config_parser.py

from dataclasses import dataclass
from os import path

import yaml

from ares.consts import CONFIG_FILE


@dataclass
class ConfigParser:
    """Process user and internal config.

    Internal config is used by default, optional user config overrides default values

    Attributes
    ----------
    ares_config_location : str
        Path to internal Ares config.yml file.
    user_config_location : str
        Path to user config.yml file.
    """

    ares_config_location: str
    user_config_location: str

    def parse(self) -> dict:
        """
        Handle internal and user config

        Returns
        -------
        Dict :
            Internal parsed config.yml by default, or the merged internal and
            users config files.
        """
        internal_config_path: str = path.join(self.ares_config_location, CONFIG_FILE)
        user_config_path: str = path.join(self.user_config_location, CONFIG_FILE)
        if path.isfile(internal_config_path):
            with open(internal_config_path, "r") as config_file:
                internal_config: dict = yaml.safe_load(config_file)
        else:
            raise Exception("Internal Ares config.yml file is missing")

        if path.isfile(user_config_path):
            with open(user_config_path, "r") as config_file:
                user_config: dict = yaml.safe_load(config_file)
        # if no user config, fine to return internal_config here
        else:
            return internal_config

        # there is a user config and internal config, sort out the differences
        return self._merge_config_files(internal_config, user_config)

    @staticmethod
    def _merge_config_files(internal_config: dict, user_config: dict) -> dict:
        """
        Merge internal and user config files so we are left with just one.

        Start off with the internal_config, then override any matching keys
        in the user_config. Types the user pass in need to be checked.

        Parameters
        ----------
        internal_config :
            Internal config dictionary already parsed from the original yaml file.
        user_config :
            User config dictionary already parsed from the original yaml file.

        Returns
        -------
        Dict :
            A single config dictionary where user values override default values.
        """
        config: dict = internal_config.copy()
        # iterate through internal config, and search for matching values in user config
        for k, v in internal_config.items():
            value_type = type(v)
            if value_type == dict and k in user_config:
                config[k] = internal_config[k] | user_config[k]

            elif k in user_config and isinstance(user_config[k], value_type):
                config[k] = user_config[k]

        return config