# -*- coding: utf-8 -*-

from __future__ import unicode_literals

import os
import urllib
import gzip
import sched, time

from django.conf import settings

from random import randint
from datetime import datetime, timedelta


class DatGetter(object):

    path = ''
    filename = 'GeoIP.dat'
    url = getattr(settings, 'COUNTRY_SEGMENT_DAT_URL', 'http://geolite.maxmind.com/download/geoip/database/GeoLiteCountry/GeoIP.dat.gz')
    daily = 24 * 3600
    weekly = 7 * 24 * 3600


    def __init__(self):
        '''
        Upon loading this module, it figures out where it is on the
        filesystem, then checks to see if it has an up-to-date GeoIP.dat file,
        and if not, tries to fetch one.

        Also, if `ALDRYN` is True in the project settings, then this will also
        spawn a process to continuously re-check and download a new dat file
        each week (note: MaxMind only updates it once per month or so,
        though.)

        If this is running on Aldryn, it is not recommended that you also use
        the management command (is this even possible?)

        If not running on Aldryn, consider using a cron-job or Celery task to
        invoke the management command about once a week to ensure reasonable,
        continuous accuracy.
        '''

        #
        # Fix-up paths
        #
        self.path = os.path.abspath(os.path.dirname(__file__))
        self.zfilepath = os.path.join(self.path, self.filename + '.gz')
        self.filepath = os.path.join(self.path, self.filename)

        #
        # To have this automaticaly schedule itself, set ALDRYN=True in
        # settings. However, using this elsewhere will likely cause issues
        # with restarting.
        #
        # Instead, use a cron-job or celery-task to run update_dat() weekly.
        #
        if getattr(settings, 'ALDRYN', False):
            pid = os.fork()
            if pid == 0:
                #
                # Set-up a scheduler in another process
                #
                self.scheduler = sched.scheduler(time.time, time.sleep)
                self.scheduler.enter(self.weekly, 1, self.update_dat, (self.scheduler,))
                self.scheduler.run()
        else:
            self.update_dat()


    def update_dat(self, scheduler=None):
        '''
        Checks to see if the GeoIP.dat file exists and is less than 1 week
        old, else will fetch (a new) one from MaxMind.

        Returns a path, filename dict suitable for passing to GeoIP(), if
        available, else None.
        '''

        #
        # Since this service may be stopped and started occassionally, we'll
        # not actually initiate a DL from MaxMind unless a GeoIP.dat file
        # doesn't exist or it is already older than 1 week old.
        #
        # This '1 week' only counts when this service is started. Once it is
        # running, it will DL a new file every 7 days. Since MaxMind only
        # update the file on a monthly basis, this could mean that the file
        # gets, at most, 38 days out-of-date. Any application that requires
        # more up-to-date data should consider a proper MaxMind subscription.
        #
        # If there was an error of some sort, it will re-try in 24 hours.
        #
        if os.path.isfile(self.filepath):
            mtime = os.path.getmtime(self.filepath)
        else:
            mtime = None

        if not mtime or datetime.fromtimestamp(mtime) < datetime.now() - timedelta(days=7):
            print 'Fetching new dat file...'
            try:
                self.get_updated_dat()
                print 'GeoIP.dat file is now updated!'

            except Exception as e:
                print 'Unable to update the GeoIP.dat file: {0}'.format(e)

                #
                # Since there was an error, let's try again in 24 hours.
                #
                if scheduler:
                    scheduler.enter(self.daily, 1, self.update_dat, (scheduler,))

                return None
        else:
            print "GeoIP.dat file is already up-to-date"

        #
        # Schedule another update in a week.
        #
        if scheduler:
            scheduler.enter(self.weekly, 1, self.update_dat, (scheduler,))

        return { 'path': self.path, 'country': self.filename }


    def get_updated_dat(self):
        '''
        Get's the GeoIP.dat.gz file from MaxMind, ungzip it into a temporary
        file, and rename it to the correct filename. May throw exceptions.
        '''

        #
        # Grab the file from MaxMind...
        #
        datfile=urllib.URLopener()
        datfile.retrieve(self.url, self.zfilepath)

        #
        # Ungzip it into a temporary file. This is to minimize having only
        # a partial .dat file in place when a read is required.
        #
        tmpfilepath = os.path.join(self.path, 'temp' + str(randint(1000,9999)) + '.dat')
        with gzip.open(self.zfilepath, 'rb') as zipfile:
            with open(tmpfilepath, 'wb') as datfile:
                datfile.write(zipfile.read())

        #
        # Rename the tmpfilepath to the correct filename
        #
        os.rename(tmpfilepath, self.filepath)


if getattr(settings, 'ALDRYN', False):
    dat_getter = DatGetter()