from __future__ import absolute_import
import logging
from functools import partial
from django.conf import settings
from django.core.urlresolvers import reverse
from django.http import Http404, HttpResponseBadRequest
from django.contrib.auth.decorators import login_required
from edxmako.shortcuts import render_to_string
from xmodule_modifiers import replace_static_urls, wrap_xblock, wrap_fragment, request_token
from xmodule.x_module import PREVIEW_VIEWS, STUDENT_VIEW, AUTHOR_VIEW
from xmodule.contentstore.django import contentstore
from xmodule.error_module import ErrorDescriptor
from xmodule.exceptions import NotFoundError, ProcessingError
from xmodule.modulestore.django import modulestore, ModuleI18nService
from opaque_keys.edx.keys import UsageKey
from xmodule.x_module import ModuleSystem
from xblock.runtime import KvsFieldData
from xblock.django.request import webob_to_django_response, django_to_webob_request
from xblock.exceptions import NoSuchHandlerError
from xblock.fragment import Fragment
from lms.lib.xblock.field_data import LmsFieldData
from cms.lib.xblock.field_data import CmsFieldData
from cms.lib.xblock.runtime import local_resource_url
from util.sandboxing import can_execute_unsafe_code, get_python_lib_zip
import static_replace
from .session_kv_store import SessionKeyValueStore
from .helpers import render_from_lms
from contentstore.views.access import get_user_role
__all__ = ['preview_handler']
log = logging.getLogger(__name__)
@login_required
def preview_handler(request, usage_key_string, handler, suffix=''):
"""
Dispatch an AJAX action to an xblock
usage_key_string: The usage_key_string-id of the block to dispatch to, passed through `quote_slashes`
handler: The handler to execute
suffix: The remainder of the url to be passed to the handler
"""
usage_key = UsageKey.from_string(usage_key_string)
descriptor = modulestore().get_item(usage_key)
instance = _load_preview_module(request, descriptor)
# Let the module handle the AJAX
req = django_to_webob_request(request)
try:
resp = instance.handle(handler, req, suffix)
except NoSuchHandlerError:
log.exception("XBlock %s attempted to access missing handler %r", instance, handler)
raise Http404
except NotFoundError:
log.exception("Module indicating to user that request doesn't exist")
raise Http404
except ProcessingError:
log.warning("Module raised an error while processing AJAX request",
exc_info=True)
return HttpResponseBadRequest()
except Exception:
log.exception("error processing ajax call")
raise
return webob_to_django_response(resp)
class PreviewModuleSystem(ModuleSystem): # pylint: disable=abstract-method
"""
An XModule ModuleSystem for use in Studio previews
"""
# xmodules can check for this attribute during rendering to determine if
# they are being rendered for preview (i.e. in Studio)
is_author_mode = True
def handler_url(self, block, handler_name, suffix='', query='', thirdparty=False):
return reverse('preview_handler', kwargs={
'usage_key_string': unicode(block.location),
'handler': handler_name,
'suffix': suffix,
}) + '?' + query
def local_resource_url(self, block, uri):
return local_resource_url(block, uri)
class StudioUserService(object):
"""
Provides a Studio implementation of the XBlock user service.
"""
def __init__(self, request):
super(StudioUserService, self).__init__()
self._request = request
@property
def user_id(self):
return self._request.user.id
def _preview_module_system(request, descriptor):
"""
Returns a ModuleSystem for the specified descriptor that is specialized for
rendering module previews.
request: The active django request
descriptor: An XModuleDescriptor
"""
course_id = descriptor.location.course_key
display_name_only = (descriptor.category == 'static_tab')
wrappers = [
# This wrapper wraps the module in the template specified above
partial(
wrap_xblock,
'PreviewRuntime',
display_name_only=display_name_only,
usage_id_serializer=unicode,
request_token=request_token(request)
),
# This wrapper replaces urls in the output that start with /static
# with the correct course-specific url for the static content
partial(replace_static_urls, None, course_id=course_id),
_studio_wrap_xblock,
]
descriptor.runtime._services['user'] = StudioUserService(request) # pylint: disable=protected-access
return PreviewModuleSystem(
static_url=settings.STATIC_URL,
# TODO (cpennington): Do we want to track how instructors are using the preview problems?
track_function=lambda event_type, event: None,
filestore=descriptor.runtime.resources_fs,
get_module=partial(_load_preview_module, request),
render_template=render_from_lms,
debug=True,
replace_urls=partial(static_replace.replace_static_urls, data_directory=None, course_id=course_id),
user=request.user,
can_execute_unsafe_code=(lambda: can_execute_unsafe_code(course_id)),
get_python_lib_zip=(lambda :get_python_lib_zip(contentstore, course_id)),
mixins=settings.XBLOCK_MIXINS,
course_id=course_id,
anonymous_student_id='student',
# Set up functions to modify the fragment produced by student_view
wrappers=wrappers,
error_descriptor_class=ErrorDescriptor,
get_user_role=lambda: get_user_role(request.user, course_id),
descriptor_runtime=descriptor.runtime,
services={
"i18n": ModuleI18nService(),
},
)
def _load_preview_module(request, descriptor):
"""
Return a preview XModule instantiated from the supplied descriptor. Will use mutable fields
if XModule supports an author_view. Otherwise, will use immutable fields and student_view.
request: The active django request
descriptor: An XModuleDescriptor
"""
student_data = KvsFieldData(SessionKeyValueStore(request))
if _has_author_view(descriptor):
field_data = CmsFieldData(descriptor._field_data, student_data) # pylint: disable=protected-access
else:
field_data = LmsFieldData(descriptor._field_data, student_data) # pylint: disable=protected-access
descriptor.bind_for_student(
_preview_module_system(request, descriptor),
field_data
)
return descriptor
def _is_xblock_reorderable(xblock, context):
"""
Returns true if the specified xblock is in the set of reorderable xblocks.
"""
return xblock.location in context['reorderable_items']
# pylint: disable=unused-argument
def _studio_wrap_xblock(xblock, view, frag, context, display_name_only=False):
"""
Wraps the results of rendering an XBlock view in a div which adds a header and Studio action buttons.
"""
# Only add the Studio wrapper when on the container page. The "Pages" page will remain as is for now.
if not context.get('is_pages_view', None) and view in PREVIEW_VIEWS:
root_xblock = context.get('root_xblock')
is_root = root_xblock and xblock.location == root_xblock.location
is_reorderable = _is_xblock_reorderable(xblock, context)
template_context = {
'xblock_context': context,
'xblock': xblock,
'content': frag.content,
'is_root': is_root,
'is_reorderable': is_reorderable,
}
html = render_to_string('studio_xblock_wrapper.html', template_context)
frag = wrap_fragment(frag, html)
return frag
def get_preview_fragment(request, descriptor, context):
"""
Returns the HTML returned by the XModule's student_view or author_view (if available),
specified by the descriptor and idx.
"""
module = _load_preview_module(request, descriptor)
preview_view = AUTHOR_VIEW if _has_author_view(module) else STUDENT_VIEW
try:
fragment = module.render(preview_view, context)
except Exception as exc: # pylint: disable=W0703
log.warning("Unable to render %s for %r", preview_view, module, exc_info=True)
fragment = Fragment(render_to_string('html_error.html', {'message': str(exc)}))
return fragment
def _has_author_view(descriptor):
"""
Returns True if the xmodule linked to the descriptor supports "author_view".
If False, "student_view" and LmsFieldData should be used.
"""
return getattr(descriptor, 'has_author_view', False)