using log4net;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Threading;

using Microsoft.Owin.Hosting;
using System.Net.Http;

namespace bsmd.AIS2Service
{
    internal static class AISManager
    {

        #region fields

        private static readonly List<IAISThread> _tasks = new List<IAISThread>();
        private static readonly ConcurrentQueue<string> _inputLines = new ConcurrentQueue<string>();
        private static readonly ConcurrentQueue<AISClass> _decodedClasses = new ConcurrentQueue<AISClass>();
        private static readonly ILog _log = LogManager.GetLogger(typeof(AISManager));
        private static readonly ConcurrentDictionary<int, AIS_Target> _sitRepList = new ConcurrentDictionary<int, AIS_Target>();
        private static readonly ConcurrentQueue<AIS_Target> _dbSaveTargets = new ConcurrentQueue<AIS_Target>();
        private static Timer _staleTargetTimer; // cleanup sitrep
        private static Timer _stalePosReportTimer; // clean db
        private static IDisposable _restAPISelfHost = null;

        #endregion

        #region public methods

        public static async void Start()
        {
            _tasks.Add(new SerialTCPReader(Properties.Settings.Default.DataSourceHost, Properties.Settings.Default.DataSourcePort, _inputLines));
            _tasks.Add(new AISDecoder(_inputLines, _decodedClasses));
            _tasks.Add(new SitRep(_decodedClasses, _sitRepList, _dbSaveTargets));
            AIS_SQLiteStorage sqliteStorage = new AIS_SQLiteStorage(_dbSaveTargets);
            _tasks.Add(sqliteStorage);

            // preload sit rep
            Dictionary<int, AIS_Target> targets = await sqliteStorage.LoadTargets();
            foreach(int key in targets.Keys)
            {
                _sitRepList.TryAdd(key, targets[key]);
            }

            foreach (var task in _tasks)
            {
                task.Start();
                _log.InfoFormat("{0} started", task.Name);
                task.FatalErrorOccurred += Task_FatalErrorOccurred;
            }

            // init timer tasks
            _staleTargetTimer = new Timer(StaleTargetTimerCheck, null, 0, 60000); // check every minute, start immediately            
            _stalePosReportTimer = new Timer(StalePosReportCheck, sqliteStorage, 0, 60000 * 10); // every ten minutes, 

            // if required start self-hosted owin endpoint
            if(Properties.Settings.Default.EnableRestAPIEndpoint)
            {
                _restAPISelfHost = WebApp.Start<StartupWebAPI>(url: Properties.Settings.Default.RestAPIBaseAddress);
            }

        }

        public static void Stop()
        {
            foreach (var task in _tasks)
            {
                task.Stop();
                _log.InfoFormat("{0} stopped", task.Name);
            }

            if (Properties.Settings.Default.EnableRestAPIEndpoint && (_restAPISelfHost != null))
                _restAPISelfHost.Dispose();

            _staleTargetTimer.Dispose();
            _stalePosReportTimer.Dispose();
        }

        #endregion

        #region Properties

        public static ConcurrentDictionary<int, AIS_Target> SitRep
        {
            get { return _sitRepList; }
        }

        #endregion

        #region private methods / timer callbacks

        private static void Task_FatalErrorOccurred(object sender, EventArgs e)
        {
            throw new NotImplementedException("TBD: shutdown the whole operation?");
        }

        private static void StaleTargetTimerCheck(object state)
        {
            List<int> removeKeyList = new List<int>();
            foreach (int key in _sitRepList.Keys)
            {
                if (!_sitRepList[key].LastUpdate.HasValue) { removeKeyList.Add(key); }
                else
                {
                    if ((DateTime.Now - _sitRepList[key].LastUpdate.Value).TotalMinutes > Properties.Settings.Default.StaleTargetTimeoutMins)
                        removeKeyList.Add(key);
                }
            }
            foreach(int key in removeKeyList)
            {
                _sitRepList.TryRemove(key, out _);
            }
        }

        private static void StalePosReportCheck(object state)
        {
            if (state is AIS_SQLiteStorage storage)
            {
                storage.RemoveOldPosReports();
            }
        }

        #endregion

    }
}