"""
EdX Branding package.

Provides a way to retrieve "branded" parts of the site.

This module provides functions to retrieve basic branded parts
such as the site visible courses, university name and logo.
"""

from __future__ import absolute_import

from django.conf import settings
from opaque_keys.edx.keys import CourseKey

from openedx.core.djangoapps.site_configuration import helpers as configuration_helpers


def get_visible_courses(org=None, filter_=None):
    """
    Yield the CourseOverviews that should be visible in this branded
    instance.

    Arguments:
        org (string): Optional parameter that allows case-insensitive
            filtering by organization.
        filter_ (dict): Optional parameter that allows custom filtering by
            fields on the course.
    """
    # Import is placed here to avoid model import at project startup.
    from openedx.core.djangoapps.content.course_overviews.models import CourseOverview

    current_site_orgs = configuration_helpers.get_current_site_orgs()

    courses = CourseOverview.objects.none()

    if org:
        # Check the current site's orgs to make sure the org's courses should be displayed
        if not current_site_orgs or org in current_site_orgs:
            courses = CourseOverview.get_all_courses(orgs=[org], filter_=filter_)
    elif current_site_orgs:
        # Only display courses that should be displayed on this site
        courses = CourseOverview.get_all_courses(orgs=current_site_orgs, filter_=filter_)
    else:
        courses = CourseOverview.get_all_courses(filter_=filter_)

    courses = courses.order_by('id')

    # Filtering can stop here.
    if current_site_orgs:
        return courses

    # See if we have filtered course listings in this domain
    filtered_visible_ids = None

    # this is legacy format, which also handle dev case, which should not filter
    subdomain = configuration_helpers.get_value('subdomain', 'default')
    if hasattr(settings, 'COURSE_LISTINGS') and subdomain in settings.COURSE_LISTINGS and not settings.DEBUG:
        filtered_visible_ids = frozenset(
            [CourseKey.from_string(c) for c in settings.COURSE_LISTINGS[subdomain]]
        )

    if filtered_visible_ids:
        return courses.filter(id__in=filtered_visible_ids)
    else:
        # Filter out any courses based on current org, to avoid leaking these.
        orgs = configuration_helpers.get_all_orgs()
        return courses.exclude(org__in=orgs)


def get_university_for_request():
    """
    Return the university name specified for the domain, or None
    if no university was specified
    """
    return configuration_helpers.get_value('university')