edx-platform/xmodule/html_block.py

# lint-amnesty, pylint: disable=missing-module-docstring

import copy
import logging
import os
import re
import sys
import textwrap
from datetime import datetime

from django.conf import settings
from fs.errors import ResourceNotFound
from lxml import etree
from path import Path as path
from web_fragments.fragment import Fragment
from xblock.core import XBlock
from xblock.fields import Boolean, List, Scope, String

from common.djangoapps.xblock_django.constants import ATTR_KEY_DEPRECATED_ANONYMOUS_USER_ID
from xmodule.contentstore.content import StaticContent
from xmodule.editing_block import EditingMixin
from xmodule.edxnotes_utils import edxnotes
from xmodule.html_checker import check_html
from xmodule.stringify import stringify_children
from xmodule.util.misc import escape_html_characters
from xmodule.util.builtin_assets import add_webpack_js_to_fragment, add_sass_to_fragment
from xmodule.x_module import (
    ResourceTemplates,
    shim_xmodule_js,
    XModuleMixin,
    XModuleToXBlockMixin,
)
from xmodule.xml_block import XmlMixin, name_to_pathname

log = logging.getLogger("edx.courseware")

# Make '_' a no-op so we can scrape strings. Using lambda instead of
#  `django.utils.translation.ugettext_noop` because Django cannot be imported in this file
_ = lambda text: text


@XBlock.needs("i18n")
@XBlock.needs("mako")
@XBlock.needs("user")
class HtmlBlockMixin(  # lint-amnesty, pylint: disable=abstract-method
    XmlMixin, EditingMixin,
    XModuleToXBlockMixin, ResourceTemplates, XModuleMixin,
):
    """
    The HTML XBlock mixin.
    This provides the base class for all Html-ish blocks (including the HTML XBlock).
    """
    display_name = String(
        display_name=_("Display Name"),
        help=_("The display name for this component."),
        scope=Scope.settings,
        # it'd be nice to have a useful default but it screws up other things; so,
        # use display_name_with_default for those
        default=_("Text")
    )
    data = String(help=_("Html contents to display for this block"), default="", scope=Scope.content)
    source_code = String(
        help=_("Source code for LaTeX documents. This feature is not well-supported."),
        scope=Scope.settings
    )
    use_latex_compiler = Boolean(
        help=_("Enable LaTeX templates?"),
        default=False,
        scope=Scope.settings
    )
    editor = String(
        help=_(
            "Select Visual to enter content and have the editor automatically create the HTML. Select Raw to edit "
            "HTML directly. If you change this setting, you must save the component and then re-open it for editing."
        ),
        display_name=_("Editor"),
        default="visual",
        values=[
            {"display_name": _("Visual"), "value": "visual"},
            {"display_name": _("Raw"), "value": "raw"}
        ],
        scope=Scope.settings
    )

    ENABLE_HTML_XBLOCK_STUDENT_VIEW_DATA = 'ENABLE_HTML_XBLOCK_STUDENT_VIEW_DATA'

    @XBlock.supports("multi_device")
    def student_view(self, _context):
        """
        Return a fragment that contains the html for the student view
        """
        fragment = Fragment(self.get_html())
        add_sass_to_fragment(fragment, 'HtmlBlockDisplay.scss')
        add_webpack_js_to_fragment(fragment, 'HtmlBlockDisplay')
        shim_xmodule_js(fragment, 'HTMLModule')
        return fragment

    @XBlock.supports("multi_device")
    def public_view(self, context):
        """
        Returns a fragment that contains the html for the preview view
        """
        return self.student_view(context)

    def student_view_data(self, context=None):  # pylint: disable=unused-argument
        """
        Return a JSON representation of the student_view of this XBlock.
        """
        if getattr(settings, 'FEATURES', {}).get(self.ENABLE_HTML_XBLOCK_STUDENT_VIEW_DATA, False):
            return {'enabled': True, 'html': self.get_html()}
        else:
            return {
                'enabled': False,
                'message': f'To enable, set FEATURES["{self.ENABLE_HTML_XBLOCK_STUDENT_VIEW_DATA}"]'
            }

    def get_html(self):
        """ Returns html required for rendering the block. """
        if self.data:
            data = self.data
            user_id = (
                self.runtime.service(self, 'user')
                .get_current_user()
                .opt_attrs.get(ATTR_KEY_DEPRECATED_ANONYMOUS_USER_ID)
            )
            if user_id:
                data = data.replace("%%USER_ID%%", user_id)
            data = data.replace("%%COURSE_ID%%", str(self.scope_ids.usage_id.context_key))
            return data
        return self.data

    def studio_view(self, _context):
        """
        Return the studio view.
        """
        fragment = Fragment(
            self.runtime.service(self, 'mako').render_template(self.mako_template, self.get_context())
        )
        add_sass_to_fragment(fragment, 'HtmlBlockEditor.scss')
        add_webpack_js_to_fragment(fragment, 'HtmlBlockEditor')
        shim_xmodule_js(fragment, 'HTMLEditingDescriptor')
        return fragment

    uses_xmodule_styles_setup = True

    mako_template = "widgets/html-edit.html"
    resources_dir = None
    filename_extension = "xml"
    template_dir_name = "html"
    show_in_read_only_mode = True

    # VS[compat] TODO (cpennington): Delete this method once all fall 2012 course
    # are being edited in the cms
    @classmethod
    def backcompat_paths(cls, filepath):
        """
        Get paths for html and xml files.
        """
        if filepath.endswith('.html.xml'):
            filepath = filepath[:-9] + '.html'  # backcompat--look for html instead of xml
        if filepath.endswith('.html.html'):
            filepath = filepath[:-5]  # some people like to include .html in filenames..
        candidates = []
        while os.sep in filepath:
            candidates.append(filepath)
            _, _, filepath = filepath.partition(os.sep)

        # also look for .html versions instead of .xml
        new_candidates = []
        for candidate in candidates:
            if candidate.endswith('.xml'):
                new_candidates.append(candidate[:-4] + '.html')
        return candidates + new_candidates

    @classmethod
    def filter_templates(cls, template, course):
        """
        Filter template that contains 'latex' from templates.

        Show them only if use_latex_compiler is set to True in
        course settings.
        """
        return 'latex' not in template['template_id'] or course.use_latex_compiler

    def get_context(self):
        """
        an override to add in specific rendering context, in this case we need to
        add in a base path to our c4x content addressing scheme
        """
        _context = EditingMixin.get_context(self)
        # Add some specific HTML rendering context when editing HTML blocks where we pass
        # the root /c4x/ url for assets. This allows client-side substitutions to occur.
        _context.update({
            'base_asset_url': StaticContent.get_base_url_path_for_course_assets(self.location.course_key),
            'enable_latex_compiler': self.use_latex_compiler,
            'editor': self.editor
        })
        return _context

    # NOTE: html descriptors are special.  We do not want to parse and
    # export them ourselves, because that can break things (e.g. lxml
    # adds body tags when it exports, but they should just be html
    # snippets that will be included in the middle of pages.

    @classmethod
    def load_definition(cls, xml_object, system, location, id_generator):  # lint-amnesty, pylint: disable=arguments-differ
        '''Load a descriptor from the specified xml_object:

        If there is a filename attribute, load it as a string, and
        log a warning if it is not parseable by etree.HTMLParser.

        If there is not a filename attribute, the definition is the body
        of the xml_object, without the root tag (do not want <html> in the
        middle of a page)

        Args:
            xml_object: an lxml.etree._Element containing the definition to load
            system: the modulestore system or runtime which caches data
            location: the usage id for the block--used to compute the filename if none in the xml_object
            id_generator: used by other impls of this method to generate the usage_id
        '''
        filename = xml_object.get('filename')
        if filename is None:
            definition_xml = copy.deepcopy(xml_object)
            cls.clean_metadata_from_xml(definition_xml)
            return {'data': stringify_children(definition_xml)}, []
        else:
            # html is special.  cls.filename_extension is 'xml', but
            # if 'filename' is in the definition, that means to load
            # from .html
            # 'filename' in html pointers is a relative path
            # (not same as 'html/blah.html' when the pointer is in a directory itself)
            pointer_path = "{category}/{url_path}".format(
                category='html',
                url_path=name_to_pathname(location.block_id)
            )
            base = path(pointer_path).dirname()
            # log.debug("base = {0}, base.dirname={1}, filename={2}".format(base, base.dirname(), filename))
            filepath = f"{base}/{filename}.html"
            # log.debug("looking for html file for {0} at {1}".format(location, filepath))

            # VS[compat]
            # TODO (cpennington): If the file doesn't exist at the right path,
            # give the class a chance to fix it up. The file will be written out
            # again in the correct format.  This should go away once the CMS is
            # online and has imported all current (fall 2012) courses from xml
            if not system.resources_fs.exists(filepath):

                candidates = cls.backcompat_paths(filepath)
                # log.debug("candidates = {0}".format(candidates))
                for candidate in candidates:
                    if system.resources_fs.exists(candidate):
                        filepath = candidate
                        break

            try:
                with system.resources_fs.open(filepath, encoding='utf-8') as infile:
                    html = infile.read()
                    # Log a warning if we can't parse the file, but don't error
                    if not check_html(html) and len(html) > 0:
                        msg = f"Couldn't parse html in {filepath}, content = {html}"
                        log.warning(msg)
                        system.error_tracker("Warning: " + msg)

                    definition = {'data': html}

                    # TODO (ichuang): remove this after migration
                    # for Fall 2012 LMS migration: keep filename (and unmangled filename)
                    definition['filename'] = [filepath, filename]

                    return definition, []

            except ResourceNotFound as err:
                msg = 'Unable to load file contents at path {}: {} '.format(
                    filepath, err)
                # add more info and re-raise
                raise Exception(msg).with_traceback(sys.exc_info()[2])

    @classmethod
    def parse_xml_new_runtime(cls, node, runtime, keys):
        """
        Parse XML in the new blockstore-based runtime. Since it doesn't yet
        support loading separate .html files, the HTML data is assumed to be in
        a CDATA child or otherwise just inline in the OLX.
        """
        block = runtime.construct_xblock_from_class(cls, keys)
        block.data = stringify_children(node)
        # Attributes become fields.
        for name, value in node.items():
            cls._set_field_if_present(block, name, value, {})
        return block

    # TODO (vshnayder): make export put things in the right places.

    def definition_to_xml(self, resource_fs):
        ''' Write <html filename="" [meta-attrs="..."]> to filename.xml, and the html
        string to filename.html.
        '''

        # Write html to file, return an empty tag
        pathname = name_to_pathname(self.url_name)
        filepath = '{category}/{pathname}.html'.format(
            category=self.category,
            pathname=pathname
        )

        resource_fs.makedirs(os.path.dirname(filepath), recreate=True)
        with resource_fs.open(filepath, 'wb') as filestream:
            html_data = self.data.encode('utf-8')
            filestream.write(html_data)

        # write out the relative name
        relname = path(pathname).basename()

        elt = etree.Element('html')
        elt.set("filename", relname)
        return elt

    @property
    def non_editable_metadata_fields(self):
        """
        `use_latex_compiler` should not be editable in the Studio settings editor.
        """
        non_editable_fields = super().non_editable_metadata_fields
        non_editable_fields.append(HtmlBlockMixin.use_latex_compiler)
        return non_editable_fields

    def index_dictionary(self):
        xblock_body = super().index_dictionary()
        # Removing script and style
        html_content = re.sub(
            re.compile(
                r"""
                    <script>.*?</script> |
                    <style>.*?</style>
                """,
                re.DOTALL |
                re.VERBOSE),
            "",
            self.data
        )
        html_content = escape_html_characters(html_content)
        html_body = {
            "html_content": html_content,
            "display_name": self.display_name,
        }
        if "content" in xblock_body:
            xblock_body["content"].update(html_body)
        else:
            xblock_body["content"] = html_body
        xblock_body["content_type"] = "Text"
        return xblock_body


@edxnotes
class HtmlBlock(HtmlBlockMixin):  # lint-amnesty, pylint: disable=abstract-method
    """
    This is the actual HTML XBlock.
    Nothing extra is required; this is just a wrapper to include edxnotes support.
    """


class AboutFields:  # lint-amnesty, pylint: disable=missing-class-docstring
    display_name = String(
        help=_("The display name for this component."),
        scope=Scope.settings,
        default="overview",
    )
    data = String(
        help=_("Html contents to display for this block"),
        default="",
        scope=Scope.content
    )


@XBlock.tag("detached")
class AboutBlock(AboutFields, HtmlBlockMixin):  # lint-amnesty, pylint: disable=abstract-method
    """
    These pieces of course content are treated as HtmlBlocks but we need to overload where the templates are located
    in order to be able to create new ones
    """
    template_dir_name = "about"


class StaticTabFields:
    """
    The overrides for Static Tabs
    """
    display_name = String(
        display_name=_("Display Name"),
        help=_("The display name for this component."),
        scope=Scope.settings,
        default="Empty",
    )
    course_staff_only = Boolean(
        display_name=_("Hide Page From Learners"),
        help=_("If you select this option, only course team members with"
               " the Staff or Admin role see this page."),
        default=False,
        scope=Scope.settings
    )
    data = String(
        default=textwrap.dedent("""\
            <p>Add the content you want students to see on this page.</p>
        """),
        scope=Scope.content,
        help=_("HTML for the additional pages")
    )


@XBlock.tag("detached")
class StaticTabBlock(StaticTabFields, HtmlBlockMixin):  # lint-amnesty, pylint: disable=abstract-method
    """
    These pieces of course content are treated as HtmlBlocks but we need to overload where the templates are located
    in order to be able to create new ones
    """
    template_dir_name = None


class CourseInfoFields:
    """
    Field overrides
    """
    items = List(
        help=_("List of course update items"),
        default=[],
        scope=Scope.content
    )
    data = String(
        help=_("Html contents to display for this block"),
        default="<ol></ol>",
        scope=Scope.content
    )


@XBlock.tag("detached")
@XBlock.needs('replace_urls')
class CourseInfoBlock(CourseInfoFields, HtmlBlockMixin):  # lint-amnesty, pylint: disable=abstract-method
    """
    These pieces of course content are treated as HtmlBlock but we need to overload where the templates are located
    in order to be able to create new ones
    """
    # statuses
    STATUS_VISIBLE = 'visible'
    STATUS_DELETED = 'deleted'
    TEMPLATE_DIR = 'courseware'

    template_dir_name = None

    def get_html(self):
        """ Returns html required for rendering XModule. """

        # When we switch this to an XBlock, we can merge this with student_view,
        # but for now the XModule mixin requires that this method be defined.
        data = super().get_html()
        if data != "":
            return data
        else:
            # This should no longer be called on production now that we are using a separate updates page
            # and using a fragment HTML file - it will be called in tests until those are removed.
            course_updates = self.order_updates(self.items)
            context = {
                'visible_updates': course_updates[:3],
                'hidden_updates': course_updates[3:],
            }
            return self.runtime.service(self, 'mako').render_template(
                f"{self.TEMPLATE_DIR}/course_updates.html",
                context,
            )

    @classmethod
    def order_updates(self, updates):  # lint-amnesty, pylint: disable=bad-classmethod-argument
        """
        Returns any course updates in reverse chronological order.
        """
        sorted_updates = [update for update in updates if update.get('status') == self.STATUS_VISIBLE]
        sorted_updates.sort(
            key=lambda item: (self.safe_parse_date(item['date']), item['id']),
            reverse=True
        )
        return sorted_updates

    @staticmethod
    def safe_parse_date(date):
        """
        Since this is used solely for ordering purposes, use today's date as a default
        """
        try:
            return datetime.strptime(date, '%B %d, %Y')
        except ValueError:  # occurs for ill-formatted date values
            return datetime.today()