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 * Copyright (c) 2005-2026 The OPC Foundation, Inc. All rights reserved.
 *
 * OPC Foundation MIT License 1.00
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
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 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
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 *
 * The above copyright notice and this permission notice shall be
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 * ======================================================================*/

using System;
using System.Collections.Generic;
using Opc.Ua.Identity;

namespace Opc.Ua.Server.Hosting
{
    /// <summary>
    /// Represents a public DI registration deposited by <c>AddIdentityAuthenticator&lt;T&gt;()</c> for deferred
    /// identity-authenticator creation.
    /// </summary>
    /// <remarks>
    /// Hosted server pipelines consume registrations of this type from the service collection so authenticator
    /// instances can be created after server configuration is available.
    /// </remarks>
    public sealed class OpcUaServerIdentityAuthenticatorRegistration
    {
        private readonly Func<
            IServiceProvider,
            ICertificateValidatorEx?,
            IEnumerable<IUserTokenAuthenticator>> m_factory;

        /// <summary>
        /// Initializes a new instance of the <see cref="OpcUaServerIdentityAuthenticatorRegistration"/> class.
        /// </summary>
        /// <param name="factory">
        /// Factory that creates authenticators for a service provider and certificate validator.
        /// </param>
        /// <exception cref="ArgumentNullException"><paramref name="factory"/> is <c>null</c>.</exception>
        public OpcUaServerIdentityAuthenticatorRegistration(
            Func<IServiceProvider, ICertificateValidatorEx?, IEnumerable<IUserTokenAuthenticator>> factory)
        {
            m_factory = factory ?? throw new ArgumentNullException(nameof(factory));
        }

        /// <summary>
        /// Creates the configured identity authenticators.
        /// </summary>
        /// <param name="services">Service provider used to resolve dependencies.</param>
        /// <param name="certificateValidator">Certificate validator supplied by the server configuration.</param>
        /// <returns>The identity authenticators created by the registration factory.</returns>
        public IEnumerable<IUserTokenAuthenticator> CreateAuthenticators(
            IServiceProvider services,
            ICertificateValidatorEx? certificateValidator)
        {
            return m_factory(services, certificateValidator);
        }
    }
}