// Copyright (c) 2022 - schick Informatik
// bsmd.AIS2Service [AISZoneMonitor.cs]: %UserDisplayName%
// Description: Background Thread Controller class for comparing AIS Targets 
// to monitor zones
// 

using log4net;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Security.Policy;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace bsmd.AIS2Service
{
    internal class AISZoneMonitor : IAISThread
    {

        #region Fields

        private readonly ConcurrentDictionary<int, AIS_Target> _sitRepDict;
        private readonly AIS_SQLiteStorage _storage;
        private Thread _thread;
        private bool _stopFlag = false;
        private static readonly ILog _log = LogManager.GetLogger(typeof(AISZoneMonitor));

        #endregion

        #region Construction

        public AISZoneMonitor(ConcurrentDictionary<int, AIS_Target> sitRepDict, AIS_SQLiteStorage sqliteStorage)
        {
            _sitRepDict = sitRepDict;
            _storage = sqliteStorage;
        }

        #endregion

        #region private methods

        private void Monitor()
        {
            // load zones from storage
            List<MonitorZone> allZones = _storage.LoadMonitorZones();
            Dictionary<int, List<AlarmAssignmentZone>> testDict = new Dictionary<int, List<AlarmAssignmentZone>>();
            // letzte Alarme
            // Dictionary<int, Alarm> currentAlarms = _storage.LoadAlarms();

            foreach(MonitorZone zone in allZones)
            {
                // load up Zone list for all assignment mmsi's (to check)
                foreach(MonitorAssignment ma in zone.Assignments)
                {
                    if(!testDict.ContainsKey(ma.MMSI)) testDict[ma.MMSI] = new List<AlarmAssignmentZone>();
                    ma.Alarms.AddRange(_storage.LoadAlarms(ma));
                    AlarmAssignmentZone aazone = new AlarmAssignmentZone();
                    aazone.Zone = zone;
                    aazone.Assignment = ma;
                    testDict[ma.MMSI].Add(aazone);
                }
            }

            // loop
            while(!_stopFlag)
            {
                // check all "current" AIS Targets against the zones

                foreach(int mmsi in _sitRepDict.Keys)
                {
                    if(testDict.ContainsKey(mmsi))
                    {
                        if (!_sitRepDict.ContainsKey(mmsi)) continue;
                        AIS_Target target = _sitRepDict[mmsi];
                        foreach(AlarmAssignmentZone aazone in testDict[mmsi]) {
                            if(aazone.Zone.IsPointInPolygon4(target.Position))
                            {
                                _log.DebugFormat("{0} is in zone {1}", target.ToString(), aazone.Zone.Name);
                                Alarm alarm;
                                if (aazone.Assignment.Alarms.Count > 0)
                                {
                                    alarm = aazone.Assignment.Alarms[0];
                                    if(alarm.Timestamp_Last.HasValue &&
                                        ((DateTime.Now - alarm.Timestamp_Last.Value).TotalMinutes > Properties.Settings.Default.MinAlarmIntervalMins))
                                    {
                                        // this "old" alarm will be triggered again (overwritten)
                                        alarm.Acknowledged = null;
                                        alarm.Timestamp_Last = null;
                                        alarm.Timestamp_First = DateTime.Now;
                                    }
                                    else
                                    {
                                        // update the last time the target registered in the zone
                                        alarm.Timestamp_Last = DateTime.Now;
                                    }
                                }
                                else
                                {
                                    // create new alarm
                                    alarm = new Alarm(-1, aazone.Assignment);
                                    alarm.Timestamp_First = DateTime.Now;
                                    alarm.ZoneMonitorType = aazone.Assignment.MonitorType;
                                    aazone.Assignment.Alarms.Add(alarm);
                                }
                                _storage.Save(alarm);
                            }
                        }
                    }
                }

                int currentSaturationSecs = 0; // (DateTime.Now - alarm.FirstDetected).TotalSeconds;
                if(currentSaturationSecs > Properties.Settings.Default.MonitorTargetSaturationSecs)
                {
                    // trigger alarm, this thing was "hot" long enough

                }

                Thread.Sleep(Properties.Settings.Default.MonitorTestIntervalSecs * 1000);
            }
        }

        #endregion

        #region IAISThread implementation

        public string Name { get { return "Zone monitor"; } }

        public event EventHandler FatalErrorOccurred;

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

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

        #endregion

        #region class AssignmentZoneAlarm composition

        private class AlarmAssignmentZone
        {
            public MonitorZone Zone { get; set; }
            public MonitorAssignment Assignment { get; set; }
        }

        #endregion

    }
}