"""
This module contains helper functions and helper classes.
"""
import time
import hmac
from django.core.cache import cache
from django.db.models import Model

from django.utils import timezone

from neboard import settings


KEY_CAPTCHA_FAILS = 'key_captcha_fails'
KEY_CAPTCHA_DELAY_TIME = 'key_captcha_delay_time'
KEY_CAPTCHA_LAST_ACTIVITY = 'key_captcha_last_activity'


def get_client_ip(request):
    x_forwarded_for = request.META.get('HTTP_X_FORWARDED_FOR')
    if x_forwarded_for:
        ip = x_forwarded_for.split(',')[-1].strip()
    else:
        ip = request.META.get('REMOTE_ADDR')
    return ip


# TODO The output format is not epoch because it includes microseconds
def datetime_to_epoch(datetime):
    return int(time.mktime(timezone.localtime(
        datetime,timezone.get_current_timezone()).timetuple())
               * 1000000 + datetime.microsecond)


def get_websocket_token(user_id='', timestamp=''):
    """
    Create token to validate information provided by new connection.
    """

    sign = hmac.new(settings.CENTRIFUGE_PROJECT_SECRET.encode())
    sign.update(settings.CENTRIFUGE_PROJECT_ID.encode())
    sign.update(user_id.encode())
    sign.update(timestamp.encode())
    token = sign.hexdigest()

    return token


def cached_result(function):
    """
    Caches method result in the Django's cache system, persisted by object name,
    object name and model id if object is a Django model.
    """
    def inner_func(obj, *args, **kwargs):
        # TODO Include method arguments to the cache key
        cache_key = obj.__class__.__name__ + '_' + function.__name__
        if isinstance(obj, Model):
            cache_key += '_' + str(obj.id)

        persisted_result = cache.get(cache_key)
        if persisted_result:
            result = persisted_result
        else:
            result = function(obj, *args, **kwargs)
            cache.set(cache_key, result)

        return result

    return inner_func