"""
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.

     [query]      -->   [location]      -->  [(lat,long)] -->
                            ^
                            |
     [ip-address] --> _get_location()

To resolve IP address into location, the module uses function `_get_location()`,
which subsequenlty utilizes one of the three methods:

* `_geoip2()` (local sqlite database);
* `_ip2location()` (an external paid service);
* `_ipinfo()` (an external free service).

IP-address resolution data is saved in cache (_ipcachewrite, _ipcache).
Cache entry format:

    COUNTRY_CODE;COUNTRY;REGION;CITY[;REST]

To resolve location name into a (lat,long) pair,
an external service is used, which is wrapped
with a function `_geolocator()`.

Exports:

    location_processing
    is_location_blocked
"""


from __future__ import print_function

import datetime
import json
import os
import socket
import sys

import geoip2.database
import pycountry
import requests

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


GEOIP_READER = geoip2.database.Reader(GEOLITE)
COUNTRY_MAP = {"Russian Federation": "Russia"}


def _debug_log(s):
    if os.environ.get("WTTR_DEBUG_LOCATION"):
        with open("/tmp/location-debug.log", "a") as f:
            f.write("%s %s\n" % (datetime.datetime.now(),s))


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

    if sys.version_info[0] < 3:
        ip_addr = ip_addr.encode("utf-8")

    try:
        socket.inet_pton(socket.AF_INET, ip_addr)
        return True
    except socket.error:
        try:
            socket.inet_pton(socket.AF_INET6, 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 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 _ipcachewrite(ip_addr, location):
    """ Write a retrieved ip+location into cache
        Can stress some filesystems after long term use, see
        https://stackoverflow.com/questions/466521/how-many-files-can-i-put-in-a-directory

        Expects a location of the form:
            `(city, region, country, country_code, <lat>, <long>)`
        Writes a cache entry of the form:
            `country_code;country;region;city;<lat>;<long>`

        The latitude and longitude are optional elements.
    """
    cachefile = os.path.join(IP2LCACHE, ip_addr)
    if not os.path.exists(IP2LCACHE):
        os.makedirs(IP2LCACHE)
    with open(cachefile, 'w') as file:
        # like ip2location format
        file.write(location[3] + ';' + location[2] + ';' + location[1] + ';' + location[0])
        if len(location) > 4:
            file.write(';' + ';'.join(map(str, location[4:])))


def _ipcache(ip_addr):
    """ Retrieve a location from cache by ip addr
        Returns a triple of (CITY, REGION, COUNTRY) or None
        TODO: When cache becomes more robust, transition to using latlong
    """
    cachefile = os.path.join(IP2LCACHE, ip_addr)

    if os.path.exists(cachefile):
        try:
            _, country, region, city, *_ = open(cachefile, 'r').read().split(';')
            return city, region, country
        except ValueError:
            # cache entry is malformed: should be
            # [ccode];country;region;city;[lat];[long];...
            return None
    else:
        _debug_log("[_ipcache] %s not found" % ip_addr)
    return None


def _ip2location(ip_addr):
    """ Convert IP address `ip_addr` to a location name using ip2location.
        Return list of location data fields:

            [ccode, country, region, city, rest...]

        Return `None` if an error occured.
    """

    # if IP2LOCATION_KEY is not set, do not query,
    # because the query wont be processed anyway
    if not IP2LOCATION_KEY:
        return None
    try:
        _debug_log("[_ip2location] %s search" % ip_addr)
        r = requests.get(
            'http://api.ip2location.com/?ip=%s&key=%s&package=WS3'  # WS5 provides latlong
            % (ip_addr, IP2LOCATION_KEY))
        r.raise_for_status()
        location = r.text

        parts = location.split(';')
        if len(parts) >= 4:
            #       ccode,    country,  region,   city,       (rest)
            _debug_log("[_ip2location] %s found" % ip_addr)
            return [parts[3], parts[2], parts[1], parts[0]] + parts[4:]
        return None
    except requests.exceptions.RequestException:
        return None


def _ipinfo(ip_addr):
    if not IPINFO_TOKEN:
        return None
    try:
        r = requests.get(
            'https://ipinfo.io/%s/json?token=%s'
            % (ip_addr, IPINFO_TOKEN))
        r.raise_for_status()
        r_json = r.json()
        # can't do two unpackings on one line
        city, region, country, ccode  = r_json["city"], r_json["region"], '', r_json["country"],
        lat, long = r_json["loc"].split(',')
        # NOTE: ipinfo only provides ISO codes for countries
        country = pycountry.countries.get(alpha_2=ccode).name
    except (requests.exceptions.RequestException, ValueError):
        # latter is thrown by failure to parse json in reponse
        return None
    return [city, region, country, ccode, lat, long]


def _geoip(ip_addr):
    try:
        _debug_log("[_geoip] %s search" % ip_addr)
        response = GEOIP_READER.city(ip_addr)
        # print(response.subdivisions)
        city, region, country, ccode, lat, long = response.city.name, response.subdivisions[0].names["en"], response.country.name, response.country.iso_code, response.location.latitude, response.location.longitude
        _debug_log("[_geoip] %s found" % ip_addr)
    except IndexError:
        # Tuple error
        try:
            city, region, country, ccode, lat, long = response.city.name, None, response.country.name, response.country.iso_code, response.location.latitude, response.location.longitude
        except IndexError:
            return None
    except (geoip2.errors.AddressNotFoundError):
        return None
    return [city, region, country, ccode, lat, long]


def _country_name_workaround(country):
    # workaround for strange bug with the country name
    # maybe some other countries has this problem too
    country = COUNTRY_MAP.get(country) or country
    return country


def _get_location(ip_addr):
    """
    Return location triple (CITY, REGION, COUNTRY) for `ip_addr`
    """
    location = _ipcache(ip_addr)
    if location:
        return location

    # location from iplocators have the following order:
    # (CITY, REGION, COUNTRY, CCODE, LAT, LONG)
    for method in IPLOCATION_ORDER:
        if method == 'geoip':
            location = _geoip(ip_addr)
        elif method == 'ip2location':
            location = _ip2location(ip_addr)
        elif method == 'ipinfo':
            location = _ipinfo(ip_addr)
        else:
            print("ERROR: invalid iplocation method specified: %s" % method)
        if location is not None:
            break

    if location is not None and all(location):
        _ipcachewrite(ip_addr, location)
        # cache write used to happen before workaround, preserve that
        location[2] = _country_name_workaround(location[2])
        return location[:3]  # city, region, country
        # ccode is cached but not needed for location

    # 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

    # No methods resulted in a location - return default
    return NOT_FOUND_LOCATION, None, None


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

    location = _location_normalize(location)
    if location.lower() 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():
            try:
                from_, to_ = line.decode('utf-8').split(':', 1)
            except AttributeError:
                from_, to_ = line.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 _get_hemisphere(location):
    """
    Return hemisphere of the location (True = North, False = South).
    Assume North and return True if location can't be found.
    """
    if all(location):
        location_string = ", ".join(location)
    else:
        return True

    geolocation = _geolocator(location_string)
    if geolocation is None:
        return True
    return geolocation["latitude"] > 0


def _fully_qualified_location(location, region, country):
    """ Return fully qualified location name with `region` and `country`,
        as a string.
    """

    # If country is not specified, location stays as is
    if not country:
        return location

    # Canonify/shorten country name
    if country == "United Kingdom of Great Britain and Northern Ireland":
        country = "United Kingdom"
    elif country == "Russian Federation":
        country = "Russia"
    elif country == "United States of America":
        country = "United States"

    # In United States region is important, because there are a lot of
    # locations with the same name in different regions.
    # In the rest of the world, usage of region name may decrease chances
    # or correct name resolution, so for the moment `region` is used
    # only for the United States
    if country == "United States" and region:
        location += ", %s, %s" % (region, country)
    else:
        location += ", %s" % country
    return location


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
    hide_full_address = False
    force_show_full_address = location is not None and location.startswith('~')

    # location ~ means that it should be detected automatically,
    # and shown in the location line below the report
    if location == '~':
        location = None

    if location and location.lstrip('~ ').startswith('@'):
        try:
            location, region, country = _get_location(
                socket.gethostbyname(
                    location.lstrip('~ ')[1:]))
            location = '~' + location
            location = _fully_qualified_location(location, region, country)
            hide_full_address = not force_show_full_address
        except:
            location, region, country = NOT_FOUND_LOCATION, None, None

    query_source_location = _get_location(ip_addr)

    # For moon queries, hemisphere must be found
    # True for North, False for South
    hemisphere = False
    if location is not None and (location.lower()+"@").startswith("moon@"):
        hemisphere = _get_hemisphere(query_source_location)

    country = None
    if not location or location == 'MyLocation':
        location = ip_addr

    if _is_ip(location):
        location, region, country = _get_location(location)
        # location is just city here

        # here too
        if location:
            location = '~' + location
            location = _fully_qualified_location(location, region, country)
            hide_full_address = not force_show_full_address

    if location and not location.startswith('~'):
        tmp_location = _location_canonical_name(location)
        if tmp_location != location:
            override_location_name = location
            location = tmp_location

    # up to this point it is possible that the name
    # contains some unicode symbols
    # here we resolve them
    if location is not None and location != NOT_FOUND_LOCATION:
        location = "~" + location.lstrip('~ ')
        if not override_location_name:
            override_location_name = location.lstrip('~')

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

    if location is not None and not location.startswith("~-,") and location.startswith('~'):
        geolocation = _geolocator(_location_canonical_name(location[1:]))
        if geolocation is not None:
            if not override_location_name:
                override_location_name = location[1:].replace('+', ' ')
            location = "%s,%s" % (geolocation['latitude'], geolocation['longitude'])
            country = None
            if not hide_full_address:
                full_address = geolocation['address']
            else:
                full_address = None
        else:
            location = NOT_FOUND_LOCATION #location[1:]

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


def _main_():
    """ Validate cache entries. Print names of invalid cache entries
        and move it to the "broken-entries" directory."""

    import glob
    import shutil

    for filename in glob.glob(os.path.join(IP2LCACHE, "*")):
        ip_address = os.path.basename(filename)
        data = _ipcache(ip_address)
        if data:
            city, region, country = data
            if any(x in city for x in "0123456789"):
                print(city)
                shutil.move(filename, os.path.join("/wttr.in/cache/ip2l-broken-format", ip_address))


if __name__ == "__main__":
    _main_()
    #print(_geoip("173.216.90.56"))