"""Regression tests for BUG-02: rate limiter must key on the real client IP
relayed by the proxy (x-forwarded-for / x-real-ip), not the proxy's own IP,
and default_limits must actually be enforced via SlowAPIMiddleware."""
from __future__ import annotations

from types import SimpleNamespace

from slowapi.middleware import SlowAPIMiddleware

from app.ratelimit import client_ip_key, limiter


def _req(headers: dict, peer: str | None = "10.0.0.1"):
    """Minimal stand-in for starlette Request: only .headers and .client are
    read by client_ip_key. Headers must be case-insensitive get()."""
    lower = {k.lower(): v for k, v in headers.items()}
    client = SimpleNamespace(host=peer) if peer is not None else None
    return SimpleNamespace(
        headers=SimpleNamespace(get=lambda k, d=None: lower.get(k.lower(), d)),
        client=client,
    )


def test_key_prefers_first_x_forwarded_for_hop():
    # Left-most XFF entry is the original client; proxies append to the right.
    r = _req({"x-forwarded-for": "203.0.113.9, 10.0.0.1, 172.16.0.1"})
    assert client_ip_key(r) == "203.0.113.9"


def test_key_falls_back_to_x_real_ip():
    r = _req({"x-real-ip": "198.51.100.7"})
    assert client_ip_key(r) == "198.51.100.7"


def test_key_falls_back_to_peer_when_no_headers():
    r = _req({}, peer="192.0.2.50")
    assert client_ip_key(r) == "192.0.2.50"


def test_key_handles_missing_client():
    r = _req({}, peer=None)
    assert client_ip_key(r) == "unknown"


def test_two_users_behind_same_proxy_get_distinct_keys():
    # The whole point of BUG-02: same TCP peer (proxy), different end users.
    a = _req({"x-forwarded-for": "203.0.113.1"}, peer="10.0.0.1")
    b = _req({"x-forwarded-for": "203.0.113.2"}, peer="10.0.0.1")
    assert client_ip_key(a) != client_ip_key(b)


def test_limiter_uses_custom_key_func():
    assert limiter._key_func is client_ip_key


def test_slowapi_middleware_registered_on_app():
    # Without the middleware, default_limits never applies to undecorated
    # (mutation) routes. Guard against silent regression.
    import app.main as main
    classes = [m.cls for m in main.app.user_middleware]
    assert SlowAPIMiddleware in classes