"""网关配置加载与校验。

从 gateway/config.json 读取配置，缺字段给默认值，启动时校验必填项。
"""

import json
import logging
from pathlib import Path
from typing import List

logger = logging.getLogger("gateway.config")

CONFIG_PATH = Path(__file__).resolve().parent / "config.json"

DEFAULTS = {
    "public_base_url": "https://hair.xiangsilian.com",
    "static_dir": "static/annotations",
    "health_check": {
        "path": "/health",
        "interval_seconds": 8,
        "timeout_seconds": 3,
        "unhealthy_threshold": 2,
        "healthy_threshold": 1,
    },
    "dispatch": {
        "per_worker_concurrency": 1,
        "queue_wait_seconds": 30,
        "request_timeout_seconds": 60,
        "retry_on_failure": True,
        "max_retries": 1,
    },
    "cleanup": {
        "interval_minutes": 60,
        "max_age_hours": 24,
    },
}

_config_cache = None


def _deep_merge(defaults: dict, overrides: dict) -> dict:
    """递归合并：overrides 中的值覆盖 defaults，嵌套 dict 递归处理。"""
    result = defaults.copy()
    for key, value in overrides.items():
        if key in result and isinstance(result[key], dict) and isinstance(value, dict):
            result[key] = _deep_merge(result[key], value)
        else:
            result[key] = value
    return result


def load_config() -> dict:
    """加载并校验配置文件，结果缓存仅加载一次。"""
    global _config_cache
    if _config_cache is not None:
        return _config_cache

    if not CONFIG_PATH.exists():
        raise FileNotFoundError(
            f"配置文件不存在: {CONFIG_PATH}\n"
            f"请从 gateway/config.example.json 复制并修改: "
            f"cp gateway/config.example.json gateway/config.json"
        )

    with open(CONFIG_PATH, "r", encoding="utf-8") as f:
        raw = json.load(f)

    # 合并默认值
    cfg = _deep_merge(DEFAULTS, raw)

    # --- 校验 ---
    workers: List[str] = cfg.get("workers", [])
    if not workers:
        raise ValueError("配置错误: workers 列表不能为空，至少需要一个 worker 地址")

    for i, w in enumerate(workers):
        if not isinstance(w, str) or not w:
            raise ValueError(f"配置错误: workers[{i}] 必须是非空字符串")

    password: str = cfg.get("shared_password", "")
    if not password or password == "REPLACE_ME_ROTATE_PERIODICALLY":
        logger.warning(
            "⚠ 安全警告: shared_password 未设置或仍为占位值 "
            "'REPLACE_ME_ROTATE_PERIODICALLY'，请立即更换！"
        )
    if len(password) < 8:
        logger.warning("⚠ 安全警告: shared_password 长度不足 8 位，建议使用更长的密码")

    public_base_url: str = cfg.get("public_base_url", "")
    if public_base_url.endswith("/"):
        cfg["public_base_url"] = public_base_url.rstrip("/")
        logger.warning("public_base_url 末尾含 '/'，已自动去除")

    # 确保 static_dir 是绝对路径
    static_dir = Path(cfg["static_dir"])
    if not static_dir.is_absolute():
        cfg["static_dir"] = str(Path(__file__).resolve().parents[1] / static_dir)

    logger.info(
        "配置加载完成 | workers=%s | public_base_url=%s | "
        "hc_interval=%ds | dispatch_timeout=%ds | queue_wait=%ds",
        cfg["workers"],
        cfg["public_base_url"],
        cfg["health_check"]["interval_seconds"],
        cfg["dispatch"]["request_timeout_seconds"],
        cfg["dispatch"]["queue_wait_seconds"],
    )

    _config_cache = cfg
    return cfg


def get_config() -> dict:
    """获取已加载的配置（必须先调用 load_config）。"""
    if _config_cache is None:
        raise RuntimeError("配置尚未加载，请先调用 load_config()")
    return _config_cache


def reload_config() -> dict:
    """强制重新加载配置（用于热更新）。"""
    global _config_cache
    _config_cache = None
    return load_config()