#if !NET40
using System;
using System.Collections.Generic;
using System.Diagnostics.Tracing;

namespace NewLife.Log
{
    /// <summary>日志事件监听器。用于监听内置事件并写入日志</summary>
    public class LogEventListener : EventListener
    {
        private readonly HashSet<String> _hash = new();
        private readonly HashSet<String> _hash2 = new();

        /// <summary>实例化</summary>
        /// <param name="sources"></param>
        public LogEventListener(String[] sources)
        {
            foreach (var item in sources)
            {
                _hash.Add(item);
            }
        }

        /// <summary>创建事件源。此时决定要不要跟踪</summary>
        /// <param name="eventSource"></param>
        protected override void OnEventSourceCreated(EventSource eventSource)
        {
            if (_hash.Contains(eventSource.Name))
            {
                var log = XTrace.Log;

                var level = log.Level switch
                {
                    LogLevel.All => EventLevel.LogAlways,
                    LogLevel.Debug => EventLevel.Verbose,
                    LogLevel.Info => EventLevel.Informational,
                    LogLevel.Warn => EventLevel.Warning,
                    LogLevel.Error => EventLevel.Error,
                    LogLevel.Fatal => EventLevel.Critical,
                    LogLevel.Off => throw new NotImplementedException(),
                    _ => EventLevel.Informational,
                };

                EnableEvents(eventSource, level);
            }
            else if (!_hash2.Contains(eventSource.Name))
            {
                _hash2.Add(eventSource.Name);

                XTrace.WriteLine($"Source={eventSource.Name}");
            }
        }

        /// <summary>写入事件。监听器拦截，并写入日志</summary>
        /// <param name="eventData"></param>
        protected override void OnEventWritten(EventWrittenEventArgs eventData)
        {
            var log = XTrace.Log;

            var level = eventData.Level switch
            {
                EventLevel.Informational => LogLevel.Info,
                EventLevel.LogAlways => LogLevel.All,
                EventLevel.Critical => LogLevel.Fatal,
                EventLevel.Error => LogLevel.Error,
                EventLevel.Warning => LogLevel.Warn,
                EventLevel.Verbose => LogLevel.Debug,
                _ => LogLevel.Info,
            };

#if NET45_OR_GREATER
            XTrace.WriteLine($"#{eventData.EventSource?.Name} ID = {eventData.EventId}");
            for (var i = 0; i < eventData.Payload.Count; i++)
            {
                XTrace.WriteLine($"\tPayload = \"{eventData.Payload[i]}\"");
            }
#elif NETCOREAPP
            XTrace.WriteLine($"#{eventData.EventSource?.Name} ThreadID = {eventData.OSThreadId} ID = {eventData.EventId} Name = {eventData.EventName}");
            for (var i = 0; i < eventData.Payload.Count; i++)
            {
                XTrace.WriteLine($"\tName = \"{eventData.PayloadNames[i]}\" Value = \"{eventData.Payload[i]}\"");
            }
#else
            XTrace.WriteLine($"#{eventData.EventSource?.Name} ID = {eventData.EventId} Name = {eventData.EventName}");
            for (var i = 0; i < eventData.Payload.Count; i++)
            {
                XTrace.WriteLine($"\tName = \"{eventData.PayloadNames[i]}\" Value = \"{eventData.Payload[i]}\"");
            }
#endif

            if (!eventData.Message.IsNullOrEmpty()) log.Write(level, eventData.Message);
        }
    }
}
#endif