/* ***************************************************************************
    * 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.helper.spring;
  
  import org.settings4j.Settings4j;
  import org.springframework.beans.factory.FactoryBean;
  import org.springframework.beans.factory.InitializingBean;
  
  
  /**
   * BeanFactory which gets the Object from {@link Settings4j#getObject(String)}.<br />
   * This can also be used for DataSource-Objects with the JNDI-Name as Key.
   * 
   * <p>
   * <h2>Simple SpringBean Example:</h2> The following Example can be configured with the settings4j-Key "env/MyVariable".
   * <br />
   * e.g.: System.setProperty("env/MyVariable", "Hallo World");<br />
   * OR with JNDI-Context OR in a Classpath-File under "classpath:env/MyVariable" Or with a custom
   * {@link org.settings4j.Connector}-Implementation.
   * 
   * <pre>
   *  &lt;bean id="MyConfigurableValue" class="org.settings4j.helper.spring.Settings4jFactoryBean"&gt;
   *      &lt;property name="key"&gt;&lt;value&gt;<b>env/MyVariable</b>&lt;/value&gt;&lt;/property&gt;
   *  &lt;/bean&gt;
   * </pre>
   * 
   * <h2>More complex SpringBean Example:</h2> This Example shows how a Hibernate SessionFactory can optional customized
   * with additional HibernateProperties.
   * 
   * <pre>
   *  &lt;bean id="hibernateProperties"
   *      class="org.springframework.beans.factory.config.PropertiesFactoryBean"&gt;
   *      &lt;property name="locations"&gt;
   *          &lt;list&gt;
   *              &lt;value&gt;classpath:org/settings4j/helper/spring/DefaultHibernate.properties&lt;/value&gt;
   *              &lt;bean class="org.settings4j.helper.spring.Settings4jFactoryBean"&gt;
   *                  &lt;property name="key"&gt;
   *                      &lt;value&gt;<b>env/MyCustomProprtiesLocationKey</b>&lt;/value&gt;
   *                  &lt;/property&gt;
   *                  &lt;property name="defaultObject"&gt;
   *                      &lt;!-- This could also be an empty Property-File But it must Exist. --&gt;
   *                      &lt;!-- PropertiesFactoryBean cannot handle invalid Paths. --&gt;
   *                      &lt;value&gt;classpath:org/settings4j/helper/spring/DefaultHibernate.properties&lt;/value&gt;
   *                  &lt;/property&gt;
   *              &lt;/bean&gt;
   *          &lt;/list&gt;
   *      &lt;/property&gt;
   *  &lt;/bean&gt;
   *  
   *  &lt;bean id="mySessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"&gt;
   *      &lt;property name="dataSource" ref="db2Datasource2" /&gt;
   *      &lt;property name="hibernateProperties" ref="hibernateProperties" /&gt;
   *      ....
   *  &lt;/bean&gt;
   * </pre>
   * 
   * @author Harald.Brabenetz
   */
  public class Settings4jFactoryBean implements FactoryBean, InitializingBean {
  
      private String key;
      private boolean singleton = true;
      private Object singletonObject;
      private Object defaultObject;
      private Class expectedType;
  
      public String getKey() {
          return this.key;
      }
  
      /**
       * @param key - the Setting4j-Key for Your Configuration-Value.
       */
      public void setKey(final String key) {
          this.key = key;
      }
  
      /**
       * @param singleton - If <code>true</code>, the Value will be read during SpringBean-Initialization. Default is
       *            <code>true</code>
       */
      public void setSingleton(final boolean singleton) {
          this.singleton = singleton;
      }
  
     /**
      * Specify the type that the configured object is supposed to be assignable to, if any.
      * 
      * @param expectedType the expected {@link Class}.
      */
     public void setExpectedType(final Class expectedType) {
         this.expectedType = expectedType;
     }
 
     /**
      * Return the type that the configured object is supposed to be assignable to, if any.
      * 
      * @return the type that the configured object is supposed to be assignable to.
      */
     public Class getExpectedType() {
         return this.expectedType;
     }
 
 
     public Object getDefaultObject() {
         return this.defaultObject;
     }
 
 
     public void setDefaultObject(final Object defaultObject) {
         this.defaultObject = defaultObject;
     }
 
     /** {@inheritDoc} */
     public Object getObject() {
         if (this.singleton) {
             return this.singletonObject;
         }
         return getSettings4jObject();
     }
 
     /** {@inheritDoc} */
     public Class getObjectType() {
         final Object obj = getObject();
         if (obj != null) {
             return obj.getClass();
         }
         return getExpectedType();
     }
 
     /** {@inheritDoc} */
     public boolean isSingleton() {
         return this.singleton;
     }
 
     /** {@inheritDoc} */
     public void afterPropertiesSet() {
         if (this.singleton) {
             this.singletonObject = getSettings4jObject();
         }
     }
 
     private Object getSettings4jObject() {
         Object result = Settings4j.getObject(this.key);
         if (result == null) {
             result = Settings4j.getString(this.key);
         }
 
         if (result == null) {
             result = this.defaultObject;
         }
         return result;
     }
 
 }