//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// 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 World
    {

        internal static StgSharpTime mainTimeProvider = new StgSharpTime();

        internal static TimeSourceProviderBase MainTimeProvider => mainTimeProvider;

    }

    public sealed class StgSharpTime : TimeSourceProviderBase
    {

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

        internal StgSharpTime() { }

        public static TimeSourceProviderBase OnlyInstance => World.MainTimeProvider;

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

        protected sealed override 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;
                }
                lock (SubscribeLock)
                {
                    List<TimeSpanProvider> toRemoveList = [];
                    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);
                        }
                    }
                }
            }
        }

    }
}