/*
* Copyright 2009 Federal Chancellery Austria and
* Graz University of Technology
*
* 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 at.gv.egiz.bku.spring;

import java.io.IOException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.jar.Attributes;
import java.util.jar.Manifest;

import org.apache.commons.configuration.CompositeConfiguration;
import org.apache.commons.configuration.Configuration;
import org.apache.commons.configuration.ConfigurationException;
import org.apache.commons.configuration.MapConfiguration;
import org.apache.commons.configuration.XMLConfiguration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.context.ResourceLoaderAware;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;

import at.gv.egiz.bku.slcommands.impl.CreateXMLSignatureCommandImpl;

/**
 * This is a {@link FactoryBean} for the creation of a {@link Configuration}.
 * 
 * @author mcentner
 */
public class ConfigurationFactoryBean implements FactoryBean, ResourceLoaderAware {
  
  protected static final Logger log = LoggerFactory.getLogger(ConfigurationFactoryBean.class);

  public static final String DEFAULT_CONFIG = "/WEB-INF/conf/configuration.xml";
  
  public static final String MOCCA_IMPLEMENTATIONNAME_PROPERTY = "ProductName";

  public static final String MOCCA_IMPLEMENTATIONVERSION_PROPERTY = "ProductVersion";
  
  public static final String SIGNATURE_LAYOUT_PROPERTY = "SignatureLayout";
  
  /**
   * The URL of the configuration file.
   */
  protected Resource configurationResource;
  
  /**
   * The ResourceLoader.
   */
  protected ResourceLoader resourceLoader;
  
  @Override
  public void setResourceLoader(ResourceLoader resourceLoader) {
    this.resourceLoader = resourceLoader;
  }

  /**
   * @return the configurationURL
   */
  public Resource getConfigurationResource() {
    return configurationResource;
  }

  /**
   * @param configurationResource the configurationURL to set
   */
  public void setConfigurationResource(Resource configurationResource) {
    this.configurationResource = configurationResource;
  }

  protected Configuration getDefaultConfiguration()
      throws ConfigurationException, IOException {
    Resource resource = resourceLoader.getResource(DEFAULT_CONFIG);
    XMLConfiguration xmlConfiguration = new XMLConfiguration();
    xmlConfiguration.load(resource.getInputStream());
    xmlConfiguration.setURL(resource.getURL());
    return xmlConfiguration;
  }
  
  protected Configuration getVersionConfiguration() throws IOException {
    
    Map<String, String> map = new HashMap<String, String>();
    map.put(MOCCA_IMPLEMENTATIONNAME_PROPERTY, "MOCCA");
    
    // implementation version
    String version = null;
    try {
      Resource resource = resourceLoader.getResource("META-INF/MANIFEST.MF");
      Manifest properties = new Manifest(resource.getInputStream());
      Attributes attributes = properties.getMainAttributes();
      // TODO: replace by Implementation-Version ?
      version = attributes.getValue("Implementation-Build");
    } catch (Exception e) {
      log.warn("Failed to get implemenation version from manifest. {}", e.getMessage());
    }
    
    if (version == null) {
      version="UNKNOWN";
    }
    map.put(MOCCA_IMPLEMENTATIONVERSION_PROPERTY, version);
    
    // signature layout
    try {
      String classContainer = CreateXMLSignatureCommandImpl.class.getProtectionDomain()
          .getCodeSource().getLocation().toString();
      URL manifestUrl = new URL("jar:" + classContainer
          + "!/META-INF/MANIFEST.MF");
      Manifest manifest = new Manifest(manifestUrl.openStream());
      Attributes attributes = manifest.getMainAttributes();
      String signatureLayout = attributes.getValue("SignatureLayout");
      if (signatureLayout != null) {
        map.put(SIGNATURE_LAYOUT_PROPERTY, signatureLayout);
      }
    } catch (Exception e) {
      log.warn("Failed to get signature layout from manifest.", e);
    }
    
    
    return new MapConfiguration(map);
    
  }
  
  @Override
  public Object getObject() throws Exception {
    
    log.info("Configuration resource is {}.", configurationResource);
    
    CompositeConfiguration configuration;
    if (configurationResource == null) {
      // initialize default configuration
      log.warn("Initializing with default configuration.");
      configuration = new CompositeConfiguration();
    } else {
      // initialize with writable configuration
      URL url = configurationResource.getURL();
      XMLConfiguration writableConfiguration = new XMLConfiguration(url);
      configuration = new CompositeConfiguration(writableConfiguration);
      log.info("Initialized with configuration from '{}'.", url);
    }
    configuration.addConfiguration(getDefaultConfiguration());
    configuration.addConfiguration(getVersionConfiguration());
    return configuration;
  }

  @Override
  public Class<?> getObjectType() {
    return Configuration.class;
  }

  @Override
  public boolean isSingleton() {
    return true;
  }


}