/*

  * Licensed to the Apache Software Foundation (ASF) under one or more

  * contributor license agreements.  See the NOTICE file distributed with

  * this work for additional information regarding copyright ownership.

  * The ASF licenses this file to You under the Apache License, Version 2.0

  * (the "License"); you may not use this file except in compliance with

  * the License.  You may obtain a copy of the License at

  *

  *      http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package org.apache.commons.id.serial;

 import org.apache.commons.id.AbstractStringIdentifierGenerator;

 /**

  * <code>PrefixedLeftPaddedNumericGenerator</code> is an Identifier Generator

  * that generates a left-padded incrementing number with a prefix as a String object.

  *

  * <p>All generated ids have the same length (prefixed and padded with 0's

  * on the left), which is determined by the <code>size</code> parameter passed

  * to the constructor.<p>

  *

  * <p>The <code>wrap</code> property determines whether or not the sequence wraps

  * when it reaches the largest value that can be represented in <code>size</code>

  * base 10 digits. If <code>wrap</code> is false and the the maximum representable

  * value is exceeded, an {@link IllegalStateException} is thrown.</p>

  *

  * @author Commons-Id team

  * @version $Id$

  */

 public class PrefixedLeftPaddedNumericGenerator extends AbstractStringIdentifierGenerator {

     /** Prefix. */

     private final String prefix;

     /** Should the counter wrap. */

     private boolean wrap = true;

     /** The counter. */

     private char[] count = null;

     /** '9' char. */

     private static final char NINE_CHAR = '9';

     /**

      * Create a new prefixed left-padded numeric generator with the specified prefix.

      *

      * @param prefix prefix, must not be null or empty

      * @param wrap should the factory wrap when it reaches the maximum

      *  value that can be represented in <code>size</code> base 10 digits

      *  (or throw an exception)

      * @param size the size of the identifier, including prefix length

      * @throws IllegalArgumentException if size less prefix length is not at least one

      * @throws NullPointerException if prefix is <code>null</code>

      */

     public PrefixedLeftPaddedNumericGenerator(String prefix, boolean wrap, int size) {

         super();

         if (prefix == null) {

             throw new NullPointerException("prefix must not be null");

         }

         if (size < 1) {

             throw new IllegalArgumentException("size must be at least one");

         }

         if (size <= prefix.length()) {

             throw new IllegalArgumentException("size less prefix length must be at least one");

         }

         this.wrap = wrap;

         this.prefix = prefix;

         int countLength = size - prefix.length();

         this.count = new char[countLength];

         for (int i = 0; i < countLength; i++) {

             count[i] = '0';

         }

     }

     /**

      * Return the prefix for this prefixed numeric generator.

      *

      * @return the prefix for this prefixed numeric generator

      */

     public String getPrefix() {

         return prefix;

     }

     public long maxLength() {

         return this.count.length + prefix.length();

     }

     public long minLength() {

         return this.count.length + prefix.length();

     }

     /**

      * Returns the (constant) size of the strings generated by this generator.

      *

      * @return the size of generated identifiers

      */

     public int getSize() {

         return this.count.length + prefix.length();

     }

     /**

      * Getter for property wrap.

      *

      * @return <code>true</code> if this generator is set up to wrap

      */

     public boolean isWrap() {

         return wrap;

     }

     /**

      * Setter for property wrap.

      *

      * @param wrap should the factory wrap when it reaches the maximum

      *  value that can be represented in <code>size</code> base 10 digits

      *  (or throw an exception)

      */

     public void setWrap(boolean wrap) {

         this.wrap = wrap;

     }

     public String nextStringIdentifier() {

         for (int i = count.length - 1; i >= 0; i--) {

             switch (count[i]) {

                 case NINE_CHAR:  // 9

                     count[i] = '0';

                     if (i == 0 && !wrap) {

                         throw new IllegalStateException

                         ("The maximum number of identifiers has been reached");

                     }

                     break;

                 default:

                     count[i]++;

                     i = -1;

                     break;

             }

         }

         StringBuffer sb = new StringBuffer(prefix);

         sb.append(count);

         return sb.toString();

     }

 }