"""This file houses various core utility functions for GPP"""
import datetime
import re
import logging

from django.contrib.sites.models import Site
from django.conf import settings

import core.tasks


def send_mail(subject, message, from_email, recipient_list, **kwargs):
    """
    The main send email function. Use this function to send email from the
    site. All applications should use this function instead of calling
    Django's directly.
    If settings.GPP_SEND_EMAIL is true, the email will be sent to a Celery task
    to actually send the email. Otherwise it is dropped. In any event, the
    email will be logged at the DEBUG level.

    """
    # Guard against empty email addresses
    recipient_list = [dest for dest in recipient_list if dest]
    if not recipient_list:
        logging.warning("Empty recipient_list in send_mail")
        return

    logging.debug('EMAIL:\nFrom: %s\nTo: %s\nSubject: %s\nMessage:\n%s',
        from_email, str(recipient_list), subject, message)

    if settings.GPP_SEND_EMAIL:
        core.tasks.send_mail.delay(subject, message, from_email, recipient_list,
                **kwargs)


def email_admins(subject, message):
    """Emails the site admins. Goes through the site send_mail function."""
    site = Site.objects.get_current()
    subject = '[%s] %s' % (site.name, subject)
    send_mail(subject,
            message,
            '%s@%s' % (settings.GPP_NO_REPLY_EMAIL, site.domain),
            [mail_tuple[1] for mail_tuple in settings.ADMINS])


def email_managers(subject, message):
    """Emails the site managers. Goes through the site send_mail function."""
    site = Site.objects.get_current()
    subject = '[%s] %s' % (site.name, subject)
    send_mail(subject,
            msg,
            '%s@%s' % (settings.GPP_NO_REPLY_EMAIL, site.domain),
            [mail_tuple[1] for mail_tuple in settings.MANAGERS])


def get_full_name(user):
    """Returns the user's full name if available, otherwise falls back
    to the username."""
    full_name = user.get_full_name()
    if full_name:
        return full_name
    return user.username


BASE_YEAR = 2010

def copyright_str():
    curr_year = datetime.datetime.now().year
    if curr_year == BASE_YEAR:
        year_range = str(BASE_YEAR)
    else:
        year_range = "%d - %d" % (BASE_YEAR, curr_year)

    return 'Copyright (C) %s, SurfGuitar101.com' % year_range


IP_PAT = re.compile('(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})')

def get_ip(request):
    """Returns the IP from the request or None if it cannot be retrieved."""
    ip = request.META.get('HTTP_X_FORWARDED_FOR',
            request.META.get('REMOTE_ADDR'))

    if ip:
        match = IP_PAT.match(ip)
        ip = match.group(1) if match else None

    return ip


def get_page(qdict):
    """Attempts to retrieve the value for "page" from the given query dict and
    return it as an integer. If the key cannot be found or converted to an
    integer, 1 is returned.
    """
    n = qdict.get('page', 1)
    try:
        n = int(n)
    except ValueError:
        n = 1
    return n