renamed old sg stuff to blag

blag/markdown.py

@@ -0,0 +1,102 @@
+from datetime import datetime
+import logging
+from urllib.parse import urlsplit, urlunsplit
+
+from markdown import Markdown
+from markdown.extensions import Extension
+from markdown.treeprocessors import Treeprocessor
+
+
+logger = logging.getLogger(__name__)
+
+
+def markdown_factory():
+    """Create a Markdown instance.
+
+    This method exists only to ensure we use the same Markdown instance
+    for tests as for the actual thing.
+
+    Returns
+    -------
+    markdown.Markdown
+
+    """
+    md = Markdown(
+        extensions=[
+            'meta', 'fenced_code', 'codehilite',
+            MarkdownLinkExtension()
+        ],
+        output_format='html5',
+    )
+    return md
+
+
+def convert_markdown(md, markdown):
+    """Convert markdown into html and extract meta data.
+
+    Parameters
+    ----------
+    md : markdown.Markdown instance
+    markdown : str
+
+    Returns
+    -------
+    str, dict :
+        html and metadata
+
+    """
+    md.reset()
+    content = md.convert(markdown)
+    meta = md.Meta
+
+    # markdowns metadata consists as list of strings -- one item per
+    # line. let's convert into single strings.
+    for key, value in meta.items():
+        value = '\n'.join(value)
+        meta[key] = value
+
+    # convert known metadata
+    # date: datetime
+    if 'date' in meta:
+        meta['date'] = datetime.fromisoformat(meta['date'])
+    # tags: list[str]
+    if 'tags' in meta:
+        tags = meta['tags'].split(',')
+        tags = [t.strip() for t in tags]
+        meta['tags'] = tags
+
+    return content, meta
+
+
+class MarkdownLinkTreeprocessor(Treeprocessor):
+    """Converts relative links to .md files to .html
+
+    """
+
+    def run(self, root):
+        for element in root.iter():
+            if element.tag == 'a':
+                url = element.get('href')
+                converted = self.convert(url)
+                element.set('href', converted)
+        return root
+
+    def convert(self, url):
+        scheme, netloc, path, query, fragment = urlsplit(url)
+        logger.debug(
+            f'{url}: {scheme=} {netloc=} {path=} {query=} {fragment=}'
+        )
+        if (scheme or netloc or not path):
+            return url
+        if path.endswith('.md'):
+            path = path[:-3] + '.html'
+
+        url = urlunsplit((scheme, netloc, path, query, fragment))
+        return url
+
+
+class MarkdownLinkExtension(Extension):
+    def extendMarkdown(self, md):
+        md.treeprocessors.register(
+                MarkdownLinkTreeprocessor(md), 'mdlink', 0,
+        )