// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
using System.Diagnostics;
using System.Threading;
 
using Internal.Cryptography;
 
namespace System.Security.Cryptography.Pkcs
{
    public sealed class Pkcs9SigningTime : Pkcs9AttributeObject
    {
        //
        // Constructors.
        //
 
        public Pkcs9SigningTime()
            : this(DateTime.Now)
        {
        }
 
        public Pkcs9SigningTime(DateTime signingTime)
            : base(Oids.SigningTimeOid.CopyOid(), Encode(signingTime))
        {
            _lazySigningTime = signingTime;
        }
 
        public Pkcs9SigningTime(byte[] encodedSigningTime)
            : base(Oids.SigningTimeOid.CopyOid(), encodedSigningTime)
        {
        }
 
        internal Pkcs9SigningTime(ReadOnlySpan<byte> encodedSigningTime)
            : base(Oids.SigningTimeOid.CopyOid(), encodedSigningTime)
        {
        }
 
        //
        // Public properties.
        //
 
        public DateTime SigningTime
        {
            get
            {
                if (!_lazySigningTime.HasValue)
                {
                    _lazySigningTime = Decode(RawData);
                    Interlocked.MemoryBarrier();
                }
                return _lazySigningTime.Value;
            }
        }
 
        public override void CopyFrom(AsnEncodedData asnEncodedData)
        {
            base.CopyFrom(asnEncodedData);
            _lazySigningTime = default(DateTime?);
        }
 
        //
        // Private methods.
        //
 
        private static DateTime Decode(byte[]? rawData)
        {
            if (rawData == null)
                return default(DateTime);
 
            return PkcsHelpers.DecodeUtcTime(rawData);
        }
 
        private static byte[] Encode(DateTime signingTime)
        {
            return PkcsHelpers.EncodeUtcTime(signingTime);
        }
 
        private DateTime? _lazySigningTime;
    }
}