"""Hardware detection and heartbeat payload construction for the streamer."""

from __future__ import annotations

from ria_toolkit_oss.sdr import detect_available

from .config import AgentConfig


def available_devices() -> list[str]:
    """Return a sorted list of device names whose driver modules import cleanly."""
    return sorted(detect_available().keys())


def heartbeat_payload(
    status: str = "idle",
    app_id: str | None = None,
    *,
    cfg: AgentConfig | None = None,
    sessions: dict | None = None,
) -> dict:
    """Build the JSON body of a periodic heartbeat frame.

    *cfg* drives the ``capabilities`` list and the ``tx_enabled`` flag. If not
    supplied, the heartbeat advertises RX-only with ``tx_enabled=False`` —
    matching the pre-TX shape.
    """
    c = cfg or AgentConfig()
    capabilities = ["rx"]
    if c.tx_enabled:
        capabilities.append("tx")

    payload: dict = {
        "type": "heartbeat",
        "hardware": available_devices(),
        "status": status,
        "capabilities": capabilities,
        "tx_enabled": bool(c.tx_enabled),
    }
    if app_id:
        payload["app_id"] = app_id
    if sessions:
        payload["sessions"] = sessions
    return payload