Implement OVER command

lib/nntp/tiny/session.py

@@ -588,6 +588,62 @@ class Session():
 
         return self.end()
 
+    def _message_overview(self, message: Message) -> dict:
+        return map(lambda s: s.replace('\t', ' '), [
+            str(message.id),
+            message.subject,
+            message.sender,
+            message.created_on.isoformat(),
+            message.message_id,
+            message.parent_id or '',
+            str(len(message.body)),
+            str(message.body.count('\n') + 1),
+        ])
+
+    def _cmd_over(self, identifier: Optional[str]=None):
+        if identifier is None:
+            if self.newsgroup is None:
+                return self.respond(ResponseCode.NNTP_NEWSGROUP_NOT_SELECTED)
+
+            if self.article_id is None:
+                return self.respond(ResponseCode.NNTP_ARTICLE_INVALID_NUMBER)
+
+            message = self.db.get(Message, self.article_id)
+
+            if message is None:
+                return self.respond(ResponseCode.NNTP_ARTICLE_INVALID_NUMBER)
+        elif identifier[0] == '<':
+            message = self.db.query(Message, {
+                'message_id': identifier
+            }).fetchone()
+
+            if message is None:
+                return self.respond(ResponseCode.NNTP_ARTICLE_NOT_FOUND_ID)
+        else:
+            if self.newsgroup is None:
+                return self.respond(ResponseCode.NNTP_NEWSGROUP_NOT_SELECTED)
+
+            msgrange = MessageRange.parse(identifier)
+
+            sql  = f"select * from {Message.name} where "
+            sql += " newsgroup_id = ? and " + msgrange.where()
+
+            cr = self.db.query_sql(Message, sql, (self.newsgroup.id,))
+
+            first = True
+
+            for message in cr.each():
+                if first:
+                    first = False
+                    self.respond(ResponseCode.NNTP_OVERVIEW_FOLLOWS)
+
+                overview = self._message_overview(message)
+
+                self.print('|'.join(overview))
+
+            if first:
+                return self.respond(ResponseCode.NNTP_ARTICLE_NOT_FOUND_RANGE)
+
     def _cmd_stat(self, identifier: Optional[str]=None):
         if self.newsgroup is None:
             return self.respond(ResponseCode.NNTP_NEWSGROUP_NOT_SELECTED)
@@ -659,6 +715,7 @@ class Session():
         'ARTICLE':      _cmd_article,
         'HDR':          _cmd_hdr,
         'XHDR':         _cmd_hdr,
+        'OVER':         _cmd_over,
         'STAT':         _cmd_stat,
         'DATE':         _cmd_date,
         'QUIT':         _cmd_quit,