text: from __future__ import absolute_import
  
  import logging
  import os
  
  from pip._internal.cli import cmdoptions
  from pip._internal.cli.base_command import RequirementCommand
  from pip._internal.cli.cmdoptions import make_target_python
  from pip._internal.legacy_resolve import Resolver
  from pip._internal.operations.prepare import RequirementPreparer
  from pip._internal.req import RequirementSet
  from pip._internal.req.req_tracker import RequirementTracker
  from pip._internal.utils.filesystem import check_path_owner
  from pip._internal.utils.misc import ensure_dir, normalize_path
  from pip._internal.utils.temp_dir import TempDirectory
  
  logger = logging.getLogger(__name__)
  
  
  class DownloadCommand(RequirementCommand):
      """
      Download packages from:
  
      - PyPI (and other indexes) using requirement specifiers.
      - VCS project urls.
      - Local project directories.
      - Local or remote source archives.
  
      pip also supports downloading from "requirements files", which provide
      an easy way to specify a whole environment to be downloaded.
      """
      name = 'download'
  
      usage = """
        %prog [options] <requirement specifier> [package-index-options] ...
        %prog [options] -r <requirements file> [package-index-options] ...
        %prog [options] <vcs project url> ...
        %prog [options] <local project path> ...
        %prog [options] <archive url/path> ..."""
  
      summary = 'Download packages.'
  
      def __init__(self, *args, **kw):
          super(DownloadCommand, self).__init__(*args, **kw)
  
          cmd_opts = self.cmd_opts
  
          cmd_opts.add_option(cmdoptions.constraints())
          cmd_opts.add_option(cmdoptions.requirements())
          cmd_opts.add_option(cmdoptions.build_dir())
          cmd_opts.add_option(cmdoptions.no_deps())
          cmd_opts.add_option(cmdoptions.global_options())
          cmd_opts.add_option(cmdoptions.no_binary())
          cmd_opts.add_option(cmdoptions.only_binary())
          cmd_opts.add_option(cmdoptions.prefer_binary())
          cmd_opts.add_option(cmdoptions.src())
          cmd_opts.add_option(cmdoptions.pre())
          cmd_opts.add_option(cmdoptions.no_clean())
          cmd_opts.add_option(cmdoptions.require_hashes())
          cmd_opts.add_option(cmdoptions.progress_bar())
          cmd_opts.add_option(cmdoptions.no_build_isolation())
          cmd_opts.add_option(cmdoptions.use_pep517())
          cmd_opts.add_option(cmdoptions.no_use_pep517())
  
          cmd_opts.add_option(
              '-d', '--dest', '--destination-dir', '--destination-directory',
              dest='download_dir',
              metavar='dir',
              default=os.curdir,
              help=("Download packages into <dir>."),
          )
  
          cmdoptions.add_target_python_options(cmd_opts)
  
          index_opts = cmdoptions.make_option_group(
              cmdoptions.index_group,
              self.parser,
          )
  
          self.parser.insert_option_group(0, index_opts)
          self.parser.insert_option_group(0, cmd_opts)
  
      def run(self, options, args):
          options.ignore_installed = True
          # editable doesn't really make sense for `pip download`, but the bowels
          # of the RequirementSet code require that property.
          options.editables = []
  
          cmdoptions.check_dist_restriction(options)
  
          options.src_dir = os.path.abspath(options.src_dir)
          options.download_dir = normalize_path(options.download_dir)
  
          ensure_dir(options.download_dir)
  
          with self._build_session(options) as session:
              target_python = make_target_python(options)
              finder = self._build_package_finder(
                  options=options,
                  session=session,
                  target_python=target_python,
              )
              build_delete = (not (options.no_clean or options.build_dir))
              if options.cache_dir and not check_path_owner(options.cache_dir):
                  logger.warning(
                      "The directory '%s' or its parent directory is not owned "
                      "by the current user and caching wheels has been "
                      "disabled. check the permissions and owner of that "
                      "directory. If executing pip with sudo, you may want "
                      "sudo's -H flag.",
                      options.cache_dir,
                  )
                  options.cache_dir = None
  
              with RequirementTracker() as req_tracker, TempDirectory(
                  options.build_dir, delete=build_delete, kind="download"
              ) as directory:
  
                  requirement_set = RequirementSet(
                      require_hashes=options.require_hashes,
                  )
                  self.populate_requirement_set(
                      requirement_set,
                      args,
                      options,
                      finder,
                      session,
                      self.name,
                      None
                  )
  
                  preparer = RequirementPreparer(
                      build_dir=directory.path,
                      src_dir=options.src_dir,
                      download_dir=options.download_dir,
                      wheel_download_dir=None,
                      progress_bar=options.progress_bar,
                      build_isolation=options.build_isolation,
                      req_tracker=req_tracker,
                  )
  
                  resolver = Resolver(
                      preparer=preparer,
                      finder=finder,
                      session=session,
                      wheel_cache=None,
                      use_user_site=False,
                      upgrade_strategy="to-satisfy-only",
                      force_reinstall=False,
                      ignore_dependencies=options.ignore_dependencies,
                      py_version_info=options.python_version,
                      ignore_requires_python=False,
                      ignore_installed=True,
                      isolated=options.isolated_mode,
                  )
                  resolver.resolve(requirement_set)
  
                  downloaded = ' '.join([
                      req.name for req in requirement_set.successfully_downloaded
                  ])
                  if downloaded:
                      logger.info('Successfully downloaded %s', downloaded)
  
                  # Clean up
                  if not options.no_clean:
                      requirement_set.cleanup_files()
  
          return requirement_set
  