"""
All location related functions and converters.

The main entry point is `location_processing`
which gets `location` and `source_ip_address`
and basing on this information generates
precise location description.

"""

import os
import json
import re
import socket
import requests
import geoip2.database

from globals import GEOLITE, GEOLOCATOR_SERVICE, IP2LCACHE, IP2LOCATION_KEY, NOT_FOUND_LOCATION, \
                    ALIASES, BLACKLIST, IATA_CODES_FILE

GEOIP_READER = geoip2.database.Reader(GEOLITE)

def ascii_only(string):
    "Check if `string` contains only ASCII symbols"

    try:
        for _ in range(5):
            string = string.encode('utf-8')
        return True
    except UnicodeDecodeError:
        return False

def is_ip(ip_addr):
    """
    Check if `ip_addr` looks like an IP Address
    """

    if re.match(r'\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}', ip_addr) is None:
        return False
    try:
        socket.inet_aton(ip_addr)
        return True
    except socket.error:
        return False

def location_normalize(location):
    """
    Normalize location name `location`
    """
    #translation_table = dict.fromkeys(map(ord, '!@#$*;'), None)
    def _remove_chars(chars, string):
        return ''.join(x for x in string if x not in chars)

    location = location.lower().replace('_', ' ').replace('+', ' ').strip()
    if not location.startswith('moon@'):
        location = _remove_chars(r'!@#$*;:\\', location)
    return location



def geolocator(location):
    """
    Return a GPS pair for specified `location` or None
    if nothing can't be found
    """

    try:
        geo = requests.get('%s/%s' % (GEOLOCATOR_SERVICE, location)).text
    except requests.exceptions.ConnectionError as exception:
        print "ERROR: %s" % exception
        return None

    if geo == "":
        return None

    try:
        answer = json.loads(geo.encode('utf-8'))
        return answer
    except ValueError as exception:
        print "ERROR: %s" % exception
        return None

    return None

def ip2location(ip_addr):
    "Convert IP address `ip_addr` to a location name"

    cached = os.path.join(IP2LCACHE, ip_addr)
    if not os.path.exists(IP2LCACHE):
        os.makedirs(IP2LCACHE)

    location = None

    if os.path.exists(cached):
        location = open(cached, 'r').read()
    else:
        try:
            ip2location_response = requests\
                    .get('http://api.ip2location.com/?ip=%s&key=%s&package=WS10' \
                            % (ip_addr, IP2LOCATION_KEY)).text
            if ';' in ip2location_response:
                open(cached, 'w').write(ip2location_response)
            location = ip2location_response
        except requests.exceptions.ConnectionError:
            pass

    if ';' in location:
        location = "%s,%s" % (location.split(';')[3], location.split(';')[1])

    return location

def get_location(ip_addr):
    """
    Return location pair (CITY, COUNTRY) for `ip_addr`
    """

    response = GEOIP_READER.city(ip_addr)
    country = response.country.iso_code
    city = response.city.name

    #
    # temporary disabled it because of geoip services capcacity
    #
    #if city is None and response.location:
    #    coord = "%s, %s" % (response.location.latitude, response.location.longitude)
    #    try:
    #        location = geolocator.reverse(coord, language='en')
    #        city = location.raw.get('address', {}).get('city')
    #    except:
    #        pass
    if city is None:
        city = ip2location(ip_addr)
    return (city or NOT_FOUND_LOCATION), country


def location_canonical_name(location):
    "Find canonical name for `location`"

    location = location_normalize(location)
    if location in LOCATION_ALIAS:
        return LOCATION_ALIAS[location.lower()]
    return location

def load_aliases(aliases_filename):
    """
    Load aliases from the aliases file
    """
    aliases_db = {}
    with open(aliases_filename, 'r') as f_aliases:
        for line in f_aliases.readlines():
            from_, to_ = line.decode('utf-8').split(':', 1)
            aliases_db[location_normalize(from_)] = location_normalize(to_)
    return aliases_db

def load_iata_codes(iata_codes_filename):
    """
    Load IATA codes from the IATA codes file
    """
    with open(iata_codes_filename, 'r') as f_iata_codes:
        result = []
        for line in f_iata_codes.readlines():
            result.append(line.strip())
    return set(result)

LOCATION_ALIAS = load_aliases(ALIASES)
LOCATION_BLACK_LIST = [x.strip() for x in open(BLACKLIST, 'r').readlines()]
IATA_CODES = load_iata_codes(IATA_CODES_FILE)

def is_location_blocked(location):
    """
    Return True if this location is blocked
    or False if it is allowed
    """
    return location is not None and location.lower() in LOCATION_BLACK_LIST


def location_processing(location, ip_addr):
    """
    """

    # if location is starting with ~
    # or has non ascii symbols
    # it should be handled like a search term (for geolocator)
    override_location_name = None
    full_address = None

    if location is not None and not ascii_only(location):
        location = "~" + location

    if location is not None and location.upper() in IATA_CODES:
        location = '~%s' % location

    if location is not None and location.startswith('~'):
        geolocation = geolocator(location_canonical_name(location[1:]))
        if geolocation is not None:
            override_location_name = location[1:].replace('+', ' ')
            location = "%s,%s" % (geolocation['latitude'], geolocation['longitude'])
            full_address = geolocation['address']
        else:
            location = NOT_FOUND_LOCATION #location[1:]
    try:
        query_source_location = get_location(ip_addr)
    except:
        query_source_location = NOT_FOUND_LOCATION, None

    country = None
    if location is None or location == 'MyLocation':
        location, country = query_source_location

    if is_ip(location):
        location, country = get_location(location)
    if location.startswith('@'):
        try:
            location, country = get_location(socket.gethostbyname(location[1:]))
        except:
            query_source_location = NOT_FOUND_LOCATION, None

    location = location_canonical_name(location)

    return location, \
            override_location_name, \
            full_address, \
            country, \
            query_source_location