CrlRevocationListDecoder.cs

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Text;
using System.Threading.Tasks;
using NeuroAccess.Nfc.TravelDocuments.Security;
using Waher.Content;
using Waher.Runtime.Inventory;
 
namespace NeuroAccess.Nfc.TravelDocuments.RevocationLists
{
    public class CrlRevocationListDecoder : IContentDecoder
    {
        public const string DefaultContentType = "application/pkix-crl";
 
        public const string DefaultFileExtension = "crl";
 
        public string[] ContentTypes => [DefaultContentType];
 
        public string[] FileExtensions => throw new NotImplementedException();
 
        public bool TryGetContentType(string FileExtension, out string ContentType)
        {
            switch (FileExtension.ToLower(CultureInfo.InvariantCulture))
            {
                case DefaultFileExtension:
                    ContentType = DefaultContentType;
                    return true;
 
                default:
                    ContentType = string.Empty;
                    return false;
            }
        }
 
        public bool TryGetFileExtension(string ContentType, out string FileExtension)
        {
            switch (ContentType.ToLower(CultureInfo.InvariantCulture))
            {
                case DefaultContentType:
                    FileExtension = DefaultFileExtension;
                    return true;
 
                default:
                    FileExtension = string.Empty;
                    return false;
            }
        }
 
        public bool Decodes(string ContentType, out Grade Grade)
        {
            if (string.Equals(ContentType, DefaultContentType, StringComparison.OrdinalIgnoreCase))
            {
                Grade = Grade.Ok;
                return true;
            }
            else
            {
                Grade = Grade.NotAtAll;
                return false;
            }
        }
 
        public Task<ContentResponse> DecodeAsync(string ContentType, byte[] Data, Encoding Encoding, KeyValuePair<string, string>[] Fields, Uri BaseUri, ICodecProgress Progress)
        {
            if (!ASN1.TryDecodeDer(Data, out object? Decoded) ||
                Decoded is not Vector Crl ||
                !CertificateList.TryParse(Crl, out CertificateList? Parsed))
            {
                return Task.FromResult(new ContentResponse(new Exception("Unable to parse and decode CRL data.")));
            }
 
            return Task.FromResult(new ContentResponse(DefaultContentType, Parsed, Data));
        }
    }
}