/*******************************************************************************
 * Copyright 2013-2014 alladin-IT GmbH
 * 
 * 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 at.alladin.rmbt.shared;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.Inet6Address;
import java.net.InetAddress;

import com.google.common.net.InetAddresses;
import com.maxmind.geoip.Country;
import com.maxmind.geoip.LookupService;

public abstract class GeoIPHelper
{
    private static volatile LookupService lookupServiceV4;
    private static volatile boolean lookupServiceV4Failure;
    private static volatile LookupService lookupServiceV6;
    private static volatile boolean lookupServiceV6Failure;
    private final static Object LOOKUP_SERVICE_LOCK = new Object(); 
    
    private static LookupService getLookupServiceV4()
    {
        synchronized (LOOKUP_SERVICE_LOCK)
        {
            if (lookupServiceV4Failure)
                return null;
            if (lookupServiceV4 != null)
                return lookupServiceV4;
            try
            {
                return lookupServiceV4 = getLookupService("/usr/share/GeoIP/GeoIP.dat");
            }
            catch (Exception e)
            {
                lookupServiceV4Failure = true;
                return null;
            }
        }
    }
    
    private static LookupService getLookupServiceV6()
    {
        synchronized (LOOKUP_SERVICE_LOCK)
        {
            if (lookupServiceV6Failure)
                return null;
            if (lookupServiceV6 != null)
                return lookupServiceV6;
            try
            {
                return lookupServiceV6 = getLookupService("/usr/share/GeoIP/GeoIPv6.dat");
            }
            catch (Exception e)
            {
                lookupServiceV6Failure = true;
                return null;
            }
        }
    }
    
    private static LookupService getLookupService(String path) throws IOException
    {
        final File file = new File(path);
        if (! (file.exists() && file.isFile() && file.canRead()))
            throw new FileNotFoundException();
        return new LookupService(file);
    }
    
    public static String lookupCountry(final InetAddress adr)
    {
        try
        {
            final Country country;
            if (adr instanceof Inet6Address)
            {
                final LookupService ls = getLookupServiceV6();
                if (ls == null)
                    return null;
                country = ls.getCountryV6(adr);
            }
            else
            {
                final LookupService ls = getLookupServiceV4();
                if (ls == null)
                    return null;
                country = ls.getCountry(adr);
            }
            return country.getCode();
        }
        catch (Throwable t)
        {
            t.printStackTrace();
            return null;
        }
    }
    
    
    //???
    public static void main(String[] args)
    {
        System.out.println(lookupCountry(InetAddresses.forString("2a01:190:1700:39::75")));
        System.out.println(lookupCountry(InetAddresses.forString("78.47.24.204")));
    }
}