Infer the title of an article/file when not specified in the header metadata

Infer the title from the first line of the file if it's a header,
otherwise use the filename.

madblog/app.py

@@ -12,6 +12,8 @@ from .latex import MarkdownLatex
 
 
 class BlogApp(Flask):
+    _title_header_regex = re.compile(r'^#\s*((\[(.*)\])|(.*))')
+
     def __init__(self, *args, **kwargs):
         super().__init__(*args, template_folder=config.templates_dir, **kwargs)
         self.pages_dir = os.path.join(config.content_dir, 'markdown')
@@ -62,10 +64,27 @@ class BlogApp(Flask):
                 else:
                     metadata[m.group(1)] = m.group(2)
 
+        if not metadata.get('title'):
+            # If the `title` header isn't available in the file,
+            # infer it from the first line of the file
+            with open(md_file, 'r') as f:
+                header = ''
+                for line in f.readlines():
+                    header = line
+                    break
+
+            metadata['title_inferred'] = True
+            m = self._title_header_regex.search(header)
+            if m:
+                metadata['title'] = m.group(3) or m.group(1)
+            else:
+                metadata['title'] = os.path.basename(md_file)
+
         if not metadata.get('published'):
             # If the `published` header isn't available in the file,
             # infer it from the file's creation date
             metadata['published'] = datetime.date.fromtimestamp(os.stat(md_file).st_ctime)
+            metadata['published_inferred'] = True
 
         return metadata
 
@@ -74,17 +93,30 @@ class BlogApp(Flask):
             page = page + '.md'
 
         metadata = self.get_page_metadata(page)
+        # Don't duplicate the page title if it's been inferred
+        if not (title or metadata.get('title_inferred')):
+            title = metadata.get('title', config.title)
+
         with open(os.path.join(self.pages_dir, page), 'r') as f:
             return render_template(
                 'article.html',
                 config=config,
-                    title=title if title else metadata.get('title', config.title),
+                title=title,
                 image=metadata.get('image'),
                 description=metadata.get('description'),
-                    author=re.match(r'(.+?)\s+<([^>]+>)', metadata['author'])[1] if 'author' in metadata else None,
+                author=(
-                    author_email=re.match(r'(.+?)\s+<([^>]+)>', metadata['author'])[2] if 'author' in metadata else None,
+                    re.match(r'(.+?)\s+<([^>]+>)', metadata['author'])[1]
-                    published=(metadata['published'].strftime('%b %d, %Y')
+                    if 'author' in metadata else None
-                               if metadata.get('published') else None),
+                ),
+                author_email=(
+                    re.match(r'(.+?)\s+<([^>]+)>', metadata['author'])[2]
+                    if 'author' in metadata else None
+                ),
+                published=(
+                    metadata['published'].strftime('%b %d, %Y')
+                    if metadata.get('published') and not metadata.get('published_inferred')
+                    else None
+                ),
                 content=markdown(f.read(), extensions=['fenced_code', 'codehilite', MarkdownLatex()]),
                 skip_header=skip_header
             )

madblog/templates/article.html

@@ -1,13 +1,15 @@
-{% with title=title or config.title or 'Blog', skip_header=skip_header or not config.header, styles=['/css/blog.css', '/css/code.css'] %}
+{% with title=title, skip_header=skip_header or not config.header, styles=['/css/blog.css', '/css/code.css'] %}
     {% include 'common-head.html' %}
 {% endwith %}
 
 <main>
     <div class="container">
         {% if not skip_header %}
+            {% if title %}
               <div class="title">
                   <h1>{{ title }}</h1>
               </div>
+            {% endif %}
 
             {% if description %}
             <div class="description">