import argparse

"""

Custom help action for argparse, it prints the help message for the main parser and all subparsers.

"""


class _HelpAction(argparse._HelpAction):
    def __call__(self, parser, namespace, values, option_string=None):
        parser.print_help()

        # retrieve subparsers from parser
        subparsers_actions = [
            action for action in parser._actions
            if isinstance(action, argparse._SubParsersAction)]
        # there will probably only be one subparser_action,
        # but better save than sorry
        for subparsers_action in subparsers_actions:
            # get all subparsers and print help
            for choice, subparser in subparsers_action.choices.items():
                print("\n### Command '{}'".format(choice))
                print(subparser.format_help())

        parser.exit()