"""Application configuration from environment variables."""
from functools import lru_cache
from typing import Optional

from pydantic_settings import BaseSettings, SettingsConfigDict


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

    DATABASE_URL: str = ""
    SITE_TITLE: str = "TiDB Community Slack"
    SITE_DESCRIPTION: str = "Join the TiDB Community on Slack."
    SENTRY_DSN: str = ""
    ENVIRONMENT: str = "development"
    REDIS_URL: str = "redis://localhost:6379/0"
    ADMIN_EMAIL: Optional[str] = None

    # Google OAuth
    GOOGLE_CLIENT_ID: str = ""
    GOOGLE_CLIENT_SECRET: str = ""
    SESSION_SECRET: str = "change-me-to-a-very-long-random-string-in-production"

    @property
    def jwt_secret(self) -> str:
        """Ensures the secret is at least 32 bytes for SHA256."""
        if len(self.SESSION_SECRET) < 32:
            import hashlib
            return hashlib.sha256(self.SESSION_SECRET.encode()).hexdigest()
        return self.SESSION_SECRET
    # Only users with this email domain are allowed to access /admin. 
    # Leave empty to allow any logged-in user.
    ADMIN_EMAIL_DOMAIN: str = ""
    # Public base URL used for OAuth redirect_uri (e.g. https://slack.tidb.io)
    # Falls back to request base URL when empty (suitable for local dev)
    BASE_URL: str = ""

    @property
    def sqlalchemy_database_uri(self) -> str:
        return self.DATABASE_URL or ""


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