package com.atlassian.plugin.spring.pluginns;
   
   import com.atlassian.plugin.osgi.hostcomponents.ContextClassLoaderStrategy;
   import com.atlassian.plugin.spring.PluginBeanDefinitionRegistry;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import org.springframework.beans.factory.config.BeanDefinitionHolder;
   import org.springframework.beans.factory.xml.BeanDefinitionDecorator;
   import org.springframework.beans.factory.xml.ParserContext;
  import org.w3c.dom.Attr;
  import org.w3c.dom.Node;
  
  import javax.annotation.Nonnull;
  
  /**
   * Processes an "contextClassLoader" strategy attribute in the plugin namespace.
   * Also handles registering the {@link com.atlassian.plugin.osgi.hostcomponents.HostComponentProvider} through
   * the {@link com.atlassian.plugin.spring.SpringHostComponentProviderFactoryBean}.
   *
   * In the case of hierarchical contexts we will put the host component provider in the lowest possible context.
   */
  public class PluginContextClassLoaderStrategyBeanDefinitionDecorator implements BeanDefinitionDecorator {
      private final static Logger log = LoggerFactory.getLogger(PluginContextClassLoaderStrategyBeanDefinitionDecorator.class);
  
      /**
       * Called when the Spring parser encounters an "available" attribute.
       *
       * @param source The attribute
       * @param holder The containing bean definition
       * @param ctx    The parser context
       * @return The containing bean definition
       */
      @Nonnull
      @Override
      public BeanDefinitionHolder decorate(@Nonnull Node source, @Nonnull BeanDefinitionHolder holder,
                                           @Nonnull ParserContext ctx) {
          final String contextClassLoaderStrategy = ((Attr) source).getValue();
          if (contextClassLoaderStrategy != null) {
              new PluginBeanDefinitionRegistry(ctx.getRegistry()).addContextClassLoaderStrategy(holder.getBeanName(), getContextClassLoaderStrategy(contextClassLoaderStrategy));
          }
          return holder;
  
      }
  
      private ContextClassLoaderStrategy getContextClassLoaderStrategy(String contextClassLoaderStrategy) {
          try {
              return ContextClassLoaderStrategy.valueOf(contextClassLoaderStrategy);
          } catch (IllegalArgumentException e) {
              log.warn("Cannot parse '{}' to a valid context class loader strategy, will use default '{}'", contextClassLoaderStrategy, ContextClassLoaderStrategy.USE_HOST);
              return ContextClassLoaderStrategy.USE_HOST;
          }
      }
  }