/*
 * Copyright (C) 2021 Christian Pierre MOMON <christian@momon.org>
 * 
 * This file is part of Logar, simple tool to manage http log files.
 * 
 * Logar is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * Logar is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with Logar.  If not, see <http://www.gnu.org/licenses/>.
 */
package fr.devinsy.logar.app.anonymizer;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.time.format.DateTimeParseException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.zip.GZIPOutputStream;

import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.april.logar.util.LineIterator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import fr.devinsy.logar.app.log.Log;
import fr.devinsy.logar.app.log.LogParser;

/**
 * The Class Anonymizer.
 */
/**
 * @author cpm
 *
 */
public final class Anonymizer
{
    private static Logger logger = LoggerFactory.getLogger(Anonymizer.class);

    public static final Pattern IPV4_PATTERN = Pattern.compile("\\d{0,3}\\.\\d{0,3}\\.\\d{0,3}\\.\\d{0,3}");
    public static final Pattern IPV6_PATTERN = Pattern.compile("([0-9a-f]{1,4}:{1,2}){4,7}([0-9a-f]){1,4}", Pattern.CASE_INSENSITIVE);

    private AnonMap map;

    /**
     * Instantiates a new anonymizer.
     */
    public Anonymizer()
    {
        this.map = new AnonMap();
    }

    /**
     * Anonymize.
     *
     * @param source
     *            the source
     */
    public void anonymize(final File source)
    {
        if (source == null)
        {
            throw new IllegalArgumentException("Null parameter.");
        }
        else if (!source.isFile())
        {
            throw new IllegalArgumentException("Parameter is not a file.");
        }
        else if (!StringUtils.containsAny(source.getName(), "access", "error"))
        {
            throw new IllegalArgumentException("File name does not contain 'access' or 'error'.");
        }
        else
        {
            System.out.println("== Anonymize log for [" + source.getName() + "]");
            boolean isAccessFile = source.getName().contains("access");

            File target;
            if (source.getName().endsWith(".log.gz"))
            {
                target = new File(source.getParentFile(), source.getName().replace(".log.gz", "-anon.log.gz"));
            }
            else
            {
                target = new File(source.getParentFile(), source.getName().replace(".log", "-anon.log"));
            }

            PrintWriter out = null;
            try
            {
                LineIterator iterator = new LineIterator(source);
                out = new PrintWriter(new GZIPOutputStream(new FileOutputStream(target)));
                while (iterator.hasNext())
                {
                    String line = iterator.next();

                    try
                    {
                        Log anon;
                        if (isAccessFile)
                        {
                            Log log = LogParser.parseAccessLog(line);
                            // logger.info("line={}", line);
                            // logger.info("log =[{}][{}][{}]", log.getIp(),
                            // log.getUser(), log.getDatetime());

                            anon = anonymizeAccess(log);
                            // logger.info("anon=[{}][{}][{}]", anon.getIp(),
                            // anon.getUser(), anon.getDatetime());
                            // logger.info("anon={}", anon);

                            // Make a check.
                            if (StringUtils.equals(line, anon.getLine()))
                            {
                                System.err.println("Anonymize failed detected: " + line);
                            }
                        }
                        else
                        {
                            Log log = LogParser.parseErrorLog(line);

                            anon = anonymizeError(log);
                        }

                        out.println(anon);
                    }
                    catch (IllegalArgumentException exception)
                    {
                        System.out.println("Bad format line: " + line);
                        exception.printStackTrace();
                    }
                    catch (DateTimeParseException exception)
                    {
                        System.out.println("Bad datetime format: " + line);
                    }
                }
            }
            catch (IOException exception)
            {
                System.err.println("Error with file [" + source.getAbsolutePath() + "]");
                exception.printStackTrace();
            }
            finally
            {
                IOUtils.closeQuietly(out);
            }
        }
    }

    /**
     * Anonymize.
     *
     * @param log
     *            the log
     * @return the log
     */
    public Log anonymizeAccess(final Log log)
    {
        Log result;

        //
        String anonIp = this.map.anonymizeIp(log.getIp());
        String line = log.getLine().replace(log.getIp(), anonIp);

        //
        if (!StringUtils.equals(log.getUser(), "-"))
        {
            String anonUser = this.map.anonymizeUser(log.getUser());
            line = line.replaceFirst(" " + log.getUser(), " " + anonUser);
        }

        //
        result = new Log(line, log.getDatetime());

        //
        return result;
    }

    /**
     * Anonymize error.
     *
     * @param log
     *            the log
     * @return the log
     */
    public Log anonymizeError(final Log log)
    {
        Log result;

        // Search and anonymized Ipv4 addresses.
        Matcher matcher = IPV4_PATTERN.matcher(log.getLine());
        String anonLine = log.getLine();
        while (matcher.find())
        {
            String left = anonLine.substring(0, matcher.start());
            String ipv4 = matcher.group();
            String right = anonLine.substring(matcher.end());

            String anonIpv4 = this.map.get(ipv4);
            anonLine = left + anonIpv4 + right;
        }

        // Search and anonymized Ipv4 addresses.
        matcher = IPV6_PATTERN.matcher(anonLine);
        while (matcher.find())
        {
            String left = anonLine.substring(0, matcher.start());
            String ipv6 = matcher.group();
            String right = anonLine.substring(matcher.end());

            String anonIpv6 = this.map.get(ipv6);
            anonLine = left + anonIpv6 + right;
        }

        result = new Log(anonLine, log.getDatetime());

        //
        return result;
    }

    /**
     * Gets the map table.
     *
     * @return the map table
     */
    public AnonMap getMapTable()
    {
        AnonMap result;

        result = this.map;

        //
        return result;
    }

    /**
     * Inits the map.
     *
     * @param source
     *            the source
     */
    public void loadMapTable(final File source)
    {
        if (source != null)
        {
            this.map.addAll(AnonMapFile.load(source));
        }
    }

    /**
     * Save map table.
     *
     * @param target
     *            the target
     */
    public void SaveMapTable(final File target)
    {
        if (target != null)
        {
            AnonMapFile.save(target, this.map);
        }
    }
}