"""
methods and properties supporting
command line interface
"""


import argparse
import sys
from .cast import keyvalue


class ConfigurationParser(argparse.ArgumentParser):
    """parse arguments with validation"""

    def __init__(self, **kwargs):
        kwargs.setdefault('formatter_class', argparse.RawTextHelpFormatter)
        argparse.ArgumentParser.__init__(self, **kwargs)
        self.add_arguments()
        self.options = None

    def add_arguments(self):
        """add arguments"""
        # Abstract Base Class

    def parse_args(self, args=sys.argv[1:]):
        options = argparse.ArgumentParser.parse_args(self, args)
        self.options = self.validate(options)
        return self.options

    def validate(self, options):
        """validate options"""
        return options

    def keyvalue(self, arg):

        try:
            return keyvalue(arg)
        except AssertionError as e:
            self.error(str(e))