"""Cached JSON config loader for config/<name>_config.json files.

Usage:
    from utils.config import load_config
    cfg = load_config("core")           # reads config/core_config.json
    conf_threshold = cfg["detection"]["conf"]

String values pass through ``os.path.expandvars`` on load, so JSON like
``"$HOME/miniconda3"`` resolves at read time.
"""
from __future__ import annotations

import json
import os
from typing import Any, Dict

from core.paths import CONFIG_DIR

_CACHE: Dict[str, Dict[str, Any]] = {}


def _expand(value):
    if isinstance(value, str):
        return os.path.expandvars(value)
    if isinstance(value, list):
        return [_expand(v) for v in value]
    if isinstance(value, dict):
        return {k: _expand(v) for k, v in value.items()}
    return value


def load_config(name: str) -> Dict[str, Any]:
    """Return the parsed JSON config for ``config/<name>_config.json`` (cached)."""
    if name in _CACHE:
        return _CACHE[name]

    path = CONFIG_DIR / f"{name}_config.json"
    if not path.exists():
        raise FileNotFoundError(f"Config not found: {path}")

    with open(path, "r") as f:
        raw = json.load(f)
    cfg = _expand(raw)
    _CACHE[name] = cfg
    return cfg