"""Runtime configuration."""

from __future__ import annotations

import os
import sys
from dataclasses import dataclass
from pathlib import Path


@dataclass(frozen=True)
class Settings:
    task_root: Path
    state_root: Path
    credentials_root: Path
    python_executable: str
    timezone_name: str | None
    allowed_proxy_ips: frozenset[str]
    cancel_grace_seconds: float

    @property
    def database_path(self) -> Path:
        return self.state_root / "server-maintenance.sqlite3"

    @classmethod
    def from_environment(cls) -> "Settings":
        allowed_proxy_ips = frozenset(
            value.strip()
            for value in os.environ.get(
                "SERVER_MAINTENANCE_ALLOWED_PROXY_IPS", ""
            ).split(",")
            if value.strip()
        )
        return cls(
            task_root=Path(
                os.environ.get("SERVER_MAINTENANCE_TASK_ROOT", "/opt/tasks")
            ),
            state_root=Path(
                os.environ.get(
                    "SERVER_MAINTENANCE_STATE_ROOT",
                    "/var/lib/server-maintenance",
                )
            ),
            credentials_root=Path(
                os.environ.get(
                    "SERVER_MAINTENANCE_CREDENTIALS_ROOT",
                    "/opt/credentials",
                )
            ),
            python_executable=os.environ.get(
                "SERVER_MAINTENANCE_PYTHON", sys.executable
            ),
            timezone_name=os.environ.get("TZ") or None,
            allowed_proxy_ips=allowed_proxy_ips,
            cancel_grace_seconds=float(
                os.environ.get("SERVER_MAINTENANCE_CANCEL_GRACE_SECONDS", "10")
            ),
        )