package at.gv.egovernment.moa.id.config.proxy;

import java.io.FileInputStream;
import java.io.IOException;

import org.w3c.dom.Element;

import at.gv.egovernment.moa.id.config.ConfigurationBuilder;
import at.gv.egovernment.moa.id.config.ConfigurationException;
import at.gv.egovernment.moa.id.config.ConfigurationProvider;
import at.gv.egovernment.moa.id.config.ConnectionParameter;
import at.gv.egovernment.moa.logging.Logger;
import at.gv.egovernment.moa.util.DOMUtils;

/**
 * A class providing access to the Proxy Part of the MOA-ID configuration data.
 * 
 * <p>Configuration data is read from an XML file, whose location is given by
 * the <code>moa.id.configuration</code> system property.</p>
 * <p>This class implements the Singleton pattern. The <code>reload()</code>
 * method can be used to update the configuration data. Therefore, it is not
 * guaranteed that consecutive calls to <code>getInstance()</code> will return
 * the same <code>ProxyConfigurationProvider</code> all the time. During the
 * processing of a web service request, the current
 * <code>TransactionContext</code> should be used to obtain the
 * <code>ProxyConfigurationProvider</code> local to that request.</p>
 * 
 * @author Stefan Knirsch
 */
public class ProxyConfigurationProvider extends ConfigurationProvider {

  /** Singleton instance. <code>null</code>, if none has been created. */
  private static ProxyConfigurationProvider instance;

  //
  // configuration data
  //
  /**
   * connection parameters for connection to MOA ID Auth component
   */
  private ConnectionParameter authComponentConnectionParameter;
  /**
   * configuration parameters for online applications
   */
  private OAProxyParameter[] onlineApplicationProxyParameter;

  /**
   * Return the single instance of configuration data.
   * 
   * @return ProxyConfigurationProvider The current configuration data.
   * @throws ConfigurationException 
   */
  public static synchronized ProxyConfigurationProvider getInstance()
    throws ConfigurationException {

    if (instance == null) {
      reload();
    }
    return instance;
  }

  /**
   * Reload the configuration data and set it if successful.
   * 
   * @return ProxyConfigurationProvider The loaded configuration data.
   * @throws ConfigurationException Failure to load the configuration data.
   */
  public static synchronized ProxyConfigurationProvider reload()
    throws ConfigurationException {
    String fileName = System.getProperty(CONFIG_PROPERTY_NAME);
    if (fileName == null) {
      throw new ConfigurationException("config.01", null);
    }
    Logger.info("Loading MOA-ID-PROXY configuration " + fileName);

    instance = new ProxyConfigurationProvider(fileName);
    return instance;
  }

  /**
   * Constructor for ProxyConfigurationProvider.
   */
  public ProxyConfigurationProvider(String fileName)
    throws ConfigurationException {

    load(fileName);
  }

  /**
   * Load the configuration data from XML file with the given name and build
   * the internal data structures representing the MOA configuration.
   * 
   * @param fileName The name of the XML file to load.
   * @throws ConfigurationException The MOA configuration could not be
   * read/built.
   */
  private void load(String fileName) throws ConfigurationException {
    FileInputStream stream = null;
    Element configElem;
    ConfigurationBuilder builder;

    try {
      // load the main config file
      stream = new FileInputStream(fileName);
      configElem = DOMUtils.parseXmlValidating(stream);
    } 
    catch (Throwable t) {
      throw new ConfigurationException("config.03", null, t);
    } 
    finally {
      try {
        if (stream != null) {
          stream.close();
        }
      } 
      catch (IOException e) {
      }
    }
		try {
      // build the internal datastructures
      builder = new ConfigurationBuilder(configElem);
      authComponentConnectionParameter = builder.buildAuthComponentConnectionParameter();
      onlineApplicationProxyParameter = builder.buildOnlineApplicationProxyParameters();  
      genericConfiguration = builder.buildGenericConfiguration();
      defaultChainingMode = builder.getDefaultChainingMode();
      chainingModes = builder.buildChainingModes();  
      trustedCACertificates = builder.getTrustedCACertificates();
    } 
    catch (Throwable t) {
      throw new ConfigurationException("config.02", null, t);
    }
  }

 /**
   * Return a bean containing all information about the ProxyComponent
   * @return The ConnectionParameter for the Proxy Component
   */
  public ConnectionParameter getAuthComponentConnectionParameter() {
    return authComponentConnectionParameter;
  }
  
  /**
   * Build an array of OnlineApplication Parameter Beans containing all
   * information about the proxy component of the online application
   * @return An OAProxyParameter array containing beans
   * with all relevant information for the proxy component of the online 
   * application
   */
  public OAProxyParameter[] getOnlineApplicationParameters() {
    return onlineApplicationProxyParameter;
  }
  /**
   * Provides configuration information regarding the online application behind
   * the given URL, relevant to the MOA-ID Proxy component.
   * 
   * @param oaURL URL requested for an online application
   * @return an <code>OAProxyParameter</code>, or <code>null</code>
   * 					if none is applicable
   */
  public OAProxyParameter getOnlineApplicationParameter(String oaURL) {
  	OAProxyParameter[] oaParams = getOnlineApplicationParameters();
  	for (int i = 0; i < oaParams.length; i++) {
  		OAProxyParameter oaParam = oaParams[i];
  		if (oaURL.startsWith(oaParam.getPublicURLPrefix()))
  			return oaParam;
  	}
    return null;
  }

}