"""
应用配置管理

使用 Pydantic Settings 进行类型安全的配置管理，
集成 ConfigLoader 支持环境变量和 YAML 配置文件。

配置优先级（从高到低）：
1. 环境变量（前缀 SATONANO_）
2. config.yaml 文件
3. .env 文件
4. 默认值
"""

from functools import lru_cache
from pathlib import Path
from typing import Any, Literal

from pydantic import Field, computed_field
from pydantic_settings import BaseSettings, SettingsConfigDict

from .config_loader import create_config_loader


def _yaml_settings_source() -> dict[str, Any]:
    """
    YAML 配置源工厂函数

    为 Pydantic Settings 提供 YAML 配置数据
    """
    # 查找配置文件路径
    config_paths = [
        Path("config.yaml"),
        Path("config.yml"),
        Path(__file__).parent.parent.parent / "config.yaml",
        Path(__file__).parent.parent.parent / "config.yml",
    ]

    yaml_path = None
    for path in config_paths:
        if path.exists():
            yaml_path = path
            break

    if yaml_path is None:
        return {}

    # 使用 ConfigLoader 加载配置（不带环境变量前缀，让 pydantic 处理）
    loader = create_config_loader(
        yaml_path=yaml_path,
        env_prefix="",  # 不读取环境变量，由 pydantic-settings 处理
        yaml_required=False,
    )
    return loader.load()


class Settings(BaseSettings):
    """应用配置"""

    model_config = SettingsConfigDict(
        env_prefix="SATONANO_",
        env_file=".env",
        env_file_encoding="utf-8",
        case_sensitive=False,
        extra="ignore",
    )

    # 应用基础配置
    app_name: str = "SatoNano"
    app_version: str = "0.1.0"
    debug: bool = False
    environment: Literal["development", "staging", "production"] = "development"

    # API 配置
    api_v1_prefix: str = "/api/v1"

    # 安全配置
    secret_key: str = Field(
        default="CHANGE-THIS-SECRET-KEY-IN-PRODUCTION",
        description="JWT 签名密钥，生产环境必须更改",
    )
    algorithm: str = "HS256"
    access_token_expire_minutes: int = 30
    refresh_token_expire_days: int = 7

    # 数据库配置
    database_type: Literal["sqlite", "mysql", "postgresql"] = "sqlite"
    database_host: str = "localhost"
    database_port: int = 3306
    database_name: str = "satonano"
    database_username: str = ""
    database_password: str = ""
    database_sqlite_path: str = "./satonano.db"
    database_echo: bool = False

    # OAuth2 配置 (Linux.do)
    oauth2_client_id: str = ""
    oauth2_client_secret: str = ""
    oauth2_callback_path: str = "/oauth2/callback"
    # 首选端点
    oauth2_authorize_endpoint: str = "https://connect.linux.do/oauth2/authorize"
    oauth2_token_endpoint: str = "https://connect.linux.do/oauth2/token"
    oauth2_user_info_endpoint: str = "https://connect.linux.do/api/user"
    # 备用端点
    oauth2_authorize_endpoint_reserve: str = "https://connect.linuxdo.org/oauth2/authorize"
    oauth2_token_endpoint_reserve: str = "https://connect.linuxdo.org/oauth2/token"
    oauth2_user_info_endpoint_reserve: str = "https://connect.linuxdo.org/api/user"
    oauth2_request_timeout: int = 10  # 请求超时时间（秒）

    # 密码策略
    password_min_length: int = 8
    password_max_length: int = 128
    password_require_uppercase: bool = True
    password_require_lowercase: bool = True
    password_require_digit: bool = True
    password_require_special: bool = False

    # 用户名策略
    username_min_length: int = 3
    username_max_length: int = 32

    # 前端静态文件配置
    frontend_static_path: str = "./frontend/out"

    @computed_field
    @property
    def database_url(self) -> str:
        """
        动态构建数据库连接 URL

        根据 database_type 自动生成对应的连接字符串
        """
        if self.database_type == "sqlite":
            return f"sqlite+aiosqlite:///{self.database_sqlite_path}"

        if self.database_type == "mysql":
            return (
                f"mysql+aiomysql://{self.database_username}:{self.database_password}"
                f"@{self.database_host}:{self.database_port}/{self.database_name}"
            )

        if self.database_type == "postgresql":
            return (
                f"postgresql+asyncpg://{self.database_username}:{self.database_password}"
                f"@{self.database_host}:{self.database_port}/{self.database_name}"
            )

        return f"sqlite+aiosqlite:///{self.database_sqlite_path}"

    @computed_field
    @property
    def is_production(self) -> bool:
        """是否为生产环境"""
        return self.environment == "production"

    @classmethod
    def settings_customise_sources(
        cls,
        settings_cls: type[BaseSettings],
        init_settings: Any,
        env_settings: Any,
        dotenv_settings: Any,
        file_secret_settings: Any,
    ) -> tuple[Any, ...]:
        """
        自定义配置源优先级

        优先级顺序（从高到低）：
        1. 初始化参数
        2. 环境变量
        3. YAML 文件
        4. .env 文件
        5. 文件密钥
        """

        class YamlConfigSettingsSource:
            """YAML 配置源适配器"""

            def __init__(self, settings_cls: type[BaseSettings]) -> None:
                self.settings_cls = settings_cls
                self._yaml_data: dict[str, Any] | None = None

            def __call__(self) -> dict[str, Any]:
                if self._yaml_data is None:
                    self._yaml_data = _yaml_settings_source()
                return self._yaml_data

        return (
            init_settings,
            env_settings,
            YamlConfigSettingsSource(settings_cls),
            dotenv_settings,
            file_secret_settings,
        )


@lru_cache
def get_settings() -> Settings:
    """获取配置单例"""
    return Settings()


settings = get_settings()