"""The SQLite blob file system implementation."""

from dfvfs.lib import definitions
from dfvfs.lib import errors
from dfvfs.path import sqlite_blob_path_spec
from dfvfs.resolver import resolver
from dfvfs.vfs import sqlite_blob_file_entry
from dfvfs.vfs import file_system


class SQLiteBlobFileSystem(file_system.FileSystem):
    """Class that implements a file system object using SQLite blob."""

    TYPE_INDICATOR = definitions.TYPE_INDICATOR_SQLITE_BLOB

    def __init__(self, resolver_context, path_spec):
        """Initializes a file system.

        Args:
          resolver_context (Context): resolver context.
          path_spec (PathSpec): a path specification.
        """
        super().__init__(resolver_context, path_spec)
        self._file_object = None
        self._number_of_rows = None

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

        Raises:
          OSError: if the close failed.
        """
        self._file_object = None
        self._number_of_rows = None

    def _Open(self, mode="rb"):
        """Opens the file system object 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 object 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
        )

        self._file_object = file_object

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

        Args:
          path_spec (PathSpec): path specification.

        Returns:
          bool: True if the file entry exists.
        """
        # All checks for correct path spec is done in SQLiteBlobFile.
        # Therefore, attempt to open the path specification and
        # check if errors occurred.
        try:
            file_object = resolver.Resolver.OpenFileObject(
                path_spec, resolver_context=self._resolver_context
            )
        except (OSError, ValueError, errors.AccessError, errors.PathSpecError):
            file_object = None

        return bool(file_object)

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

        Args:
          path_spec (PathSpec): path specification.

        Returns:
          FileEntry: a file entry or None.
        """
        row_index = getattr(path_spec, "row_index", None)
        row_condition = getattr(path_spec, "row_condition", None)

        # If no row_index or row_condition is provided, return a directory.
        if row_index is None and row_condition is None:
            return sqlite_blob_file_entry.SQLiteBlobFileEntry(
                self._resolver_context, self, path_spec, is_root=True, is_virtual=True
            )

        return sqlite_blob_file_entry.SQLiteBlobFileEntry(
            self._resolver_context, self, path_spec
        )

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

        Returns:
          FileEntry: a file entry or None.
        """
        path_spec = sqlite_blob_path_spec.SQLiteBlobPathSpec(
            table_name=self._path_spec.table_name,
            column_name=self._path_spec.column_name,
            parent=self._path_spec.parent,
        )
        return self.GetFileEntryByPathSpec(path_spec)
