"""HTTP cross-cutting concerns."""

from collections.abc import Awaitable, Callable

from starlette.requests import Request
from starlette.responses import Response

TRACE_ID_HEADER = "X-Trace-ID"
RequestHandler = Callable[[Request], Awaitable[Response]]


async def attach_trace_id(request: Request, call_next: RequestHandler) -> Response:
    """Return the request trace identifier on both success and error responses."""
    response = await call_next(request)
    context = getattr(request.state, "request_context", None)
    trace_id = getattr(context, "trace_id", None) or getattr(request.state, "trace_id", None)
    trace_id = trace_id or request.headers.get(TRACE_ID_HEADER)
    if trace_id:
        response.headers[TRACE_ID_HEADER] = str(trace_id)
    return response