Implement MIME header decoding

lib/nntp/tiny/mbox.py

@@ -2,6 +2,7 @@ import re
 import enum
 
 from dateparser.search import search_dates
+from email.header      import decode_header
 
 class MBoxReaderError(Exception):
     pass
@@ -62,6 +63,14 @@ class MBoxMessageState(enum.Enum):
     HEADER = 1
     BODY   = 2
 
+def decode(text: str):
+    decoded = decode_header(text)[0]
+
+    if decoded[1] is None:
+        return decoded[0]
+
+    return str(decoded[0], decoded[1])
+
 class MBoxMessage():
     __slots__ = 'state', 'headers', 'line', 'content', 'body', 'key',
 
@@ -84,14 +93,14 @@ class MBoxMessage():
             if line == '\n' or line == '\r\n':
                 self.state = MBoxMessageState.BODY
             elif line[0] == ' ' or line[0] == '\t':
-                self.headers[self.key] += ' ' + line.strip()
+                self.headers[self.key] += ' ' + decode(line.strip())
             else:
                 match = re.match('^([^:]+): (.*)$', line)
 
                 if match:
                     self.key = match[1].lower()
 
-                    self.headers[self.key] = match[2].rstrip()
+                    self.headers[self.key] = decode(match[2].rstrip())
         elif self.state is MBoxMessageState.BODY:
             if self.body is None:
                 self.body = ''