"""The SleuthKit (TSK) partition file-like object implementation."""

from dfvfs.file_io import data_range_io
from dfvfs.lib import errors
from dfvfs.lib import tsk_partition
from dfvfs.resolver import resolver


class TSKPartitionFile(data_range_io.DataRange):
    """File input/output (IO) object using pytsk3."""

    def __init__(self, resolver_context, path_spec):
        """Initializes a file input/output (IO) object.

        Args:
          resolver_context (Context): resolver context.
          path_spec (PathSpec): a path specification.
        """
        super().__init__(resolver_context, path_spec)
        self._file_system = None

    def _Close(self):
        """Closes the file-like object."""
        self._file_system = None

    def _Open(self):
        """Opens the file-like object defined by path specification.

        Raises:
          AccessError: if the access to open the file was denied.
          OSError: if the file-like object could not be opened.
          PathSpecError: if the path specification is incorrect.
        """
        if not self._path_spec.HasParent():
            raise errors.PathSpecError("Unsupported path specification without parent.")

        self._file_system = resolver.Resolver.OpenFileSystem(
            self._path_spec, resolver_context=self._resolver_context
        )
        tsk_volume = self._file_system.GetTSKVolume()
        tsk_vs, _ = tsk_partition.GetTSKVsPartByPathSpec(tsk_volume, self._path_spec)

        if tsk_vs is None:
            raise errors.PathSpecError(
                "Unable to retrieve TSK volume system part from path specification."
            )

        range_offset = tsk_partition.TSKVsPartGetStartSector(tsk_vs)
        range_size = tsk_partition.TSKVsPartGetNumberOfSectors(tsk_vs)

        if range_offset is None or range_size is None:
            raise errors.PathSpecError(
                "Unable to retrieve TSK volume system part data range from path "
                "specification."
            )

        bytes_per_sector = tsk_partition.TSKVolumeGetBytesPerSector(tsk_volume)
        range_offset *= bytes_per_sector
        range_size *= bytes_per_sector

        self._SetRange(range_offset, range_size)
        self._file_object = resolver.Resolver.OpenFileObject(
            self._path_spec.parent, resolver_context=self._resolver_context
        )
