4.0AuthenticationServiceCollectionExtensions&AuthenticationCoreServiceCollectionExtensions

using System;
using Microsoft.AspNetCore.Authentication;
using Microsoft.Extensions.DependencyInjection.Extensions;
using Microsoft.Extensions.Options;

namespace Microsoft.Extensions.DependencyInjection
{
    /// <summary>
    /// Extension methods for setting up authentication services in an <see cref="IServiceCollection" />.
    /// </summary>
    public static class AuthenticationServiceCollectionExtensions
    {
        /// <summary>
        /// Registers services required by authentication services.
        /// </summary>
        /// <param name="services">The <see cref="IServiceCollection"/>.</param>
        /// <returns>A <see cref="AuthenticationBuilder"/> that can be used to further configure authentication.</returns>
        public static AuthenticationBuilder AddAuthentication(this IServiceCollection services)
        {
            if (services == null)
            {
                throw new ArgumentNullException(nameof(services));
            }

            services.AddAuthenticationCore();
            services.AddDataProtection();
            services.AddWebEncoders();
            services.TryAddSingleton<ISystemClock, SystemClock>();
            return new AuthenticationBuilder(services);
        }

        /// <summary>
        /// Registers services required by authentication services. <paramref name="defaultScheme"/> specifies the name of the
        /// scheme to use by default when a specific scheme isn't requested.
        /// </summary>
        /// <param name="services">The <see cref="IServiceCollection"/>.</param>
        /// <param name="defaultScheme">The default scheme used as a fallback for all other schemes.</param>
        /// <returns>A <see cref="AuthenticationBuilder"/> that can be used to further configure authentication.</returns>
        public static AuthenticationBuilder AddAuthentication(this IServiceCollection services, string defaultScheme)
            => services.AddAuthentication(o => o.DefaultScheme = defaultScheme);

        /// <summary>
        /// Registers services required by authentication services and configures <see cref="AuthenticationOptions"/>.
        /// </summary>
        /// <param name="services">The <see cref="IServiceCollection"/>.</param>
        /// <param name="configureOptions">A delegate to configure <see cref="AuthenticationOptions"/>.</param>
        /// <returns>A <see cref="AuthenticationBuilder"/> that can be used to further configure authentication.</returns>
        public static AuthenticationBuilder AddAuthentication(this IServiceCollection services, Action<AuthenticationOptions> configureOptions)
        {
            if (services == null)
            {
                throw new ArgumentNullException(nameof(services));
            }

            if (configureOptions == null)
            {
                throw new ArgumentNullException(nameof(configureOptions));
            }

            var builder = services.AddAuthentication();
            services.Configure(configureOptions);
            return builder;
        }

    }
}

using System;
using Microsoft.AspNetCore.Authentication;
using Microsoft.Extensions.DependencyInjection.Extensions;

namespace Microsoft.Extensions.DependencyInjection
{
    /// <summary>
    /// Extension methods for setting up authentication services in an <see cref="IServiceCollection" />.
    /// </summary>
    public static class AuthenticationCoreServiceCollectionExtensions
    {
        /// <summary>
        /// Add core authentication services needed for <see cref="IAuthenticationService"/>.
        /// </summary>
        /// <param name="services">The <see cref="IServiceCollection"/>.</param>
        /// <returns>The service collection.</returns>
        public static IServiceCollection AddAuthenticationCore(this IServiceCollection services)
        {
            if (services == null)
            {
                throw new ArgumentNullException(nameof(services));
            }

            services.TryAddScoped<IAuthenticationService, AuthenticationService>();
            services.TryAddSingleton<IClaimsTransformation, NoopClaimsTransformation>(); // Can be replaced with scoped ones that use DbContext
            services.TryAddScoped<IAuthenticationHandlerProvider, AuthenticationHandlerProvider>();
            services.TryAddSingleton<IAuthenticationSchemeProvider, AuthenticationSchemeProvider>();
            return services;
        }

        /// <summary>
        /// Add core authentication services needed for <see cref="IAuthenticationService"/>.
        /// </summary>
        /// <param name="services">The <see cref="IServiceCollection"/>.</param>
        /// <param name="configureOptions">Used to configure the <see cref="AuthenticationOptions"/>.</param>
        /// <returns>The service collection.</returns>
        public static IServiceCollection AddAuthenticationCore(this IServiceCollection services, Action<AuthenticationOptions> configureOptions) {
            if (services == null)
            {
                throw new ArgumentNullException(nameof(services));
            }

            if (configureOptions == null)
            {
                throw new ArgumentNullException(nameof(configureOptions));
            }

            services.AddAuthenticationCore();
            services.Configure(configureOptions);
            return services;
        }
    }
}