// Copyright (c) .NET Foundation. All rights reserved.

// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;

using System.Collections.Concurrent;

using System.Reflection;

using JetBrains.Annotations;

namespace Microsoft.EntityFrameworkCore.Internal

{

/// <summary>

/// This API supports the Entity Framework Core infrastructure and is not intended to be used

/// directly from your code. This API may change or be removed in future releases.

/// </summary>

public class DbSetSource : IDbSetSource

{

private static readonly MethodInfo _genericCreate

= typeof(DbSetSource).GetTypeInfo().GetDeclaredMethod(nameof(CreateConstructor));

private readonly ConcurrentDictionary<Type, Func<DbContext, object>> _cache

= new ConcurrentDictionary<Type, Func<DbContext, object>>();

/// <summary>

/// This API supports the Entity Framework Core infrastructure and is not intended to be used

/// directly from your code. This API may change or be removed in future releases.

/// </summary>

public virtual object Create(DbContext context, Type type)

=> _cache.GetOrAdd(

type,

t => (Func<DbContext, object>)_genericCreate.MakeGenericMethod(t).Invoke(null, null))(context);

[UsedImplicitly]

private static Func<DbContext, object> CreateConstructor<TEntity>() where TEntity : class

=> c => new InternalDbSet<TEntity>(c);

}

}