import logging
import os

import yaml

LOG = logging.getLogger(__name__)


class Singleton(type):
    _instance = None

    def __call__(cls, *args, **kwargs):
        if cls._instance is None:
            cls._instance = super(Singleton, cls).__call__(*args, **kwargs)
        else:
            cls._instance.__init__(*args, **kwargs)
        return cls._instance


class Config(dict, metaclass=Singleton):
    filename = 'cis-collector.yml'

    locations = [
        '/etc/{conf}'.format(conf=filename),
        '{home}/{conf}'.format(home=os.environ.get('HOME'), conf=filename),
        '{cwd}/{conf}'.format(cwd=os.getcwd(), conf=filename),
    ]

    def read_config(self):
        current_config = dict()
        for path in self.locations:
            try:
                with open(path) as config:
                    current_config.update(yaml.safe_load(config))
                    LOG.info('Loaded config from %s', path)
            except FileNotFoundError:
                LOG.debug('No config file at %s, skipping...', path)

        self.update(current_config)
        return current_config

    def __init__(self):
        self.read_config()
        super().__init__()