package de.ugoe.cs.eventbench.web;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import de.ugoe.cs.eventbench.web.data.WebEvent;
import de.ugoe.cs.util.FileTools;
import de.ugoe.cs.util.console.Console;

public class WeblogParser {
	
	private long timeout;
	
	private int minLength = 2;
	
	private List<List<WebEvent>> sequences;
	
	private static final String ROBOTFILTERFILE = "misc/robotfilter.txt";
	
	private String robotRegex = ".*";
	
	public WeblogParser() {
		timeout = 3600000; // 1 hour session-timeout as default
	}
	
	public WeblogParser(long timeout) {
		this.timeout = timeout;
	}
	
	public List<List<WebEvent>> getSequences() {
		return sequences; 
	}
	
	public void setTimeout(long timeout) {
		this.timeout = timeout;
	}
	
	public void setMinLength(int minLength) {
		this.minLength = minLength;
	}
	
	public void parseFile(String filename) throws IOException, FileNotFoundException, ParseException {
		String[] lines = FileTools.getLinesFromFile(filename);
		
		Map<String, List<Integer>> cookieSessionMap = new HashMap<String, List<Integer>>();
		int lastId = -1;
		
		SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		loadRobotRegex();
		
		sequences = new ArrayList<List<WebEvent>>();
		
		for( String line : lines ) {
			String[] values = line.substring(1, line.length()-1).split("\" \"");
			
			// use cookie as session identifier
			int cookieStart = values[0].lastIndexOf('.');
			String cookie = values[0].substring(cookieStart+1);
			String dateString = values[1];
			long timestamp = dateFormat.parse(dateString).getTime();
			String uri = values[2];
			// String ref = values[3]; // referer is not yet used!
			String agent = values[4]; // agent is not yet used!
			List<String> postedVars = new ArrayList<String>();
			if( values.length==6 ) { // post vars found
				for( String postVar : values[5].split(" ") ) {
					postedVars.add(postVar);
				}
			}
			if( !isRobot(agent) ) {
				WebEvent event = new WebEvent(uri, timestamp, postedVars);
				
				// find session and add event
				List<Integer> sessionIds = cookieSessionMap.get(cookie);
				if( sessionIds==null ) {
					sessionIds = new ArrayList<Integer>();
					// start new session
					sessionIds.add(++lastId);
					cookieSessionMap.put(cookie, sessionIds);
					sequences.add(new LinkedList<WebEvent>());
				} 
				Integer lastSessionIndex = sessionIds.get(sessionIds.size()-1);
				List<WebEvent> lastSession = sequences.get(lastSessionIndex);
				long lastEventTime = timestamp;
				if( !lastSession.isEmpty() ) {
					lastEventTime = lastSession.get(lastSession.size()-1).getTimestamp();
				}
				if( timestamp-lastEventTime>timeout ) {
					sessionIds.add(++lastId);
					List<WebEvent> newSession = new LinkedList<WebEvent>();
					newSession.add(event);
					sequences.add(newSession);
				} else {
					lastSession.add(event);
				}
			}
		}
		pruneShortSequences();
	}

	private void pruneShortSequences() {
		Console.traceln(""+sequences.size()+ " user sequences found");
		// prune sequences shorter than min-length
		int i=0;
		while( i<sequences.size() ) {
			if( sequences.get(i).size()<minLength ) {
				sequences.remove(i);
			} else {
				i++;
			}
		}
		Console.traceln(""+sequences.size()+ " remaining after pruning of sequences shorter than " + minLength);
	}
	
	private void loadRobotRegex() throws IOException, FileNotFoundException {
		String[] lines = FileTools.getLinesFromFile(ROBOTFILTERFILE);
		StringBuilder regex = new StringBuilder();
		for( int i=0; i<lines.length; i++ ) {
			regex.append("(.*"+lines[i]+".*)");
			if( i!=lines.length-1 ) {
				regex.append("|");
			}
		}
		robotRegex = regex.toString();
	}
	
	private boolean isRobot(String agent) {
		return agent.matches(robotRegex);
	}
}