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

from pydantic import model_validator
from pydantic_settings import BaseSettings, SettingsConfigDict


class Settings(BaseSettings):
    model_config = SettingsConfigDict(
        env_file=".env",
        env_file_encoding="utf-8",
        extra="ignore",
    )

    app_name: str = "OpenCloud API"
    environment: Literal["development", "test", "production"] = "development"
    api_v1_prefix: str = "/api/v1"
    debug: bool = False

    database_url: str
    database_pool_size: int = 10
    database_max_overflow: int = 20

    secret_key: str
    jwt_algorithm: str = "HS256"
    access_token_expire_minutes: int = 15
    refresh_token_expire_days: int = 30

    refresh_cookie_name: str = "opencloud_refresh"
    cookie_secure: bool = False
    cookie_samesite: Literal["lax", "strict", "none"] = "lax"
    cookie_domain: str | None = None

    frontend_url: str = "http://localhost:5173"
    public_base_url: str = "http://localhost:8000"
    cors_origins: str = "http://localhost:5173"

    upload_dir: Path = Path("data/uploads")
    max_upload_bytes: int = 20 * 1024 * 1024
    max_image_pixels: int = 50_000_000
    thumbnail_max_edge: int = 640

    email_delivery_mode: Literal["console", "smtp"] = "console"
    smtp_host: str | None = None
    smtp_port: int = 587
    smtp_username: str | None = None
    smtp_password: str | None = None
    smtp_starttls: bool = True
    email_from: str = "OpenCloud <no-reply@opencloud.local>"
    email_confirmation_expire_hours: int = 24
    password_reset_expire_minutes: int = 30

    admin_email: str | None = None
    admin_password: str | None = None
    admin_username: str = "管理员"

    @property
    def cors_origin_list(self) -> list[str]:
        return [item.strip() for item in self.cors_origins.split(",") if item.strip()]

    @property
    def media_base_url(self) -> str:
        return f"{self.public_base_url.rstrip('/')}/media"

    @model_validator(mode="after")
    def validate_production_settings(self) -> "Settings":
        if self.environment == "production":
            if self.secret_key.startswith("change-me") or len(self.secret_key) < 32:
                raise ValueError("生产环境必须配置至少 32 个字符的 SECRET_KEY")
            if not self.cookie_secure:
                raise ValueError("生产环境必须启用 COOKIE_SECURE")
            if self.email_delivery_mode == "smtp" and not self.smtp_host:
                raise ValueError("SMTP 模式必须配置 SMTP_HOST")
        return self


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


settings = get_settings()