text: # Licensed to the Apache Software Foundation (ASF) under one
  # or more contributor license agreements.  See the NOTICE file
  # distributed with this work for additional information
  # regarding copyright ownership.  The ASF licenses this file
  # to you under the Apache License, Version 2.0 (the
  # "License"); you may not use this file except in compliance
  # with the License.  You may obtain a copy of the License at
  #
  #   http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing,
  # software distributed under the License is distributed on an
  # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  # KIND, either express or implied.  See the License for the
  # specific language governing permissions and limitations
  # under the License.
  
  import logging
  from typing import Any, Dict
  
  from marshmallow.exceptions import ValidationError
  
  from superset.commands.base import BaseCommand
  from superset.commands.exceptions import CommandInvalidError
  from superset.commands.importers.exceptions import IncorrectVersionError
  from superset.datasets.commands.importers import v0, v1
  
  logger = logging.getLogger(__name__)
  
  # list of different import formats supported; v0 should be last because
  # the files are not versioned
  command_versions = [
      v1.ImportDatasetsCommand,
      v0.ImportDatasetsCommand,
  ]
  
  
  class ImportDatasetsCommand(BaseCommand):
      """
      Import datasets.
  
      This command dispatches the import to different versions of the command
      until it finds one that matches.
      """
  
      # pylint: disable=unused-argument
      def __init__(self, contents: Dict[str, str], *args: Any, **kwargs: Any):
          self.contents = contents
  
      def run(self) -> None:
          # iterate over all commands until we find a version that can
          # handle the contents
          for version in command_versions:
              command = version(self.contents)
              try:
                  command.run()
                  return
              except IncorrectVersionError:
                  # file is not handled by command, skip
                  pass
              except (CommandInvalidError, ValidationError) as exc:
                  # found right version, but file is invalid
                  logger.info("Command failed validation")
                  raise exc
              except Exception as exc:
                  # validation succeeded but something went wrong
                  logger.exception("Error running import command")
                  raise exc
  
          raise CommandInvalidError("Could not find a valid command to import file")
  
      def validate(self) -> None:
          pass
  