"""The SleuthKit (TSK) 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 TSKAnalyzerHelper(analyzer_helper.AnalyzerHelper):
    """TSK analyzer helper."""

    FORMAT_CATEGORIES = frozenset([definitions.FORMAT_CATEGORY_FILE_SYSTEM])

    TYPE_INDICATOR = definitions.TYPE_INDICATOR_TSK

    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)

        if definitions.PREFERRED_FAT_BACK_END == self.TYPE_INDICATOR:
            # Boot sector signature.
            format_specification.AddNewSignature(b"\x55\xaa", offset=510)

            # FAT-12 and FAT-16 file system hint.
            format_specification.AddNewSignature(b"FAT12   ", offset=54)
            format_specification.AddNewSignature(b"FAT16   ", offset=54)

            # FAT-32 file system hint.
            format_specification.AddNewSignature(b"FAT32   ", offset=82)

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

        if definitions.PREFERRED_NTFS_BACK_END == self.TYPE_INDICATOR:
            # NTFS file system signature.
            format_specification.AddNewSignature(b"NTFS    ", offset=3)

        if definitions.PREFERRED_HFS_BACK_END == self.TYPE_INDICATOR:
            # HFS boot block signature.
            # format_specification.AddNewSignature(b'LK', offset=0)

            # HFS+ file system signature.
            format_specification.AddNewSignature(b"H+", offset=1024)

            # HFSX file system signature.
            format_specification.AddNewSignature(b"HX", offset=1024)

        if definitions.PREFERRED_EXT_BACK_END == self.TYPE_INDICATOR:
            # Ext file system signature.
            format_specification.AddNewSignature(b"\x53\xef", offset=1080)

        # ISO9660 file system signature.
        format_specification.AddNewSignature(b"CD001", offset=32769)

        # UFS file system signature.

        # YAFFS file system signature.

        return format_specification


analyzer.Analyzer.RegisterHelper(TSKAnalyzerHelper())
