/* ========================================================================
 * Copyright (c) 2005-2025 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
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * The complete license agreement can be found here:
 * http://opcfoundation.org/License/MIT/1.00/
 * ======================================================================*/

using System;

namespace Opc.Ua.Client
{
    /// <summary>
    /// Factory that creates <see cref="ClassicSubscriptionEngine"/>
    /// instances. This is the default factory used when no custom
    /// factory is provided at session creation time.
    /// </summary>
    public sealed class ClassicSubscriptionEngineFactory
        : ISubscriptionEngineFactory
    {
        /// <summary>
        /// Gets the singleton instance of the factory.
        /// </summary>
        public static ClassicSubscriptionEngineFactory Instance { get; } = new();

        /// <summary>
        /// Initializes a new instance of the
        /// <see cref="ClassicSubscriptionEngineFactory"/> class bound to
        /// <see cref="TimeProvider.System"/>.
        /// </summary>
        public ClassicSubscriptionEngineFactory()
            : this(null)
        {
        }

        /// <summary>
        /// Initializes a new instance of the
        /// <see cref="ClassicSubscriptionEngineFactory"/> class.
        /// </summary>
        /// <param name="timeProvider">Optional <see cref="TimeProvider"/>
        /// forwarded to the engines created by this factory. Defaults to
        /// <see cref="TimeProvider.System"/> when <c>null</c>.</param>
        public ClassicSubscriptionEngineFactory(TimeProvider? timeProvider = null)
        {
            m_timeProvider = timeProvider ?? TimeProvider.System;
        }

        /// <inheritdoc/>
        public ISubscriptionEngine Create(ISubscriptionEngineContext context)
        {
            return new ClassicSubscriptionEngine(context, m_timeProvider);
        }

        private readonly TimeProvider m_timeProvider;
    }
}