// 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.Buffers;
using System.Formats.Asn1;
using System.Security.Cryptography;
using System.Security.Cryptography.Asn1.Pkcs7;
 
namespace Internal.Cryptography.Pal.AnyOS
{
    internal sealed partial class ManagedPkcsPal : PkcsPal
    {
        public override unsafe Oid GetEncodedMessageType(ReadOnlySpan<byte> encodedMessage)
        {
            fixed (byte* pin = encodedMessage)
            {
                using (var manager = new PointerMemoryManager<byte>(pin, encodedMessage.Length))
                {
                    AsnValueReader reader = new AsnValueReader(encodedMessage, AsnEncodingRules.BER);
 
                    ContentInfoAsn.Decode(ref reader, manager.Memory, out ContentInfoAsn contentInfo);
 
                    switch (contentInfo.ContentType)
                    {
                        case Oids.Pkcs7Data:
                        case Oids.Pkcs7Signed:
                        case Oids.Pkcs7Enveloped:
                        case Oids.Pkcs7SignedEnveloped:
                        case Oids.Pkcs7Hashed:
                        case Oids.Pkcs7Encrypted:
                            return new Oid(contentInfo.ContentType);
                    }
 
                    throw new CryptographicException(SR.Cryptography_Cms_InvalidMessageType);
                }
            }
        }
    }
}