" in which each adjacent pair
** of fields is separated by a single occurrence of the SEPARATOR character,
** which here is defined to be the comma character (',').
** 
** For example, the string "The,cat,in,the,hat" has five fields, namely
** "The", "cat", "in", "the", and "hat", in that order.  We number the 
** fields starting at zero (so that the 0-th field is "The" and the 4th 
** field is "hat"). 
** 
** Authors: Jackowitz, McCloskey, and < STUDENT's NAME >
** For: CMPS 134, Fall 2025, Prog. Assg. #4
** Date: October 2025
** Collaborated with: ...
** Known Defects: ...
*/
public class CSV_Utility {

   public static final char SEPARATOR = ',';
   
   /* Returns the number of fields in the given CSV-string (s).  In the 
   ** case that s is the empty string, that is zero; otherwise, it is 
   ** one more than the number of occurrences of the SEPARATOR character in s.
   */
   public static int numberOfFieldsIn(String s) {
      int result = 0;
      if (s.length() != 0) {
         int sepCntr = 0;
         for (int i=0; i != s.length(); i++) {
            if(s.charAt(i) == SEPARATOR) {
               sepCntr = sepCntr + 1;
            }
         }
         result = sepCntr + 1;
      }
      return result;
   }

   /* Reports whether or not the given CSV-string s has an i-th field
   ** (which is to say that i >= 0 and s has at least i+1 fields).
   */
   public static boolean hasIthField(String s, int i) {
      return false;   // STUB
   }
   
   /* If the given CSV-string s has an i-th field, that field is returned.
   ** Otherwise, null is returned.
   */
   public static String getIthField(String s, int i) {
      return null;   // STUB
   }
   
   /* If the given CSV-string s has an i-th field, the string returned
   ** is obtained by replacing that field with the given one (field).
   ** Otherwise, s itself is returned.
   */
   public static String setIthField(String s, int i, String field) {
      return null;   // STUB
   }
   
   /* If the given CSV-string s has an i-th field, the string returned is
   ** obtained by removing the i-th field from s.  Otherwise, s itself
   ** is returned.
   */
   public static String removeIthField(String s, int i) {
      return null;   // STUB
   }

   /* If the given CSV-string s has at least i fields, the CSV-string s'
   ** returned is obtained by inserting the specified field into the i-th
   ** position of s.  (Thus, the i-th field in s is the (i+1)-st field in 
   ** s', etc.)  Otherwise, s itself is returned.
   */
   public static String insertIthField(String s, int i, String field) {
      return null;   // STUB
   }


   // private methods
   // ---------------
   
   /* Returns the position within the given CSV-string (s) at which its i-th
   ** field begins.  For the 0-th field, that is position zero.  For the
   ** i-th field, where 0 < i < numberOfFieldsIn(s), that is the position
   ** immediately following the i-th occurrence of the SEPARATOR character.
   ** For i >= numberOfFieldsIn(s), it is s.length (i.e., the position
   ** immediately following the last field).
   */
   private static int indexOfIthField(String s, int i) {
      final int LEN_OF_S = s.length();
      int pos = 0;
      int cntr = 0;
      while (pos != LEN_OF_S  &&  cntr != i) {
         if (s.charAt(pos) == SEPARATOR) {
            cntr = cntr + 1;
         }
         pos = pos + 1; 
      }
      return pos;
   }

   /* Returns the lowest numbered position within the given CSV-string (s), 
   ** not less than startIndex, at which the SEPARATOR character occurs.
   ** If no such position exists, the length of s is returned.
   */
   private static int indexOfNextSeparator(String s, int startIndex) {
      int length = s.length();
      int index = startIndex;
      while(index < length  &&  s.charAt(index) != SEPARATOR) {
         index = index + 1;
      }
      return index;
   }
   
}