/*

  * 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.any23.vocab;

 import org.apache.any23.rdf.RDFUtils;

 import org.openrdf.model.URI;

 import java.lang.annotation.Retention;

 import java.lang.annotation.Target;

 import java.lang.reflect.Field;

 import java.util.Collection;

 import java.util.Collections;

 import java.util.HashMap;

 import java.util.Map;

 import static java.lang.annotation.ElementType.FIELD;

 import static java.lang.annotation.RetentionPolicy.RUNTIME;

 /**

  * Base class for the definition of a vocabulary.

  *

  * @author Michele Mostarda ( michele.mostarda@gmail.com )

  * @version $Id$

  */

 public abstract class Vocabulary {

     /**

      * Allows to add comments to <code>namespaces</code>,

      * <code>classes</code> and <code>properties</code>.

      */

     @Target({FIELD})

     @Retention(RUNTIME)

     @interface Comment {

         String value();

     }

     /**

      * Vocabulary namespace.

      */

     private final URI namespace;

     /**

      * Map of vocabulary resources.

      */

     private Map<String,URI> classes;

     /**

      * Map of vocabulary properties.

      */

     private Map<String,URI> properties;

     /**

      * Map any resource with the relative comment.

      */

     private Map<URI,String> resourceToCommentMap;

     /**

      * Constructor.

      *

      * @param namespace the namespace URI prefix.

      */

     public Vocabulary(String namespace) {

         try {

         this.namespace =  RDFUtils.uri(namespace);

         } catch (Exception e) {

             throw new IllegalArgumentException("Invalid namespace '" + namespace + "'", e);

         }

     }

     /**

      * @return the namespace associated to this vocabulary.

      */

     public URI getNamespace() {

         return namespace;

     }

     /**

      * Returns a class defined within this vocabulary.

      *

      * @param name class name.

      * @return the URI associated to such resource.

      */

     public URI getClass(String name) {

         URI res = classes.get(name);

         if (null == res) {

             throw new IllegalArgumentException("Unknown resource name '" + name + "'");

         }

         return res;

     }

     /**

      * Returns a property defined within this vocabulary.

      *

      * @param name property name.

      * @return the URI associated to such property.

      */

     public URI getProperty(String name) {

         URI prop = properties.get(name);

         if (null == prop) {

             throw new IllegalArgumentException("Unknown property name '" + name + "'");

         }

         return prop;

     }

     /**

      * Returns a property defined within this vocabulary, if not found the

      * <code>defaultValue</code> will be returned.

      *

      * @param name property name.

      * @param defaultValue the default value if property name not found.

      * @return the URI associated to such property.

      */

     public URI getProperty(String name, URI defaultValue) {

         URI prop = properties.get(name);

         if (null == prop) {

             return defaultValue;

         }

         return prop;

     }

     /**

      * Returns the property URI for the specified property string.

      * If the string contains a list of words separated by blank chars,

      * such words are merged and camel case separated.

      *

      * @param property property name.

      * @return property URI.

      */

     public URI getPropertyCamelCase(String property) {

         String[] names = property.split("\\W");

         String camelCase = names[0];

         for (int i = 1; i < names.length; i++) {

             String tmp = names[i];

             camelCase += tmp.replaceFirst("(.)", tmp.substring(0, 1).toUpperCase());

         }

         return getProperty(camelCase);

     }

     /**

      * @return the list of all defined classes.

      */

     public URI[] getClasses() {

         if(classes == null) {

             return new URI[0];

         }

         final Collection<URI> uris = classes.values();

         return uris.toArray( new URI[ uris.size() ] );

     }

     /**

      * @return the list of all defined properties.

      */

     public URI[] getProperties() {

         if(properties == null) {

             return new URI[0];

         }

         final Collection<URI> uris = properties.values();

         return uris.toArray( new URI[ uris.size() ] );

     }

     /**

      * Returns all the defined comments for resources.

      *

      * @return unmodifiable list of comments.

      */

     public Map<URI,String> getComments() {

         fillResourceToCommentMap();

         return Collections.unmodifiableMap(resourceToCommentMap);

     }

     /**

      * Returns the comment for the given resource.

      *

      * @param resource input resource to have a comment.

      * @return the human readable comment associated to the

      *         given resource.

      */

     public String getCommentFor(URI resource) {

         fillResourceToCommentMap();

         return resourceToCommentMap.get(resource);

     }

     /**

      * Creates a URI.

      *

      * @param uriStr the URI string

      * @return the URI instance.

      */

     protected URI createURI(String uriStr) {

         return RDFUtils.uri(uriStr);

     }

     /**

      * Creates a resource and register it to the {@link #classes} map.

      *

      * @param namespace vocabulary namespace.

      * @param resource name of the resource.

      * @return the created resource URI.

      */

     protected URI createClass(String namespace, String resource) {

         URI res = createURI(namespace, resource);

         if(classes == null) {

             classes = new HashMap<String, URI>(10);

         }

         classes.put(resource, res);

         return res;

     }

     /**

      * Creates a property and register it to the {@link #properties} map.

      *

      * @param namespace vocabulary namespace.

      * @param property name of the property.

      * @return the created property URI.

      */

     protected URI createProperty(String namespace, String property) {

         URI res = createURI(namespace, property);

         if(properties == null) {

             properties = new HashMap<String, URI>(10);

         }

         properties.put(property, res);

         return res;

     }

     /**

      * Creates a URI.

      *

      * @param namespace

      * @param localName

      * @return

      */

     private URI createURI(String namespace, String localName) {

         return RDFUtils.uri(namespace, localName);

     }

     private void fillResourceToCommentMap() {

         if(resourceToCommentMap != null) return;

         final Map<URI,String> newMap = new HashMap<URI, String>();

         for (Field field : this.getClass().getFields()) {

             try {

                 final Object value = field.get(this);

                 if(value instanceof URI) {

                     final Comment comment = field.getAnnotation(Comment.class);

                     if(comment != null) newMap.put((URI) value, comment.value());

                 }

             } catch (IllegalAccessException iae) {

                 throw new RuntimeException("Error while creating resource to comment map.", iae);

             }

         }

         resourceToCommentMap = newMap;

     }

 }