feat: message time helpers that return None instead of now()

src/saic_ismart_client_ng/api/message/schema.py

@@ -32,18 +32,54 @@ class MessageEntity:
 
     @property
     def message_time(self) -> datetime.datetime:
-        if self.messageTime:
-            for date_format in MESSAGE_DATE_TIME_FORMATS:
-                try:
-                    return datetime.datetime.strptime(self.messageTime, date_format)
-                except ValueError:
-                    pass
-            LOGGER.error(
-                "Could not parse messageTime '%s'. This is a bug. Please file a ticket",
-                self.messageTime,
-            )
+        """The message time, or the current local time if there isn't one.
+
+        Falling back to now() means a message with no time looks brand new.
+        Prefer ``message_time_or_none`` or ``create_time_utc`` when that
+        matters (e.g. deciding whether a message is old).
+        """
+        parsed = self.message_time_or_none
+        if parsed is not None:
+            return parsed
         return datetime.datetime.now()
 
+    @property
+    def message_time_or_none(self) -> datetime.datetime | None:
+        """``messageTime`` parsed, or None if it is missing or unreadable.
+
+        The result is naive: SAIC sends it in the server's local time with no
+        timezone (the EU servers use CET/CEST), so it can't safely be compared
+        with UTC. Use ``create_time_utc`` for that.
+        """
+        if not self.messageTime:
+            return None
+        for date_format in MESSAGE_DATE_TIME_FORMATS:
+            try:
+                return datetime.datetime.strptime(self.messageTime, date_format)
+            except ValueError:
+                pass
+        LOGGER.error(
+            "Could not parse messageTime '%s'. This is a bug. Please file a ticket",
+            self.messageTime,
+        )
+        return None
+
+    @property
+    def create_time_utc(self) -> datetime.datetime | None:
+        """``createTime`` (Unix milliseconds) as a UTC datetime, or None.
+
+        None when the message has no createTime (common on EU accounts) or
+        it can't be read. Unlike ``messageTime`` this has no timezone doubt.
+        """
+        if self.createTime is None:
+            return None
+        try:
+            return datetime.datetime.fromtimestamp(
+                self.createTime / 1000.0, tz=datetime.UTC
+            )
+        except (TypeError, OSError, OverflowError, ValueError):
+            return None
+
     @property
     def read_status(self) -> str:
         if self.readStatus is None:

tests/test_message_times.py

@@ -0,0 +1,51 @@
+from __future__ import annotations
+
+import datetime
+
+from saic_ismart_client_ng.api.message.schema import MessageEntity
+
+UTC = datetime.UTC
+
+
+def test_create_time_utc_from_milliseconds() -> None:
+    created = datetime.datetime(2026, 9, 25, 17, 57, 38, tzinfo=UTC)
+    msg = MessageEntity(createTime=int(created.timestamp() * 1000))
+    assert msg.create_time_utc == created
+    assert msg.create_time_utc is not None
+    assert msg.create_time_utc.tzinfo is not None
+
+
+def test_create_time_utc_missing_is_none() -> None:
+    assert MessageEntity().create_time_utc is None
+
+
+def test_create_time_utc_unreadable_is_none() -> None:
+    assert MessageEntity(createTime="soon").create_time_utc is None  # type: ignore[arg-type]
+    assert MessageEntity(createTime=10**20).create_time_utc is None
+
+
+def test_message_time_or_none_parses_every_known_format() -> None:
+    expected = datetime.datetime(2026, 9, 25, 18, 57, 38)
+    for text in ("2026-09-25 18:57:38", "25-09-2026 18:57:38", "25/09/2026 18:57:38"):
+        assert MessageEntity(messageTime=text).message_time_or_none == expected
+
+
+def test_message_time_or_none_is_naive() -> None:
+    parsed = MessageEntity(messageTime="2026-09-25 18:57:38").message_time_or_none
+    assert parsed is not None
+    assert parsed.tzinfo is None
+
+
+def test_message_time_or_none_missing_or_unreadable_is_none() -> None:
+    assert MessageEntity().message_time_or_none is None
+    assert MessageEntity(messageTime="").message_time_or_none is None
+    assert MessageEntity(messageTime="yesterday").message_time_or_none is None
+
+
+def test_message_time_still_falls_back_to_now() -> None:
+    # Unchanged behaviour for existing callers.
+    before = datetime.datetime.now()
+    fallback = MessageEntity().message_time
+    assert before <= fallback <= datetime.datetime.now()
+    parsed = MessageEntity(messageTime="2026-09-25 18:57:38").message_time
+    assert parsed == datetime.datetime(2026, 9, 25, 18, 57, 38)