#!/usr/bin/env python
# -*- coding: utf-8 -*-

#
# Copyright 2016 Grégory Soutadé
#
# This file is part of iptogeo.
#
# iptogeo is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# iptogeo 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with iptogeo.  If not, see <http://www.gnu.org/licenses/>.
#

import socket
import struct

class IPToGeoException(Exception):
    pass

class IPToGeo(object):

    MAGIC = 0x179E08EF
    VERSION = 1
    REQ = 1
    RESP = 0
    IPV4 = 4
    IPV6 = 16

    IP_NOT_FOUND = 6

    PACKET_SIZE = 32
    
    ERRORS = {1 : 'Bad magic',
              2 : 'Bad version',
              3 : 'Bad request field' ,
              4 : 'Bad IP version',
              5 : 'Unsupported IP version',
              6 : 'IP not found'}

    MAX_REQUESTS = 50

    def __init__(self, remote_addr='127.0.0.1', remote_port=53333, timeout=None, family=socket.AF_INET):
        self._remote_addr = remote_addr
        self._remote_port = remote_port
        self._timeout = timeout
        self._family = family
        self._nb_requests_sent = self.MAX_REQUESTS # Force socket creation
        self._socket = None

    def _create_socket(self):
        if self._socket:
            self._socket.close()
        self._socket = socket.socket(self._family, socket.SOCK_STREAM)
        if not self._timeout is None:
            self._socket.settimeout(self._timeout)
        self._socket.connect((self._remote_addr, self._remote_port))

    def _extend_ipv6(self, ipv6):
        tmp = ''
        for s in ipv6.split(':'):
            if not s: break
            while len(s) != 4:
                s = '0' + s
            tmp += s
        while len(tmp) < 16*2:
            tmp += '0'
        res = ''
        for i in range(0, 15*2, 2):
            res += tmp[i] + tmp[i+1] + ':'
        res += tmp[30] + tmp[31]

        return res

    def _create_request(self, ip, ip_type):
        packet = b''
        packet += struct.pack('<IBBBBI', IPToGeo.MAGIC, IPToGeo.VERSION, IPToGeo.REQ,
                              0, #err
                              ip_type, # ip type
                              0) # flags
        for i in ip:
            packet += struct.pack('<B', i) # ipv4
        packet += struct.pack('<III', 0, 0, 0) # ipv6
        packet += struct.pack('<I', 0) # country code

        return packet

    def _check_request(self, packet):
        (magic, version, req, err, ip_type, flags, ipv4, ipv6b, ipv6c, ipv6d) = struct.unpack_from('<IBBBBIIIII', packet, 0)

        if magic != IPToGeo.MAGIC:
            raise IPToGeoException('Invalid magic %08x' % (magic))
        
        ip_res = '%08x' % (ipv4)
        if ip_type == IPToGeo.IPV6:
            ip_res += '%08x' % (ipv6b)
            ip_res += '%08x' % (ipv6c)
            ip_res += '%08x' % (ipv6d)

        if err == IPToGeo.IP_NOT_FOUND: return (ip_res, None) # IP not found
        if err != 0:
            raise IPToGeoException(IPToGeo.ERRORS[err])

        (cc0, cc1, cc2, cc3) = struct.unpack_from('BBBB', packet, 7*4)

        return (ip_res, '%c%c%c%c' % (cc0, cc1, cc2, cc3))

    def _send_request(self, packet, second_chance=True):
        self._nb_requests_sent += 1
        if self._nb_requests_sent >= self.MAX_REQUESTS:
            self._create_socket()
            self._nb_requests_sent = 0
        try:
            self._socket.send(packet)
            packet = self._socket.recv(IPToGeo.PACKET_SIZE)
            if not packet:
                raise socket.timeout
            return packet
        except socket.timeout as e:
            if second_chance:
                self._nb_requests_sent = self.MAX_REQUESTS
                return self._send_request(packet, False)
            else:
                raise e
            
    def ip_to_geo(self, ip):
        ip_type = IPToGeo.IPV4
        if ip.find('.') >= 0:
            splitted_ip = [int(a) for a in ip.split('.')]
            if len(splitted_ip) != 4:
                raise Exception('Bad IP %s' % (ip))
        elif ip.find(':') >= 0:
            splitted_ip = [int(a, 16) for a in self._extend_ipv6(ip).split(':')]
            if len(splitted_ip) != 16:
                raise Exception('Bad IP %s' % (ip))
            ip_type = IPToGeo.IPV6
        else:
            raise Exception('Bad IP %s' % (ip))

        packet = self._create_request(splitted_ip, ip_type)
        packet = self._send_request(packet)
        (ip, country_code) = self._check_request(packet)
        if country_code:
            # convert to string
            country_code = '%c%c' % (country_code[0], country_code[1])
        return (ip, country_code)

    def close(self):
        self._socket.close()