from collections.abc import MutableMapping
from json import load
from pathlib import Path

LANG_DIR = Path(__file__).parent / "lang"
FALLBACK_LANG = "en"
LANG_CACHE: dict[str, dict[str, str]] = {}


# https://stackoverflow.com/questions/6027558/flatten-nested-dictionaries-compressing-keys
def __flatten(dictionary: dict, parent_key: str = "") -> dict[str, str]:
    items = []
    for key, value in dictionary.items():
        new_key = parent_key + "." + key if parent_key else key
        if isinstance(value, MutableMapping):
            items.extend(__flatten(value, new_key).items())
        else:
            items.append((new_key, value))
    return dict(items)


def __get_lang_data(lang: str) -> dict[str, str]:
    if lang not in LANG_CACHE:
        file = LANG_DIR / f"{lang}.json"
        if not file.exists():
            return __get_lang_data(FALLBACK_LANG)
        with file.open() as f:
            raw_data: dict = load(f)
            LANG_CACHE[lang] = __flatten(raw_data)
    return LANG_CACHE[lang]


def get_lang(lang: str, key: str) -> str:
    data = __get_lang_data(lang)
    return data.get(key, key)