/**

  * 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.cli2.option;

 import java.util.Comparator;

 import java.util.Set;

 import org.apache.commons.cli2.HelpLine;

 import org.apache.commons.cli2.Option;

 /**

  * Represents a line in the help screen.

  */

 public class HelpLineImpl implements HelpLine {

     /** The option that this HelpLineImpl describes */

     private final Option option;

     /** The level of indenting for this item */

     private final int indent;

     /** The help settings used to obtain the previous usage */

     private transient Set cachedHelpSettings;

     /** The comparator used to obtain the previous usage */

     private transient Comparator cachedComparator;

     /** The previously obtained usage */

     private transient String cachedUsage;

     /**

      * Creates a new HelpLineImpl to represent a particular Option in the online

      * help.

      *

      * @param option

      *            Option that the HelpLineImpl describes

      * @param indent

      *            Level of indentation for this line

      */

     public HelpLineImpl(final Option option, final int indent) {

         this.option = option;

         this.indent = indent;

     }

     /**

      * @return The description of the option

      */

     public String getDescription() {

         return option.getDescription();

     }

     /**

      * @return The level of indentation for this line

      */

     public int getIndent() {

         return indent;

     }

     /**

      * @return The Option that the help line relates to

      */

     public Option getOption() {

         return option;

     }

     /**

      * Builds a usage string for the option using the specified settings and

      * comparator.

      *

      *

      * @param helpSettings the settings to apply

      * @param comparator a comparator to sort options when applicable

      * @return the usage string

      */

     public String usage(final Set helpSettings, final Comparator comparator) {

         if (cachedUsage == null

             || cachedHelpSettings != helpSettings

             || cachedComparator != comparator) {

             // cache the arguments to avoid redoing work

             cachedHelpSettings = helpSettings;

             cachedComparator = comparator;

             // build the new buffer

             final StringBuffer buffer = new StringBuffer();

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

                 buffer.append("  ");

             }

             option.appendUsage(buffer, helpSettings, comparator);

             // cache the usage string

             cachedUsage = buffer.toString();

         }

         return cachedUsage;

     }

 }