//
// InterProcess.cs
//
// Author:
//       Carsten Sonne Larsen <cs@innolan.dk>
//
// Copyright (c) 2016 Carsten Sonne Larsen
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
using System;
using Ntp.Analyzer.Log;

#if __MonoCS__
using Mono.Unix;
using Mono.Unix.Native;
#else
using System.Threading;
#endif

namespace Ntp.System
{
    public static class InterProcess
    {
        public enum Signal
        {
            Error = 0,
            Exit,
            Refresh,
            Reload
        }

        #if __MonoCS__
        public static Signal Wait (string name, LogBase log)
        {
            UnixSignal[] signals = new UnixSignal[] {
                new UnixSignal (Signum.SIGTERM),
                new UnixSignal (Signum.SIGQUIT),
                new UnixSignal (Signum.SIGINT),
                new UnixSignal (Signum.SIGHUP),
                new UnixSignal (Signum.SIGUSR1)
            };

            int sig = 0;
            while (true) {
                try {
                    sig = UnixSignal.WaitAny (signals, -1);
                } catch (Exception e) {
                    log.WriteLine ("Error in Signum handling.", Severity.Error);
                    log.WriteLine (e, Severity.Trace);
                    return Signal.Error;
                }

                if (sig >= 0 && sig < signals.Length) {
                    Signum signal = signals [sig].Signum;

                    switch (signal) {
                    case Signum.SIGINT:
                        log.WriteLine ("Interrupted.", Severity.Notice);
                        return Signal.Exit;
                    case Signum.SIGTERM:
                        log.WriteLine ("Received kill signal.", Severity.Notice);
                        return Signal.Exit;
                    case Signum.SIGQUIT:
                        log.WriteLine ("Received quit signal.", Severity.Notice);
                        return Signal.Exit;
                    case Signum.SIGHUP:
                        log.WriteLine ("Received log restart signal.", Severity.Debug);
                        return Signal.Refresh;
                    case Signum.SIGUSR1:
                        log.WriteLine ("Received reload config signal.", Severity.Debug);
                        return Signal.Reload;
                    default:
                        log.WriteLine ("Unknown signal received.", Severity.Warn);
                        break;
                    } 
                } else {
                    log.WriteLine ("Unknown signal received.", Severity.Warn);
                }
            }
        }

        #else

        public static bool Release (string name, LogBase log)
        {
            try {
                EventWaitHandle handle = EventWaitHandle.OpenExisting (name);                                             
                handle.Set ();
                return Signal.Exit;
            } catch (Exception e) {
                log.WriteLine ("Error in mutex handling.", Severity.Error);
                log.WriteLine (e, Severity.Trace);
                return Signal.Error;
            }
        }

        public static Signal Wait (string name, LogBase log)
        {
            try {
                EventWaitHandle handle = new EventWaitHandle (
                                             false, EventResetMode.ManualReset,
                                             name);
                handle.WaitOne ();
                return true;
            } catch (Exception e) {
                log.WriteLine ("Error in mutex handling.", Severity.Error);
                log.WriteLine (e, Severity.Trace);
                return false;
            }
        }

        #endif
    }
}