"""
Unit tests for utils/rate_limiter.py's pure counting/enforcement logic.

Scope: enforce_rate_limit() itself (fixed-window counting, per-tier limits,
429 on breach). The with_rate_limit() FastAPI dependency composition and the
Firestore violation-logging side effect are thin wrappers around this and are
not separately unit-tested (per docs/qa/test-strategy.md, the FastAPI/
Firestore integration belongs at the integration layer, not here).
"""
import time
import pytest
from fastapi import HTTPException
import utils.rate_limiter as rl


@pytest.fixture(autouse=True)
def reset_limiter_state(monkeypatch):
    # Each test gets a clean set of counters and a violation logger that
    # never touches Firestore (no app is initialized in this test process).
    monkeypatch.setattr(rl, "_counters", rl.defaultdict(rl._Window))
    monkeypatch.setattr(rl, "_violation_counts", rl.defaultdict(int))
    monkeypatch.setattr(rl, "_log_violation", lambda *a, **k: None)


def test_allows_requests_within_the_limit():
    for _ in range(8):
        rl.enforce_rate_limit("uid-1", "generation")  # 8/hour is the limit — must not raise


def test_blocks_the_request_that_exceeds_the_limit():
    for _ in range(8):
        rl.enforce_rate_limit("uid-1", "generation")
    with pytest.raises(HTTPException) as exc_info:
        rl.enforce_rate_limit("uid-1", "generation")
    assert exc_info.value.status_code == 429


def test_counters_are_isolated_per_uid():
    for _ in range(8):
        rl.enforce_rate_limit("uid-1", "generation")
    # A different uid must not be affected by uid-1 exhausting its limit.
    rl.enforce_rate_limit("uid-2", "generation")


def test_counters_are_isolated_per_tier():
    for _ in range(8):
        rl.enforce_rate_limit("uid-1", "generation")
    # The same uid hitting a different tier must not be blocked by "generation".
    rl.enforce_rate_limit("uid-1", "chat")


def test_a_tier_with_multiple_windows_enforces_the_tighter_one_first():
    # "chat" is 10/minute and 200/day -- the per-minute window binds first.
    for _ in range(10):
        rl.enforce_rate_limit("uid-1", "chat")
    with pytest.raises(HTTPException) as exc_info:
        rl.enforce_rate_limit("uid-1", "chat")
    assert exc_info.value.status_code == 429
    assert "minute" in exc_info.value.detail


def test_window_resets_after_its_period_elapses(monkeypatch):
    fake_now = [1_000_000.0]
    monkeypatch.setattr(rl.time, "time", lambda: fake_now[0])

    for _ in range(8):
        rl.enforce_rate_limit("uid-1", "generation")
    with pytest.raises(HTTPException):
        rl.enforce_rate_limit("uid-1", "generation")

    # Jump past the 1-hour window.
    fake_now[0] += 3600 + 1
    rl.enforce_rate_limit("uid-1", "generation")  # must not raise — window reset


def test_unknown_tier_raises_a_programmer_error_not_a_silent_pass():
    with pytest.raises(ValueError):
        rl.enforce_rate_limit("uid-1", "not-a-real-tier")