/*
 * 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;

import static java.util.Collections.emptySet;
import static java.util.Optional.of;
import static org.mule.runtime.config.spring.parsers.AbstractMuleBeanDefinitionParser.getConfigFileIdentifier;
import org.mule.runtime.api.app.declaration.ArtifactDeclaration;
import org.mule.runtime.api.exception.MuleRuntimeException;
import org.mule.runtime.config.spring.dsl.model.ApplicationModel;
import org.mule.runtime.config.spring.dsl.model.ComponentBuildingDefinitionRegistry;
import org.mule.runtime.config.spring.dsl.processor.ArtifactConfig;
import org.mule.runtime.config.spring.dsl.processor.ConfigFile;
import org.mule.runtime.config.spring.dsl.processor.ConfigLine;
import org.mule.runtime.config.spring.dsl.processor.xml.XmlApplicationParser;
import org.mule.runtime.config.spring.dsl.spring.BeanDefinitionFactory;

import java.util.ArrayList;
import java.util.List;
import java.util.Stack;

import org.springframework.beans.factory.xml.BeanDefinitionParserDelegate;
import org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader;
import org.springframework.beans.factory.xml.XmlReaderContext;
import org.springframework.util.StringUtils;
import org.w3c.dom.Element;

/**
 * Allows us to hook in our own Hierarchical Parser delegate. this enables the parsing of custom spring bean elements nested
 * within each other
 */
public class MuleBeanDefinitionDocumentReader extends DefaultBeanDefinitionDocumentReader {

  private final BeanDefinitionFactory beanDefinitionFactory;
  private final XmlApplicationParser xmlApplicationParser;
  // This same instance is called several time to parse different XML files so a stack is needed to save previous state.
  private final Stack<ApplicationModel> applicationModelStack = new Stack<>();
  private final ComponentBuildingDefinitionRegistry componentBuildingDefinitionRegistry;

  public MuleBeanDefinitionDocumentReader(BeanDefinitionFactory beanDefinitionFactory,
                                          XmlApplicationParser xmlApplicationParser,
                                          ComponentBuildingDefinitionRegistry componentBuildingDefinitionRegistry) {
    this.beanDefinitionFactory = beanDefinitionFactory;
    this.xmlApplicationParser = xmlApplicationParser;
    this.componentBuildingDefinitionRegistry = componentBuildingDefinitionRegistry;
  }

  @Override
  protected BeanDefinitionParserDelegate createDelegate(XmlReaderContext readerContext, Element root,
                                                        BeanDefinitionParserDelegate parentDelegate) {
    BeanDefinitionParserDelegate delegate = createBeanDefinitionParserDelegate(readerContext);
    delegate.initDefaults(root, parentDelegate);
    return delegate;
  }

  protected MuleHierarchicalBeanDefinitionParserDelegate createBeanDefinitionParserDelegate(XmlReaderContext readerContext) {
    return new MuleHierarchicalBeanDefinitionParserDelegate(readerContext, this, applicationModelStack::peek,
                                                            beanDefinitionFactory, getElementsValidator());
  }

  protected ElementValidator[] getElementsValidator() {
    return new ElementValidator[0];
  }

  /**
   * Override to reject configuration files with no namespace, e.g. mule legacy configuration file.
   */
  @Override
  protected void parseBeanDefinitions(Element root, BeanDefinitionParserDelegate delegate) {
    if (!StringUtils.hasLength(root.getNamespaceURI())) {
      getReaderContext().error("Unable to locate NamespaceHandler for namespace [null]", root);
    } else {
      super.parseBeanDefinitions(root, delegate);
    }
  }

  @Override
  protected void preProcessXml(Element root) {
    try {
      List<ConfigLine> configLines = new ArrayList<>();
      configLines.add(xmlApplicationParser.parse(root).get());
      ArtifactConfig artifactConfig = new ArtifactConfig.Builder()
          .addConfigFile(new ConfigFile(getConfigFileIdentifier(getReaderContext().getResource()), configLines)).build();
      applicationModelStack.push(new ApplicationModel(artifactConfig, new ArtifactDeclaration(), emptySet(),
                                                      of(componentBuildingDefinitionRegistry)));
    } catch (Exception e) {
      throw new MuleRuntimeException(e);
    }
  }

  @Override
  protected void postProcessXml(Element root) {
    applicationModelStack.pop();
  }

}