namespace bsmd.util
{

    using log4net.Appender;
    using log4net.Core;
    using Newtonsoft.Json;
    using System;
    using System.Net.Http;
    using System.Text;
    using System.Threading.Tasks;

    public class LokiAppender : AppenderSkeleton
    {

        public string LokiUrl { get; set; }
        public string ApplicationName { get; set; } = "log4net-app";

        private static readonly HttpClient httpClient = new HttpClient();

        protected override void Append(LoggingEvent loggingEvent)
        {
            try
            {
                var timestamp = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds().ToString() + "000000"; // nanoseconds
                var message = RenderLoggingEvent(loggingEvent);

                var payload = new
                {
                    streams = new[]
                    {
                        new
                        {
                            stream = new
                            {
                                app = ApplicationName,
                                level = loggingEvent.Level.Name.ToLower()
                            },
                            values = new[]
                            {
                                new[] { timestamp, message }
                            }
                        }
                    }
                };

                var json = JsonConvert.SerializeObject(payload);

                var content = new StringContent(json, Encoding.UTF8, "application/json");

                // Fire and forget
                Task.Run(() => httpClient.PostAsync(LokiUrl, content));
            }
            catch (Exception ex)
            {
                ErrorHandler.Error("Error sending log to Loki", ex);
            }
        }
    }
}