1 files changed, 117 insertions, 0 deletions
diff --git a/mediagoblin/tools/text.py b/mediagoblin/tools/text.py
new file mode 100644
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+++ b/mediagoblin/tools/text.py
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+# GNU MediaGoblin -- federated, autonomous media hosting
+# Copyright (C) 2011 MediaGoblin contributors.  See AUTHORS.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import wtforms
+import markdown
+from lxml.html.clean import Cleaner
+
+from mediagoblin import mg_globals
+from mediagoblin.tools import url
+
+# A super strict version of the lxml.html cleaner class
+HTML_CLEANER = Cleaner(
+    scripts=True,
+    javascript=True,
+    comments=True,
+    style=True,
+    links=True,
+    page_structure=True,
+    processing_instructions=True,
+    embedded=True,
+    frames=True,
+    forms=True,
+    annoying_tags=True,
+    allow_tags=[
+        'div', 'b', 'i', 'em', 'strong', 'p', 'ul', 'ol', 'li', 'a', 'br'],
+    remove_unknown_tags=False, # can't be used with allow_tags
+    safe_attrs_only=True,
+    add_nofollow=True, # for now
+    host_whitelist=(),
+    whitelist_tags=set([]))
+
+def clean_html(html):
+    # clean_html barfs on an empty string
+    if not html:
+        return u''
+
+    return HTML_CLEANER.clean_html(html)
+
+def convert_to_tag_list_of_dicts(tag_string):
+    """
+    Filter input from incoming string containing user tags,
+
+    Strips trailing, leading, and internal whitespace, and also converts
+    the "tags" text into an array of tags
+    """
+    taglist = []
+    if tag_string:
+
+        # Strip out internal, trailing, and leading whitespace
+        stripped_tag_string = u' '.join(tag_string.strip().split())
+
+        # Split the tag string into a list of tags
+        for tag in stripped_tag_string.split(
+                                       mg_globals.app_config['tags_delimiter']):
+
+            # Ignore empty or duplicate tags
+            if tag.strip() and tag.strip() not in [t['name'] for t in taglist]:
+
+                taglist.append({'name': tag.strip(),
+                                'slug': url.slugify(tag.strip())})
+    return taglist
+
+def media_tags_as_string(media_entry_tags):
+    """
+    Generate a string from a media item's tags, stored as a list of dicts
+
+    This is the opposite of convert_to_tag_list_of_dicts
+    """
+    media_tag_string = ''
+    if media_entry_tags:
+        media_tag_string = mg_globals.app_config['tags_delimiter'].join(
+                                      [tag['name'] for tag in media_entry_tags])
+    return media_tag_string
+
+TOO_LONG_TAG_WARNING = \
+    u'Tags must be shorter than %s characters.  Tags that are too long: %s'
+
+def tag_length_validator(form, field):
+    """
+    Make sure tags do not exceed the maximum tag length.
+    """
+    tags = convert_to_tag_list_of_dicts(field.data)
+    too_long_tags = [
+        tag['name'] for tag in tags
+        if len(tag['name']) > mg_globals.app_config['tags_max_length']]
+
+    if too_long_tags:
+        raise wtforms.ValidationError(
+            TOO_LONG_TAG_WARNING % (mg_globals.app_config['tags_max_length'], \
+                                    ', '.join(too_long_tags)))
+
+
+MARKDOWN_INSTANCE = markdown.Markdown(safe_mode='escape')
+
+def cleaned_markdown_conversion(text):
+    """
+    Take a block of text, run it through MarkDown, and clean its HTML.
+    """
+    # Markdown will do nothing with and clean_html can do nothing with
+    # an empty string :)
+    if not text:
+        return u''
+
+    return clean_html(MARKDOWN_INSTANCE.convert(text))