"""配置加载：优先 YAML（若安装了 pyyaml），否则回退 JSON。

设计原则：router_system 核心零依赖，因此 pyyaml 是"可选"的。
默认 config/config.yaml 存在；若 pyyaml 不可用，可提供同名 .json。
"""
from __future__ import annotations

import json
import os
from pathlib import Path
from typing import Any, Dict, Optional

DEFAULT_CONFIG_PATH = Path(__file__).resolve().parent.parent / "config" / "config.yaml"

_DEFAULTS: Dict[str, Any] = {
    "system": {"name": "multi-expert-router", "version": "0.1.0"},
    "router": {
        "low_confidence_threshold": 0.60,   # 分类置信度低于此值 -> 直接走最后处理者
        "judge_fallback_threshold": 0.70,   # Judge 质量分低于此值 -> 升级最后处理者
        "default_temperature": 0.2,
    },
    "execution": {
        "mode": "rule",              # rule（L0 零参数）| hybrid
        "planner": "rule",           # rule | hf
        "expert_backend": "rule",    # rule（规则执行器）| hf | api
        "model_level": "L0",         # L0 | L1 | L2
        "max_plan_depth": 3,
    },
    "classifier": {"type": "rule", "model": "Qwen/Qwen3-0.6B", "confidence_floor": 0.55},
    "domains": ["code", "math", "legal", "medical", "finance", "life", "education", "general"],
    # 两级路由：大领域分组（用户接口指定 group → 组内路由模型 → 组内专业小模型）
    # 组内路由模型只识别本组领域，体积约为统一路由模型的 1/4
    "domain_groups": {
        "tech": ["code", "math"],
        "professional": ["legal", "medical", "finance"],
        "lifestyle": ["life", "education"],
        "general": ["general"],
    },
    "experts": {
        "code": {"type": "mock", "model": "Qwen/Qwen2.5-Coder-7B-Instruct"},
        "math": {"type": "mock", "model": "Qwen/Qwen3-4B-Instruct"},
        "legal": {"type": "mock", "model": "Qwen/Qwen3-4B-Instruct"},
        "medical": {"type": "mock", "model": "Qwen/Qwen3-4B-Instruct"},
        "finance": {"type": "mock", "model": "Qwen/Qwen3-4B-Instruct"},
        "life": {"type": "mock", "model": "Qwen/Qwen3-1.7B-Instruct"},
        "education": {"type": "mock", "model": "Qwen/Qwen3-1.7B-Instruct"},
        "general": {"type": "mock", "model": "Qwen/Qwen3-1.7B-Instruct"},
    },
    "fallback": {
        "type": "mock",
        "model": "deepseek-v4-flash",
        "base_url": "https://api.deepseek.com",
        "api_key_env": "DEEPSEEK_API_KEY",
    },
    "judge": {"type": "rule", "model": "Qwen/Qwen3-1.7B-Instruct"},
    "cache": {
        "enabled": True,
        "semantic_enabled": True,
        "similarity_threshold": 0.88,
        "promote_frequency": 5,
    },
}


def load_defaults() -> Dict[str, Any]:
    return _DEFAULTS


def _try_load_yaml(path: Path) -> Optional[Dict[str, Any]]:
    try:
        import yaml  # type: ignore
    except ImportError:
        return None
    try:
        with open(path, "r", encoding="utf-8") as f:
            data = yaml.safe_load(f)
        return data if isinstance(data, dict) else None
    except Exception:
        return None


def _try_load_json(path: Path) -> Optional[Dict[str, Any]]:
    json_path = path.with_suffix(".json")
    if not json_path.exists():
        return None
    try:
        with open(json_path, "r", encoding="utf-8") as f:
            data = json.load(f)
        return data if isinstance(data, dict) else None
    except Exception:
        return None


def _merge_defaults(data: Dict[str, Any]) -> Dict[str, Any]:
    """将用户配置与内置默认配置做一层合并（用户优先）。"""
    merged = dict(_DEFAULTS)
    for k, v in data.items():
        if isinstance(v, dict) and isinstance(merged.get(k), dict):
            merged[k] = {**merged[k], **v}
        else:
            merged[k] = v
    return merged


def load_config(path: Optional[Path | str] = None) -> Dict[str, Any]:
    """加载配置，返回 dict。文件不存在或解析失败时返回内置默认配置。"""
    cfg_path = Path(path) if path else DEFAULT_CONFIG_PATH
    if cfg_path.exists():
        data = _try_load_yaml(cfg_path) or _try_load_json(cfg_path)
        if data is not None:
            return _merge_defaults(data)
    return dict(_DEFAULTS)


def get_api_key(cfg: Dict[str, Any]) -> Optional[str]:
    """从环境变量读取 API Key（用于 api 类型后端）。"""
    env_name = cfg.get("api_key_env") or "API_KEY"
    return os.environ.get(env_name) or None