//   Copyright 2012 Georg-August-Universität Göttingen, Germany
//
//   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 de.ugoe.cs.autoquest.plugin.http;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Collection;
import java.util.LinkedList;
import java.util.List;
import java.util.Properties;
import java.util.logging.Level;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
import javax.xml.soap.MessageFactory;
import javax.xml.soap.SOAPMessage;
import javax.xml.transform.stream.StreamSource;

import org.xml.sax.SAXException;

import de.ugoe.cs.autoquest.eventcore.Event;
import de.ugoe.cs.autoquest.eventcore.IEventType;
import de.ugoe.cs.autoquest.plugin.http.eventcore.HTTPEventType;
import de.ugoe.cs.autoquest.plugin.http.eventcore.HTTPTarget;
import de.ugoe.cs.autoquest.plugin.http.eventcore.SOAPEventType;
import de.ugoe.cs.autoquest.plugin.http.logdata.Content;
import de.ugoe.cs.autoquest.plugin.http.logdata.HttpExchange;
import de.ugoe.cs.autoquest.plugin.http.logdata.Session;
import de.ugoe.cs.util.console.Console;

/**
 * <p>
 * Parser for HTTP Monitor logs. Uses JAXB for parsing and is therefore quite simple. For each
 * exchange in the log, it creates an appropriate event. It differes between default HTTP events
 * and SOAP events.
 * </p>
 * 
 * @author Patrick Harms
 */
public class HTTPLogParser {

    /**
     * <p>
     * the event sequences parsed by this parser
     * </p>
     */
    private Collection<List<Event>> sequences = new LinkedList<List<Event>>();
    
    /**
     * <p>
     * the message factory used for parsing SOAP messages
     * </p>
     */
    private MessageFactory soapMessageFactory;
    
    /**
     * <p>
     * properties used to map the path of a service to its logical name
     * </p>
     */
    private Properties urlNameMap = null;
    
    /**
     * <p>
     * Constructor. Creates a new HTTPLogParser without a urlNameMap. 
     * </p>
     */
    public HTTPLogParser() {
        
    }
    
    /**
     * <p>
     * Constructor. Creates a new HTTPLogParser with a urlNameMap
     * </p>
     *
     * @param urlNameMapFile properties file with the path to logical name map
     * @throws IOException thrown if there is an error load in the service name map
     */
    public HTTPLogParser(File urlNameMapFile) throws IOException {
        this(new FileInputStream(urlNameMapFile));
    }
    
    /**
     * <p>
     * Constructor. Creates a new HTTPLogParser with a urlNameMap
     * </p>
     *
     * @param urlNameMapFile properties file with the path to logical name map
     * @throws IOException thrown if there is an error load in the service name map
     */
    public HTTPLogParser(InputStream urlNameMapStream) throws IOException {
        this();
        urlNameMap = new Properties();
        urlNameMap.load(urlNameMapStream);
    }

    /**
     * <p>
     * Parses a log file written by the HTTPMonitor and creates a collection of event sequences.
     * </p>
     * 
     * @param filename
     *            name and path of the log file
     *
     * @throws SAXException in the case, the file could not be parsed
     */
    public void parseFile(String filename) throws JAXBException {
        if (filename == null) {
            throw new IllegalArgumentException("filename must not be null");
        }

        parseFile(new File(filename));
    }

    /**
     * <p>
     * Parses a log file written by the HTTPMonitor and creates a collection of event sequences.
     * </p>
     * 
     * @param file
     *            file to be parsed
     *
     * @throws SAXException in the case, the file could not be parsed
     */
    public void parseFile(File file) throws JAXBException {
        if (file == null) {
            throw new IllegalArgumentException("file must not be null");
        }
        
        try {
            parseFile(new FileInputStream(file));
        }
        catch (FileNotFoundException e) {
            Console.printerr("Error parsing file + " + file.getName());
            Console.logException(e);
            return;
        }
    }
    
    /**
     * <p>
     * Parses a log file written by the HTTPMonitor and creates a collection of event sequences.
     * </p>
     * 
     * @param stream
     *            file to be parsed
     *
     * @throws SAXException in the case, the file could not be parsed
     */
    public void parseFile(InputStream stream) throws JAXBException {
        if (stream == null) {
            throw new IllegalArgumentException("stream must not be null");
        }
        
        JAXBContext jc = JAXBContext.newInstance(Session.class.getPackage().getName());
        
        Unmarshaller unmarshaller = jc.createUnmarshaller();
        StreamSource source = new StreamSource(stream);
        
        @SuppressWarnings("unchecked")
        JAXBElement<Session> sessionObj = (JAXBElement<Session>) unmarshaller.unmarshal(source);
        
        Session session = sessionObj.getValue();

        if ((session.getHttpExchange() != null) && (session.getHttpExchange().size() > 0)) {
            List<Event> sequence = new LinkedList<Event>();
            for (HttpExchange exchange : session.getHttpExchange()) {
                sequence.add(new Event(createEvent(exchange),
                                       new HTTPTarget(exchange.getReceiver())));
            }
            sequences.add(sequence);
        }
        
    }

    /**
     * <p>
     * instantiates the appropriate event type. If it encounters a SOAP exchange, a SOAP event type
     * is instantiated. Otherwise a normal HTTP event type is created.
     * </p>
     *
     * @param exchange the exchange for which an event type is to be created
     * 
     * @return as described
     */
    private IEventType createEvent(HttpExchange exchange) {
        Content requestContent =
            exchange.getRequest() != null ? exchange.getRequest().getContent() : null;
        
        SOAPMessage soapRequest = getSOAPMessage(requestContent);
        
        Content responseContent =
            exchange.getResponse() != null ? exchange.getResponse().getContent() : null;
            
        SOAPMessage soapResponse = getSOAPMessage(responseContent);
        
        if (soapRequest != null) {
            return new SOAPEventType(exchange, soapRequest, soapResponse, urlNameMap);
        }
        else {
            return new HTTPEventType(exchange);
        }
    }

    /**
     * <p>
     * convenience method to convert the content of an HTTP request or response into a SOAP message
     * </p>
     *
     * @param content the content to be converted into a SOAP message
     * 
     * @return the SOAP message contained in the content or null if either the content is null or
     *         the content does not contain a SOAP message
     */
    private SOAPMessage getSOAPMessage(Content content) {
        if ((content != null) && (content.getData() != null)) {
            try {
                if (soapMessageFactory == null) {
                    soapMessageFactory = MessageFactory.newInstance();
                }
            
                String encoding = content.getEncoding();
                if (encoding == null) {
                    encoding = "UTF-8";
                }
                
                InputStream in = new ByteArrayInputStream(content.getData().getBytes(encoding));
                SOAPMessage message = soapMessageFactory.createMessage(null, in);
                
                // try to access something to see, if everything worked fine.
                message.getSOAPHeader();
                message.getSOAPBody();
                
                return message;
            }
            catch (Exception e) {
                if (content.getData().toLowerCase().indexOf("envelope") > 0) {
                    Console.traceln(Level.WARNING, "HTTP message seems to be a SOAP message but " +
                                    "it could not be parsed as such: " + e);
                    //Console.logException(e);
                }
            }
        }
        
        return null;
    }

    /**
     * <p>
     * returns the sequences parsed by this parser
     * </p>
     * 
     * @return as described
     */
    public Collection<List<Event>> getSequences() {
        return sequences;
    }
}
