"""应用配置：全部从 .env 读取，代码不硬编码任何连接/模型值。

.env 路径由本文件位置推导（绝对路径），与启动工作目录无关；每个子配置各自声明
env_file，保证嵌套配置也读文件（否则默认实例会吞掉环境变量）；任一必需键缺失，
启动即报错（fail-fast），避免带着错误配置静默运行。
"""
from pathlib import Path
from typing import Optional

from pydantic_settings import BaseSettings, SettingsConfigDict
from sqlalchemy.engine import URL

# 项目根 = settings.py 的上两级；无论从哪个 cwd 启动都能定位 .env
_ENV_FILE: Path = Path(__file__).resolve().parent.parent / ".env"


class MysqlCfg(BaseSettings):
    host: str
    port: int
    user: str
    password: str
    database: str
    pool_size: int
    max_overflow: int
    pool_recycle: int
    connect_timeout: int
    pool_timeout: int

    model_config = SettingsConfigDict(env_prefix="MYSQL_", env_file=_ENV_FILE, extra="ignore")

    @property
    def url(self) -> URL:
        return URL.create(
            "mysql+aiomysql",
            username=self.user,
            password=self.password,
            host=self.host,
            port=self.port,
            database=self.database,
            query={"charset": "utf8mb4"},
        )


class RedisCfg(BaseSettings):
    host: str
    port: int
    db: int
    password: Optional[str] = None  # 可缺省（空串/未设置表示无密码）
    socket_connect_timeout: int
    socket_timeout: int
    health_check_interval: int
    max_connections: int

    model_config = SettingsConfigDict(env_prefix="REDIS_", env_file=_ENV_FILE, extra="ignore")


class Neo4jCfg(BaseSettings):
    uri: str
    user: str
    password: str
    max_connection_pool_size: int
    connection_acquisition_timeout: int
    connection_timeout: int
    max_transaction_retry_time: int

    model_config = SettingsConfigDict(env_prefix="NEO4J_", env_file=_ENV_FILE, extra="ignore")


class MilvusCfg(BaseSettings):
    uri: str
    token: Optional[str] = None  # 可缺省（无需鉴权时留空）
    user: Optional[str] = None
    password: Optional[str] = None
    db_name: Optional[str] = None
    connect_timeout: int  # 建连/通道就绪超时（构造是急切连接，必须短）
    timeout: int  # 数据操作超时，调用处可覆盖

    model_config = SettingsConfigDict(env_prefix="MILVUS_", env_file=_ENV_FILE, extra="ignore")


class LLMCfg(BaseSettings):
    """大模型配置：本地 Ollama / OpenAI 兼容 API 双模式见 tool/llm.py。"""

    mode: str
    # —— 本地 Ollama ——
    ollama_base: str
    ollama_chat_model: str
    ollama_embed_model: str
    # —— OpenAI 兼容 API（base_url 以 /v1 结尾）——
    api_base: str
    api_key: str
    api_chat_model: str
    api_embed_model: str
    # —— 通用超参 ——
    temperature: float
    max_tokens: int
    timeout: int
    max_retries: int
    retry_backoff_sec: float  # 指数退避基数
    fallback_chat_model: str  # 备用模型：主模型失败后自动切换（空则不启用）

    model_config = SettingsConfigDict(env_prefix="LLM_", env_file=_ENV_FILE, extra="ignore")


class JwtCfg(BaseSettings):
    """JWT 鉴权配置（service/auth.py）。"""
    secret: str            # 签名密钥，生产必须换强随机值
    algorithm: str         # 签名算法，如 HS256
    expire_seconds: int    # Token 有效期（秒）

    model_config = SettingsConfigDict(env_prefix="JWT_", env_file=_ENV_FILE, extra="ignore")


class DBMaintenanceCfg(BaseSettings):
    """数据库启动策略：连接重试与严格模式（config/database/__init__.py）。"""
    strict_startup: bool = False  # true=任一核心库启动失败即阻止应用启动（生产建议开启）
    conn_retries: int = 3         # 各库 init 最大尝试次数
    retry_backoff_sec: float = 1.0  # 指数退避基数：1s/2s/4s

    model_config = SettingsConfigDict(env_prefix="DB_", env_file=_ENV_FILE, extra="ignore")


class Settings(BaseSettings):
    app_env: str
    db: DBMaintenanceCfg = DBMaintenanceCfg()
    jwt: JwtCfg = JwtCfg()

    mysql: MysqlCfg = MysqlCfg()
    redis: RedisCfg = RedisCfg()
    neo4j: Neo4jCfg = Neo4jCfg()
    milvus: MilvusCfg = MilvusCfg()
    llm: LLMCfg = LLMCfg()

    model_config = SettingsConfigDict(env_file=_ENV_FILE, extra="ignore")


settings = Settings()