# -*- coding: utf-8 -*-
"""配置管理主类"""
from copy import deepcopy
from .defaults import DEFAULTS
from .env_parser import load_env_overrides

class AppConfig:
    """应用配置管理器"""
    
    def __init__(self, config_dict: dict):
        self.config = config_dict
    
    @classmethod
    def load(cls, cli_overrides: dict = None):
        """加载配置: DEFAULTS < ENV < CLI"""
        cfg = load_env_overrides(DEFAULTS)
        
        if cli_overrides:
            cls._deep_merge(cfg, cli_overrides)
        
        # 规范化
        cls._normalize(cfg)
        cls._validate(cfg)
        
        return cls(cfg)
    
    @staticmethod
    def _deep_merge(dst, src):
        """深度合并字典"""
        for k, v in src.items():
            if isinstance(v, dict) and isinstance(dst.get(k), dict):
                AppConfig._deep_merge(dst[k], v)
            else:
                dst[k] = v
    
    @staticmethod
    def _normalize(cfg):
        """规范化配置"""
        # 转换 store_id 为整数
        try:
            cfg["app"]["store_id"] = int(str(cfg["app"]["store_id"]).strip())
        except Exception:
            raise SystemExit("app.store_id 必须为整数")
        
        # DSN 组装
        if not cfg["db"]["dsn"]:
            cfg["db"]["dsn"] = (
                f"postgresql://{cfg['db']['user']}:{cfg['db']['password']}"
                f"@{cfg['db']['host']}:{cfg['db']['port']}/{cfg['db']['name']}"
            )
        
        # connect_timeout 限定 1-20 秒
        try:
            timeout_sec = int(cfg["db"].get("connect_timeout_sec") or 5)
        except Exception:
            raise SystemExit("db.connect_timeout_sec 必须为整数")
        cfg["db"]["connect_timeout_sec"] = max(1, min(timeout_sec, 20))

        # 会话参数
        cfg["db"].setdefault("session", {})
        sess = cfg["db"]["session"]
        sess.setdefault("timezone", cfg["app"]["timezone"])
        
        for k in ("statement_timeout_ms", "lock_timeout_ms", "idle_in_tx_timeout_ms"):
            if k in sess and sess[k] is not None:
                try:
                    sess[k] = int(sess[k])
                except Exception:
                    raise SystemExit(f"db.session.{k} 需为整数毫秒")
    
    @staticmethod
    def _validate(cfg):
        """验证必填配置"""
        missing = []
        if not cfg["app"]["store_id"]:    
            missing.append("app.store_id")
        if missing:
            raise SystemExit("缺少必需配置: " + ", ".join(missing))
    
    def get(self, key: str, default=None):
        """获取配置值（支持点号路径）"""
        keys = key.split(".")
        val = self.config
        for k in keys:
            if isinstance(val, dict):
                val = val.get(k)
            else:
                return default
        return val if val is not None else default
    
    def __getitem__(self, key):
        return self.config[key]