using Microsoft.ApplicationInsights;
using Microsoft.ApplicationInsights.Channel;
using Microsoft.ApplicationInsights.DataContracts;
using Microsoft.Extensions.Hosting;
using PlanTempus.Core.Telemetry;

namespace PlanTempus.Core.SeqLogging
{
    public class SeqBackgroundService : BackgroundService
    {
        private readonly IMessageChannel<ITelemetry> _messageChannel;
        private readonly TelemetryClient _telemetryClient;
        private readonly SeqLogger<SeqBackgroundService> _seqLogger;

        public SeqBackgroundService(TelemetryClient telemetryClient,
                                    IMessageChannel<ITelemetry> messageChannel,
                                    SeqLogger<SeqBackgroundService> seqlogger)
        {
            _telemetryClient = telemetryClient;
            _messageChannel = messageChannel;
            _seqLogger = seqlogger;

            _telemetryClient.TrackTrace("SeqBackgroundService started");

        }

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            try
            {
                while (!stoppingToken.IsCancellationRequested)
                    await foreach (var telemetry in _messageChannel.Reader.ReadAllAsync(stoppingToken))
                    {
                        try
                        {
                            switch (telemetry)
                            {
                                case ExceptionTelemetry et:
                                    await _seqLogger.LogAsync(et);
                                    break;

                                case TraceTelemetry et:
                                    await _seqLogger.LogAsync(et);
                                    break;

                                case DependencyTelemetry et:
                                    await _seqLogger.LogAsync(et);
                                    break;

                                case RequestTelemetry et:
                                    await _seqLogger.LogAsync(et);
                                    break;

                                case EventTelemetry et:
                                    await _seqLogger.LogAsync(et);
                                    break;


                                default:
                                    throw new NotSupportedException(telemetry.GetType().Name);
                            }
                        }
                        catch
                        {
                            throw;
                            //_telemetryClient.TrackException(ex); this is disabled for now, we need to think about the channel structure first
                        }
                    }
            }
            catch (Exception ex)
            {
                if (ex is not OperationCanceledException)
                {
                    _telemetryClient.TrackException(ex);
                    throw;
                }

            }
        }

        public override async Task StopAsync(CancellationToken cancellationToken)
        {
            _telemetryClient.TrackTrace("StopAsync called: Service shutdown started");
            _messageChannel.Dispose();
            await base.StopAsync(cancellationToken);
        }
    }
}