package qq_obv11

import (
	"errors"
	"testing"
	"time"
)

func TestRateLimiterAllowWithinWindow(t *testing.T) {
	t.Parallel()

	rl := newRateLimiter(3, 10*time.Second)
	now := time.Now()
	for i := 0; i < 3; i++ {
		if !rl.allow(now) {
			t.Fatalf("allow #%d denied, want allowed", i)
		}
	}
	if rl.allow(now) {
		t.Error("4th allow in window accepted, want denied")
	}
}

func TestRateLimiterDeniedOverWindow(t *testing.T) {
	t.Parallel()

	rl := newRateLimiter(2, 10*time.Second)
	base := time.Now()
	if !rl.allow(base) || !rl.allow(base) {
		t.Fatal("first two sends should be allowed")
	}
	if rl.allow(base) {
		t.Error("third send within window allowed, want denied")
	}
	// After the window elapses, the budget frees up.
	if !rl.allow(base.Add(11 * time.Second)) {
		t.Error("send after window elapsed denied, want allowed")
	}
}

func TestRateLimiterDisabledAllowsAll(t *testing.T) {
	t.Parallel()

	rl := newRateLimiter(0, 10*time.Second)
	for i := 0; i < 100; i++ {
		if !rl.allow(time.Now()) {
			t.Fatalf("disabled limiter denied send #%d", i)
		}
	}
}

func TestRateLimiterNilAllows(t *testing.T) {
	t.Parallel()

	var rl *rateLimiter
	if !rl.allow(time.Now()) {
		t.Error("nil limiter denied send, want allowed")
	}
}

func TestErrRateLimitedSentinel(t *testing.T) {
	t.Parallel()

	if !errors.Is(ErrRateLimited, ErrRateLimited) {
		t.Error("ErrRateLimited should be its own sentinel")
	}
}