NdefInterface.cs

using Android.Nfc;
using Android.Nfc.Tech;
using NeuroAccess.Nfc;
using NeuroAccess.Nfc.Records;
using NeuroAccessMaui.AndroidPlatform.Nfc.Records;
using System.Text;
using Waher.Content;
using Waher.Runtime.Inventory;
 
namespace NeuroAccessMaui.AndroidPlatform.Nfc
{
    public class NdefInterface(Tag Tag, Ndef Technology)
        : NfcInterface(Tag, Technology), INdefInterface
    {
        private readonly Ndef ndef = Technology;
 
        public Task<bool> CanMakeReadOnly()
        {
            return Task.FromResult(this.ndef.CanMakeReadOnly());
        }
 
        public Task<bool> IsWritable()
        {
            return Task.FromResult(this.ndef.IsWritable);
        }
 
        public Task<INdefRecord[]> GetMessage()
        {
            NdefMessage? Message = this.ndef.NdefMessage ?? throw UnableToReadDataFromDevice();
            NdefRecord[]? Records = Message.GetRecords() ?? throw UnableToReadDataFromDevice();
            List<INdefRecord> Result = [];
 
            foreach (NdefRecord Record in Records)
            {
                switch (Record.Tnf)
                {
                    case NdefRecord.TnfAbsoluteUri:
                        Result.Add(new UriRecord(Record));
                        break;
 
                    case NdefRecord.TnfMimeMedia:
                        Result.Add(new MimeTypeRecord(Record));
                        break;
 
                    case NdefRecord.TnfWellKnown:
                        byte[] Bin = Record.GetTypeInfo() ?? throw UnableToReadDataFromDevice();
                        string TypeInfo = Encoding.UTF8.GetString(Bin);
 
                        if (TypeInfo == "U")
                            Result.Add(new UriRecord(Record));
                        else
                            Result.Add(new WellKnownTypeRecord(Record));
                        break;
 
                    case NdefRecord.TnfExternalType:
                        Result.Add(new ExternalTypeRecord(Record));
                        break;
 
                    case NdefRecord.TnfEmpty:
                    case NdefRecord.TnfUnchanged:
                    case NdefRecord.TnfUnknown:
                    default:
                        break;
                }
            }
 
            return Task.FromResult<INdefRecord[]>([.. Result]);
        }
 
        public async Task<bool> SetMessage(params object[] Items)
        {
            try
            {
                NdefMessage Message = await CreateMessage(Items);
                await this.ndef.WriteNdefMessageAsync(Message);
 
                return true;
            }
            catch (Exception)
            {
                return false;
            }
        }
 
        public static async Task<NdefMessage> CreateMessage(params object[] Items)
        {
            List<NdefRecord> Records = [];
 
            foreach (object Item in Items)
            {
                if (Item is null)
                    continue;
 
                if (Item is Uri Uri)
                {
                    if (Uri.IsAbsoluteUri)
                        Records.Add(NdefRecord.CreateUri(Uri.AbsoluteUri) ?? throw new ArgumentException("Unable to create URI record.", nameof(Items)));
                    else
                        throw new ArgumentException("URI not absolute.", nameof(Items));
                }
                else if (Item is string s)
                    Records.Add(NdefRecord.CreateTextRecord(null, s) ?? throw new ArgumentException("Unable to create text record.", nameof(Items)));
                else
                {
                    if (Item is not KeyValuePair<byte[], string> Mime)
                    {
                        if (!InternetContent.Encodes(Item, out Grade _, out IContentEncoder Encoder))
                            throw new ArgumentException("Unable to encode objects of type " + Item.GetType().FullName + ".", nameof(Items));
 
                        Mime = await Encoder.EncodeAsync(Item, Encoding.UTF8);
                    }
 
                    Records.Add(NdefRecord.CreateMime(Mime.Value, Mime.Key) ?? throw new ArgumentException("Unable to create MIME record.", nameof(Items)));
                }
            }
 
            return new(Records.ToArray());
        }
 
    }
}