"""Runtime configuration, read from environment variables."""
from __future__ import annotations

import os
from dataclasses import dataclass
from pathlib import Path


@dataclass(frozen=True)
class Config:
    data_dir: Path
    plugins_dir: Path
    database_url: str
    bootstrap_admin_token: str | None
    invite_code: str | None
    admin_username: str
    max_plugin_bytes: int

    @classmethod
    def from_env(cls) -> "Config":
        data_dir = Path(os.environ.get("DSH_DATA_DIR", "data")).resolve()
        database_url = os.environ.get("DSH_DATABASE_URL", "").strip()
        if not database_url:
            raise RuntimeError(
                "DSH_DATABASE_URL is required, e.g. "
                "postgresql://dsh:secret@localhost:5432/dsh"
            )
        return cls(
            data_dir=data_dir,
            plugins_dir=data_dir / "plugins",
            database_url=database_url,
            bootstrap_admin_token=os.environ.get("DSH_BOOTSTRAP_ADMIN_TOKEN") or None,
            invite_code=os.environ.get("DSH_INVITE_CODE") or None,
            admin_username=os.environ.get("DSH_ADMIN_USERNAME", "admin"),
            max_plugin_bytes=int(os.environ.get("DSH_MAX_PLUGIN_MB", "20")) * 1024 * 1024,
        )

    def ensure_dirs(self) -> None:
        self.data_dir.mkdir(parents=True, exist_ok=True)
        self.plugins_dir.mkdir(parents=True, exist_ok=True)