from __future__ import annotations

import asyncio
from typing import Any

from fastapi import APIRouter, HTTPException, Query, WebSocket, status
from fastapi.encoders import jsonable_encoder
from fastapi.websockets import WebSocketDisconnect
from sqlmodel import Session

from app.api.deps import CurrentUser, SessionDep, resolve_user_from_token
from app.core.db import engine
from app.mqtt.telemetry import build_telemetry_snapshot

router = APIRouter(prefix="/telemetry", tags=["telemetry"])
STREAM_INTERVAL_SECONDS = 1.0


@router.get("/latest")
def read_telemetry_latest(
    session: SessionDep,
    _current_user: CurrentUser,
    device_id: str | None = None,
    limit: int = Query(default=50, ge=1, le=200),
) -> dict[str, Any]:
    """
    Return the latest parsed GNSS telemetry snapshot.
    """
    return build_telemetry_snapshot(session=session, device_id=device_id, limit=limit)


@router.websocket("/ws")
async def telemetry_websocket(
    websocket: WebSocket,
    token: str | None = Query(default=None),
    device_id: str | None = Query(default=None),
    limit: int = Query(default=50, ge=1, le=200),
) -> None:
    if not token:
        await websocket.close(code=status.WS_1008_POLICY_VIOLATION)
        return

    with Session(engine) as session:
        try:
            resolve_user_from_token(session=session, token=token)
        except HTTPException:
            await websocket.close(code=status.WS_1008_POLICY_VIOLATION)
            return

    await websocket.accept()

    try:
        while True:
            with Session(engine) as session:
                payload = build_telemetry_snapshot(
                    session=session,
                    device_id=device_id,
                    limit=limit,
                )
            await websocket.send_json(jsonable_encoder(payload))
            await asyncio.sleep(STREAM_INTERVAL_SECONDS)
    except (WebSocketDisconnect, RuntimeError):
        return