"""The NTFS format analyzer helper implementation."""

from dfvfs.analyzer import analyzer
from dfvfs.analyzer import analyzer_helper
from dfvfs.analyzer import specification
from dfvfs.lib import definitions


class NTFSAnalyzerHelper(analyzer_helper.AnalyzerHelper):
    """NTFS analyzer helper."""

    FORMAT_CATEGORIES = frozenset([definitions.FORMAT_CATEGORY_FILE_SYSTEM])

    TYPE_INDICATOR = definitions.TYPE_INDICATOR_NTFS

    def GetFormatSpecification(self):
        """Retrieves the format specification.

        Returns:
          FormatSpecification: format specification or None if the format cannot
              be defined by a specification object.
        """
        format_specification = specification.FormatSpecification(self.type_indicator)

        # NTFS file system signature.
        format_specification.AddNewSignature(b"NTFS    ", offset=3)

        return format_specification

    def IsEnabled(self):
        """Determines if the analyzer helper is enabled.

        Returns:
          bool: True if the analyzer helper is enabled.
        """
        return definitions.PREFERRED_NTFS_BACK_END == self.TYPE_INDICATOR


analyzer.Analyzer.RegisterHelper(NTFSAnalyzerHelper())
