hold-slayer/api/websocket.py

"""WebSocket API — Real-time call events and audio classification stream."""

import asyncio
import logging
import secrets

from fastapi import APIRouter, WebSocket, WebSocketDisconnect

from api.deps import get_gateway
from config import get_settings
from models.events import EventType, GatewayEvent

logger = logging.getLogger(__name__)

router = APIRouter()


async def _authorize(websocket: WebSocket) -> bool:
    """
    Check the static bearer token before accepting the socket.

    Browsers can't set headers on WebSocket connects, so a `token`
    query parameter is accepted alongside the Authorization header.
    """
    token = get_settings().api_token.get_secret_value()
    if not token:
        return True
    supplied = websocket.query_params.get("token", "")
    auth = websocket.headers.get("authorization", "")
    if auth.lower().startswith("bearer "):
        supplied = auth[7:]
    if secrets.compare_digest(supplied, token):
        return True
    await websocket.close(code=4401, reason="Missing or invalid bearer token")
    return False


async def _send_trunk_status(websocket: WebSocket, gateway) -> None:
    """Send current SIP trunk status as a synthetic event to a newly connected client."""
    try:
        trunk_status = await gateway.sip_engine.get_trunk_status()
        registered = trunk_status.get("registered", False)
        event_type = (
            EventType.SIP_TRUNK_REGISTERED if registered
            else EventType.SIP_TRUNK_REGISTRATION_FAILED
        )
        reason = trunk_status.get("reason", "Trunk registration failed or not configured")
        event = GatewayEvent(
            type=event_type,
            message=(
                f"SIP trunk registered with {trunk_status.get('host')}"
                if registered
                else f"SIP trunk not registered — {reason}"
            ),
            data=trunk_status,
        )
        await websocket.send_json(event.to_ws_message())
    except Exception as exc:
        logger.warning(f"Could not send trunk status on connect: {exc}")


@router.websocket("/events")
async def event_stream(websocket: WebSocket):
    """
    Real-time event stream.

    Sends all gateway events as JSON:
    - Call lifecycle (initiated, ringing, connected, ended)
    - Hold Slayer events (IVR steps, DTMF, hold detected, human detected)
    - Audio classifications
    - Transcript chunks
    - Device status changes

    Example message:
    {
        "type": "holdslayer.human_detected",
        "call_id": "call_abc123",
        "timestamp": "2025-01-15T14:30:00",
        "data": {"audio_type": "live_human", "confidence": 0.92},
        "message": "🚨 Human detected!"
    }
    """
    if not await _authorize(websocket):
        return
    await websocket.accept()
    logger.info("WebSocket client connected")

    gateway = getattr(websocket.app.state, "gateway", None)
    if not gateway:
        await websocket.send_json({"error": "Gateway not initialized"})
        await websocket.close()
        return

    # Immediately push current trunk status so the dashboard doesn't start blank
    await _send_trunk_status(websocket, gateway)

    subscription = gateway.event_bus.subscribe(replay_last=25)

    try:
        async for event in subscription:
            await websocket.send_json(event.to_ws_message())
    except WebSocketDisconnect:
        logger.info("WebSocket client disconnected")
    except Exception as e:
        logger.error(f"WebSocket error: {e}")
    finally:
        subscription.close()


@router.websocket("/calls/{call_id}/events")
async def call_event_stream(websocket: WebSocket, call_id: str):
    """
    Event stream filtered to a specific call.

    Same format as /events but only sends events for the specified call.
    """
    if not await _authorize(websocket):
        return
    await websocket.accept()
    logger.info(f"WebSocket client connected for call {call_id}")

    gateway = getattr(websocket.app.state, "gateway", None)
    if not gateway:
        await websocket.send_json({"error": "Gateway not initialized"})
        await websocket.close()
        return

    subscription = gateway.event_bus.subscribe()

    try:
        async for event in subscription:
            if event.call_id == call_id:
                await websocket.send_json(event.to_ws_message())
    except WebSocketDisconnect:
        logger.info(f"WebSocket client disconnected for call {call_id}")
    except Exception as e:
        logger.error(f"WebSocket error: {e}")
    finally:
        subscription.close()