from __future__ import annotations

import dataclasses
import os.path
import typing

import yaml


_cached_config: typing.Optional[Config] = None


@dataclasses.dataclass
class Config:
    controllers: typing.List[str]
    server_names: typing.List[str]
    comm_secret: str
    cookie_secret: str
    venue_info_url: typing.Optional[str]
    session_timeout: int  # in seconds
    debug: bool

    @staticmethod
    def load_default_once() -> Config:
        global _cached_config
        if not _cached_config:
            _cached_config = Config.load()
        return _cached_config

    @staticmethod
    def load(filename: typing.Optional[str]=None) -> Config:
        if filename is None:
            for name in ('capport.yaml', '/etc/capport.yaml'):
                if os.path.exists(name):
                    return Config.load(name)
            raise RuntimeError("Missing config file")
        with open(filename) as f:
            data = yaml.safe_load(f)
        controllers = list(map(str, data['controllers']))
        return Config(
            controllers=controllers,
            server_names=data.get('server-names', []),
            comm_secret=str(data.get('comm-secret', None) or data['secret']),
            cookie_secret=str(data['cookie-secret']),
            venue_info_url=str(data.get('venue-info-url')),
            session_timeout=data.get('session-timeout', 3600),
            debug=data.get('debug', False)
        )