from bson import encode, decode, CodecOptions, DatetimeConversion
from bson.tz_util import utc, FixedOffset
import datetime

tz = FixedOffset(60, "Custom")
opts = CodecOptions(datetime_conversion=DatetimeConversion.DATETIME_CLAMP, tz_aware=True, tzinfo=tz)
now = datetime.datetime.now(tz)
doc = {"d": now}
print(f'doc: {doc}')
print(f'decoded as naive: {decode(encode(doc))}' )
decode(encode(doc), opts)  # Fails

doc: {'d': datetime.datetime(2024, 8, 23, 0, 20, 28, 759709, tzinfo=FixedOffset(datetime.timedelta(seconds=3600), 'Custom'))}
decoded as naive: {'d': datetime.datetime(2024, 8, 22, 23, 20, 28, 759000)}
Traceback (most recent call last):
  File "/Users/shane/git/mongo-python-driver/repro.py", line 11, in <module>
    decode(encode(doc), opts)
  File "/Users/shane/git/mongo-python-driver/bson/__init__.py", line 1078, in decode
    return cast("Union[dict[str, Any], _DocumentType]", _bson_to_dict(data, opts))
                                                        ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/shane/git/mongo-python-driver/bson/__init__.py", line 618, in _bson_to_dict
    raise InvalidBSON(str(exc_value)).with_traceback(exc_tb) from None
  File "/Users/shane/git/mongo-python-driver/bson/__init__.py", line 612, in _bson_to_dict
    return cast("_DocumentType", _elements_to_dict(data, view, 4, end, opts))
                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/shane/git/mongo-python-driver/bson/__init__.py", line 596, in _elements_to_dict
    key, value, position = _element_to_dict(
                           ^^^^^^^^^^^^^^^^^
  File "/Users/shane/git/mongo-python-driver/bson/__init__.py", line 551, in _element_to_dict
    value, position = _ELEMENT_GETTER[element_type](
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/shane/git/mongo-python-driver/bson/__init__.py", line 422, in _get_date
    return _millis_to_datetime(_UNPACK_LONG_FROM(data, position)[0], opts), position + 8
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/shane/git/mongo-python-driver/bson/datetime_ms.py", line 141, in _millis_to_datetime
    millis = max(_min_datetime_ms(tz), min(millis, _max_datetime_ms(tz)))
                 ^^^^^^^^^^^^^^^^^^^^
  File "/Users/shane/git/mongo-python-driver/bson/datetime_ms.py", line 122, in _min_datetime_ms
    return _datetime_to_millis(datetime.datetime.min.replace(tzinfo=tz))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/shane/git/mongo-python-driver/bson/datetime_ms.py", line 170, in _datetime_to_millis
    dtm = dtm - dtm.utcoffset()  # type: ignore
          ~~~~^~~~~~~~~~~~~~~~~
bson.errors.InvalidBSON: date value out of range

@functools.lru_cache(maxsize=None)
def _min_datetime_ms(tz: datetime.timezone = datetime.timezone.utc) -> int:
    return _datetime_to_millis(datetime.datetime.min.replace(tzinfo=tz))


@functools.lru_cache(maxsize=None)
def _max_datetime_ms(tz: datetime.timezone = datetime.timezone.utc) -> int:
    return _datetime_to_millis(datetime.datetime.max.replace(tzinfo=tz))

>>> tz = FixedOffset(60, "Custom")
>>> datetime.datetime.min.replace(tzinfo=tz)
datetime.datetime(1, 1, 1, 0, 0, tzinfo=FixedOffset(datetime.timedelta(seconds=3600), 'Custom'))
>>> datetime.datetime.min.replace(tzinfo=utc).astimezone(tz)
datetime.datetime(1, 1, 1, 1, 0, tzinfo=FixedOffset(datetime.timedelta(seconds=3600), 'Custom'))
>>> datetime.datetime.max.replace(tzinfo=utc)
datetime.datetime(9999, 12, 31, 23, 59, 59, 999999, tzinfo=FixedOffset(datetime.timedelta(0), 'UTC'))
>>> datetime.datetime.max.replace(tzinfo=utc).astimezone(tz)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: date value out of range

>>> max_utc = datetime.datetime.max.replace(tzinfo=utc)
>>> max_tz = (max_utc - tz.utcoffset(max_utc)).astimezone(tz)
>>> max_tz
datetime.datetime(9999, 12, 31, 23, 59, 59, 999999, tzinfo=FixedOffset(datetime.timedelta(seconds=3600), 'Custom'))
>>> max_tz.astimezone(utc)
datetime.datetime(9999, 12, 31, 22, 59, 59, 999999, tzinfo=FixedOffset(datetime.timedelta(0), 'UTC'))