import time

import pytz

from django.conf import settings
from django.utils import timezone
from django.conf.locale.en import formats as formats_en_us


def update_en_us_date_formats():
    """
    Update the datetime formats for the en-US locale. This is handled here and
    not using `FORMAT_MODULE_PATH` because the processing of format modules
    does not allow us to distinguish appropriately between en-US and en-GB
    based on user settings.
    """
    if settings.USE_24_HOUR_TIME_FORMAT:
        formats_en_us.DATETIME_FORMAT = 'N j, Y, H:i:s'
        custom_input_formats = [
            '%m/%d/%Y %H:%M:%S',  # '10/25/2006 14:30:59'
            '%m/%d/%Y %H:%M',  # '10/25/2006 14:30'
        ]
        formats_en_us.SHORT_DATETIME_FORMAT = 'm/d/Y G:i:s'
        formats_en_us.TIME_FORMAT = 'H:i:s'
    else:
        # These formats are added to support the locale style of Baby Buddy's
        # frontend library, which uses momentjs.
        custom_input_formats = [
            '%m/%d/%Y %I:%M:%S %p',  # '10/25/2006 2:30:59 PM'
            '%m/%d/%Y %I:%M %p',  # '10/25/2006 2:30 PM'
        ]

    # Add custom "short" version of `MONTH_DAY_FORMAT`.
    formats_en_us.SHORT_MONTH_DAY_FORMAT = 'M j'

    # Append all other input formats from the base locale.
    formats_en_us.DATETIME_INPUT_FORMATS = \
        custom_input_formats + formats_en_us.DATETIME_INPUT_FORMATS


class UserLanguageMiddleware:
    """
    Customizes settings based on user language setting.
    """
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        user = request.user
        if hasattr(user, 'settings') and user.settings.language == 'en-US':
            update_en_us_date_formats()

        return self.get_response(request)


class UserTimezoneMiddleware:
    """
    Sets the timezone based on a user specific setting that falls back on
    `settings.TIME_ZONE`. This middleware must run after
    `django.contrib.auth.middleware.AuthenticationMiddleware` because it uses
    the request.user object.
    """
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        user = request.user
        if hasattr(user, 'settings') and user.settings.timezone:
            try:
                timezone.activate(pytz.timezone(user.settings.timezone))
            except pytz.UnknownTimeZoneError:
                pass
        return self.get_response(request)


class RollingSessionMiddleware:
    """
    Periodically resets the session expiry for existing sessions.
    """
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        if request.session.keys():
            session_refresh = request.session.get('session_refresh')
            if session_refresh:
                try:
                    delta = int(time.time()) - session_refresh
                except (ValueError, TypeError):
                    delta = settings.ROLLING_SESSION_REFRESH + 1
                if delta > settings.ROLLING_SESSION_REFRESH:
                    request.session['session_refresh'] = int(time.time())
                    request.session.set_expiry(settings.SESSION_COOKIE_AGE)
            else:
                request.session['session_refresh'] = int(time.time())
        return self.get_response(request)