Use homegrown date parsing

lib/nntp/tiny/message.py

@@ -2,8 +2,7 @@ import re
 import enum
 import datetime
 
-from dateparser.search import search_dates
+from email.header import decode_header
-from email.header      import decode_header
 
 from nntp.tiny.db import DatabaseTable
 
@@ -42,6 +41,61 @@ def each_line(text: str):
             yield text[start:end]
             break
 
+DATE_MONTHS = {
+    'jan':  1, 'january':    1,
+    'feb':  2, 'february':   2,
+    'mar':  3, 'march':      3,
+    'apr':  4, 'april':      4,
+    'may':  5,
+    'jun':  6, 'june':       6,
+    'jul':  7, 'july':       7,
+    'aug':  8, 'august':     8,
+    'sep':  9, 'september':  9,
+    'oct': 10, 'october':   10,
+    'nov': 11, 'november':  11,
+    'dec': 12, 'december':  12
+}
+
+DATE_RE = [
+    re.compile(r'^(?:[A-Za-z]+),\s+(?P<dd>\d{1,2}) (?P<month>[A-Za-z]+) (?P<yyyy>\d{4}) (?P<hh>\d{2}):(?P<MM>\d{2}):(?P<ss>\d{2}) (?P<offset_sign>[+\-])(?P<offset_hour>\d{2})(?P<offset_minute>\d{2})$'),
+    re.compile(r'^(?:[A-Za-z]+),\s+(?P<dd>\d{1,2}) (?P<month>[A-Za-z]+) (?P<yyyy>\d{4}) (?P<hh>\d{2}):(?P<MM>\d{2}):(?P<ss>\d{2}) (?P<offset_sign>[+\-])(?P<offset_hour>\d{2})(?P<offset_minute>\d{2}) \((?:[A-Za-z ]+)\)$'),
+    re.compile(r'^(?:[A-Za-z]+),\s+(?P<dd>\d{1,2}) (?P<month>[A-Za-z]+) (?P<yyyy>\d{4}) (?P<hh>\d{2}):(?P<MM>\d{2}):(?P<ss>\d{2}) (?:GMT|UTC)$'),
+    re.compile(r'^(?:[A-Za-z]+),\s+(?P<dd>\d{1,2}) (?P<month>[A-Za-z]+) (?P<yyyy>\d{4}) (?P<hh>\d{2}):(?P<MM>\d{2}) (?P<offset_sign>[+\-])(?P<offset_hour>\d{2})(?P<offset_minute>\d{2})$'),
+    re.compile(r'^(?:[A-Za-z]+),\s+(?P<dd>\d{1,2}) (?P<month>[A-Za-z]+) (?P<yyyy>\d{4}) (?P<hh>\d{2}):(?P<MM>\d{2}) (?P<offset_sign>[+\-])(?P<offset_hour>\d{2})(?P<offset_minute>\d{2}) \((?:[A-Z ]+)\)$'),
+    re.compile(r'^(?:[A-Za-z]+),\s+(?P<dd>\d{1,2}) (?P<month>[A-Za-z]+) (?P<yyyy>\d{4}) (?P<hh>\d{2}):(?P<MM>\d{2}) (?:GMT|UTC)$'),
+    re.compile(r'^(?P<dd>\d{1,2}) (?P<month>[A-Za-z]+) (?P<yyyy>\d{4}) (?P<hh>\d{2}):(?P<MM>\d{2}):(?P<ss>\d{2}) (?P<offset_sign>[+\-])(?P<offset_hour>\d{2})(?P<offset_minute>\d{2})$'),
+    re.compile(r'^(?P<dd>\d{1,2}) (?P<month>[A-Za-z]+) (?P<yyyy>\d{4}) (?P<hh>\d{2}):(?P<MM>\d{2}):(?P<ss>\d{2}) (?:GMT|UTC)$'),
+]
+
+def parse_timestamp(timestamp: str):
+    if timestamp is None or timestamp == '':
+        return datetime.datetime.fromtimestamp(0)
+
+    for re in DATE_RE:
+        match = re.match(timestamp)
+
+        if match is not None:
+            capture = match.groupdict()
+            mult    = -1 if capture.get('offset_sign', '+') == '-' else 1
+            tz      = datetime.timezone(datetime.timedelta(
+                hours   = mult * int(capture.get('offset_hour', 0)),
+                minutes = mult * int(capture.get('offset_minute', 0))
+            ))
+
+            yyyy = int(capture['yyyy'])
+
+            if 'month' in capture:
+                mm = DATE_MONTHS[capture['month'].lower()]
+            else:
+                mm = int(capture['mm'])
+
+            dd = int(capture['dd'])
+            hh = int(capture.get('hh', 0))
+            MM = int(capture.get('MM', 0))
+            ss = int(capture.get('ss', 0))
+
+            return datetime.datetime(yyyy, mm, dd, hh, MM, ss, 0, tz)
+
 class MessageState(enum.Enum):
     EMPTY  = 0
     HEADER = 1
@@ -147,7 +201,7 @@ class Message(DatabaseTable):
                 value = self.header('Date')
 
                 if value is not None:
-                    ret = search_dates(value)[0][1]
+                    ret = parse_timestamp(value)
 
                     self._cache['created_on'] = str(ret)
         except: