"""The CPIO archive file system implementation."""

from dfvfs.lib import cpio
from dfvfs.lib import definitions
from dfvfs.lib import errors
from dfvfs.path import cpio_path_spec
from dfvfs.resolver import resolver
from dfvfs.vfs import cpio_file_entry
from dfvfs.vfs import file_system


class CPIOFileSystem(file_system.FileSystem):
    """CPIO archive file system."""

    TYPE_INDICATOR = definitions.TYPE_INDICATOR_CPIO

    def __init__(self, resolver_context, path_spec, encoding="utf-8"):
        """Initializes a CPIO archive file system.

        Args:
          resolver_context (Context): resolver context.
          path_spec (PathSpec): a path specification.
          encoding (Optional[str]): file entry name encoding.
        """
        super().__init__(resolver_context, path_spec)
        self._cpio_archive_file = None
        self._file_object = None
        self.encoding = encoding

    def _Close(self):
        """Closes the file system.

        Raises:
          OSError: if the close failed.
        """
        self._cpio_archive_file.Close()
        self._cpio_archive_file = None
        self._file_object = None

    def _Open(self, mode="rb"):
        """Opens the file system defined by path specification.

        Args:
          mode (Optional[str]): file access mode. The default is 'rb' which
              represents read-only binary.

        Raises:
          AccessError: if the access to open the file was denied.
          OSError: if the file system could not be opened.
          PathSpecError: if the path specification is incorrect.
          ValueError: if the path specification is invalid.
        """
        if not self._path_spec.HasParent():
            raise errors.PathSpecError("Unsupported path specification without parent.")

        file_object = resolver.Resolver.OpenFileObject(
            self._path_spec.parent, resolver_context=self._resolver_context
        )

        cpio_archive_file = cpio.CPIOArchiveFile()
        cpio_archive_file.Open(file_object)

        self._file_object = file_object
        self._cpio_archive_file = cpio_archive_file

    def FileEntryExistsByPathSpec(self, path_spec):
        """Determines if a file entry for a path specification exists.

        Args:
          path_spec (PathSpec): a path specification.

        Returns:
          bool: True if the file entry exists.
        """
        location = getattr(path_spec, "location", None)
        if location is None or not location.startswith(self.LOCATION_ROOT):
            return False

        if len(location) == 1:
            return True

        return self._cpio_archive_file.FileEntryExistsByPath(location[1:])

    def GetCPIOArchiveFile(self):
        """Retrieves the CPIO archive file.

        Returns:
          CPIOArchiveFile: a CPIO archive file.
        """
        return self._cpio_archive_file

    def GetCPIOArchiveFileEntryByPathSpec(self, path_spec):
        """Retrieves the CPIO archive file entry for a path specification.

        Args:
          path_spec (PathSpec): a path specification.

        Returns:
          CPIOArchiveFileEntry: CPIO archive file entry or None if not available.

        Raises:
          PathSpecError: if the path specification is incorrect.
        """
        location = getattr(path_spec, "location", None)
        if location is None:
            raise errors.PathSpecError("Path specification missing location.")

        if not location.startswith(self.LOCATION_ROOT):
            raise errors.PathSpecError("Invalid location in path specification.")

        if len(location) == 1:
            return None

        return self._cpio_archive_file.GetFileEntryByPath(location[1:])

    def GetFileEntryByPathSpec(self, path_spec):
        """Retrieves a file entry for a path specification.

        Args:
          path_spec (PathSpec): a path specification.

        Returns:
          CPIOFileEntry: a file entry or None if not available.
        """
        location = getattr(path_spec, "location", None)

        if location is None or not location.startswith(self.LOCATION_ROOT):
            return None

        if len(location) == 1:
            return cpio_file_entry.CPIOFileEntry(
                self._resolver_context, self, path_spec, is_root=True, is_virtual=True
            )

        cpio_archive_file_entry = self._cpio_archive_file.GetFileEntryByPath(
            location[1:]
        )
        if cpio_archive_file_entry is None:
            return None

        return cpio_file_entry.CPIOFileEntry(
            self._resolver_context,
            self,
            path_spec,
            cpio_archive_file_entry=cpio_archive_file_entry,
        )

    def GetRootFileEntry(self):
        """Retrieves the root file entry.

        Returns:
          CPIOFileEntry: a file entry or None if not available.
        """
        path_spec = cpio_path_spec.CPIOPathSpec(
            location=self.LOCATION_ROOT, parent=self._path_spec.parent
        )
        return self.GetFileEntryByPathSpec(path_spec)
