// <copyright file="InMemoryHlcStateStoreTests.Save.cs" company="StellaOps">
// Copyright (c) StellaOps. Licensed under BUSL-1.1.
// </copyright>
using FluentAssertions;
using System;
using System.Threading;
using Xunit;

namespace StellaOps.HybridLogicalClock.Tests;

public sealed partial class InMemoryHlcStateStoreTests
{
    [Fact]
    public async Task SaveAsync_ThenLoadAsync_ReturnsStateAsync()
    {
        var store = new InMemoryHlcStateStore();
        var timestamp = CreateTimestamp("node1", 1000, 5);

        await store.SaveAsync(timestamp, CancellationToken.None);
        var result = await store.LoadAsync("node1", CancellationToken.None);

        result.Should().Be(timestamp);
    }

    [Fact]
    public async Task SaveAsync_GreaterTimestamp_UpdatesAsync()
    {
        var store = new InMemoryHlcStateStore();
        var first = CreateTimestamp("node1", 1000, 5);
        var second = CreateTimestamp("node1", 1000, 10);

        await store.SaveAsync(first, CancellationToken.None);
        await store.SaveAsync(second, CancellationToken.None);
        var result = await store.LoadAsync("node1", CancellationToken.None);

        result.Should().Be(second);
    }

    [Fact]
    public async Task SaveAsync_SmallerTimestamp_DoesNotUpdateAsync()
    {
        var store = new InMemoryHlcStateStore();
        var first = CreateTimestamp("node1", 1000, 10);
        var second = CreateTimestamp("node1", 1000, 5);

        await store.SaveAsync(first, CancellationToken.None);
        await store.SaveAsync(second, CancellationToken.None);
        var result = await store.LoadAsync("node1", CancellationToken.None);

        result.Should().Be(first);
    }

    [Fact]
    public async Task SaveAsync_Cancelled_ThrowsOperationCanceledExceptionAsync()
    {
        var store = new InMemoryHlcStateStore();
        using var cts = new CancellationTokenSource();
        cts.Cancel();

        var act = () => store.SaveAsync(CreateTimestamp("node1", 1000, 1), cts.Token);

        await act.Should().ThrowAsync<OperationCanceledException>();
    }
}