// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
#pragma warning disable SA1028 // ignore whitespace warnings for generated code
using System;
using System.Formats.Asn1;
using System.Runtime.InteropServices;
 
namespace System.Security.Cryptography.Pkcs.Asn1
{
    [StructLayout(LayoutKind.Sequential)]
    internal partial struct IssuerAndSerialNumberAsn
    {
        internal ReadOnlyMemory<byte> Issuer;
        internal ReadOnlyMemory<byte> SerialNumber;
 
        internal readonly void Encode(AsnWriter writer)
        {
            Encode(writer, Asn1Tag.Sequence);
        }
 
        internal readonly void Encode(AsnWriter writer, Asn1Tag tag)
        {
            writer.PushSequence(tag);
 
            // Validator for tag constraint for Issuer
            {
                if (!Asn1Tag.TryDecode(Issuer.Span, out Asn1Tag validateTag, out _) ||
                    !validateTag.HasSameClassAndValue(new Asn1Tag((UniversalTagNumber)16)))
                {
                    throw new CryptographicException();
                }
            }
 
            try
            {
                writer.WriteEncodedValue(Issuer.Span);
            }
            catch (ArgumentException e)
            {
                throw new CryptographicException(SR.Cryptography_Der_Invalid_Encoding, e);
            }
            writer.WriteInteger(SerialNumber.Span);
            writer.PopSequence(tag);
        }
 
        internal static IssuerAndSerialNumberAsn Decode(ReadOnlyMemory<byte> encoded, AsnEncodingRules ruleSet)
        {
            return Decode(Asn1Tag.Sequence, encoded, ruleSet);
        }
 
        internal static IssuerAndSerialNumberAsn Decode(Asn1Tag expectedTag, ReadOnlyMemory<byte> encoded, AsnEncodingRules ruleSet)
        {
            try
            {
                AsnValueReader reader = new AsnValueReader(encoded.Span, ruleSet);
 
                DecodeCore(ref reader, expectedTag, encoded, out IssuerAndSerialNumberAsn decoded);
                reader.ThrowIfNotEmpty();
                return decoded;
            }
            catch (AsnContentException e)
            {
                throw new CryptographicException(SR.Cryptography_Der_Invalid_Encoding, e);
            }
        }
 
        internal static void Decode(ref AsnValueReader reader, ReadOnlyMemory<byte> rebind, out IssuerAndSerialNumberAsn decoded)
        {
            Decode(ref reader, Asn1Tag.Sequence, rebind, out decoded);
        }
 
        internal static void Decode(ref AsnValueReader reader, Asn1Tag expectedTag, ReadOnlyMemory<byte> rebind, out IssuerAndSerialNumberAsn decoded)
        {
            try
            {
                DecodeCore(ref reader, expectedTag, rebind, out decoded);
            }
            catch (AsnContentException e)
            {
                throw new CryptographicException(SR.Cryptography_Der_Invalid_Encoding, e);
            }
        }
 
        private static void DecodeCore(ref AsnValueReader reader, Asn1Tag expectedTag, ReadOnlyMemory<byte> rebind, out IssuerAndSerialNumberAsn decoded)
        {
            decoded = default;
            AsnValueReader sequenceReader = reader.ReadSequence(expectedTag);
            ReadOnlySpan<byte> rebindSpan = rebind.Span;
            int offset;
            ReadOnlySpan<byte> tmpSpan;
 
            if (!sequenceReader.PeekTag().HasSameClassAndValue(new Asn1Tag((UniversalTagNumber)16)))
            {
                throw new CryptographicException();
            }
 
            tmpSpan = sequenceReader.ReadEncodedValue();
            decoded.Issuer = rebindSpan.Overlaps(tmpSpan, out offset) ? rebind.Slice(offset, tmpSpan.Length) : tmpSpan.ToArray();
            tmpSpan = sequenceReader.ReadIntegerBytes();
            decoded.SerialNumber = rebindSpan.Overlaps(tmpSpan, out offset) ? rebind.Slice(offset, tmpSpan.Length) : tmpSpan.ToArray();
 
            sequenceReader.ThrowIfNotEmpty();
        }
    }
}