import argparse

class ArgumentParser(argparse.ArgumentParser):
    """
    extended with some optparse functionality

    """
    def get_option(self, opt_str):
        """action with opt_str flag
        None if no match
        """
        return self._option_string_actions.get(opt_str)

    def get_action_by_dest(self, dest):
        """action with matching 'dest'
        empty list if no match"""
        return [a for a in self._actions if a.dest==dest]

    def option_groups(self):
        """the parser action_groups
        Argument Groups are different in argparse
        They are only used for input, and for help display
        They are not used in parsing
        Their ._actions list is shared with the parser
        Their own actions are available in ._group_actions
        All actions belong to a group.
        There are 2 default groups

        to see group titles use
        [i.title for i in p.option_groups()]
        """
        return self._action_groups[:]

    def option_list(self):
        "list of all actions"
        return self._actions[:]

    def get_option_group(self, opt_str):
        """action group that contains this action
        match on flag or dest
        an action does not record its 'container'
        so we have to search the groups
        Here we accept either flag strings or dest values
        """
        dest = None
        if opt_str.startswith('-'):
            dest = self.get_option(opt_str)
            if dest:
                dest = dest.dest
        if dest is None:
            dest = opt_str
        for g in self.option_groups():
            actions = [a for a in g._group_actions if a.dest==dest]
            if actions:
                break
        return g if actions else None

if __name__=='__main__':
    p = ArgumentParser()
    g = p.add_argument_group('test group')
    g.add_argument('foo')
    p.add_argument('-b','--bar')
    p.add_argument('duplicate')
    g.add_argument('-d', dest='duplicate') # duplicate dest

    p.print_help()
    print()
    print('help help:\n', p.get_option('-h').help)
    print('1st help:\n', p._actions[0].help)
    print('foo action:\n', p.get_action_by_dest('foo'))
    print('duplicate actions:\n', p.get_action_by_dest('duplicate'))
    print('group titles:\n', [g.title for g in p.option_groups()])
    print('action dests:\n', [a.dest for a in p.option_list()])
    print(p.get_option('--bar').dest, 'is in',
        p.get_option_group('bar').title)
    print("bar's group:", p.get_option_group('--bar').title)
    print("foo's group:",p.get_option_group('foo').title)
    print("'wrong' not found:", p.get_option_group('wrong'))
    print('actions by group')
    # note similarity to parser.format_help
    # and parser._add_container_actions
    for g in p.option_groups():
        print("\t",g.title)
        for a in g._group_actions:
            print("\t\t", a.dest, a.option_strings)
    # to avoid using private g._group_actions we'd have to add a method
    # to _ArgumentGroup class