"""The APFS 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 APFSAnalyzerHelper(analyzer_helper.AnalyzerHelper):
    """APFS analyzer helper."""

    FORMAT_CATEGORIES = frozenset([definitions.FORMAT_CATEGORY_FILE_SYSTEM])

    TYPE_INDICATOR = definitions.TYPE_INDICATOR_APFS

    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)

        # APFS file system signature.
        format_specification.AddNewSignature(b"APSB", offset=32)

        return format_specification


analyzer.Analyzer.RegisterHelper(APFSAnalyzerHelper())
