"""WebSocket-поток метрик: GET /api/v1/metrics/stream."""

from __future__ import annotations

import asyncio

from fastapi import APIRouter, WebSocket, WebSocketDisconnect

from awg_api.deps import SESSION_COOKIE_NAME, token_matches
from awg_api.state import MockState

router = APIRouter(tags=["metrics"])

WS_ACCESS_DENIED = 4401
MIN_INTERVAL_MS = 250


def _authorized(websocket: WebSocket, token: str | None) -> bool:
    expected: str = websocket.app.state.api_token
    header = websocket.headers.get("authorization", "")
    scheme, _, credentials = header.partition(" ")
    if scheme.lower() == "bearer" and token_matches(credentials.strip(), expected):
        return True
    if token_matches(token, expected):
        return True
    session_id = websocket.cookies.get(SESSION_COOKIE_NAME)
    state: MockState = websocket.app.state.mock_state
    return token_matches(session_id, state.session_token)


@router.websocket("/api/v1/metrics/stream")
async def stream_metrics(
    websocket: WebSocket, token: str | None = None, interval_ms: int = 1000
) -> None:
    """Отправляет кадры ``WsFrame``: метрики до отключения клиента."""
    if not _authorized(websocket, token):
        await websocket.close(code=WS_ACCESS_DENIED)
        return
    state: MockState = websocket.app.state.mock_state
    await websocket.accept()
    interval_s = max(MIN_INTERVAL_MS, interval_ms) / 1000
    try:
        while True:
            await websocket.send_json(state.metrics_frame())
            await asyncio.sleep(interval_s)
    except (WebSocketDisconnect, RuntimeError):
        return