/* ***************************************************************************
    * Copyright (c) 2008 Brabenetz Harald, Austria.
    *
    * 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 org.settings4j.objectresolver;
  
  import java.util.Properties;
  
  import org.apache.commons.lang3.StringUtils;
  import org.settings4j.ContentResolver;
  import org.settings4j.helper.spring.ByteArrayXMLApplicationContext;
  
  /**
   * This implementation parses a Spring-Beans XML File and returns the Object from the generated Spring Application
   * Context.
   * <p>
   * Per Default the bean with id = key.replace('/', '.') will be returned. But you can configure a key "bean-ref" in the
   * {@link Properties}-File for the given Object.
   * <p>
   * Example: The following code should return a {@link javax.sql.DataSource} Object:<br/>
   * <code>
   * Settings4j.getObject("com/myCompany/myApp/MyDatasource");
   * </code>
   * <p>
   * In normal Cases the DataSource comes from the JNDI-Context (available in most Servlet Containers).<br/>
   * But in some environments there are no JNDI-Context (Commandline-Clients, UnitTests).<br/>
   * <p>
   * With Settings4j (default configuration) you can also place two Files into your Classpath:
   * <ol>
   * <li><code>"com/myCompany/myApp/MyDatasource"</code>: The File which defines the DataSource
   * <li><code>"com/myCompany/myApp/MyDatasource.properties"</code>: Some Properties, like which ObjectResolver should be
   * use.
   * </ol>
   * <p>
   * The File Content whould be the following:
   * 
   * <ul>
   * <li><b>objectResolverKey:</b> A unique identifier for the Object Resolver Implementation.
   * <li><b>bean-ref:</b> The bean name/id from the Spring-Context.
   * </ul>
   * <pre>
   * Classpath File "com/myCompany/myApp/MyDatasource.properties":
   * <div style="border-width:1px;border-style:solid;">
   * objectResolverKey=org.settings4j.objectresolver.SpringConfigObjectResolver
   * bean-ref=<b>SpringBeanReferneceId</b>
   * </div>
   * </pre>
   * <p>
   * <pre>
   * Classpath File "com/myCompany/myApp/MyDatasource":
   * <div style="border-width:1px;border-style:solid;">
   * &lt;?xml version="1.0" encoding="UTF-8"?&gt;
   * &lt;!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd"&gt;
   * &lt;beans&gt;
   *   &lt;!-- HSQLDB --&gt;
   *   &lt;bean id="<b>SpringBeanReferneceId</b>" class="org.springframework.jdbc.datasource.DriverManagerDataSource"&gt;
   *     &lt;property name="driverClassName"&gt;&lt;value&gt;org.hsqldb.jdbcDriver&lt;/value&gt;&lt;/property&gt;
   *     &lt;property name="url"&gt;&lt;value&gt;jdbc:hsqldb:mem:test&lt;/value&gt;&lt;/property&gt;
   *     &lt;property name="username"&gt;&lt;value&gt;sa&lt;/value&gt;&lt;/property&gt;
   *     &lt;property name="password"&gt;&lt;value&gt;&lt;/value&gt;&lt;/property&gt;
   *   &lt;/bean&gt;
   * &lt;/beans&gt;
   * </div>
   * </pre>
   * <p>
   * 
   * @author Harald.Brabenetz
   */
  public class SpringConfigObjectResolver extends AbstractObjectResolver {
  
      /** General Logger for this Class. */
      private static final org.slf4j.Logger LOG = org.slf4j.LoggerFactory.getLogger(SpringConfigObjectResolver.class);
  
      private static final String PROPERTY_BEAN_REF = "bean-ref";
  
      /** {@inheritDoc} */
      @Override
      protected Object contentToObject(final String key, final Properties properties, final byte[] content,
              final ContentResolver contentResolver) {
  
          String beanRef = properties.getProperty(PROPERTY_BEAN_REF);
          if (StringUtils.isEmpty(beanRef)) {
              beanRef = key.replace('/', '.');
          }
  
          final Object result = ByteArrayXMLApplicationContext.getBean(content, beanRef);
         if (result == null) {
             LOG.warn("SpringContext-Object with ID '{}' for Key '{}' is null!", beanRef, key);
         }
         return result;
     }
 
 }