import ast

import configparser

from collections.abc import Mapping

from os import getenv

def parse_values(config):

    config_parsed = {}

    for section in config.sections():

        config_parsed[section] = {}

        for key, value in config[section].items():

            config_parsed[section][key] = ast.literal_eval(value)

    return config_parsed

class Settings(Mapping):

    def __init__(self, setting_file=getenv('COMPNET_CONFIG')):

        if not setting_file:

            raise EnvironmentError('environment variable COMPNET_CONFIG is not defined, see docs/README.md for details')

        config = configparser.ConfigParser()

        config.read(setting_file)

        self.settings_dict = parse_values(config)

    def __getitem__(self, key):

        return self.settings_dict[key]

    def __len__(self):

        return len(self.settings_dict)

    def __iter__(self):

        return self.settings_dict.items()