/***
   *
   * Copyright 2003-2005 Core Developers Network Ltd.
   *
   *  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.
  */
  
  //this started life as org.mortbay.servlet.ProxyServlet. I copied the
  //whole thing to use as a starting point - Thanks Greg !
  
  // ========================================================================
  // $Id: CommonsHttpProxy.java 1737 2006-04-27 15:13:16 +0100 (Thu, 27 Apr 2006) jules $
  // Copyright 2004-2004 Mort Bay Consulting Pty. Ltd.
  // ------------------------------------------------------------------------
  // 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 org.codehaus.wadi.web.impl;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.net.URI;
  import java.util.Enumeration;
  import java.util.HashMap;
  import java.util.Map;
  
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.apache.commons.httpclient.ConnectMethod;
  import org.apache.commons.httpclient.Cookie;
  import org.apache.commons.httpclient.Header;
  import org.apache.commons.httpclient.HostConfiguration;
  import org.apache.commons.httpclient.HttpClient;
  import org.apache.commons.httpclient.HttpMethod;
  import org.apache.commons.httpclient.HttpState;
  import org.apache.commons.httpclient.methods.DeleteMethod;
  import org.apache.commons.httpclient.methods.EntityEnclosingMethod;
  import org.apache.commons.httpclient.methods.GetMethod;
  import org.apache.commons.httpclient.methods.HeadMethod;
  import org.apache.commons.httpclient.methods.MultipartPostMethod;
  import org.apache.commons.httpclient.methods.OptionsMethod;
  import org.apache.commons.httpclient.methods.PutMethod;
  import org.apache.commons.httpclient.methods.TraceMethod;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  //This does not seem as performant as the StandardHttpProxy - it also seems to be able to crash Firefox reproducibly !
  //commons-httpclient does not [seem to] allow us to pass Cookie headers straight through. So, we have
  //to deal with them explicitly - This leaves scope for cookie mutation as request passes through proxy - Bad news.
  
  //I've tried moving up to 3.0rc1, but ProxyServlet with this HttpProxy produces wierd browser effects...
  
  /***
   * HttpProxy implementation based on commons-httpclient
   *
   * @author <a href="mailto:jules@coredevelopers.net">Jules Gosnell</a>
   * @author <a href="mailto:gregw@mortbay.com">Greg Wilkins</a>
   * @version $Revision: 1737 $
   */
  public class CommonsHttpProxy extends AbstractHttpProxy {
  	
  	protected static final Log _log=LogFactory.getLog(CommonsHttpProxy.class);
  	
  	protected static final Map _methods=new HashMap();
  	static {
  		_methods.put("CONNECT",ConnectMethod.class);
  		_methods.put("DELETE",DeleteMethod.class);
  		_methods.put("GET", GetMethod.class);
  		_methods.put("HEAD",HeadMethod.class);
  		_methods.put("OPTIONS",OptionsMethod.class);
  		_methods.put("TRACE",TraceMethod.class);
  		_methods.put("POST",MultipartPostMethod.class);
  		_methods.put("PUT",PutMethod.class);
  		// WebDav methods ? e.g. PROCFIND ?
  	}
  	
  	public CommonsHttpProxy(String sessionPathParamKey) {
  		super(sessionPathParamKey);
  	}
 	
     protected void doProxy(URI uri, WebInvocation context) throws ProxyingException {
 		HttpServletRequest hreq = context.getHreq();
 		HttpServletResponse hres = context.getHres();
 		
 		long startTime=System.currentTimeMillis();
 		
 		String m=hreq.getMethod();
 		Class clazz=(Class)_methods.get(m);
 		if (clazz==null) {
 			throw new IrrecoverableException("unsupported http method: "+m);
 		}
 		
 		HttpMethod hm=null;
 		try {
 			hm=(HttpMethod)clazz.newInstance();
 		} catch (Exception e) {
 			throw new IrrecoverableException("could not create HttpMethod instance", e); // should never happen
 		}
 		
 		String requestURI = getRequestURI(hreq);
 		hm.setPath(requestURI);
 		
 		String queryString=hreq.getQueryString();
 		if (queryString!=null) {
 			hm.setQueryString(queryString);
             requestURI += queryString;
 		}
 		
 		hm.setFollowRedirects(false);
 		//hm.setURI(new URI(uri));
 		hm.setStrictMode(false);
 		
 		// check connection header
 		String connectionHdr = hreq.getHeader("Connection"); // TODO - what if there are multiple values ?
 		if (connectionHdr != null) {
 			connectionHdr = connectionHdr.toLowerCase();
 			if (connectionHdr.equals("keep-alive")|| connectionHdr.equals("close"))
 				connectionHdr = null; // TODO  ??
 		}
 		
 		// copy headers
 		boolean xForwardedFor = false;
 		boolean hasContent = false;
 		int contentLength=0;
 		Enumeration enm = hreq.getHeaderNames();
 		while (enm.hasMoreElements()) {
 			// TODO could be better than this! - using javax.servlet ?
 			String hdr = (String) enm.nextElement();
 			String lhdr = hdr.toLowerCase();
 			
 			if (_DontProxyHeaders.contains(lhdr))
 				continue;
 			if (connectionHdr != null && connectionHdr.indexOf(lhdr) >= 0)
 				continue;
 			
 			if ("content-length".equals(lhdr)) {
 				try {
 					contentLength=hreq.getIntHeader(hdr);
 					hasContent=contentLength>0;
 				} catch (NumberFormatException e) {
 					if (_log.isWarnEnabled()) _log.warn("bad Content-Length header value: "+hreq.getHeader(hdr), e);
 				}
 			}
 			
 			if ("content-type".equals(lhdr)) {
 				hasContent=true;
 			}
 			
 			Enumeration vals = hreq.getHeaders(hdr);
 			while (vals.hasMoreElements()) {
 				String val = (String) vals.nextElement();
 				if (val != null) {
 					hm.addRequestHeader(hdr, val);
 					// if (_log.isInfoEnabled()) _log.info("Request " + hdr + ": " + val);
 					xForwardedFor |= "X-Forwarded-For".equalsIgnoreCase(hdr); // why is this not in the outer loop ?
 				}
 			}
 		}
 		
 		// cookies...
 		
 		// although we copy cookie headers into the request abover - commons-httpclient thinks it knows better and strips them out before sending.
 		// we have to explicitly use their interface to add the cookies - painful...
 		
 		// DOH! - an org.apache.commons.httpclient.Cookie is NOT a
 		// javax.servlet.http.Cookie - and it looks like the two don't
 		// map onto each other without data loss...
 		HttpState state=new HttpState();
 		javax.servlet.http.Cookie[] cookies=hreq.getCookies();
 		if (cookies!=null)
 		{
 			for (int i=0;i<cookies.length;i++)
 			{
 				javax.servlet.http.Cookie c=cookies[i];
 				String domain=c.getDomain();
 				if (domain==null) {
 					domain=hreq.getServerName(); // TODO - tmp test
 					// _log.warn("defaulting cookie domain");
 				}
 				//	  domain=null;
 				String cpath=c.getPath();
 				if (cpath==null) {
 					cpath=hreq.getContextPath(); // fix for Jetty
 					// _log.warn("defaulting cookie path");
 				}
 				//if (_log.isTraceEnabled()) _log.trace("PATH: value="+path+" length="+(path==null?0:path.length()));
 				Cookie cookie=new Cookie(domain, c.getName(), c.getValue(), cpath, c.getMaxAge(), c.getSecure()); // TODO - sort out domain
 				//if (_log.isTraceEnabled()) _log.trace("Cookie: "+cookie.getDomain()+","+ cookie.getName()+","+ cookie.getValue()+","+ cookie.getPath()+","+ cookie.getExpiryDate()+","+ cookie.getSecure());
 				state.addCookie(cookie);
 				//if (_log.isTraceEnabled()) _log.trace("Cookie: "+cookie.toString());
 			}
 		}
 		
 		// Proxy headers
 		hm.addRequestHeader("Via", "1.1 "+hreq.getLocalName()+":"+hreq.getLocalPort()+" \"WADI\"");
 		if (!xForwardedFor)
 			hm.addRequestHeader("X-Forwarded-For", hreq.getRemoteAddr());
 		// Max-Forwards...
 		
 		// a little bit of cache control
 //		String cache_control = hreq.getHeader("Cache-Control");
 //		if (cache_control != null && (cache_control.indexOf("no-cache") >= 0 || cache_control.indexOf("no-store") >= 0))
 //		httpMethod.setUseCaches(false);
 		
 		// customize Connection
 //		uc.setDoInput(true);
 		
 		int client2ServerTotal=0;
 		if (hasContent) {
 //			uc.setDoOutput(true);
 			
 			try {
 				if (hm instanceof EntityEnclosingMethod)
 					((EntityEnclosingMethod)hm).setRequestBody(hreq.getInputStream());
 				// TODO - do we need to close response stream at end... ?
 			} catch (IOException e) {
 				throw new IrrecoverableException("could not pss request input across proxy", e);
 			}
 		}
 		
 		try
 		{
 			HttpClient client=new HttpClient();
 			HostConfiguration hc=new HostConfiguration();
 			//String host=location.getAddress().getHostAddress();
 			// inefficient - but stops httpclient from rejecting half our cookies...
 			String host= uri.getHost();
 			hc.setHost(host, uri.getPort());
 			client.executeMethod(hc, hm, state);
 		}
 		catch (IOException e)	// TODO
 		{
 			_log.warn("problem proxying connection:", e);
 		}
 		
 		InputStream fromServer = null;
 		
 		// handler status codes etc.
 		int code=502;
 //		String message="Bad Gateway: could not read server response code or message";
 		
 		code=hm.getStatusCode(); // IOException
 //		message=hm.getStatusText(); // IOException
 		hres.setStatus(code);
 //		hres.setStatus(code, message); - deprecated...
 		
 		try {
 			fromServer=hm.getResponseBodyAsStream(); // IOException
 		} catch (IOException e) {
 			_log.warn("problem acquiring http client output", e);
 		}
 		
 		
 		// clear response defaults.
 		hres.setHeader("Date", null);
 		hres.setHeader("Server", null);
 		
 		// set response headers
 		// TODO - is it a bug in Jetty that I have to start my loop at 1 ? or that key[0]==null ?
 		// Try this inside Tomcat...
 		Header[] headers=hm.getResponseHeaders();
 		for (int i=0; i<headers.length; i++) {
 			String h=headers[i].toExternalForm();
 			int index=h.indexOf(':');
 			String key=h.substring(0, index).trim().toLowerCase();
 			String val=h.substring(index+1, h.length()).trim();
 			if (val!=null && !_DontProxyHeaders.contains(key)) {
 				hres.addHeader(key, val);
 				// if (_log.isInfoEnabled()) _log.info("Response: "+key+" - "+val);
 			}
 		}
 		
 		hres.addHeader("Via", "1.1 (WADI)");
 		
 		// copy server->client
 		int server2ClientTotal=0;
 		if (fromServer!=null) {
 			try {
 				OutputStream toClient=hres.getOutputStream();// IOException
 				server2ClientTotal+=copy(fromServer, toClient, 8192);// IOException
 			} catch (IOException e) {
 				_log.warn("problem proxying server response back to client", e);
 			} finally {
 				try {
 					fromServer.close();
 				} catch (IOException e) {
 					// well - we did our best...
 					_log.warn("problem closing server response stream", e);
 				}
 			}
 		}
 		
 		long endTime=System.currentTimeMillis();
 		long elapsed=endTime-startTime;
 		if (_log.isDebugEnabled()) {
             _log.debug("in:" + client2ServerTotal + ", out:" + server2ClientTotal + ", status:" + code + ", time:"
                     + elapsed + ", uri:" + uri);
         }
 	}
 }