from __future__ import annotations

import socket
from typing import Optional


class ClientConnection:
    def __init__(self, host: str, port: int, timeout: float = 30.0) -> None:
        self.host = host
        self.port = port
        self.timeout = timeout
        self.sock: Optional[socket.socket] = None
        self._buffer = b""

    def connect(self) -> None:
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.connect((self.host, self.port))
        self.sock = s

    def send_line(self, line: str) -> None:
        if self.sock is None:
            raise RuntimeError("Not connected")
        data = (line + "\n").encode("utf-8")
        self.sock.sendall(data)

    def read_line(self) -> Optional[str]:
        if self.sock is None:
            raise RuntimeError("Not connected")
        while True:
            if b"\n" in self._buffer:
                line, self._buffer = self._buffer.split(b"\n", 1)
                return line.decode("utf-8", errors="replace").rstrip("\r")
            chunk = self.sock.recv(4096)
            if not chunk:
                return None
            self._buffer += chunk

    def close(self) -> None:
        if self.sock is not None:
            try:
                self.sock.close()
            finally:
                self.sock = None