from __future__ import annotations

import asyncio
import json
from typing import Any


class UnitySocketClient:
    def __init__(self, host: str, port: int) -> None:
        self._host = host
        self._port = port
        self._lock = asyncio.Lock()
        self._writer: asyncio.StreamWriter | None = None

    @property
    def host(self) -> str:
        return self._host

    @property
    def port(self) -> int:
        return self._port

    async def send_json(self, payload: dict[str, Any]) -> None:
        data = (json.dumps(payload, ensure_ascii=False, separators=(",", ":")) + "\n").encode("utf-8")
        async with self._lock:
            writer = await self._ensure_connected()
            try:
                writer.write(data)
                await writer.drain()
            except Exception:
                await self._close_writer()
                raise

    async def _ensure_connected(self) -> asyncio.StreamWriter:
        if self._writer is not None and not self._writer.is_closing():
            return self._writer
        reader, writer = await asyncio.open_connection(self._host, self._port)
        self._writer = writer
        return writer

    async def _close_writer(self) -> None:
        if self._writer is None:
            return
        try:
            self._writer.close()
            await self._writer.wait_closed()
        finally:
            self._writer = None