from dataclasses import dataclass
from functools import lru_cache
import os
from typing import Any

try:
    from pathlib import Path as _Path

    from dotenv import load_dotenv

    # 显式指定 backend 目录下的 .env，并强制覆盖已有环境变量，
    # 确保远程数据库配置生效，不被本地默认值或残留环境变量影响。
    _env_path = _Path(__file__).resolve().parent.parent.parent / ".env"
    load_dotenv(dotenv_path=_env_path, override=True)
except ImportError:
    pass


def _int_env(name: str, default: int) -> int:
    raw = os.getenv(name)
    if raw is None or raw == "":
        return default
    return int(raw)


def _list_env(name: str, default: list[str]) -> list[str]:
    raw = os.getenv(name)
    if raw is None or raw.strip() == "":
        return default
    return [item.strip() for item in raw.split(",") if item.strip()]


def _bool_env(name: str, default: bool) -> bool:
    raw = os.getenv(name)
    if raw is None or raw.strip() == "":
        return default
    return raw.strip().lower() in {"1", "true", "yes", "on"}


def docs_kwargs(enabled: bool) -> dict[str, Any]:
    """Swagger UI / ReDoc / OpenAPI schema 路由开关。

    关闭时 FastAPI 不注册 /docs、/redoc、/openapi.json，访问一律返回 404，
    避免未授权访问泄露 API 结构。
    """
    if enabled:
        return {}
    return {"docs_url": None, "redoc_url": None, "openapi_url": None}


@dataclass(frozen=True)
class Settings:
    app_name: str = os.getenv("APP_NAME", "YG Fine-Tune Platform API")
    app_env: str = os.getenv("APP_ENV", "local")
    route_prefix: str = os.getenv("MODELTF_ROUTE_PREFIX", "/modelTF")
    app_mode: str = os.getenv("APP_MODE", "local")
    database_url: str = os.getenv("DATABASE_URL", "postgresql+psycopg://yg_ft:change_me@localhost:15432/yg_ft")
    cors_allow_origins: list[str] = None  # type: ignore[assignment]
    compute_mode: str = os.getenv("COMPUTE_MODE", "real")
    compute_status_sync_mode: str = os.getenv("COMPUTE_STATUS_SYNC_MODE", "polling")
    compute_poll_interval_seconds: int = _int_env("COMPUTE_POLL_INTERVAL_SECONDS", 3)
    compute_request_timeout_seconds: int = _int_env("COMPUTE_REQUEST_TIMEOUT_SECONDS", 5)
    compute_service_token: str = os.getenv("COMPUTE_SERVICE_TOKEN", "")
    log_level: str = os.getenv("LOG_LEVEL", "INFO")
    log_dir: str = os.getenv("LOG_DIR", "./logs")
    log_file_prefix: str = os.getenv("LOG_FILE_PREFIX", "backend")
    log_error_file_prefix: str = os.getenv("LOG_ERROR_FILE_PREFIX", "error")
    log_max_bytes: int = _int_env("LOG_MAX_BYTES", 20 * 1024 * 1024)
    log_retention_days: int = _int_env("LOG_RETENTION_DAYS", 10)
    enable_docs: bool = None  # type: ignore[assignment]

    def __post_init__(self) -> None:
        object.__setattr__(
            self,
            "cors_allow_origins",
            _list_env(
                "CORS_ALLOW_ORIGINS",
                [
                    "http://localhost:16801",
                    "http://127.0.0.1:16801",
                    "http://localhost:17861",
                    "http://127.0.0.1:17861",
                ],
            ),
        )
        # Swagger UI / ReDoc / OpenAPI 文档路由开关：
        # 未显式配置 ENABLE_DOCS 时，仅本地/开发环境开放，生产环境默认关闭，
        # 避免未授权访问泄露 API 结构。从运行时环境读取 APP_ENV，而非类定义时
        # 缓存的默认值，保证生产默认关闭始终生效且便于测试。
        object.__setattr__(
            self,
            "enable_docs",
            _bool_env("ENABLE_DOCS", os.getenv("APP_ENV", "local") != "prod"),
        )


@lru_cache
def get_settings() -> Settings:
    return Settings()