from __future__ import annotations

import os
import re
from pathlib import Path

import yaml

from app.models import AppConfig

_ENV_PATTERN = re.compile(r"\$\{([A-Z0-9_]+)\}")


def _expand_env(value):
    if isinstance(value, str):
        return _ENV_PATTERN.sub(lambda m: os.getenv(m.group(1), ""), value)
    if isinstance(value, list):
        return [_expand_env(v) for v in value]
    if isinstance(value, dict):
        return {k: _expand_env(v) for k, v in value.items()}
    return value


def load_app_config(path: Path) -> AppConfig:
    raw = yaml.safe_load(path.read_text(encoding="utf-8")) or {}
    expanded = _expand_env(raw)
    return AppConfig.model_validate(expanded)