"""The CPIO 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 CPIOAnalyzerHelper(analyzer_helper.AnalyzerHelper):
    """CPIO analyzer helper."""

    FORMAT_CATEGORIES = frozenset([definitions.FORMAT_CATEGORY_ARCHIVE])

    TYPE_INDICATOR = definitions.TYPE_INDICATOR_CPIO

    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)

        # CPIO binary file big-endian signature.
        format_specification.AddNewSignature(b"\x71\xc7", offset=0)

        # CPIO binary file little-endian signature.
        format_specification.AddNewSignature(b"\xc7\x71", offset=0)

        # CPIO portable ASCII file signature.
        format_specification.AddNewSignature(b"070707", offset=0)

        # CPIO new ASCII file signature.
        format_specification.AddNewSignature(b"070701", offset=0)

        # CPIO new ASCII file with checksum signature.
        format_specification.AddNewSignature(b"070702", offset=0)

        return format_specification


analyzer.Analyzer.RegisterHelper(CPIOAnalyzerHelper())
