"""signal_alert."""

from __future__ import annotations

import json
import logging
import socket

logger = logging.getLogger(__name__)


class SignalRPCError(RuntimeError):
    """signal-cli returned an error or closed without responding."""


def signal_alert(body: str, from_phone: str, to_phone: str, *, timeout: float = 4.0) -> None:
    """Send a Signal alert through the local signal-cli daemon.

    Args:
        body: The body of the alert.
        from_phone: The Signal account sending the alert.
        to_phone: The Signal account receiving the alert.
        timeout: Seconds to wait on each socket operation.

    Raises:
        SignalRPCError: If signal-cli returns an error or closes the
            connection before responding.
        OSError: If the socket is unreachable or an operation times out.
    """
    signal_rpc_id = "signal-alert"
    request = {
        "jsonrpc": "2.0",
        "method": "send",
        "params": {
            "account": from_phone,
            "recipient": [to_phone],
            "message": body,
        },
        "id": signal_rpc_id,
    }

    try:
        with socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) as client:
            client.settimeout(timeout)
            client.connect("/run/signal-cli/socket")
            client.sendall(json.dumps(request).encode() + b"\n")

            buffer = b""
            while chunk := client.recv(65536):
                buffer += chunk
                while b"\n" in buffer:
                    line, buffer = buffer.split(b"\n", maxsplit=1)
                    response = json.loads(line)
                    if response.get("id") != signal_rpc_id:
                        continue
                    if rpc_error := response.get("error"):
                        error = f"Signal RPC returned an error: {rpc_error}"
                        raise SignalRPCError(error)
                    return
            error = "Signal RPC socket closed before returning a response"
            raise SignalRPCError(error)
    except (OSError, json.JSONDecodeError) as exc:
        error = f"Signal RPC failed: {exc!r}"
        raise SignalRPCError(error) from exc