// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
#nullable disable
 
using System;
using System.Collections.Immutable;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Remote;
using Microsoft.CodeAnalysis.Test.Utilities;
using Roslyn.Test.Utilities;
using Xunit;
 
namespace Roslyn.VisualStudio.Next.UnitTests.Remote;
 
[UseExportProvider]
[Trait(Traits.Feature, Traits.Features.RemoteHost)]
public sealed class SolutionAssetCacheTests
{
    private static void ForceGC()
    {
        for (var i = 0; i < 3; i++)
            GC.Collect();
    }
 
    [Fact]
    public void TestGetAssets()
    {
        var storage = new SolutionAssetCache();
 
        var checksum = Checksum.Create(ImmutableArray.CreateRange(Guid.NewGuid().ToByteArray()));
        var data = new object();
 
        Assert.Equal(data, storage.GetOrAdd(checksum, data));
 
        Assert.True(storage.TryGetAsset(checksum, out object _));
    }
 
    [Fact]
    public async Task TestCleanup()
    {
        var storage = new SolutionAssetCache(
            remoteWorkspace: null, cleanupInterval: TimeSpan.FromMilliseconds(1), purgeAfter: TimeSpan.FromMilliseconds(2));
 
        var checksum = Checksum.Create(ImmutableArray.CreateRange(Guid.NewGuid().ToByteArray()));
        var data = new object();
 
        Assert.Equal(data, storage.GetOrAdd(checksum, data));
 
        for (var i = 0; i < 10; i++)
        {
            await Task.Delay(10);
 
            if (!storage.TryGetAsset(checksum, out object _))
            {
                // asset is deleted
                return;
            }
 
            ForceGC();
        }
 
        // it should not reach here
        AssertEx.Fail("asset not cleaned up");
    }
 
    [Fact]
    public async Task TestSolutionKeepsAssetPinned()
    {
        var workspace = new RemoteWorkspace(FeaturesTestCompositions.RemoteHost.GetHostServices());
        var solution = workspace.CurrentSolution;
        var checksums = await solution.CompilationState.GetStateChecksumsAsync(CancellationToken.None);
 
        // Ensure the lazy has computed its value.
        var storage = new SolutionAssetCache(
            workspace, cleanupInterval: TimeSpan.FromMilliseconds(1), purgeAfter: TimeSpan.FromMilliseconds(2));
 
        var checksum1 = checksums.Checksum;
        var data1 = new object();
 
        var checksum2 = Checksum.Create(ImmutableArray.CreateRange(Guid.NewGuid().ToByteArray()));
        var data2 = new object();
 
        Assert.Equal(data1, storage.GetOrAdd(checksum1, data1));
        Assert.Equal(data2, storage.GetOrAdd(checksum2, data2));
 
        var gotChecksum2 = true;
 
        for (var i = 0; i < 10; i++)
        {
            await Task.Delay(10);
 
            // We should always get this asset, as the solution is keeping it alive.
            Assert.True(storage.TryGetAsset(checksum1, out object current1));
            Assert.Equal(data1, current1);
 
            gotChecksum2 = storage.TryGetAsset(checksum2, out object _);
            ForceGC();
        }
 
        // By the end, checksum2/data2 should be gone.
        Assert.False(gotChecksum2);
 
        // Now, add a project.  At this point, the original pinned object should go away.
        workspace.SetCurrentSolution(solution => solution.AddProject("Project", "Assembly", LanguageNames.CSharp).Solution, WorkspaceChangeKind.ProjectAdded);
 
        for (var i = 0; i < 10; i++)
        {
            await Task.Delay(10);
 
            // Eventually, this asset should go away.
            if (!storage.TryGetAsset(checksum1, out object _))
                return;
 
            ForceGC();
        }
 
        // it should not reach here
        AssertEx.Fail("asset not cleaned up");
    }
}