// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Diagnostics;
using Microsoft.AspNetCore.Mvc.Filters;
using Microsoft.Extensions.DependencyInjection;
 
namespace Microsoft.AspNetCore.Mvc;
 
/// <summary>
/// A filter that finds another filter in an <see cref="IServiceProvider"/>.
/// </summary>
/// <remarks>
/// <para>
/// Primarily used in <see cref="M:FilterCollection.AddService"/> calls.
/// </para>
/// <para>
/// Similar to the <see cref="TypeFilterAttribute"/> in that both use constructor injection. Use
/// <see cref="TypeFilterAttribute"/> instead if the filter is not itself a service.
/// </para>
/// </remarks>
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = true, Inherited = true)]
[DebuggerDisplay("Type = {ServiceType}, Order = {Order}")]
public class ServiceFilterAttribute : Attribute, IFilterFactory, IOrderedFilter
{
    /// <summary>
    /// Instantiates a new <see cref="ServiceFilterAttribute"/> instance.
    /// </summary>
    /// <param name="type">The <see cref="Type"/> of filter to find.</param>
    public ServiceFilterAttribute(Type type)
    {
        ServiceType = type ?? throw new ArgumentNullException(nameof(type));
    }
 
    /// <inheritdoc />
    public int Order { get; set; }
 
    /// <summary>
    /// Gets the <see cref="Type"/> of filter to find.
    /// </summary>
    public Type ServiceType { get; }
 
    /// <inheritdoc />
    public bool IsReusable { get; set; }
 
    /// <inheritdoc />
    public IFilterMetadata CreateInstance(IServiceProvider serviceProvider)
    {
        ArgumentNullException.ThrowIfNull(serviceProvider);
 
        var filter = (IFilterMetadata)serviceProvider.GetRequiredService(ServiceType);
        if (filter is IFilterFactory filterFactory)
        {
            // Unwrap filter factories
            filter = filterFactory.CreateInstance(serviceProvider);
        }
 
        return filter;
    }
}