def main_cli():
    parser = argparse.ArgumentParser(
        description='GNU MediaGoblin utilities.')
    parser.add_argument(
        '-cf', '--conf_file', default=None,
        help=(
            "Config file used to set up environment.  "
            "Default to mediagoblin_local.ini if readable, "
            "otherwise mediagoblin.ini"))

    subparsers = parser.add_subparsers(help='sub-command help')
    for command_name, command_struct in SUBCOMMAND_MAP.iteritems():
        if 'help' in command_struct:
            subparser = subparsers.add_parser(
                command_name, help=command_struct['help'])
        else:
            subparser = subparsers.add_parser(command_name)

        setup_func = import_component(command_struct['setup'])
        exec_func = import_component(command_struct['func'])

        setup_func(subparser)

        subparser.set_defaults(func=exec_func)

    args = parser.parse_args()
    args.orig_conf_file = args.conf_file
    if args.conf_file is None:
        if os.path.exists('mediagoblin_local.ini') \
                and os.access('mediagoblin_local.ini', os.R_OK):
            args.conf_file = 'mediagoblin_local.ini'
        else:
            args.conf_file = 'mediagoblin.ini'

    args.func(args)

    def main(self, args, db, global_config):
        options = self.parser.parse_args(args.args_for_alembic)

        # This is useful for people running commands involving plugins, such
        # as building autogenerated revisions.
        if args.with_plugins:
            plugins = global_config.get('plugins', {}).keys()
            for plugin in plugins:
                try:
                    import_component('{0}.models:MODELS'.format(plugin))
                except ImportError:
                    # It doesn't really matter if there's no models to import
                    # here.
                    pass

        # This code is inspired by a hack in Alembic, but isn't the same really.
        # Regardless, Alembic is Expat licensed.
        if not hasattr(options, "cmd"):
            print(
                "* Only use this command if you know what you are doing! *\n"
                "If not, use the 'gmg dbupdate' command instead.\n\n"
                "(You can also pass --with-plugins here.)"
                "Alembic help:\n")
            self.parser.print_help()
            return
        else:
            Session = sessionmaker(bind=db.engine)
            session = Session()

            cfg = build_alembic_config(global_config, options, session)

            self.run_cmd(cfg, options)

def gather_database_data(plugins):
    """
    Gather all database data relevant to the extensions we have
    installed so we can do migrations and table initialization.

    Returns a list of DatabaseData objects.
    """
    managed_dbdata = []

    # Add main first
    from mediagoblin.db.models import MODELS as MAIN_MODELS
    from mediagoblin.db.migrations import MIGRATIONS as MAIN_MIGRATIONS
    from mediagoblin.db.models import FOUNDATIONS as MAIN_FOUNDATIONS

    managed_dbdata.append(
        DatabaseData(
            u'__main__', MAIN_MODELS, MAIN_FOUNDATIONS, MAIN_MIGRATIONS))

    for plugin in plugins:
        try:
            models = import_component('{0}.models:MODELS'.format(plugin))
        except ImportError as exc:
            _log.debug('No models found for {0}: {1}'.format(
                plugin,
                exc))

            models = []
        except AttributeError as exc:
            _log.warning('Could not find MODELS in {0}.models, have you \
forgotten to add it? ({1})'.format(plugin, exc))
            models = []

        try:
            migrations = import_component('{0}.migrations:MIGRATIONS'.format(
                plugin))
        except ImportError as exc:
            _log.debug('No migrations found for {0}: {1}'.format(
                plugin,
                exc))

            migrations = {}
        except AttributeError as exc:
            _log.debug('Could not find MIGRATIONS in {0}.migrations, have you \
forgotten to add it? ({1})'.format(plugin, exc))
            migrations = {}

        try:
            foundations = import_component('{0}.models:FOUNDATIONS'.format(plugin))
        except ImportError as exc:
            foundations = {}
        except AttributeError as exc:
            foundations = {}

        if models:
            managed_dbdata.append(
                    DatabaseData(plugin, models, foundations, migrations))


    return managed_dbdata

def main_cli():
    parser = argparse.ArgumentParser(
        description='GNU MediaGoblin utilities.')
    parser.add_argument(
        '-cf', '--conf_file', default=None,
        help=(
            "Config file used to set up environment.  "
            "Default to mediagoblin_local.ini if readable, "
            "otherwise mediagoblin.ini"))

    subparsers = parser.add_subparsers(help='sub-command help')
    for command_name, command_struct in six.iteritems(SUBCOMMAND_MAP):
        if 'help' in command_struct:
            subparser = subparsers.add_parser(
                command_name, help=command_struct['help'])
        else:
            subparser = subparsers.add_parser(command_name)

        setup_func = import_component(command_struct['setup'])
        exec_func = import_component(command_struct['func'])

        setup_func(subparser)

        subparser.set_defaults(func=exec_func)

    args = parser.parse_args()
    args.orig_conf_file = args.conf_file
    if args.conf_file is None:
        if os.path.exists('mediagoblin_local.ini') \
                and os.access('mediagoblin_local.ini', os.R_OK):
            args.conf_file = 'mediagoblin_local.ini'
        else:
            args.conf_file = 'mediagoblin.ini'

    # This is a hopefully TEMPORARY hack for adding a mediagoblin.ini
    # if none exists, to make up for a deficiency as we are migrating
    # our docs to the new "no mediagoblin.ini by default" workflow.
    # Normally, the docs should provide instructions for this, but
    # since 0.7.1 docs say "install from master!" and yet we removed
    # mediagoblin.ini, we need to cover our bases...

    parent_directory = os.path.split(os.path.abspath(args.conf_file))[0]
    if os.path.split(args.conf_file)[1] == 'mediagoblin.ini' \
       and not os.path.exists(args.conf_file) \
       and os.path.exists(
           os.path.join(
               parent_directory, 'mediagoblin.example.ini')):
        # Do the copy-over of the mediagoblin config for the user
        _log.warning(
            "No mediagoblin.ini found and no other path given, "
            "so making one for you.")
        shutil.copy(
            os.path.join(parent_directory, "mediagoblin.example.ini"),
            os.path.join(parent_directory, "mediagoblin.ini"))

    args.func(args)

def endpoint_to_controller(rule):
    endpoint = rule.endpoint
    view_func = rule.gmg_controller

    _log.debug('endpoint: {0} view_func: {1}'.format(endpoint, view_func))

    # import the endpoint, or if it's already a callable, call that
    if isinstance(view_func, basestring):
        view_func = import_component(view_func)
        rule.gmg_controller = view_func

    return view_func

 def get_fail_exception(self):
     """
     Get the exception that's appropriate for this error
     """
     if self.fail_error:
         try:
             return common.import_component(self.fail_error)
         except ImportError:
             # TODO(breton): fail_error should give some hint about why it
             # failed. fail_error is used as a path to import().
             # Unfortunately, I didn't know about that and put general error
             # message there. Maybe it's for the best, because for admin,
             # we could show even some raw python things. Anyway, this
             # should be properly resolved. Now we are in a freeze, that's
             # why I simply catch ImportError.
             return None

    def media_data_init(self, **kwargs):
        """
        Initialize or update the contents of a media entry's media_data row
        """
        media_data = self.media_data

        if media_data is None:
            # Get the correct table:
            table = import_component(self.media_type + '.models:DATA_MODEL')
            # No media data, so actually add a new one
            media_data = table(**kwargs)
            # Get the relationship set up.
            media_data.get_media_entry = self
        else:
            # Update old media data
            for field, value in kwargs.iteritems():
                setattr(media_data, field, value)

def storage_system_from_config(config_section):
    """
    Utility for setting up a storage system from a config section.

    Note that a special argument may be passed in to
    the config_section which is "storage_class" which will provide an
    import path to a storage system.  This defaults to
    "mediagoblin.storage:BasicFileStorage" if otherwise undefined.

    Arguments:
     - config_section: dictionary of config parameters

    Returns:
      An instantiated storage system.

    Example:
      storage_system_from_config(
        {'base_url': '/media/',
         'base_dir': '/var/whatever/media/'})

       Will return:
         BasicFileStorage(
           base_url='/media/',
           base_dir='/var/whatever/media')
    """
    # This construct is needed, because dict(config) does
    # not replace the variables in the config items.
    config_params = dict(six.iteritems(config_section))

    if 'storage_class' in config_params:
        storage_class = config_params['storage_class']
        config_params.pop('storage_class')
    else:
        storage_class = 'mediagoblin.storage.filestorage:BasicFileStorage'

    storage_class = common.import_component(storage_class)
    return storage_class(**config_params)

def run_foundations(db, global_config):
    """
    Gather foundations data and run it.
    """
    from mediagoblin.db.models import FOUNDATIONS as MAIN_FOUNDATIONS
    all_foundations = [(u"__main__", MAIN_FOUNDATIONS)]

    Session = sessionmaker(bind=db.engine)
    session = Session()

    plugins = global_config.get('plugins', {})

    for plugin in plugins:
        try:
            foundations = import_component(
                '{0}.models:FOUNDATIONS'.format(plugin))
            all_foundations.append((plugin, foundations))
        except ImportError as exc:
            continue
        except AttributeError as exc:
            continue

    for name, foundations in all_foundations:
        populate_table_foundations(session, foundations, name)

    def __init__(self, config_path, setup_celery=True):
        """
        Initialize the application based on a configuration file.

        Arguments:
         - config_path: path to the configuration file we're opening.
         - setup_celery: whether or not to setup celery during init.
           (Note: setting 'celery_setup_elsewhere' also disables
           setting up celery.)
        """
        _log.info("GNU MediaGoblin %s main server starting", __version__)
        _log.debug("Using config file %s", config_path)
        ##############
        # Setup config
        ##############

        # Open and setup the config
        global_config, app_config = setup_global_and_app_config(config_path)

        media_type_warning()

        setup_crypto()

        ##########################################
        # Setup other connections / useful objects
        ##########################################

        # Setup Session Manager, not needed in celery
        self.session_manager = session.SessionManager()

        # load all available locales
        setup_locales()

        # Set up plugins -- need to do this early so that plugins can
        # affect startup.
        _log.info("Setting up plugins.")
        setup_plugins()

        # Set up the database
        self.db = setup_database(app_config['run_migrations'])

        # Quit app if need to run dbupdate
        check_db_up_to_date()

        # Register themes
        self.theme_registry, self.current_theme = register_themes(app_config)

        # Get the template environment
        self.template_loader = get_jinja_loader(
            app_config.get('local_templates'),
            self.current_theme,
            PluginManager().get_template_paths()
            )

        # Check if authentication plugin is enabled and respond accordingly.
        self.auth = check_auth_enabled()
        if not self.auth:
            app_config['allow_comments'] = False

        # Set up storage systems
        self.public_store, self.queue_store = setup_storage()

        # set up routing
        self.url_map = get_url_map()

        # set up staticdirector tool
        self.staticdirector = get_staticdirector(app_config)

        # Setup celery, if appropriate
        if setup_celery and not app_config.get('celery_setup_elsewhere'):
            if os.environ.get('CELERY_ALWAYS_EAGER', 'false').lower() == 'true':
                setup_celery_from_config(
                    app_config, global_config,
                    force_celery_always_eager=True)
            else:
                setup_celery_from_config(app_config, global_config)

        #######################################################
        # Insert appropriate things into mediagoblin.mg_globals
        #
        # certain properties need to be accessed globally eg from
        # validators, etc, which might not access to the request
        # object.
        #######################################################

        setup_globals(app=self)

        # Workbench *currently* only used by celery, so this only
        # matters in always eager mode :)
        setup_workbench()

        # instantiate application meddleware
        self.meddleware = [common.import_component(m)(self)
                           for m in meddleware.ENABLED_MEDDLEWARE]

 def media_data_ref(self):
     return import_component(self.media_type + '.models:BACKREF_NAME')

 def get_fail_exception(self):
     """
     Get the exception that's appropriate for this error
     """
     if self.fail_error:
         return common.import_component(self.fail_error)

def test_import_component():
    imported_func = common.import_component(
        'mediagoblin.tests.test_util:_import_component_testing_method')
    result = imported_func('hooobaladoobala')
    expected = u"'hooobaladoobala' is the silliest string I've ever seen"
    assert result == expected

    def call_backend(self, environ, start_response):
        request = Request(environ)

        ## Compatibility webob -> werkzeug
        request.GET = request.args
        request.accept_language = request.accept_languages
        request.accept = request.accept_mimetypes

        ## Routing / controller loading stuff
        path_info = request.path
        route_match = self.routing.match(path_info)

        # By using fcgi, mediagoblin can run under a base path
        # like /mediagoblin/. request.path_info contains the
        # path inside mediagoblin. If the something needs the
        # full path of the current page, that should include
        # the basepath.
        # Note: urlgen and routes are fine!
        request.full_path = environ["SCRIPT_NAME"] + request.path
        # python-routes uses SCRIPT_NAME. So let's use that too.
        # The other option would be:
        # request.full_path = environ["SCRIPT_URL"]

        # Fix up environ for urlgen
        # See bug: https://bitbucket.org/bbangert/routes/issue/55/cache_hostinfo-breaks-on-https-off
        if environ.get('HTTPS', '').lower() == 'off':
            environ.pop('HTTPS')

        ## Attach utilities to the request object
        request.matchdict = route_match
        request.urlgen = routes.URLGenerator(self.routing, environ)
        # Do we really want to load this via middleware?  Maybe?
        request.session = request.environ['beaker.session']
        # Attach self as request.app
        # Also attach a few utilities from request.app for convenience?
        request.app = self
        request.locale = translate.get_locale_from_request(request)

        request.template_env = template.get_jinja_env(
            self.template_loader, request.locale)
        request.db = self.db
        request.staticdirect = self.staticdirector

        mg_request.setup_user_in_request(request)

        # No matching page?
        if route_match is None:
            # Try to do see if we have a match with a trailing slash
            # added and if so, redirect
            if not path_info.endswith('/') \
                    and request.method == 'GET' \
                    and self.routing.match(path_info + '/'):
                new_path_info = path_info + '/'
                if request.GET:
                    new_path_info = '%s?%s' % (
                        new_path_info, urllib.urlencode(request.GET))
                redirect = exc.HTTPFound(location=new_path_info)
                return request.get_response(redirect)(environ, start_response)

            # Okay, no matches.  404 time!
            request.matchdict = {}  # in case our template expects it
            return render_404(request)(environ, start_response)

        # import the controller, or if it's already a callable, call that
        route_controller = route_match['controller']
        if isinstance(route_controller, unicode) \
                or isinstance(route_controller, str):
            controller = common.import_component(route_match['controller'])
        else:
            controller = route_match['controller']

        # pass the request through our meddleware classes
        for m in self.meddleware:
            response = m.process_request(request, controller)
            if response is not None:
                return response(environ, start_response)

        request.start_response = start_response

        # get the response from the controller
        response = controller(request)

        # pass the response through the meddleware
        for m in self.meddleware[::-1]:
            m.process_response(request, response)

        return response(environ, start_response)