from django.core.mail.message import EmailMultiAlternatives
from django.core.urlresolvers import reverse
from django.conf import settings


def mail_managers(subject, message, fail_silently=False, connection=None,
                  html_message=None, **kwargs):
    """Send a message to the managers, as defined by the MANAGERS setting."""
    if not settings.MANAGERS:
        return
    mail = EmailMultiAlternatives(
        '%s%s' % (settings.EMAIL_SUBJECT_PREFIX, subject), message,
        settings.SERVER_EMAIL, [a[1] for a in settings.MANAGERS],
        connection=connection, **kwargs
    )
    if html_message:
        mail.attach_alternative(html_message, 'text/html')
    mail.send(fail_silently=fail_silently)


def notify_allocation(request, new_alloc, old_alloc=None):
    fields = ['resource', 'service', 'route', 'start', 'end', 'notes']

    benevole = '%s <%s>' % (request.user.username, request.user.email)
    message = 'Bénévole : ' + benevole
    message += '\n\nAllocation :'

    diff = False
    for field in fields:
        new_attr = getattr(new_alloc, field)
        if new_attr == '' or new_attr is None:
            new_attr = '-'
        if old_alloc:
            old_attr = getattr(old_alloc, field)
            if old_attr == '' or old_attr is None:
                old_attr = '-'
        if old_alloc and old_attr != new_attr:
            message += '\n-%12s: %s\n+%12s: %s' % (field, old_attr, field, new_attr)
            diff = True
        else:
            message += '\n %12s: %s' % (field, new_attr)

    url = 'https' if request.is_secure() else 'http'
    url += '://' + request.get_host()
    url += reverse('admin:services_ipresource_change', args=(new_alloc.resource.pk,))
    message += '\n\nVoir : ' + url

    if old_alloc and diff:
        sujet = 'Modification d’une allocation'
    elif not old_alloc:
        sujet = 'Nouvelle allocation'
    else:
        sujet = None

    if sujet:
        sujet += ' ADT%d' % new_alloc.service.adhesion.pk
        mail_managers(sujet, message, cc=[benevole])