#   Copyright (c) 2008 Mikeal Rogers
#
#   Licensed under the Apache License, Version 2.0 (the "License");
#   you may not use this file except in compliance with the License.
#   You may obtain a copy of the License at
#
#       http://www.apache.org/licenses/LICENSE-2.0
#
#   Unless required by applicable law or agreed to in writing, software
#   distributed under the License is distributed on an "AS IS" BASIS,
#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#   See the License for the specific language governing permissions and
#   limitations under the License.

from django.template import Context
from django.http import HttpResponse
import logging

from . import middleware
from django.conf import settings
from django.core.urlresolvers import reverse
log = logging.getLogger(__name__)


def marketing_link(name):
    """Returns the correct URL for a link to the marketing site
    depending on if the marketing site is enabled

    Since the marketing site is enabled by a setting, we have two
    possible URLs for certain links. This function is to decides
    which URL should be provided.
    """

    # link_map maps URLs from the marketing site to the old equivalent on
    # the Django site
    link_map = settings.MKTG_URL_LINK_MAP
    if settings.MITX_FEATURES.get('ENABLE_MKTG_SITE') and name in settings.MKTG_URLS:
        # special case for when we only want the root marketing URL
        if name == 'ROOT':
            return settings.MKTG_URLS.get('ROOT')
        return settings.MKTG_URLS.get('ROOT') + settings.MKTG_URLS.get(name)
    # only link to the old pages when the marketing site isn't on
    elif not settings.MITX_FEATURES.get('ENABLE_MKTG_SITE') and name in link_map:
        # don't try to reverse disabled marketing links
        if link_map[name] is not None:
            return reverse(link_map[name])
    else:
        log.warning("Cannot find corresponding link for name: {name}".format(name=name))
        return '#'


def marketing_link_context_processor(request):
    """
    A django context processor to give templates access to marketing URLs

    Returns a dict whose keys are the marketing link names usable with the
    marketing_link method (e.g. 'ROOT', 'CONTACT', etc.) prefixed with
    'MKTG_URL_' and whose values are the corresponding URLs as computed by the
    marketing_link method.
    """
    return dict(
        [
            ("MKTG_URL_" + k, marketing_link(k))
            for k in (
                settings.MKTG_URL_LINK_MAP.viewkeys() |
                settings.MKTG_URLS.viewkeys()
            )
        ]
    )


def render_to_string(template_name, dictionary, context=None, namespace='main'):
    context_instance = Context(dictionary)
    # add dictionary to context_instance
    context_instance.update(dictionary or {})
    # collapse context_instance to a single dictionary for mako
    context_dictionary = {}
    context_instance['settings'] = settings
    context_instance['MITX_ROOT_URL'] = settings.MITX_ROOT_URL
    context_instance['marketing_link'] = marketing_link

    # In various testing contexts, there might not be a current request context.
    if middleware.requestcontext is not None:
        for d in middleware.requestcontext:
            context_dictionary.update(d)
    for d in context_instance:
        context_dictionary.update(d)
    if context:
        context_dictionary.update(context)
    # fetch and render template
    template = middleware.lookup[namespace].get_template(template_name)
    return template.render_unicode(**context_dictionary)


def render_to_response(template_name, dictionary, context_instance=None, namespace='main', **kwargs):
    """
    Returns a HttpResponse whose content is filled with the result of calling
    lookup.get_template(args[0]).render with the passed arguments.
    """
    return HttpResponse(render_to_string(template_name, dictionary, context_instance, namespace), **kwargs)
