"""The compressed stream path specification implementation."""

from dfvfs.lib import definitions
from dfvfs.path import factory
from dfvfs.path import path_spec


class CompressedStreamPathSpec(path_spec.PathSpec):
    """Compressed stream path specification.

    Attributes:
      compression_method (str): method used to the compress the data.
    """

    TYPE_INDICATOR = definitions.TYPE_INDICATOR_COMPRESSED_STREAM

    def __init__(self, compression_method=None, parent=None, **kwargs):
        """Initializes a path specification.

        Note that the compressed stream path specification must have a parent.

        Args:
          compression_method (Optional[str]): method used to the compress the data.
          parent (Optional[PathSpec]): parent path specification.

        Raises:
          ValueError: when compression method or parent are not set.
        """
        if not compression_method or not parent:
            raise ValueError("Missing compression method or parent value.")

        super().__init__(parent=parent, **kwargs)
        self.compression_method = compression_method

    @property
    def comparable(self):
        """str: comparable representation of the path specification."""
        return self._GetComparable(
            sub_comparable_string=(f"compression_method: {self.compression_method:s}")
        )


factory.Factory.RegisterPathSpec(CompressedStreamPathSpec)
