package org.kuali.ole.ingest;
   
   import java.util.regex.Matcher;
   import java.util.regex.Pattern;
   
   /**
    * ISBNUtil is for processing the request based on ISBN values
    */
   public class ISBNUtil {
      /**
       *  This method returns normalized isbn value based on isbn object.
       * @param isbn
       * @return  value
       * @throws Exception
       */
      public String normalizeISBN(Object isbn) throws Exception {
          String value = (String) isbn;
          if (value != null) {
              String modifiedValue = getModifiedString(value);
              int len = modifiedValue.length();
              if (len == 13) {
                  return modifiedValue;
              } else if (len == 10) {
                  String regex = "[0-9]{9}[xX]{1}";
                  String regexNum = "[0-9]{10}";
                  value = getIsbnRegexValue(regexNum, modifiedValue);
                  if (value.length() == 0) {
                      value = getIsbnRegexValue(regex, modifiedValue);
                  }
                  if (value.length() > 0) {
                      value = calculateIsbnValue(value);
                  }
              } else {
                  throw new Exception("Invalid input" + isbn);
              }
              if (value.length() == 0) {
                  throw new Exception("Normalization failed" + isbn);
              }
          }
          return value;
      }
  
      /**
       *  This method returns isbn value with in the parentheses of parameter value.
       * @param value
       * @return  modifiedValue.
       */
      private String getModifiedString(String value) {
          String modifiedValue = value;
          if (modifiedValue.contains("(") && modifiedValue.contains(")")) {
              String parenthesesValue = modifiedValue
                      .substring(modifiedValue.indexOf("("), modifiedValue.lastIndexOf(")") + 1);
              modifiedValue = modifiedValue.replace(parenthesesValue, "");
          }
          modifiedValue = modifiedValue.replaceAll("[-:\\s]", "");
          return modifiedValue;
      }
  
      /**
       *  This method gets the isbn value based on matching regular expressions.
       * @param regex
       * @param value
       * @return  matchingValue.
       */
      private String getIsbnRegexValue(String regex, String value) {
          Pattern pattern = Pattern.compile(regex);
          Matcher matcher = pattern.matcher(value);
          String matchingValue = null;
          if (matcher.find()) {
              matchingValue = matcher.group(0);
              matchingValue = value.substring(0, 9);
          } else {
              matchingValue = "";
          }
          return matchingValue;
      }
  
      /**
       * This method returns isbn number.
       *  This method will calculate the isbn value if the length of the isbn value is 9.
       * @param value
       * @return  num.
       */
      private String calculateIsbnValue(String value) {
          String num = value;
          if (num.length() == 9) {
              num = "978" + num;
              num = getNormalizedIsbn(num);
          }
          return num;
      }
  
      /**
       *  This method returns normalized isbn value.
       * @param value
       * @return normalizeIsbn.
       */
      private String getNormalizedIsbn(String value) {
          String normalizeIsbn = value;
         int count = 0;
         int multiple = 1;
         for (int i = 0; i < value.length(); i++) {
             Character c = new Character(value.charAt(i));
             int j = Integer.parseInt(c.toString());
             int sum = j * multiple;
             count = count + sum;
             if (i != 0 && i % 2 != 0) {
                 multiple = 1;
             } else {
                 multiple = 3;
             }
         }
         count = count % 10;
         if (count == 0) {
             count = 0;
         } else {
             count = 10 - count;
         }
         normalizeIsbn = normalizeIsbn + Integer.toString(count);
         return normalizeIsbn;
     }
 }