package org.pojomatic.formatter;
   
   import java.util.Arrays;
   
   import org.pojomatic.annotations.Property;
   
   /**
    * A property formatter which shows only the last 4 characters of the string representation of the
    * {@link Property}, with all others replaced by an asterisk ('*').
   * Useful for credit card numbers, social security numbers, etc.
   * <p>
   * For example, a 16 character {@code String} representing a credit card number would
   * be formatted as "************1234".
   *
   * @deprecated While this formatter can prevent the toString representation of an object including a full account
   * number, the full number can still be visible in heap dumps. A more secure approach is to avoid storing plaintext
   * private account numbers in memory at all (or at most, for as long as it takes to encrypt them). This formatter will
   * be removed in a future release of Pojomatic. Clients who feel they still need this functionality should implement it
   * themselves.
   */
  @Deprecated
  public class AccountNumberFormatter extends DefaultPropertyFormatter {
    private static final int DEFAULT_PLAINTEXT_CHARS = 4;
    private static final int DEFAULT_FILL_CHAR = '*';
  
    private int plaintextChars = DEFAULT_PLAINTEXT_CHARS;
    private char fillChar = DEFAULT_FILL_CHAR;
  
    @Override
    public String format(Object value) {
      String rep = super.format(value);
      int repLength = rep.length();
      if (repLength <= getPlaintextChars()) {
        return rep;
      } else {
        char[] repChars = rep.toCharArray();
        Arrays.fill(repChars, 0, repLength - getPlaintextChars(), getFillChar());
        return String.valueOf(repChars);
      }
    }
  
    protected int getPlaintextChars() {
      return plaintextChars;
    }
  
    protected void setPlaintextChars(int plaintextChars) {
      this.plaintextChars = plaintextChars;
    }
  
    protected char getFillChar() {
      return fillChar;
    }
  
    protected void setFillChar(char fillChar) {
      this.fillChar = fillChar;
    }
  
  }