// 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.Generic;
using System.Collections.Immutable;
using System.Linq;
using System.Reflection;
using System.Text;
using Microsoft.CodeAnalysis.Host;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.VisualStudio.Composition;
using Roslyn.Utilities;
using Xunit;
 
namespace Microsoft.CodeAnalysis.Test.Utilities;
 
/// <summary>
/// Represents a MEF composition used for testing.
/// </summary>
public sealed class TestComposition
{
    public static readonly TestComposition Empty = new TestComposition([], [], []);
 
    private static readonly Dictionary<CacheKey, IExportProviderFactory> s_factoryCache = [];
 
    private readonly struct CacheKey : IEquatable<CacheKey>
    {
        private readonly ImmutableArray<Assembly> _assemblies;
        private readonly ImmutableArray<Type> _parts;
        private readonly ImmutableArray<Type> _excludedPartTypes;
 
        public CacheKey(ImmutableHashSet<Assembly> assemblies, ImmutableHashSet<Type> parts, ImmutableHashSet<Type> excludedPartTypes)
        {
            _assemblies = [.. assemblies.OrderBy((a, b) => string.CompareOrdinal(a.FullName, b.FullName))];
            _parts = [.. parts.OrderBy((a, b) => string.CompareOrdinal(a.FullName, b.FullName))];
            _excludedPartTypes = [.. excludedPartTypes.OrderBy((a, b) => string.CompareOrdinal(a.FullName, b.FullName))];
        }
 
        public override bool Equals(object? obj)
            => obj is CacheKey key && Equals(key);
 
        public bool Equals(CacheKey other)
            => _parts.SequenceEqual(other._parts) &&
               _excludedPartTypes.SequenceEqual(other._excludedPartTypes) &&
               _assemblies.SequenceEqual(other._assemblies);
 
        public override int GetHashCode()
            => Hash.Combine(Hash.Combine(Hash.CombineValues(_assemblies), Hash.CombineValues(_parts)), Hash.CombineValues(_excludedPartTypes));
 
        public static bool operator ==(CacheKey left, CacheKey right)
            => left.Equals(right);
 
        public static bool operator !=(CacheKey left, CacheKey right)
            => !(left == right);
    }
 
    /// <summary>
    /// Assemblies to include in the composition.
    /// </summary>
    public readonly ImmutableHashSet<Assembly> Assemblies;
 
    /// <summary>
    /// Types to exclude from the composition.
    /// All subtypes of types specified in <see cref="ExcludedPartTypes"/> and defined in <see cref="Assemblies"/> are excluded before <see cref="Parts"/> are added.
    /// </summary>
    public readonly ImmutableHashSet<Type> ExcludedPartTypes;
 
    /// <summary>
    /// Additional part types to add to the composition.
    /// </summary>
    public readonly ImmutableHashSet<Type> Parts;
 
    private readonly Lazy<IExportProviderFactory> _exportProviderFactory;
 
    private TestComposition(ImmutableHashSet<Assembly> assemblies, ImmutableHashSet<Type> parts, ImmutableHashSet<Type> excludedPartTypes)
    {
        Assemblies = assemblies;
        Parts = parts;
        ExcludedPartTypes = excludedPartTypes;
 
        _exportProviderFactory = new Lazy<IExportProviderFactory>(GetOrCreateFactory);
    }
 
    /// <summary>
    /// Returns a new instance of <see cref="HostServices"/> for the composition. This will either be a MEF composition or VS MEF composition host, 
    /// depending on what layer the composition is for. Editor Features and VS layers use VS MEF composition while anything else uses System.Composition.
    /// </summary>
    public HostServices GetHostServices()
        => VisualStudioMefHostServices.Create(ExportProviderFactory.CreateExportProvider());
 
    /// <summary>
    /// VS MEF <see cref="ExportProvider"/>.
    /// </summary>
    public IExportProviderFactory ExportProviderFactory => _exportProviderFactory.Value;
 
    private IExportProviderFactory GetOrCreateFactory()
    {
        var key = new CacheKey(Assemblies, Parts, ExcludedPartTypes);
 
        lock (s_factoryCache)
        {
            if (s_factoryCache.TryGetValue(key, out var existing))
            {
                return existing;
            }
        }
 
        var newFactory = ExportProviderCache.CreateExportProviderFactory(GetCatalog(), IsRemote);
 
        lock (s_factoryCache)
        {
            if (s_factoryCache.TryGetValue(key, out var existing))
            {
                return existing;
            }
 
            s_factoryCache.Add(key, newFactory);
        }
 
        return newFactory;
    }
 
    public bool IsRemote
        => Assemblies.Contains(typeof(Remote.BrokeredServiceBase).Assembly);
 
    private ComposableCatalog GetCatalog()
    {
        // Compositions should not be realized if they contain the same part in both the explicit include list and
        // the explicit exclude list.
        var configurationOverlap = Parts.Intersect(ExcludedPartTypes);
        Assert.Empty(configurationOverlap);
 
        return ExportProviderCache.CreateAssemblyCatalog(Assemblies, ExportProviderCache.CreateResolver()).WithoutPartsOfTypes(ExcludedPartTypes).WithParts(Parts);
    }
 
    public CompositionConfiguration GetCompositionConfiguration()
        => CompositionConfiguration.Create(GetCatalog());
 
    public TestComposition Add(TestComposition composition)
        => AddAssemblies(composition.Assemblies).AddParts(composition.Parts).AddExcludedPartTypes(composition.ExcludedPartTypes);
 
    public TestComposition AddAssemblies(params Assembly[]? assemblies)
        => AddAssemblies((IEnumerable<Assembly>?)assemblies);
 
    public TestComposition AddAssemblies(IEnumerable<Assembly>? assemblies)
        => WithAssemblies(Assemblies.Union(assemblies ?? []));
 
    public TestComposition AddParts(IEnumerable<Type>? types)
        => WithParts(Parts.Union(types ?? []));
 
    public TestComposition AddParts(params Type[]? types)
        => AddParts((IEnumerable<Type>?)types);
 
    public TestComposition AddExcludedPartTypes(IEnumerable<Type>? types)
        => WithExcludedPartTypes(ExcludedPartTypes.Union(types ?? []));
 
    public TestComposition AddExcludedPartTypes(params Type[]? types)
        => AddExcludedPartTypes((IEnumerable<Type>?)types);
 
    public TestComposition Remove(TestComposition composition)
        => RemoveAssemblies(composition.Assemblies).RemoveParts(composition.Parts).RemoveExcludedPartTypes(composition.ExcludedPartTypes);
 
    public TestComposition RemoveAssemblies(params Assembly[]? assemblies)
        => RemoveAssemblies((IEnumerable<Assembly>?)assemblies);
 
    public TestComposition RemoveAssemblies(IEnumerable<Assembly>? assemblies)
        => WithAssemblies(Assemblies.Except(assemblies ?? []));
 
    public TestComposition RemoveParts(IEnumerable<Type>? types)
        => WithParts(Parts.Except(types ?? []));
 
    public TestComposition RemoveParts(params Type[]? types)
        => RemoveParts((IEnumerable<Type>?)types);
 
    public TestComposition RemoveExcludedPartTypes(IEnumerable<Type>? types)
        => WithExcludedPartTypes(ExcludedPartTypes.Except(types ?? []));
 
    public TestComposition RemoveExcludedPartTypes(params Type[]? types)
        => RemoveExcludedPartTypes((IEnumerable<Type>?)types);
 
    public TestComposition WithAssemblies(ImmutableHashSet<Assembly> assemblies)
    {
        if (assemblies == Assemblies)
        {
            return this;
        }
 
        var testAssembly = assemblies.FirstOrDefault(IsTestAssembly);
        Contract.ThrowIfFalse(testAssembly == null, $"Test assemblies are not allowed in test composition: {testAssembly}. Specify explicit test parts instead.");
 
        return new TestComposition(assemblies, Parts, ExcludedPartTypes);
 
        static bool IsTestAssembly(Assembly assembly)
        {
            var name = assembly.GetName().Name!;
            return
                name.EndsWith(".Tests", StringComparison.OrdinalIgnoreCase) ||
                name.EndsWith(".UnitTests", StringComparison.OrdinalIgnoreCase) ||
                name.IndexOf("Test.Utilities", StringComparison.OrdinalIgnoreCase) >= 0;
        }
    }
 
    public TestComposition WithParts(ImmutableHashSet<Type> parts)
        => (parts == Parts) ? this : new TestComposition(Assemblies, parts, ExcludedPartTypes);
 
    public TestComposition WithExcludedPartTypes(ImmutableHashSet<Type> excludedPartTypes)
        => (excludedPartTypes == ExcludedPartTypes) ? this : new TestComposition(Assemblies, Parts, excludedPartTypes);
 
    /// <summary>
    /// Use for VS MEF composition troubleshooting.
    /// </summary>
    /// <returns>All composition error messages.</returns>
    internal string GetCompositionErrorLog()
    {
        var configuration = CompositionConfiguration.Create(GetCatalog());
 
        var sb = new StringBuilder();
        foreach (var errorGroup in configuration.CompositionErrors)
        {
            foreach (var error in errorGroup)
            {
                sb.Append(error.Message);
                sb.AppendLine();
            }
        }
 
        return sb.ToString();
    }
}