using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace StackExchange.Redis
{
#if DEBUG
    internal partial class ResultBox
    {
        internal static long allocations;
        public static long GetAllocationCount() => System.Threading.Interlocked.Read(ref allocations);
        static partial void OnAllocated() => System.Threading.Interlocked.Increment(ref allocations);
    }

    public partial interface IServer
    {
        /// <summary>
        /// Break the connection without mercy or thought
        /// </summary>
        void SimulateConnectionFailure();
    }
    

    internal partial class ServerEndPoint
    {
        internal void SimulateConnectionFailure()
        {
            interactive?.SimulateConnectionFailure();
            subscription?.SimulateConnectionFailure();
        }
    }

    internal partial class RedisServer
    {
        void IServer.SimulateConnectionFailure() => server.SimulateConnectionFailure();
    }

    public partial class ConnectionMultiplexer
    {
        /// <summary>
        /// Gets how many result-box instances were allocated
        /// </summary>
        public static long GetResultBoxAllocationCount() => ResultBox.GetAllocationCount();

        private volatile bool allowConnect = true,
                              ignoreConnect = false;

        /// <summary>
        /// For debugging; when not enabled, servers cannot connect
        /// </summary>
        public bool AllowConnect { get { return allowConnect; } set { allowConnect = value; } }

        /// <summary>
        /// For debugging; when not enabled, end-connect is silently ignored (to simulate a long-running connect)
        /// </summary>
        public bool IgnoreConnect { get { return ignoreConnect; } set { ignoreConnect = value; } }
    }

    internal partial class PhysicalBridge
    {
        internal void SimulateConnectionFailure()
        {
            if (!Multiplexer.RawConfig.AllowAdmin)
            {
                throw ExceptionFactory.AdminModeNotEnabled(Multiplexer.IncludeDetailInExceptions, RedisCommand.DEBUG, null, ServerEndPoint); // close enough
            }
            physical?.RecordConnectionFailed(ConnectionFailureType.SocketFailure);
        }
    }

    internal partial class PhysicalConnection
    {
        partial void ShouldIgnoreConnect(ref bool ignore)
        {
            ignore = IgnoreConnect;
        }

        partial void OnDebugAbort()
        {
            if (!Multiplexer.AllowConnect)
            {
                throw new RedisConnectionException(ConnectionFailureType.InternalFailure, "debugging");
            }
        }

        public bool IgnoreConnect => Multiplexer.IgnoreConnect;

        private static volatile bool emulateStaleConnection;
        public static bool EmulateStaleConnection
        {
            get => emulateStaleConnection;
            set => emulateStaleConnection = value;
        }
    }
#endif

    internal static class PerfCounterHelper
    {
        private static readonly object staticLock = new object();
        private static volatile PerformanceCounter _cpu;
        private static volatile bool _disabled = !RuntimeInformation.IsOSPlatform(OSPlatform.Windows);

        public static bool TryGetSystemCPU(out float value)
        {
            value = -1;

            try
            {
                if (!_disabled && _cpu == null)
                {
                    lock (staticLock)
                    {
                        if (_cpu == null)
                        {
                            _cpu = new PerformanceCounter("Processor", "% Processor Time", "_Total");

                            // First call always returns 0, so get that out of the way.
                            _cpu.NextValue();
                        }
                    }
                }
            }
            catch (UnauthorizedAccessException)
            {
                // Some environments don't allow access to Performance Counters, so stop trying.
                _disabled = true;
            }
            catch (Exception e)
            {
                // this shouldn't happen, but just being safe...
                Trace.WriteLine(e);
            }

            if (!_disabled && _cpu != null)
            {
                value = _cpu.NextValue();
                return true;
            }
            return false;
        }
    }

#if VERBOSE

    partial class ConnectionMultiplexer
    {
        private readonly int epoch = Environment.TickCount;

        partial void OnTrace(string message, string category)
        {
            Debug.WriteLine(message,
                ((Environment.TickCount - epoch)).ToString().PadLeft(5, ' ') + "ms on " +
                Environment.CurrentManagedThreadId + " ~ " + category);
        }
        static partial void OnTraceWithoutContext(string message, string category)
        {
            Debug.WriteLine(message, Environment.CurrentManagedThreadId + " ~ " + category);
        }

        partial void OnTraceLog(TextWriter log, string caller)
        {
            lock (UniqueId)
            {
                Trace(log.ToString(), caller); // note that this won't always be useful, but we only do it in debug builds anyway
            }
        }
    }
#endif

#if LOGOUTPUT
    partial class PhysicalConnection
    {
        partial void OnWrapForLogging(ref IDuplexPipe pipe, string name, SocketManager mgr)
        {
            foreach(var c in Path.GetInvalidFileNameChars())
            {
                name = name.Replace(c, '_');
            }
            pipe = new LoggingPipe(pipe, $"{name}.in.resp", $"{name}.out.resp", mgr);
        }
    }
#endif
}
