/*
 * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.com
 * The software in this package is published under the terms of the CPAL v1.0
 * license, a copy of which has been included with this distribution in the
 * LICENSE.txt file.
 */
package org.mule.runtime.config.spring.parsers.specific;

import org.mule.runtime.config.spring.parsers.AbstractMuleBeanDefinitionParser;
import org.mule.runtime.config.spring.parsers.MuleDefinitionParser;
import org.mule.runtime.config.spring.parsers.PreProcessor;
import org.mule.runtime.config.spring.parsers.assembly.configuration.PropertyConfiguration;
import org.mule.runtime.config.spring.parsers.delegate.AbstractParallelDelegatingDefinitionParser;
import org.mule.runtime.config.spring.util.SpringXMLUtils;
import org.mule.runtime.core.util.StringUtils;

import org.springframework.beans.factory.xml.ParserContext;
import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;

/**
 * Allows for parsing either a shortcut component configuration by delegating to two different component parses depending on the
 * existence of the class attribute. If the class attribute is used then an embedded object factory element cannot be used.
 * 
 * <pre>
 * <component class="">
 * </pre>
 * 
 * or one with an embedded object factory element.
 * 
 * <pre>
 * <component>
 *     <singleon-object class=".."/>
 * </component>
 * </pre>
 */
public class ComponentDelegatingDefinitionParser extends AbstractParallelDelegatingDefinitionParser {

  private MuleDefinitionParser normalConfig;
  private MuleDefinitionParser shortcutConfig;

  public ComponentDelegatingDefinitionParser(Class clazz) {
    normalConfig = new ComponentDefinitionParser(clazz);
    shortcutConfig = new ShortcutComponentDefinitionParser(clazz);
    addDelegate(normalConfig);
    addDelegate(shortcutConfig);
    registerPreProcessor(new CheckExclusiveClassAttributeObjectFactory());
  }

  @Override
  protected MuleDefinitionParser getDelegate(Element element, ParserContext parserContext) {
    if (StringUtils.isEmpty(element.getAttribute(AbstractMuleBeanDefinitionParser.ATTRIBUTE_CLASS))) {
      return normalConfig;
    } else {
      return shortcutConfig;
    }
  }

  /**
   * Given that the service object-factory is extensible and new object factory types can be implemented and used by substitution,
   * the only way of checking for the existence of an object-factory if by object factory element convention.<br>
   * This pre-processor checks for the existence of a <i>"class"</i> attribute on the service, and throws an exception if the
   * service has any elements that match the object factory element convention (i.e. that end in "object"). NOTE: We used to test
   * by exclusion here allowing all other elements, but that no longer works now extensible interceptors elements can be used.
   */
  class CheckExclusiveClassAttributeObjectFactory implements PreProcessor {

    private static final String OBJECT_FACTORY_ELEMENT_CONVENTION_SUFFIX = "object";

    @Override
    public void preProcess(PropertyConfiguration config, Element element) {
      NamedNodeMap attributes = element.getAttributes();
      for (int i = 0; i < attributes.getLength(); i++) {
        String alias = SpringXMLUtils.attributeName((Attr) attributes.item(i));
        if (alias.equals(AbstractMuleBeanDefinitionParser.ATTRIBUTE_CLASS)) {
          for (int j = 0; j < element.getChildNodes().getLength(); j++) {
            Node child = element.getChildNodes().item(j);
            if (child instanceof Element && child.getLocalName().endsWith(OBJECT_FACTORY_ELEMENT_CONVENTION_SUFFIX)) {
              StringBuilder message = new StringBuilder("The child element '");
              message.append(child.getLocalName());
              message.append("' cannot appear with the 'class' attribute");
              message.append(" in element ");
              message.append(SpringXMLUtils.elementToString(element));
              message.append(".");
              throw new CheckExclusiveClassAttributeObjectFactoryException(message.toString());
            }
          }
        }
      }
    }
  }

  public class CheckExclusiveClassAttributeObjectFactoryException extends IllegalStateException {

    private static final long serialVersionUID = 4625276914151932111L;

    CheckExclusiveClassAttributeObjectFactoryException(String message) {
      super(message);
    }
  }

}