Impinj Speedway R420 & R700 RFID Middleware | Portal Gate & Conveyor Tag Filtering

using System;
using System.Threading.Channels;
using System.Threading.Tasks;
using Impinj.OctaneSdk;

namespace RfidSoftwares.Speedway.Gateway
{
    public class SpeedwayPortalController
    {
        private readonly ImpinjReader _reader = new();
        private readonly Channel<TagReport> _ringBuffer = Channel.CreateUnbounded<TagReport>();

        public async Task InitializePortalAsync(string readerIp)
        {
            await _reader.ConnectAsync(readerIp);
            Settings settings = _reader.QueryDefaultSettings();
            
            // Enable RF Phase Angle and Doppler vendor extensions
            settings.Report.IncludePhaseAngle = true;
            settings.Report.IncludeDopplerFrequency = true;
            settings.Antennas.GetAntenna(1).TxPowerinDbm = 31.5; // Ant 1/2 Entry
            settings.Antennas.GetAntenna(3).TxPowerinDbm = 31.5; // Ant 3/4 Exit

            // Non-blocking socket ingest: prevents LLRP buffer overflow
            _reader.TagsReported += (r, report) => _ringBuffer.Writer.TryWrite(report);
            await _reader.ApplySettingsAsync(settings);
        }

        // Sub-15ms Directionality & 24V GPIO Relay Actuation
        public async Task ProcessTransitVectorAsync(TagReport entry, TagReport exit, bool isValidAsn)
        {
            double phaseDelta = exit.RfPhaseInRadians - entry.RfPhaseInRadians;
            string direction = phaseDelta > 0 ? "OUTBOUND_DISPATCH" : "INBOUND_RECEIPT";

            if (isValidAsn) {
                // Actuate 24V Industrial Stack Light (GPO Port 1 Green)
                await _reader.SetGpoAsync(port: 1, state: GpoState.High);
                await Task.Delay(1500);
                await _reader.SetGpoAsync(port: 1, state: GpoState.Low);
            } else {
                // Trigger Red Strobe Alarm (GPO Port 2)
                await _reader.SetGpoAsync(port: 2, state: GpoState.High);
            }
        }
    }
}