"""The Logical Volume Manager (LVM) 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 LVMAnalyzerHelper(analyzer_helper.AnalyzerHelper):
    """LVM analyzer helper."""

    FORMAT_CATEGORIES = frozenset([definitions.FORMAT_CATEGORY_VOLUME_SYSTEM])

    TYPE_INDICATOR = definitions.TYPE_INDICATOR_LVM

    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)

        # LVM signature.
        format_specification.AddNewSignature(b"LABELONE", offset=0)
        format_specification.AddNewSignature(b"LABELONE", offset=512)
        format_specification.AddNewSignature(b"LABELONE", offset=1024)
        format_specification.AddNewSignature(b"LABELONE", offset=1536)

        return format_specification


analyzer.Analyzer.RegisterHelper(LVMAnalyzerHelper())
