fix: remove python-dateutil runtime dependency

.sampo/changesets/ardent-king-tursas.md

@@ -0,0 +1,5 @@
+---
+pypi/posthog: patch
+---
+
+Remove python-dateutil as a runtime dependency

mypy-baseline.txt

@@ -1,21 +1,15 @@
-posthog/utils.py:0: error: Library stubs not installed for "dateutil.tz"  [import-untyped]
 posthog/request.py:0: error: Library stubs not installed for "requests"  [import-untyped]
 posthog/request.py:0: note: Hint: "python3 -m pip install types-requests"
-posthog/request.py:0: error: Library stubs not installed for "dateutil.tz"  [import-untyped]
+posthog/request.py:0: note: (or run "mypy --install-types" to install all missing stub packages)
+posthog/request.py:0: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
 posthog/request.py:0: error: Incompatible types in assignment (expression has type "bytes", variable has type "str")  [assignment]
 posthog/consumer.py:0: error: Name "Empty" already defined (possibly by an import)  [no-redef]
 posthog/consumer.py:0: error: Need type annotation for "items" (hint: "items: list[<type>] = ...")  [var-annotated]
 posthog/consumer.py:0: error: Unsupported operand types for <= ("int" and "str")  [operator]
 posthog/consumer.py:0: note: Right operand is of type "int | str"
 posthog/consumer.py:0: error: Unsupported operand types for < ("str" and "int")  [operator]
 posthog/consumer.py:0: note: Left operand is of type "int | str"
-posthog/feature_flags.py:0: error: Library stubs not installed for "dateutil"  [import-untyped]
-posthog/feature_flags.py:0: error: Library stubs not installed for "dateutil.relativedelta"  [import-untyped]
 posthog/feature_flags.py:0: error: Unused "type: ignore" comment  [unused-ignore]
-posthog/client.py:0: error: Library stubs not installed for "dateutil.tz"  [import-untyped]
-posthog/client.py:0: note: Hint: "python3 -m pip install types-python-dateutil"
-posthog/client.py:0: note: (or run "mypy --install-types" to install all missing stub packages)
-posthog/client.py:0: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
 posthog/client.py:0: error: Name "queue" already defined (by an import)  [no-redef]
 posthog/client.py:0: error: Need type annotation for "queue"  [var-annotated]
 posthog/client.py:0: error: Incompatible types in assignment (expression has type "Any | list[Any]", variable has type "None")  [assignment]

posthog/client.py

@@ -3,11 +3,10 @@
 import os
 import sys
 import warnings
-from datetime import datetime, timedelta
+from datetime import datetime, timedelta, timezone
 from typing import Any, Dict, Optional, Union
 from uuid import uuid4
 
-from dateutil.tz import tzutc
 from typing_extensions import Unpack
 
 from posthog.args import ID_TYPES, ExceptionArg, OptionalCaptureArgs, OptionalSetArgs
@@ -1100,7 +1099,7 @@ def _enqueue(self, msg, disable_geoip):
 
         timestamp = msg["timestamp"]
         if timestamp is None:
-            timestamp = datetime.now(tz=tzutc())
+            timestamp = datetime.now(tz=timezone.utc)
 
         # add common
         timestamp = guess_timezone(timestamp)
@@ -1277,7 +1276,7 @@ def _load_feature_flags(self):
                     self._update_flag_state(
                         cached_data, old_flags_by_key=self.feature_flags_by_key or {}
                     )
-                    self._last_feature_flag_poll = datetime.now(tz=tzutc())
+                    self._last_feature_flag_poll = datetime.now(tz=timezone.utc)
                     return
                 else:
                     # Emergency fallback: if cache is empty and we have no flags, fetch anyway.
@@ -1324,7 +1323,7 @@ def _fetch_feature_flags_from_api(self):
                 self.log.debug(
                     "[FEATURE FLAGS] Flags not modified (304), using cached data"
                 )
-                self._last_feature_flag_poll = datetime.now(tz=tzutc())
+                self._last_feature_flag_poll = datetime.now(tz=timezone.utc)
                 return
 
             if response.data is None:
@@ -1395,7 +1394,7 @@ def _fetch_feature_flags_from_api(self):
             )
             self.log.warning(e)
 
-        self._last_feature_flag_poll = datetime.now(tz=tzutc())
+        self._last_feature_flag_poll = datetime.now(tz=timezone.utc)
 
     def load_feature_flags(self):
         """

posthog/feature_flags.py

@@ -1,13 +1,11 @@
+import calendar
 import datetime
 import hashlib
 import logging
 import re
 import warnings
 from typing import Optional
 
-from dateutil import parser
-from dateutil.relativedelta import relativedelta
-
 from posthog import utils
 from posthog.types import FlagValue
 from posthog.utils import convert_to_datetime_aware, is_valid_regex
@@ -530,7 +528,7 @@ def compare(lhs, rhs, operator):
             parsed_date = relative_date_parse_for_feature_flag_matching(str(value))
 
             if not parsed_date:
-                parsed_date = parser.parse(str(value))
+                parsed_date = parse_datetime(str(value))
                 parsed_date = convert_to_datetime_aware(parsed_date)
         except Exception as e:
             raise InconclusiveMatchError(
@@ -555,7 +553,7 @@ def compare(lhs, rhs, operator):
                 return override_value > parsed_date.date()
         elif isinstance(override_value, str):
             try:
-                override_date = parser.parse(override_value)
+                override_date = parse_datetime(override_value)
                 override_date = convert_to_datetime_aware(override_date)
                 if operator == "is_date_before":
                     return override_date < parsed_date
@@ -776,6 +774,40 @@ def match_property_group(
         return property_group_type == "AND"
 
 
+def parse_datetime(value: str) -> datetime.datetime:
+    text = value.strip()
+    if text.endswith("Z"):
+        text = text[:-1] + "+00:00"
+    elif text.upper().endswith(" UTC"):
+        text = text[:-4] + "+00:00"
+    elif re.fullmatch(r"\d{4}", text):
+        now = datetime.datetime.now()
+        return datetime.datetime(int(text), now.month, now.day)
+
+    text = re.sub(r" ([+-]\d{2}:\d{2})$", r"\1", text)
+    return datetime.datetime.fromisoformat(text)
+
+
+# Python's stdlib doesn't provide a calendar-aware month/year delta.
+# Clamp the day to the target month's end to match dateutil.relativedelta behavior.
+def _subtract_months(dt: datetime.datetime, months: int) -> Optional[datetime.datetime]:
+    month_index = dt.year * 12 + dt.month - 1 - months
+    year = month_index // 12
+    month = month_index % 12 + 1
+    if not 1 <= year <= 9999:
+        return None
+    day = min(dt.day, calendar.monthrange(year, month)[1])
+    return dt.replace(year=year, month=month, day=day)
+
+
+def _subtract_years(dt: datetime.datetime, years: int) -> Optional[datetime.datetime]:
+    year = dt.year - years
+    if not 1 <= year <= 9999:
+        return None
+    day = min(dt.day, calendar.monthrange(year, dt.month)[1])
+    return dt.replace(year=year, day=day)
+
+
 def relative_date_parse_for_feature_flag_matching(
     value: str,
 ) -> Optional[datetime.datetime]:
@@ -791,15 +823,15 @@ def relative_date_parse_for_feature_flag_matching(
 
         interval = match.group("interval")
         if interval == "h":
-            parsed_dt = parsed_dt - relativedelta(hours=number)
+            parsed_dt = parsed_dt - datetime.timedelta(hours=number)
         elif interval == "d":
-            parsed_dt = parsed_dt - relativedelta(days=number)
+            parsed_dt = parsed_dt - datetime.timedelta(days=number)
         elif interval == "w":
-            parsed_dt = parsed_dt - relativedelta(weeks=number)
+            parsed_dt = parsed_dt - datetime.timedelta(weeks=number)
         elif interval == "m":
-            parsed_dt = parsed_dt - relativedelta(months=number)
+            return _subtract_months(parsed_dt, number)
         elif interval == "y":
-            parsed_dt = parsed_dt - relativedelta(years=number)
+            return _subtract_years(parsed_dt, number)
         else:
             return None
 

posthog/request.py

@@ -9,7 +9,6 @@
 from typing import Any, List, Optional, Tuple, Union
 
 import requests
-from dateutil.tz import tzutc
 from requests.adapters import HTTPAdapter  # type: ignore[import-untyped]
 from urllib3.connection import HTTPConnection
 from urllib3.util.retry import Retry
@@ -197,7 +196,7 @@ def post(
     """Post the `kwargs` to the API"""
     log = logging.getLogger("posthog")
     body = kwargs
-    body["sentAt"] = datetime.now(tz=tzutc()).isoformat()
+    body["sentAt"] = datetime.now(tz=timezone.utc).isoformat()
     trimmed_host = remove_trailing_slash(normalize_host(host))
     url = trimmed_host + path
     body["api_key"] = api_key