"""Client for the predatord socket."""

import json
import socket

from . import SOCKET_PATH, STATE_PATH


class DaemonError(RuntimeError):
    pass


class Client:
    def __init__(self, path=SOCKET_PATH, timeout=10):
        self.path = path
        self.timeout = timeout
        self._sock = None
        self._file = None

    def _connect(self):
        s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
        s.settimeout(self.timeout)
        try:
            s.connect(self.path)
        except OSError as e:
            s.close()
            raise DaemonError("cannot reach the predatord service (%s). "
                              "Check 'systemctl status predatord'." % e) from e
        self._sock = s
        self._file = s.makefile("rwb")

    def close(self):
        if self._sock:
            self._file.close()
            self._sock.close()
        self._sock = self._file = None

    def call(self, cmd, **args):
        for attempt in (0, 1):
            if self._sock is None:
                self._connect()
            try:
                self._file.write((json.dumps({"cmd": cmd, "args": args}) + "\n").encode())
                self._file.flush()
                line = self._file.readline()
                if not line:
                    raise OSError("connection closed")
                break
            except OSError:
                self.close()
                if attempt:
                    raise DaemonError("lost connection to the service")
        res = json.loads(line)
        if not res.get("ok"):
            raise DaemonError(res.get("error", "unknown error"))
        return res.get("result")


def read_state():
    """Read the latest state snapshot (no socket needed)."""
    try:
        with open(STATE_PATH) as f:
            return json.load(f)
    except (OSError, ValueError):
        return None