"""Apple File System (APFS) time implementation."""

import decimal

from dfdatetime import definitions
from dfdatetime import factory
from dfdatetime import posix_time


class APFSTime(posix_time.PosixTimeInNanoseconds):
    """Apple File System (APFS) timestamp.

    The APFS timestamp is a signed 64-bit integer that contains the number of
    nanoseconds since 1970-01-01 00:00:00.

    Attributes:
      is_local_time (bool): True if the date and time value is in local time.
    """

    def _GetNormalizedTimestamp(self):
        """Retrieves the normalized timestamp.

        Returns:
          decimal.Decimal: normalized timestamp, which contains the number of
              seconds since January 1, 1970 00:00:00 and a fraction of second used
              for increased precision, or None if the normalized timestamp cannot be
              determined.
        """
        if self._normalized_timestamp is None:
            if (
                self._timestamp is not None
                and self._timestamp >= self._INT64_MIN
                and self._timestamp <= self._INT64_MAX
            ):
                self._normalized_timestamp = (
                    decimal.Decimal(self._timestamp)
                    / definitions.NANOSECONDS_PER_SECOND
                )

                if self._time_zone_offset:
                    self._normalized_timestamp -= self._time_zone_offset * 60

        return self._normalized_timestamp

    def CopyFromDateTimeString(self, time_string):
        """Copies a APFS timestamp from a date and time string.

        Args:
          time_string (str): date and time value formatted as:
              YYYY-MM-DD hh:mm:ss.######[+-]##:##

              Where # are numeric digits ranging from 0 to 9 and the seconds
              fraction can be either 3, 6 or 9 digits. The time of day, seconds
              fraction and time zone offset are optional. The default time zone
              is UTC.

        Raises:
          ValueError: if the date and time value is not supported.
        """
        super().CopyFromDateTimeString(time_string)

        if (
            self._timestamp is None
            or self._timestamp < self._INT64_MIN
            or self._timestamp > self._INT64_MAX
        ):
            raise ValueError("Date time value not supported.")

    def CopyToDateTimeString(self):
        """Copies the APFS timestamp to a date and time string.

        Returns:
          str: date and time value formatted as: "YYYY-MM-DD hh:mm:ss.#########" or
              None if the timestamp is missing or invalid.
        """
        if (
            self._timestamp is None
            or self._timestamp < self._INT64_MIN
            or self._timestamp > self._INT64_MAX
        ):
            return None

        return super().CopyToDateTimeString()


factory.Factory.RegisterDateTimeValues(APFSTime)
