Refactor OVER, HDR

Refactor OVER, HDR to be simpler, using a single convenience method to
implement similar semantics for commands which operate on both single
and ranges of messages

lib/nntp/tiny/session.py

@@ -518,17 +518,62 @@ class Session():
 
         return self.end()
 
-    def _message_by_id(self, identifier: str):
+    def _each_message_by_id(self, identifier: str):
-        if identifier[0] == '<':
+        if identifier is None:
-            return self.db.get(Message, {
+            if self.newsgroup is None:
-                'newsgroup_id': self.newsgroup.id,
+                self.respond(ResponseCode.NNTP_NEWSGROUP_NOT_SELECTED)
-                'message_id':   identifier
+                return
-            })
+
+            if self.article_id is None:
+                self.respond(ResponseCode.NNTP_ARTICLE_INVALID_NUMBER)
+                return
+
+            message = self.db.get(Message, self.article_id)
+
+            if message is None:
+                self.respond(ResponseCode.NNTP_ARTICLE_INVALID_NUMBER)
+                return
+
+            self.respond(ResponseCode.NNTP_INFORMATION_FOLLOWS)
+
+            yield message
+        elif identifier[0] == '<':
+            message = self.db.query(Message, {
+                'message_id': identifier
+            }).fetchone()
+
+            if message is None:
+                self.respond(ResponseCode.NNTP_ARTICLE_NOT_FOUND_ID)
+                return
+
+            self.respond(ResponseCode.NNTP_INFORMATION_FOLLOWS)
+
+            yield message
         else:
-            return self.db.get(Message, {
+            if self.newsgroup is None:
-                'newsgroup_id': self.newsgroup.id,
+                self.respond(ResponseCode.NNTP_NEWSGROUP_NOT_SELECTED)
-                'id':           int(identifier)
+                return
-            })
+
+            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_INFORMATION_FOLLOWS)
+
+                yield message
+
+            if first:
+                self.respond(ResponseCode.NNTP_ARTICLE_NOT_FOUND_RANGE)
+
+        self.end()
 
     def _send_message_headers(self, message: Message):
         for name in message.headers:
@@ -587,39 +632,9 @@ class Session():
             message.id, message.headers.get(name, '')
         ))
 
-    def _cmd_hdr(self, name: str, msg: Optional[str]=None):
+    def _cmd_hdr(self, name: str, identifier: Optional[str]=None):
-        if self.newsgroup is None:
+        for message in self._each_message_by_id(identifier):
-            return self.respond(ResponseCode.NNTP_NEWSGROUP_NOT_SELECTED)
-
-        if msg is None:
-            if self.article_id is None:
-                return self.respond(ResponseCode.NNTP_ARTICLE_INVALID_NUMBER)
-
-            message = self.db.get(Message, self.article_id)
-
-            self.respond(ResponseCode.NNTP_HEADERS_FOLLOW)
             self._send_message_header(message, name)
-        else:
-            msgrange = MessageRange.parse(msg)
-
-            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_HEADERS_FOLLOW)
-
-                self._send_message_header(message, name)
-
-            if first:
-                return self.respond(ResponseCode.NNTP_ARTICLE_NOT_FOUND_RANGE)
-
-        return self.end()
 
     def _message_overview(self, message: Message) -> dict:
         return map(lambda s: s.replace('\t', ' '), [
@@ -634,48 +649,10 @@ class Session():
         ])
 
     def _cmd_over(self, identifier: Optional[str]=None):
-        if identifier is None:
+        for message in self._each_message_by_id(identifier):
-            if self.newsgroup is None:
+            overview = self._message_overview(message)
-                return self.respond(ResponseCode.NNTP_NEWSGROUP_NOT_SELECTED)
 
-            if self.article_id is None:
+            self.print('|'.join(overview))
-                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: