"""Request correlation middleware (``API-STANDARD.md`` §7)."""

from __future__ import annotations

import uuid
from collections.abc import Callable

from django.http import HttpRequest, HttpResponse

__all__ = ["RequestIdMiddleware", "RateLimitHeadersMiddleware"]

_HEADER = "X-Request-Id"


class RequestIdMiddleware:
    """Ensures every request has an id, echoed in the response header and meta."""

    def __init__(self, get_response: Callable[[HttpRequest], HttpResponse]) -> None:
        self.get_response = get_response

    def __call__(self, request: HttpRequest) -> HttpResponse:
        request_id = request.headers.get(_HEADER) or f"req_{uuid.uuid4().hex[:20]}"
        request.request_id = request_id  # type: ignore[attr-defined]
        response = self.get_response(request)
        response[_HEADER] = request_id
        return response


class RateLimitHeadersMiddleware:
    """Adds ``X-RateLimit-*`` headers whenever a throttle recorded state."""

    def __init__(self, get_response: Callable[[HttpRequest], HttpResponse]) -> None:
        self.get_response = get_response

    def __call__(self, request: HttpRequest) -> HttpResponse:
        from .throttling import apply_rate_limit_headers

        response = self.get_response(request)
        apply_rate_limit_headers(response, request)
        return response