/*   
 *  Copyright 1999-2004 The Apache Sofware Foundation.
 *
 *  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.apache.tomcat.modules.loggers;


import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;

import org.apache.tomcat.core.BaseInterceptor;
import org.apache.tomcat.core.ContextManager;
import org.apache.tomcat.core.Request;
import org.apache.tomcat.core.Response;
import org.apache.tomcat.core.TomcatException;


/** 
This is a TomCat RequestInterceptor that creates log files
 * in the style of the Apache servers "AccessLog". It used by
 * embedding a line like the following into server.xml:
 * 
 *   <RequestInterceptor
 *     className="org.apache.tomcat.logging.AccessLogInterceptor"
 *     logFile="logs/AccessLog" format="combined"/>
 * 
 * 
Possible attributes of the above XML element are:
 * 
 *   
 *     
 *     
 *   
 *   
 *     
 *     
 *   
 *   
 *     
 *     
 *    
 * 
logFile
Name of the logfile being generated. Defaults to "logs/AccessLog".
 *       Tomcat.home is prepended, if the file name is relative.
flush
An optional boolean attribute, that enables (value = "true")
 *       or disables (value="false", default) flushing the log file
 *       after every request. For performance reasons, you should
 *       not enable flushing unless you are debugging this class.
 *     
format

 *       A string describing the logfile format. Possible values are
 *       "combined" (Apache httpd combined format, default), "common"
 *       (Apache httpd common format) or a format string like
 *       
 *         '%h %l %u %t "%r" %>s %b "%{Referer}" "%{User-Agent}"'
 *         '%h %l %u %t "%r" %>s %b'
 *       
 *       (The above examples are used when "combined" or "common"
 *       format is requested.) Possible patterns are:
 *       
 *         
 *           
 *         
 *         
 *           
 *           
 *         
 *           
 *           
 *         
 *         
 *           
 *           
 *         
 *         
 *           
 *           
 *         
 *         
 *           
 *           
 *         
 *         
 *           
 *           
 *         
 *         
 *           
 *           
 *         
 *         
 *           
 *           
 *         
 *         
 *           
 *           .
 *         
 *         
 *       
%%
The percent character itself
%{var}
The value of request.getHeader("var") or
 *             empty string for null.

 *         
%b
The value of response.getContentLength().
%h
The value of request.getRemoteHost().
%l
Should be the remote users name, as indicated by an
 *             identd lookup. Currently it is always "-".
%r
First line of the request submitted by the client, for
 *             example
 *             
 *               GET /index.html?frame=main HTTP/1.0
 *             
 *             The first line is rebuilt from the values of
 *             request.getMethod(),
 *             request.getRequestURI(),
 *             request.getQueryString() and
 *             request.getProtocol(). It should probably
 *             better be recorded while reading the headers.
 *           
%s
The value of response.getStatus().
%>s
The value of response.getStatus().
 *             Should differ between different internal requests, as
 *             Apache httpd does, but this is currently not supported.
%t
The current time and date in the format
 *             
 *               [20/Apr/2001:19:45:23 0200]
 *             
 *           
%u
The value of request.getRemoteUser() or
 *             "-" for null.

 *     
 * 
 *
 * @author  Jochen Wiedmann, jochen.wiedmann@softwareag.com
 */
public class AccessLogInterceptor extends BaseInterceptor {
    private static final String LOGFORMAT_COMBINED = "%h %l %u %t \"%r\" %>s %b \"%{Referer}\" \"%{User-Agent}\"";
    private static final String LOGFORMAT_COMMON = "%h %l %u %t \"%r\" %>s %b";
    private static FileWriter fw = null;
    private static String fileName = "logs/AccessLog";
    private static boolean useFlush = false;
    private static String logformat = LOGFORMAT_COMBINED;
    private static DateFormat df = new SimpleDateFormat("dd/MMM/yyyy:HH:mm:ss");
    private static String crlf = System.getProperty("line.separator");
    
    /** Creates a new AccessLogInterceptor */
    public AccessLogInterceptor() {}
    
    /** 
Sets the logfile name.
     */
    public static void setLogFile(String logFile) {
	synchronized (AccessLogInterceptor.class) {
	    fileName = logFile;
	}
    }
    
    /** 
Enables (true) or disables (false, default) flushing
     * the log file after any request.
     */
    public static void setFlush(boolean flush) {
	synchronized (AccessLogInterceptor.class) {
	    useFlush = flush;
	}
    }
    
    /** 
Sets the logfile format.
     */
    public static void setFormat(String format) {
	synchronized (AccessLogInterceptor.class) {
	    if (format.equalsIgnoreCase("combined")) {
		logformat = LOGFORMAT_COMBINED;
	    } else if (format.equalsIgnoreCase("common")) {
		logformat = LOGFORMAT_COMMON;
	    } else {
		logformat = format;
	    }
	}
    }
    
    /** 
This method must be called while
     * synchronizing on AccessLogIntercepror.class!
     */
    private FileWriter getFileWriter() {
	if (fw != null) {
	    return fw;
	}
	if (fileName != null) {
	    try {
		File f = new File(fileName);
		if (!f.isAbsolute()) {
		    f=new File( cm.getHome());
		    f=new File( f, fileName );
		    //f = cm.getAbsolute(f);
		}
		fw = new FileWriter(f.getAbsolutePath(), true);
	    } catch (IOException e) {
		e.printStackTrace(System.err);
	    }
	}
	return fw;
    }
    
    /** 
This method is actually creating an entry in the log file.
     */
    public int postRequest(Request request, Response response) {
	synchronized (AccessLogInterceptor.class) {
	    FileWriter fw = getFileWriter();
	    if (fw != null) {
		try {
		    for (int i = 0;  i < logformat.length();  i++) {
			char c = logformat.charAt(i);
			if (c == '%'  &&  ++i < logformat.length()) {
			    c = logformat.charAt(i);
			    switch (c) {
			    case 'h':
				if( request.remoteHost().toString() != null )
				    fw.write(request.remoteHost().toString());
				else
				    fw.write( "DEFAULT" );
				break;
			    case 'l':
				fw.write('-');
				break; // identd not supported
			    case 'u':
				String user = request.getRemoteUser();
				fw.write(user == null ? "-" : user);
				break;
			    case 't':
				Calendar cal =
				    Calendar.getInstance();
				fw.write('[');
				fw.write(df.format(cal.getTime()));
				fw.write(' ');
				long millis =
				    cal.get(Calendar.ZONE_OFFSET) +
				    cal.get(Calendar.DST_OFFSET);
				String msecstr =
				    Long.toString((millis+60*500)/(60*1000));
				for (int j = msecstr.length();  j < 4;  j++) {
				    fw.write('0');
				}
				fw.write(msecstr);
				fw.write(']');
				break;
			    case 'r':
				fw.write(request.method().toString());
				fw.write(' ');
				fw.write(request.requestURI().toString());
				String q = request.queryString().toString();
				if (q != null && q.length() > 0) {
				    fw.write('?');
				    fw.write(q);
				}
				fw.write(' ');
				fw.write(request.protocol().toString().trim());
				break;
			    case 'b':
				String cl;
				if(response.getStatus() == 201) {
				    cl = request.getHeader("Content-Length");
				} else {
				    cl = response.getMimeHeaders().
					getHeader("Content-Length");
				}
				if(cl != null && !"0".equals(cl)) {
				    fw.write(cl);
				} else {
				    fw.write("-");
				}
				break;
			    case 's':
				fw.write(Integer.
					 toString(response.getStatus()));
				break;
			    case '>':
				if (++i < logformat.length()) {
				    c = logformat.charAt(i);
				    if (c == 's') {
					fw.write(Integer.toString(response.getStatus()));
				    } else {
					fw.write('>');
					fw.write(c);
				    }
				} else {
				    fw.write(c);
				}
				break;
			    case '{':
				int offset = logformat.indexOf('}', i);
				if (offset == -1) {
				    fw.write(c);
				} else {
				    String var =
					logformat.substring(i+1, offset);
				    String val = request.getHeader(var);
				    if (val != null) {
					fw.write(val);
				    }
				    i = offset;
				}
				break;
			    default:  fw.write(c); break;
			    } 
			} else {
			    fw.write(c);
			}
		    }
		    fw.write(crlf);
		    if (useFlush) {
			fw.flush();
		    }
		} catch (IOException e) {
		}
	    }
	}
	return 0;
    }

    public void engineShutdown(ContextManager cm) throws TomcatException {
	// From: Mike Schrag  
	try {
	    getFileWriter().flush();
	    getFileWriter().close();
	} catch (IOException e) {
	    e.printStackTrace();
	}
    }
}