from __future__ import annotations

from fastapi import APIRouter, Request

from app.presets import PRESETS
from app.services.i18n import DEFAULT_LOCALE, locale_from_request

router = APIRouter(prefix="/api")


def _localize(value, locale: str):
    """Recursively unwrap {en, zh} dicts to the requested locale.

    Falls back to the default locale, then to the first available value.
    Strings (and other scalars) are returned as-is.
    """
    if isinstance(value, dict):
        # Heuristic: dicts with only "en"/"zh" keys are translation maps.
        keys = set(value.keys())
        if keys <= {"en", "zh"}:
            if locale in value:
                return value[locale]
            if DEFAULT_LOCALE in value:
                return value[DEFAULT_LOCALE]
            return next(iter(value.values()))
        return {k: _localize(v, locale) for k, v in value.items()}
    if isinstance(value, list):
        return [_localize(v, locale) for v in value]
    return value


@router.get("/presets")
async def get_presets(request: Request):
    locale = locale_from_request(request)
    return {"presets": _localize(PRESETS, locale)}