// 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.
 
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Composition;
using System.Linq;
using System.Runtime.Versioning;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Host;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.Serialization;
using Roslyn.Test.Utilities;
using Roslyn.Utilities;
using ReferenceEqualityComparer = Roslyn.Utilities.ReferenceEqualityComparer;
 
#pragma warning disable CA1416 // Validate platform compatibility
 
namespace Microsoft.CodeAnalysis.UnitTests.Remote;
 
#if NET
[SupportedOSPlatform("windows")]
#endif
[method: Obsolete(MefConstruction.FactoryMethodMessage, error: true)]
internal sealed class TestSerializerService(
    ConcurrentDictionary<Guid, TestGeneratorReference> sharedTestGeneratorReferences,
    SolutionServices workspaceServices)
    : SerializerService(workspaceServices)
{
    private static readonly ImmutableDictionary<MetadataReference, string?> s_wellKnownReferenceNames = ImmutableDictionary.Create<MetadataReference, string?>(ReferenceEqualityComparer.Instance)
        .Add(TestBase.MscorlibRef_v46, nameof(TestBase.MscorlibRef_v46))
        .Add(TestBase.SystemRef_v46, nameof(TestBase.SystemRef_v46))
        .Add(TestBase.SystemCoreRef_v46, nameof(TestBase.SystemCoreRef_v46))
        .Add(TestBase.ValueTupleRef, nameof(TestBase.ValueTupleRef))
        .Add(TestBase.SystemRuntimeFacadeRef, nameof(TestBase.SystemRuntimeFacadeRef));
    private static readonly ImmutableDictionary<string, MetadataReference> s_wellKnownReferences = ImmutableDictionary.Create<string, MetadataReference>()
        .AddRange(s_wellKnownReferenceNames.Select(pair => KeyValuePairUtil.Create(pair.Value!, pair.Key)));
 
    private readonly ConcurrentDictionary<Guid, TestGeneratorReference> _sharedTestGeneratorReferences = sharedTestGeneratorReferences;
 
    protected override void WriteMetadataReferenceTo(MetadataReference reference, ObjectWriter writer)
    {
        var wellKnownReferenceName = s_wellKnownReferenceNames.GetValueOrDefault(reference, null);
        if (wellKnownReferenceName is not null)
        {
            writer.WriteBoolean(true);
            writer.WriteString(wellKnownReferenceName);
        }
        else
        {
            writer.WriteBoolean(false);
            base.WriteMetadataReferenceTo(reference, writer);
        }
    }
 
    protected override MetadataReference ReadMetadataReferenceFrom(ObjectReader reader)
        => reader.ReadBoolean()
            ? s_wellKnownReferences[reader.ReadRequiredString()]
            : base.ReadMetadataReferenceFrom(reader);
 
    protected override Checksum CreateChecksum(AnalyzerReference reference)
    {
#if NET
        // If we're in the oop side and we're being asked to produce our local checksum (so we can compare it to the
        // host checksum), then we want to just defer to the underlying analyzer reference of our isolated reference.
        // This underlying reference corresponds to the reference that the host has, and we do not want to make any
        // changes as long as they're both in agreement.
        if (reference is IsolatedAnalyzerFileReference { UnderlyingAnalyzerFileReference: var underlyingReference })
            reference = underlyingReference;
#endif
 
        return reference switch
        {
            TestGeneratorReference generatorReference => generatorReference.Checksum,
            TestAnalyzerReferenceByLanguage analyzerReferenceByLanguage => analyzerReferenceByLanguage.Checksum,
            _ => base.CreateChecksum(reference)
        };
    }
 
    protected override void WriteAnalyzerReferenceTo(AnalyzerReference reference, ObjectWriter writer)
    {
        if (reference is TestGeneratorReference generatorReference)
        {
            // It's a test reference, we'll just store it in a map and then just write out our GUID
            _sharedTestGeneratorReferences.TryAdd(generatorReference.Guid, generatorReference);
            writer.WriteGuid(generatorReference.Guid);
        }
        else
        {
            writer.WriteGuid(Guid.Empty);
            base.WriteAnalyzerReferenceTo(reference, writer);
        }
    }
 
    protected override AnalyzerReference ReadAnalyzerReferenceFrom(ObjectReader reader)
    {
        var testGeneratorReferenceGuid = reader.ReadGuid();
 
        if (testGeneratorReferenceGuid != Guid.Empty)
        {
            Contract.ThrowIfFalse(_sharedTestGeneratorReferences.TryGetValue(testGeneratorReferenceGuid, out var generatorReference));
            return generatorReference;
        }
        else
        {
            return base.ReadAnalyzerReferenceFrom(reader);
        }
    }
 
    [ExportWorkspaceServiceFactory(typeof(ISerializerService), layer: ServiceLayer.Test), Shared, PartNotDiscoverable]
    [Export(typeof(Factory))]
    [method: ImportingConstructor]
    [method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
    internal new sealed class Factory() : IWorkspaceServiceFactory
    {
        private ConcurrentDictionary<Guid, TestGeneratorReference>? _sharedTestGeneratorReferences;
 
        /// <summary>
        /// Gate to serialize reads/writes to <see cref="_sharedTestGeneratorReferences"/>.
        /// </summary>
        private readonly object _gate = new();
 
        /// <summary>
        /// In unit tests that are testing OOP, we want to be able to share test generator references directly
        /// from one side to another. We'll create multiple instances of the TestSerializerService -- one for each
        /// workspace and in different MEF compositions, but we'll share the generator references across them. This
        /// property allows the shared dictionary to be read/set.
        /// </summary>
        public ConcurrentDictionary<Guid, TestGeneratorReference> SharedTestGeneratorReferences
        {
            get
            {
                lock (_gate)
                {
                    _sharedTestGeneratorReferences ??= [];
 
                    return _sharedTestGeneratorReferences;
                }
            }
 
            set
            {
                lock (_gate)
                {
                    // If we're already being assigned the same set of references as before, we're fine as that
                    // won't change anything. Ideally, every time we created a new RemoteWorkspace we'd have a new
                    // MEF container; this would ensure that the assignment earlier before we create the
                    // RemoteWorkspace was always the first assignment. However the ExportProviderCache.cs in our
                    // unit tests hands out the same MEF container multiple times instead of implementing the
                    // expected contract. See https://github.com/dotnet/roslyn/issues/25863 for further details.
                    Contract.ThrowIfFalse(_sharedTestGeneratorReferences == null ||
                        _sharedTestGeneratorReferences == value, "We already have a shared set of references, we shouldn't be getting another one.");
                    _sharedTestGeneratorReferences = value;
                }
            }
        }
 
        [Obsolete(MefConstruction.FactoryMethodMessage, error: true)]
        public IWorkspaceService CreateService(HostWorkspaceServices workspaceServices)
            => new TestSerializerService(SharedTestGeneratorReferences, workspaceServices.SolutionServices);
    }
}