// Copyright (c) 2022 - schick Informatik
// bsmd.AIS2Service [SitRep.cs]: Daniel Schick
// Description: Current, memory-mapped situation of what the receiver "sees"
// 

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

using log4net;

namespace bsmd.AIS2Service
{

    /// <summary>
    /// Manager / Thread Klasse um die "aktuelle" Situation zu aktualisieren und die Daten
    /// in die (Sqlite-Zwischen-) Datenbank zu schieben
    /// </summary>
    internal class SitRep : IAISThread
    {

        #region Fields

        private Thread _thread;
        private bool _stopFlag = false;
        private static readonly ILog _log = LogManager.GetLogger(typeof(SitRep));
        private readonly ConcurrentQueue<AISClass> _inputQueue;
        private readonly ConcurrentDictionary<int, AIS_Target> _sitRep;
        private readonly Dictionary<int, AIS_BaseStation> _baseStations = new Dictionary<int, AIS_BaseStation>();
        private readonly ConcurrentQueue<AIS_Target> _dbQueue;

        #endregion

        #region Construction

        public SitRep(ConcurrentQueue<AISClass> inputQueue, ConcurrentDictionary<int, AIS_Target> sitRep, ConcurrentQueue<AIS_Target> dbQueue)
        {
            _inputQueue = inputQueue; _sitRep = sitRep; _dbQueue = dbQueue;
        }

        #endregion

        #region Properties

        public Dictionary<int, AIS_BaseStation> BaseStations
        {
            get { return _baseStations; }
        }

        #endregion

        #region mainloop thread

        private void ReadMessages()
        {
            try
            {
                while (!_stopFlag)
                {
                    if(_inputQueue.TryDequeue(out AISClass aisMessage))
                    {
                        switch(aisMessage.MessageType)
                        {
                            case AISClass.AISType.POSITION_REPORT:
                            case AISClass.AISType.POSITION_REPORT_ASSIGNED:
                            case AISClass.AISType.POSITION_REPORT_SPECIAL:
                                {
                                    AIS_PosReport posReport = aisMessage as AIS_PosReport;
                                    if(!_sitRep.ContainsKey(posReport.MMSI))
                                    {
                                        AIS_Target target = new AIS_Target(posReport.MMSI);
                                        _sitRep[posReport.MMSI] = target;
                                    }
                                    DateTime? lastUpdate = _sitRep[posReport.MMSI].LastUpdate;
                                    _sitRep[posReport.MMSI].Update(posReport);
                                    if (!lastUpdate.HasValue ||
                                        ((DateTime.Now - lastUpdate.Value).TotalSeconds > Properties.Settings.Default.PosReportMinTimeDiffSecs))
                                        _dbQueue.Enqueue(_sitRep[posReport.MMSI]);                                        
                                }
                                break;
                            case AISClass.AISType.STATIC_VOYAGE_DATA:
                                {
                                    AIS_StaticData staticData = aisMessage as AIS_StaticData;
                                    if(!_sitRep.ContainsKey(staticData.MMSI))
                                    {
                                        AIS_Target target = new AIS_Target(staticData.MMSI);
                                        _sitRep[staticData.MMSI] = target;
                                    }
                                    _sitRep[staticData.MMSI].Update(staticData);
                                    _dbQueue.Enqueue(_sitRep[staticData.MMSI]);
                                }
                                break;
                                case AISClass.AISType.CLASS_B_STATIC_DATA:
                                {
                                    AIS_ClassBStatic bStaticData = aisMessage as AIS_ClassBStatic;
                                    if(!_sitRep.ContainsKey(bStaticData.MMSI))
                                    {
                                        AIS_Target target = new AIS_Target(bStaticData.MMSI);
                                        _sitRep[bStaticData.MMSI] = target;
                                    }
                                    _sitRep[bStaticData.MMSI].Update(bStaticData);
                                    _dbQueue.Enqueue(_sitRep[bStaticData.MMSI]);
                                }
                                break;
                            case AISClass.AISType.POSITION_REPORT_B_EQUIP:
                                {
                                    AIS_ClassB bPos = aisMessage as AIS_ClassB;
                                    if(!_sitRep.ContainsKey(bPos.MMSI))
                                    {
                                        AIS_Target target = new AIS_Target(bPos.MMSI);
                                        _sitRep[bPos.MMSI] = target;
                                    }
                                    _sitRep[bPos.MMSI].Update(bPos);
                                    _dbQueue.Enqueue(_sitRep[bPos.MMSI]);
                                }
                                break;
                            case AISClass.AISType.POSITION_REPORT_B_EQUIP_EXT:
                                {
                                    AIS_ClassBExt bPosExt = aisMessage as AIS_ClassBExt;
                                    if (!_sitRep.ContainsKey(bPosExt.MMSI))
                                    {
                                        AIS_Target target = new AIS_Target(bPosExt.MMSI);
                                        _sitRep[bPosExt.MMSI] = target;
                                    }
                                    _sitRep[bPosExt.MMSI].Update(bPosExt);
                                    _dbQueue.Enqueue(_sitRep[bPosExt.MMSI]);
                                }
                                break;
                            case AISClass.AISType.BASE_STATION_REPORT:
                                {
                                    AIS_BaseStationReport bsr = aisMessage as AIS_BaseStationReport;
                                    if(!_baseStations.ContainsKey(bsr.MMSI))
                                    {
                                        AIS_BaseStation baseStation = new AIS_BaseStation(bsr.MMSI);
                                        _baseStations[bsr.MMSI] = baseStation;
                                    }
                                    _baseStations[bsr.MMSI].Update(bsr);
                                }
                                break;
                            default:
                                _log.InfoFormat("currently discarding AIS message {0}", aisMessage.MessageType);
                                break;
                        }
                    }
                    else
                    {
                        Thread.Sleep(Properties.Settings.Default.ThreadSleepMS);                        
                    }
                }
            }

            catch (Exception ex)
            {
                _log.ErrorFormat("Something bad has happened: {0}", ex.Message);
                this.FatalErrorOccurred?.Invoke(this, new EventArgs());
            }
        }

        #endregion

        #region IAISThread implementation

        public string Name { get { return "Sit rep"; } }

        public event EventHandler FatalErrorOccurred;

        public void Start()
        {
            if (_thread != null) return; // may not run twice
            ThreadStart runReader = new ThreadStart(this.ReadMessages);
            _thread = new Thread(runReader);
            _thread.Start();
        }

        public void Stop()
        {
            if (_thread == null) return;
            _stopFlag = true;
            _thread.Join();
            _thread = null;
        }

        #endregion

    }
}