/*
* Copyright 2003 Federal Chancellery Austria
*
* 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.egovernment.moa.id.proxy;

import java.io.IOException;
import java.net.URL;
import java.net.URLStreamHandler;
import java.util.Iterator;
import java.util.Vector;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSocketFactory;
import javax.servlet.http.HttpServletRequest;

import HTTPClient.HTTPConnection;
import HTTPClient.HttpURLConnection;
import at.gv.egovernment.moa.id.config.ConfigurationException;
import at.gv.egovernment.moa.id.config.proxy.ProxyConfigurationProvider;
import at.gv.egovernment.moa.id.util.MOAIDMessageProvider;
import at.gv.egovernment.moa.logging.Logger;
import at.gv.egovernment.moa.util.BoolUtils;


/**
 * Outlook Web Access (OWA) Implementierung von <code>ConnectionBuilder</code>.
 * uses the HTTP(s)Client from Ronald Tschalär.
 * origin version (without https support) is available at http://www.innovation.ch/java/HTTPClient/
 * 
 * @author pdanner
 */
public class EnhancedConnectionBuilder implements ConnectionBuilder {
	  
	  /** a boolean to disable the HostnameVerification (default = false)*/
	  private static boolean cbDisableHostnameVerification = false;
	  /** Name of the Parameter for the Target */
	  private static final String PARAM_TARGET = "Target";
	  /** Name of the Parameter for the SAMLArtifact */  
	  private static final String PARAM_SAMLARTIFACT = "SAMLArtifact";
	  /** Name of the Attribute for marking the session as authenticated*/  
	  private static final String ATT_AUTHDATAFETCHED = "AuthDataFetched";

	  static {
	    HTTPConnection.setDefaultTimeout(0);
	    try {
	      HTTPConnection.removeDefaultModule(Class.forName("HTTPClient.AuthorizationModule"));
	      HTTPConnection.removeDefaultModule(Class.forName("HTTPClient.RedirectionModule"));
	      HTTPConnection.removeDefaultModule(Class.forName("HTTPClient.CookieModule"));
	      //HTTPConnection.removeDefaultModule(Class.forName("HTTPClient.RetryModule"));
	    } catch (ClassNotFoundException e) {
	    	
	    }
	  }
	  
	  /**
	   * Constructor for OWAConnectionBuilder.
	   * @throws ConfigurationException on any config error
	   */
	  public EnhancedConnectionBuilder() throws ConfigurationException {
	    cbDisableHostnameVerification = BoolUtils.valueOf(
	      ProxyConfigurationProvider.getInstance().getGenericConfigurationParameter(
	        "ProxyComponent.DisableHostnameVerification"));
	    //TODO MOA-ID BRZ undocumented feature
	    if (cbDisableHostnameVerification)
	      Logger.warn("ProxyComponent.DisableHostnameVerification: " + cbDisableHostnameVerification);
	  }

	  /**
	   * @see at.gv.egovernment.moa.id.proxy.ConnectionBuilder#buildConnection
	   */
	  public java.net.HttpURLConnection buildConnection(HttpServletRequest req, String publicURLPrefix, String realURLPrefix, SSLSocketFactory sslSocketFactory, Vector parameters) throws IOException {

	    String requestedURL = req.getRequestURL().toString();
	    // check whether requested URL starts with publicURLPrefix
	    
	    if (! requestedURL.startsWith(publicURLPrefix.substring(0,5)))
	      throw new IOException(MOAIDMessageProvider.getInstance().getMessage(
	        "proxy.01", new Object[] {requestedURL, publicURLPrefix}));

	    String query = req.getQueryString();
    	if (req.getSession().getAttribute(ATT_AUTHDATAFETCHED)!=null) {
  	      query = removeParameter(query, PARAM_SAMLARTIFACT);
	      query = removeParameter(query, PARAM_TARGET);
	      req.getSession().removeAttribute(ATT_AUTHDATAFETCHED);
    	}
	    if (null != query && 0 != query.length() ) {
    	  requestedURL = requestedURL + "?" + query;

	      String parameter[] = new String[2];  
	      for (Iterator iter = parameters.iterator(); iter.hasNext();) {
  	        parameter = (String[]) iter.next();   	
	        if(query.indexOf(parameter[0]) >= 0) iter.remove();
	      }
	    }
	    
	    // build real URL in online application
	    String realURLString = realURLPrefix + requestedURL.substring(publicURLPrefix.length());

	    // build real URL in online application
        URLStreamHandler urlStreamHandler = null;
        
	    //URL url = new URL(realURLString);
        if (realURLString.startsWith("https")) {
        	urlStreamHandler = new HTTPClient.https.Handler();
        } else{
        	urlStreamHandler = new HTTPClient.http.Handler();
        }
        URL url = new URL(null, realURLString, urlStreamHandler);
	    Logger.debug("OA Request: " + req.getMethod() + " " + url.toString());

	    HttpURLConnection conn = (HttpURLConnection)url.openConnection();
	    
	    conn.setRequestMethod(req.getMethod());
	    conn.setDoInput(true);
	    conn.setDoOutput(true);
	    //conn.setUseCaches(false);
	    //conn.setAllowUserInteraction(true);
	    conn.setInstanceFollowRedirects(false);

	    if (realURLString.startsWith("https") && sslSocketFactory != null) {
	    	conn.setSSLSocketFactory(sslSocketFactory);
	    	//Not available in HTTPClient
	    	//if (cbDisableHostnameVerification)
	        //    conn.setHostnameVerifier(new HostnameNonVerifier());
	    }
	    
	   return conn;
	    
	  }
	  
	  /**
	   * Disconnects the HttpURLConnection if necessary.
	   * The implementation of the Connectionbuilder decides wether 
	   * if this should be happen or not.
	   *
	   * @param conn the HttpURLConnection which is normaly to be closed
	   */	  
	  public void disconnect(java.net.HttpURLConnection conn) {
	  	// In HTTPClient there must not be an diconnect!
	  	// conn.disconnect();
	  }
		  
	  /**
	     * @author Stefan Knirsch
	     * @version $Id$
	     * A private class to change the standard HostName verifier to disable the
	     * Hostname Verification Check
	     */
	// JSSE Abhängigkeit
	  private class HostnameNonVerifier implements HostnameVerifier {
	    
	    
	      public boolean verify(String hostname, SSLSession session) {
	         return true;
	      }

	     /**
	        * @see com.sun.net.ssl.HostnameVerifier#verify(String, String)
	        */
//	     public boolean verify(String arg0, String arg1) {
//	      return true;
//	    }

	  }
	  
	  /**
	   * Removes parameters from the query-URL recursively
	   *
	   * @param query the query from which the parameter is to be removed
	   * @param parameter the parameter to be removed
	   * @return the parameterclean query
	   */	  
	  private String removeParameter(String query, String parameter) {
		  return removeParameter(query, parameter, true);
	  }

	  /**
	   * Removes one parameter from the query-URL recursively
	   *
	   * @param query the query from which the parameter is to be removed
	   * @param parameter the parameter to be removed
	   * @param remove. Boolean value wether a parameter was removed in last call or not. In initial call set to true to check for new occurrences
	   * @return the parameterclean query
	   */	  
	  private String removeParameter(String query, String parameter, boolean remove) {
		  String result = query;
		  if (remove && query!=null && !query.equals("") && parameter!=null && !parameter.equals("")) {
			  String param = parameter;
			  int capEnd=0;
			  if (!param.endsWith("=")) param=param+"=";
			  if (query.startsWith(param)) {
				  //remove leading
				  result="";
			  } else { 
				  if (!param.startsWith("&")) param="&"+param;
				  capEnd = query.indexOf(param);
				  if (capEnd!=-1) {
					  //leading part
				      result=query.substring(0, capEnd);
				  }
			  }
			  if (capEnd!=-1) {
				  //trailing part
				  capEnd += param.length();
				  int capBegin = -1;
				  if (capEnd <query.length()) capBegin = query.indexOf("&", capEnd);
				  if (capBegin!=-1) {
					  if (capBegin<query.length()) {
						  result=result + query.substring(capBegin);
						  if (result.startsWith("&")) result = result.substring(1); //if now is leading part
					  }
				  }
		      }
			  result = removeParameter(result, parameter, !query.equals(result));
		  }  
		  return result;
	  }

	}