from django.template import loader, RequestContext
from django.core.exceptions import ObjectDoesNotExist
from django.core.xheaders import populate_xheaders
from django.db.models.fields import DateTimeField
from django.http import Http404, HttpResponse


def archive_week(request, year, week, queryset, date_field,
        template_name=None, template_loader=loader,
        extra_context=None, allow_empty=True, context_processors=None,
        template_object_name='object', mimetype=None, allow_future=False):
    """
    Generic weekly archive view.

    Templates: ``<app_label>/<model_name>_archive_week.html``
    Context:
        week:
            (date) this week
        object_list:
            list of objects published in the given week
    """
    if extra_context is None: extra_context = {}
    try:
        date = datetime.date(*time.strptime(year+'-1-'+week, '%Y-%w-%U')[:3])
    except ValueError:
        raise Http404

    model = queryset.model
    now = datetime.datetime.now()

    # Calculate first and last day of week, for use in a date-range lookup.
    first_day = date
    last_day = date + datetime.timedelta(days=7)
    lookup_kwargs = {
        '%s__gte' % date_field: first_day,
        '%s__lt' % date_field: last_day,
    }

    # Only bother to check current date if the week isn't in the past and future objects aren't requested.
    if last_day >= now.date() and not allow_future:
        lookup_kwargs['%s__lte' % date_field] = now
    object_list = queryset.filter(**lookup_kwargs)
    if not object_list and not allow_empty:
        raise Http404
    if not template_name:
        template_name = "%s/%s_archive_week.html" % (model._meta.app_label, model._meta.object_name.lower())
    t = template_loader.get_template(template_name)
    c = RequestContext(request, {
        '%s_list' % template_object_name: object_list,
        'week': date,
    })
    for key, value in extra_context.items():
        if callable(value):
            c[key] = value()
        else:
            c[key] = value
    return HttpResponse(t.render(c), mimetype=mimetype)