/*
    * 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 --------------------------------------------------------
 
 }