//-----------------------------------------------------------------------
//-----------------------------------------------------------------------
//     file="TimeProvider.cs"
//     Project: StgSharp
//     AuthorGroup: Nitload Space
//     Copyright (c) Nitload Space. All rights reserved.
//     
//     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 StgSharp.Timing;

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Threading;

namespace StgSharp
{
    public static partial class StgSharp
    {

        internal static StgSharpTime mainTimeProvider = new StgSharpTime();

        internal static TimeSourceProviderBase MainTimeProvider => mainTimeProvider;

    }

    public sealed class StgSharpTime : TimeSourceProviderBase
    {

        private static List<TimeSpanProvider> subscriberList = new List<TimeSpanProvider>(
            );
        private static long accuracy;
        private static Stopwatch mainProvider = new Stopwatch();
        private static Thread timeProvideThread;

        internal StgSharpTime() { }

        public static TimeSourceProviderBase OnlyInstance => StgSharp.MainTimeProvider;

        public override sealed void StartProvidingTime()
        {
            if( mainProvider.IsRunning ) {
                return;
            }
            mainProvider.Start();

            //speed test
            long totalMS, internalFrequncy = Stopwatch.Frequency;
            for( int i = 0; i < 100; i++ ) {
                totalMS = mainProvider.ElapsedTicks / ( internalFrequncy / ( 1000L * 1000L ) );
                for( int t = 0; t < 10; t++ ) {
                    if( totalMS < 1000 ) {
                        subscriberList.Add(
                            new TimeSpanProvider(
                                100L, TimeSpanProvider.DefaultProvider ) );
                    }
                }
            }
            mainProvider.Stop();
            subscriberList.Clear();
            totalMS = mainProvider.ElapsedTicks / ( internalFrequncy / ( 1000L * 1000L ) ) / 100L;
            accuracy = ( totalMS * 2 ) / 3;
            mainProvider.Reset();
            timeProvideThread = new Thread( new ThreadStart( ProvideTime ) );
            timeProvideThread.Start();
        }

        public override void StopProvidingTime()
        {
            lock( mainProvider ) {
                mainProvider.Stop();
            }
        }

        public void Terminate()
        {
            lock( mainProvider ) {
                mainProvider.Stop();
            }
        }

        protected override sealed void AddSubscriberUnsynced(
            TimeSpanProvider subscriber )
        {
            subscriberList.Add( subscriber );
        }

        protected override sealed void RemoveSubscriberUnsynced(
            TimeSpanProvider subscriber )
        {
            subscriberList.Remove( subscriber );
        }

        private void ProvideTime()
        {
            long totalMS, internalFrequncy = Stopwatch.Frequency;
            lock( mainProvider ) {
                mainProvider.Restart();
            }
            while( mainProvider.IsRunning ) {
                totalMS = mainProvider.ElapsedTicks / ( internalFrequncy / ( 1000L * 1000L ) );
                if( subscriberList.Count == 0 ) {
                    continue;
                }
                CheckSubscriberSemaphore.Wait();
                List<TimeSpanProvider> toRemoveList = new List<TimeSpanProvider>(
                    );
                foreach( TimeSpanProvider subscriber in subscriberList ) {
                    if( !subscriber.CheckTime( totalMS ) ) {
                        toRemoveList.Add( subscriber );
                        InternalIO.InternalWriteLog(
                            $"Time subscriber {subscriber} is to be removed.",
                            LogType.Info );
                    }
                    ;
                }
                if( toRemoveList.Count != 0 ) {
                    foreach( TimeSpanProvider subscriber in toRemoveList ) {
                        subscriberList.Remove( subscriber );
                    }
                }
                CheckSubscriberSemaphore.Release();
            }
        }

    }
}