Implement method to fetch message summaries from newsgroups

lib/nntp/tiny/client.py

@@ -2,15 +2,19 @@ import re
 import socket
 import ssl
 import datetime
+import email.utils
 
 from typing import Optional
 
 from nntp.tiny.socket   import Connection
 from nntp.tiny.host     import Host
 from nntp.tiny.response import Response, ResponseCode
-from nntp.tiny.remote   import RemoteNewsgroup
 from nntp.tiny.message  import MessageRange
 
+from nntp.tiny.remote import (
+    RemoteException, RemoteNewsgroup, RemoteMessage
+)
+
 class ClientException(Exception):
     pass
 
@@ -62,7 +66,12 @@ class Client(Connection):
     def request(self, *args):
         self.print(' '.join(args))
 
-        return self._read_response()
+        response = self._read_response()
+
+        if response.code.value >= 400:
+            raise RemoteException(response)
+
+        return response
 
     def each_response_line(self):
         while True:
@@ -88,9 +97,33 @@ class Client(Connection):
             parts = self.RE_SPLIT.split(line)
 
             if len(parts) != 4:
-                raise ClientException('Unexpected result from NEWGROUPS')
+                raise RemoteException('Unexpected result from NEWGROUPS')
             
             yield RemoteNewsgroup(parts[0],
                                   int(parts[1]),
                                   int(parts[2]),
                                   parts[3] == 'y')
+
+    def each_newsgroup_message(self, newsgroup: RemoteNewsgroup, msgrange: Optional[MessageRange]):
+        self.request('GROUP', newsgroup.name)
+        self.request('OVER',  str(msgrange))
+
+        for line in self.each_response_line():
+            message = RemoteMessage()
+            parts   = line.split('\t')
+
+            message.id         = int(parts[0])
+            message.subject    = parts[1]
+            message.sender     = parts[2]
+            message.created_on = email.utils.parsedate_to_datetime(parts[3])
+            message.message_id = parts[4]
+            message.references = parts[5]
+            message.size       = int(parts[6])
+            message.lines      = int(parts[7])
+
+            for part in parts[8:]:
+                key, value = part.split(': ')
+
+                message.headers[key] = value
+
+            yield message

lib/nntp/tiny/remote.py

@@ -1,11 +1,14 @@
+class RemoteException(Exception):
+    pass
+
 class RemoteNewsgroup():
     __slots__ = 'name', 'low', 'high', 'post',
     
     def __init__(self, name: str, low: int, high: int, post: bool):
-        self.name = name
-        self.low  = low
-        self.high = high
-        self.post = post
+        self.name: str  = name
+        self.low:  int  = low
+        self.high: int  = high
+        self.post: bool = post
 
     def __str__(self):
         return "%s %d %d %s" % (
@@ -14,3 +17,12 @@ class RemoteNewsgroup():
             self.high,
             'y' if self.post else 'n'
         )
+
+class RemoteMessage():
+    __slots__ = (
+        'id', 'subject', 'sender', 'created_on', 'message_id',
+        'references', 'size', 'lines', 'headers'
+    )
+
+    def __init__(self):
+        self.headers = dict()