Switch to markdown-it (#595)

Fixes #537, fixes #586

app/markdown/__init__.py

@@ -0,0 +1,106 @@
+# ContentDB
+# Copyright (C) rubenwardy
+#
+# 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 <https://www.gnu.org/licenses/>.
+
+from typing import Sequence
+from urllib.parse import urljoin
+from bs4 import BeautifulSoup
+from jinja2.utils import markupsafe
+from markdown_it import MarkdownIt
+from markdown_it.common.utils import unescapeAll, escapeHtml
+from markdown_it.token import Token
+from markdown_it.presets import gfm_like
+from pygments import highlight
+from pygments.lexers import get_lexer_by_name
+from pygments.formatters.html import HtmlFormatter
+
+from .cleaner import clean_html
+from .mention import init_mention
+
+
+def highlight_code(code, name, attrs):
+	if name == "":
+		return None
+
+	lexer = get_lexer_by_name(name)
+	formatter = HtmlFormatter()
+
+	return highlight(code, lexer, formatter)
+
+
+def render_code(self, tokens: Sequence[Token], idx, options, env):
+	token = tokens[idx]
+	info = unescapeAll(token.info).strip() if token.info else ""
+	langName = info.split(maxsplit=1)[0] if info else ""
+
+	if options.highlight:
+		return options.highlight(
+			token.content, langName, ""
+		) or f"<pre><code>{escapeHtml(token.content)}</code></pre>"
+
+	return f"<pre><code>{escapeHtml(token.content)}</code></pre>"
+
+
+
+gfm_like.make()
+md = MarkdownIt("gfm-like", {"highlight": highlight_code})
+md.add_render_rule("fence", render_code)
+init_mention(md)
+
+
+def render_markdown(source):
+	html = md.render(source)
+	return clean_html(html)
+
+
+def init_markdown(app):
+	@app.template_filter()
+	def markdown(source):
+		return markupsafe.Markup(render_markdown(source))
+
+
+def get_headings(html: str):
+	soup = BeautifulSoup(html, "html.parser")
+	headings = soup.find_all(["h1", "h2", "h3"])
+
+	root = []
+	stack = []
+	for heading in headings:
+		this = {"link": heading.get("id") or "", "text": heading.text, "children": []}
+		this_level = int(heading.name[1:]) - 1
+
+		while this_level <= len(stack):
+			stack.pop()
+
+		if len(stack) > 0:
+			stack[-1]["children"].append(this)
+		else:
+			root.append(this)
+
+		stack.append(this)
+
+	return root
+
+
+def get_user_mentions(html: str) -> set:
+	soup = BeautifulSoup(html, "html.parser")
+	links = soup.select("a[data-username]")
+	return set([x.get("data-username") for x in links])
+
+
+def get_links(html: str, url: str) -> set:
+	soup = BeautifulSoup(html, "html.parser")
+	links = soup.select("a[href]")
+	return set([urljoin(url, x.get("href")) for x in links])