Show content metadata on link topic comments pages

Very basic version - should probably exclude some of the fields (like
domain) and do some other changes in addition to this, but it's a
reasonable start.

tildes/scss/modules/_topic.scss

@@ -268,6 +268,35 @@
   font-size: 0.6rem;
 }
 
+.topic-full-content-metadata {
+  margin: 1rem 0 1rem 1rem;
+
+  h2 {
+    font-size: 0.8rem;
+  }
+
+  dl {
+    display: grid;
+    grid-template-columns: max-content minmax(auto, $paragraph-max-width);
+    align-items: baseline;
+
+    margin: 0;
+  }
+
+  dt {
+    grid-column-start: 1;
+    padding: 0.2rem;
+    font-size: 0.6rem;
+  }
+
+  dd {
+    grid-column-start: 2;
+    margin: 0;
+    padding: 0.2rem;
+    font-size: 0.6rem;
+  }
+}
+
 .topic-full-tags {
   margin-bottom: 0.4rem;
   font-size: 0.6rem;

tildes/tildes/enums.py

@@ -100,6 +100,11 @@ class ContentMetadataFields(enum.Enum):
         """Return the key to store this field under."""
         return self.name.lower()
 
+    @property
+    def display_name(self) -> str:
+        """Return the field's name in a format more suitable for display."""
+        return self.name.replace("_", " ").capitalize()
+
     @classmethod
     def detail_fields_for_content_type(
         cls, content_type: "TopicContentType",

tildes/tildes/models/topic/topic.py

@@ -519,6 +519,23 @@ class Topic(DatabaseModel):
 
         return ", ".join(metadata_strings)
 
+    @property
+    def content_metadata_fields_for_display(self) -> Dict[str, str]:
+        """Return a dict of the metadata fields and values, suitable for display."""
+        if not self.content_metadata:
+            return {}
+
+        output_fields = {}
+        for field_name, value in self.content_metadata.items():
+            try:
+                field = ContentMetadataFields[field_name.upper()]
+            except KeyError:
+                continue
+
+            output_fields[field.display_name] = field.format_value(value)
+
+        return output_fields
+
     @property
     def content_excerpt(self) -> Optional[str]:
         """Return the topic's content excerpt (if it has one)."""

tildes/tildes/templates/topic.jinja2

@@ -79,6 +79,10 @@
     {% if topic.additional_content_html %}
       <div class="topic-full-content">{{ topic.additional_content_html|safe }}</div>
     {% endif %}
+
+    {% if topic.content_metadata %}
+      {{ content_metadata(topic) }}
+    {% endif %}
   {% endif %}
 {% endif %}
 
@@ -300,3 +304,16 @@
   {% endif %}
 </dl>
 {% endblock %}
+
+{% macro content_metadata(topic) %}
+  <section class="topic-full-content-metadata">
+  <h2>Link information</h2>
+  <p class="text-small text-secondary">This data is scraped automatically and may be incorrect.</p>
+  <dl>
+  {% for field, value in topic.content_metadata_fields_for_display.items() %}
+    <dt>{{ field }}</dt>
+    <dd>{{ value }}</dd>
+  {% endfor %}
+  </dl>
+  </section>
+{% endmacro %}