// 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 Microsoft.AspNetCore.Authorization.Policy;
using Microsoft.Extensions.DependencyInjection.Extensions;

namespace Microsoft.Extensions.DependencyInjection
{
    /// <summary>
    /// Extension methods for setting up authorization services in an <see cref="IServiceCollection" />.
    /// </summary>
    public static class PolicyServiceCollectionExtensions
    {
        /// <summary>
        /// Adds authorization policy services to the specified <see cref="IServiceCollection" />. 
        /// </summary>
        /// <param name="services">The <see cref="IServiceCollection" /> to add services to.</param>
        /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
        public static IServiceCollection AddAuthorizationPolicyEvaluator(this IServiceCollection services)
        {
            if (services == null)
            {
                throw new ArgumentNullException(nameof(services));
            }
            
            services.TryAdd(ServiceDescriptor.Transient<IPolicyEvaluator, PolicyEvaluator>());
            return services;
        }
    }
}