from configparser import RawConfigParser
from os import environ
from .maybe import Maybe
from pathlib import Path
from itertools import chain
from dataclasses import dataclass
from typing import Optional

_config_file_name = 'client.properties'


@dataclass
class Config:
    server_url: str
    auth_server_url: str
    repo_folders: tuple[Path, ...]


config_file_candidates = [
    (Maybe.of(Path('/etc') / 'jpacrepo' / _config_file_name)
     .filter(Path.exists)),
    (Maybe.of_nullable(environ.get('XDG_CONFIG_HOME', None))
     .map(Path)
     .map(lambda xdg_config_home: xdg_config_home / 'jpacrepo' / _config_file_name)
     .filter(Path.exists)),
    (Maybe.of_nullable(environ['HOME'])
     .map(Path)
     .map(lambda home: home / '.config' / _config_file_name)
     .filter(Path.exists))
]


def load_configuration() -> Config:
    main_section = 'main'
    server_url: Optional[str] = None
    auth_server_url: Optional[str] = None
    repo_folders: list[Path] = []
    for config_file_maybe in config_file_candidates:
        def process_configuration(config_file: Path) -> None:
            nonlocal server_url
            nonlocal auth_server_url
            config = RawConfigParser()
            with open(config_file, 'r') as lines:
                config.read_file(chain((f'[{main_section}]',), lines))
            (Maybe.of_nullable(config.get(main_section, 'RepoFolder', fallback=None))
             .map(lambda v: v.format(**environ))
             .map(Path)
             .if_present(repo_folders.append))
            server_url = config.get(main_section, 'ServerURL', fallback=server_url)
            auth_server_url = config.get(main_section, 'AuthServerURL', fallback=auth_server_url)

        config_file_maybe.if_present(process_configuration)
    return Config(server_url or 'https://woggioni.net/jpacrepo/',
                  auth_server_url or 'https://woggioni.net/auth/realms/woggioni.net',
                  tuple(repo_folders) or (Path('/var/cache/pacman/pkg'),)
                  )