from __future__ import annotations

import json
import socket
from dataclasses import asdict, dataclass
from datetime import datetime, timezone
from pathlib import Path

from .config import BackupConfig


@dataclass(frozen=True)
class ServerStatus:
    reachable: bool
    checked_at: str
    message: str


def check_server(config: BackupConfig) -> ServerStatus:
    checked_at = datetime.now(timezone.utc).isoformat()
    if config.server_check.type != "tcp":
        return ServerStatus(False, checked_at, f"Unsupported check type: {config.server_check.type}")

    try:
        with socket.create_connection(
            (config.server_host, config.server_check.port),
            timeout=config.server_check.timeout_seconds,
        ):
            return ServerStatus(True, checked_at, "Server reachable")
    except OSError as exc:
        return ServerStatus(False, checked_at, str(exc))


def write_status(path: Path, status: ServerStatus, pending_count: int) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    payload = asdict(status)
    payload["pending_count"] = pending_count
    path.write_text(json.dumps(payload, indent=2), encoding="utf-8")