// Copyright 2021-2025 The NATS Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

using Shouldly;
using ZB.MOM.NatsNet.Server.Internal;

namespace ZB.MOM.NatsNet.Server.Tests.Internal;

/// <summary>
/// Tests for <see cref="RateCounter"/>.
/// Mirrors server/rate_counter_test.go: TestRateCounter (ID 2720).
/// </summary>
public sealed class RateCounterTests
{
    [Fact]
    public void NewRateCounter_ShouldCreateWithDefaultInterval()
    {
        var counter = RateCounter.NewRateCounter(2);
        counter.Interval.ShouldBe(TimeSpan.FromSeconds(1));

        counter.Allow().ShouldBeTrue();
        counter.Allow().ShouldBeTrue();
        counter.Allow().ShouldBeFalse();
    }

    [Fact]
    public async Task RateCounter_ShouldAllowUpToLimitThenBlockAndReset()
    {
        // Mirror: TestRateCounter
        var counter = new RateCounter(10) { Interval = TimeSpan.FromMilliseconds(100) };

        // First 10 calls should be allowed (counts 0–9 < limit 10).
        for (var i = 0; i < 10; i++)
            counter.Allow().ShouldBeTrue($"should allow on iteration {i}");

        // Next 5 should be blocked.
        for (var i = 0; i < 5; i++)
            counter.Allow().ShouldBeFalse($"should not allow on iteration {i}");

        // countBlocked returns and resets the blocked count.
        counter.CountBlocked().ShouldBe(5UL);
        counter.CountBlocked().ShouldBe(0UL);

        // After the window expires, should allow again.
        await Task.Delay(150);
        counter.Allow().ShouldBeTrue("should allow after window expired");
    }
}
