"""Load global config."""
import os
from pathlib import Path
from typing import Union

from dotenv import load_dotenv
from yaml import load

from jarvis_core.util import Singleton

try:
    from yaml import CLoader as Loader
except ImportError:
    from yaml import Loader

DEFAULT_YAML_PATH = Path("config.yaml")
DEFAULT_ENV_PATH = Path(".env")


class Config(Singleton):
    REQUIRED = []
    OPTIONAL = {}
    ENV_REQUIRED = []
    ENV_OPTIONAL = {}

    @classmethod
    def _process_env(cls, **kwargs) -> dict:
        """Process environment variables into standard arguments"""

    @classmethod
    def from_env(cls, filepath: Union[Path, str] = DEFAULT_ENV_PATH) -> "Config":
        """Loag the environment config."""
        if inst := cls.__dict__.get("inst"):
            return inst

        load_dotenv(filepath)

        data = {}
        for item in cls.ENV_REQUIRED:
            data[item] = os.environ.get(item, None)
        for item, default in cls.ENV_OPTIONAL.items():
            data[item] = os.environ.get(item, default)

        data = cls._process_env(**data)

        return cls(**data)

    @classmethod
    def from_yaml(cls, filepath: Union[Path, str] = DEFAULT_YAML_PATH) -> "Config":
        """Load the yaml config file."""
        if inst := cls.__dict__.get("inst"):
            return inst

        if isinstance(filepath, str):
            filepath = Path(filepath)

        with filepath.open() as f:
            raw = f.read()

        y = load(raw, Loader=Loader)
        return cls(**y)

    @classmethod
    def load(cls) -> "Config":
        if DEFAULT_ENV_PATH.exists():
            return cls.from_env()
        return cls.from_yaml()

    @classmethod
    def reload(cls) -> bool:
        """Reload the config."""
        return cls.__dict__.pop("inst", None) is None