import json
from pathlib import Path

from webapp.auth import SUPPORTED_UI_LANGUAGES, normalize_translation_language
from webapp.config import ConfigFileError


TRANSLATIONS_DIR = Path(__file__).resolve().parent / "translations"
TRANSLATION_CATALOG_FILE = TRANSLATIONS_DIR / "catalog.json"


def load_translations(language: str) -> dict:
    normalized = normalize_translation_language(language)
    catalog = load_translation_catalog()
    merged: dict[str, object] = {}
    for key, translations in catalog.items():
        if not isinstance(translations, dict):
            continue
        english_value = translations.get("en")
        localized_value = translations.get(normalized)
        if localized_value not in (None, ""):
            merged[key] = localized_value
        elif english_value is not None:
            merged[key] = english_value
    return merged


def load_translation_catalog() -> dict:
    if not TRANSLATION_CATALOG_FILE.exists():
        return {}
    try:
        payload = json.loads(TRANSLATION_CATALOG_FILE.read_text(encoding="utf-8"))
    except json.JSONDecodeError as error:
        detail = f"Invalid JSON: {error.msg}"
        if "Invalid control character" in error.msg:
            detail += " JSON strings cannot contain raw line breaks; use \\n instead."
        raise ConfigFileError(TRANSLATION_CATALOG_FILE, detail) from error
    return payload if isinstance(payload, dict) else {}


def language_options() -> list[dict[str, str]]:
    return [{"code": code, "label_key": f"ui_language.{code}"} for code in SUPPORTED_UI_LANGUAGES]