def _generate_text_metadata(topic: Topic) -> None:
"""Generate metadata for a text topic (word count and excerpt)."""
html_tree = HTMLParser().parseFragment(topic.rendered_html)
# extract the text from all of the HTML elements
extracted_text = ''.join(
[element_text for element_text in html_tree.itertext()])
# sanitize unicode, remove leading/trailing whitespace, etc.
extracted_text = simplify_string(extracted_text)
# create a short excerpt by truncating the simplified string
excerpt = truncate_string(
extracted_text,
length=200,
truncate_at_chars=' ',
)
topic.content_metadata = {
'word_count': word_count(extracted_text),
'excerpt': excerpt,
}
