/*

  * Copyright 2012-2013 smartics, Kronseder & Reiner GmbH

  *

  * Licensed 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 de.smartics.properties.api.core.context.alias;

 import java.io.Serializable;

 import java.util.HashMap;

 import java.util.Map;

 import java.util.Map.Entry;

 import javax.annotation.concurrent.NotThreadSafe;

 import de.smartics.util.lang.Arg;

 import de.smartics.util.lang.BlankArgumentException;

 /**

  * The mapping of alias names of property reports to their physical names. The

  * physical names are those file names that are stored in the

  * <code>META-INF</code> folder or on the server in the case of HTML reports.

  * The alias names are alternative, unique naming schemes that refer to the same

  * files.

  */

 @NotThreadSafe

 public final class PropertyAliasMapping implements Serializable

 {

   // ********************************* Fields *********************************

   // --- constants ------------------------------------------------------------

   /**

    * The class version identifier.

    */

   private static final long serialVersionUID = 1L;

   // --- members --------------------------------------------------------------

   /**

    * The mapping of alias names of property reports to their physical names. The

    * physical names are those file names that are stored in the

    * <code>META-INF</code> folder or on the server in the case of HTML reports.

    * The alias names are alternative, unique naming schemes that refer to the

    * same files.

    * <p>

    * The key is the name of the alias, the value is the physical resource. There

    * is only one physical for each alias, but different aliases may point to the

    * same resource.

    * </p>

    *

    * @serial

    */

   private final Map<String, String> aliasMapping =

       new HashMap<String, String>();

   // ****************************** Initializer *******************************

   // ****************************** Constructors ******************************

   /**

    * Default constructor.

    */

   public PropertyAliasMapping()

   {

   }

   // ****************************** Inner Classes *****************************

   // ********************************* Methods ********************************

   // --- init -----------------------------------------------------------------

   // --- get&set --------------------------------------------------------------

   // --- business -------------------------------------------------------------

   /**

    * Adds a new alias to the given physical resource.

    *

    * @param alias the new alias.

    * @param target the resource the alias refers to.

    * @throws BlankArgumentException if either {@code alias} or {@code target} is

    *           blank.

    * @throws DuplicateAliasException if there is already an alias registered

    *           that points to a different physical resource.

    */

   public void add(final String alias, final String target)

     throws BlankArgumentException, DuplicateAliasException

   {

     Arg.checkNotBlank("alias", alias); // NOPMD

     Arg.checkNotBlank("target", target);

     final String oldTarget = aliasMapping.put(alias, target);

     if (oldTarget != null && !oldTarget.equals(target))

     {

       throw new DuplicateAliasException(alias, oldTarget, target);

     }

   }

   /**

    * Checks if the given alias is registered.

    *

    * @param alias the alias to check.

    * @throws BlankArgumentException if {@code alias} is blank.

    * @return <code>true</code> if the alias is known to the system,

    *         <code>false</code> otherwise.

    */

   public boolean has(final String alias) throws BlankArgumentException

   {

     Arg.checkNotBlank("alias", alias);

     return aliasMapping.containsKey(alias);

   }

   /**

    * Returns the target the alias points to.

    *

    * @param alias the alias whose physical resource is requested.

    * @return the target the alias points to.

    * @throws BlankArgumentException if {@code alias} is blank.

    * @throws UnknownAliasException if the alias is not known.

    */

   public String get(final String alias) throws BlankArgumentException,

     UnknownAliasException

   {

     Arg.checkNotBlank("alias", alias);

     final String physical = aliasMapping.get(alias);

     if (physical != null)

     {

       return physical;

     }

     throw new UnknownAliasException(alias);

   }

   /**

    * Traverses the registered aliases.

    *

    * @param traverser the traverser to use.

    * @throws NullPointerException if {@code traverser} is <code>null</code>.

    */

   public void traverse(final AliasTraverser traverser)

     throws NullPointerException

   {

     Arg.checkNotNull("traverser", traverser);

     for (final Entry<String, String> entry : aliasMapping.entrySet())

     {

       final String alias = entry.getKey();

       final String physical = entry.getValue();

       traverser.handle(alias, physical);

     }

   }

   /**

    * Checks whether any aliases are registered.

    *

    * @return <code>false</code> if at least one alias is registered,

    *         <code>true</code> otherwise.

    */

   public boolean isEmpty()

   {

     return aliasMapping.isEmpty();

   }

   // --- object basics --------------------------------------------------------

 }