namespace GMap.NET.Internals
{
   using System;
   using System.Collections.Generic;
   using System.Diagnostics;
   using System.Threading;
   using GMap.NET.Projections;
   using System.IO;
   using GMap.NET.MapProviders;
   using System.ComponentModel;

#if PocketPC
   using OpenNETCF.ComponentModel;
   using OpenNETCF.Threading;
   using Thread=OpenNETCF.Threading.Thread2;
#endif

   /// <summary>
   /// internal map control core
   /// </summary>
   internal class Core : IDisposable
   {
      public PointLatLng position;
      public GPoint positionPixel;

      public GPoint renderOffset;
      public GPoint centerTileXYLocation;
      public GPoint centerTileXYLocationLast;
      public GPoint dragPoint;
      public GPoint compensationOffset;

      public GPoint mouseDown;
      public GPoint mouseCurrent;
      public GPoint mouseLastZoom;

      public MouseWheelZoomType MouseWheelZoomType = MouseWheelZoomType.MousePositionAndCenter;

      public PointLatLng? LastLocationInBounds = null;
      public bool VirtualSizeEnabled = false;

      public GSize sizeOfMapArea;
      public GSize minOfTiles;
      public GSize maxOfTiles;

      public GRect tileRect;
      public GRect tileRectBearing;
      //public GRect currentRegion;
      public float bearing = 0;
      public bool IsRotated = false;

      public bool fillEmptyTiles = true;

      public TileMatrix Matrix = new TileMatrix();

      public List<DrawTile> tileDrawingList = new List<DrawTile>();
      public FastReaderWriterLock tileDrawingListLock = new FastReaderWriterLock();

      public readonly Stack<LoadTask> tileLoadQueue = new Stack<LoadTask>();

#if !PocketPC
      static readonly int GThreadPoolSize = 5;
#else
      static readonly int GThreadPoolSize = 2;
#endif

      DateTime LastTileLoadStart = DateTime.Now;
      DateTime LastTileLoadEnd = DateTime.Now;
      internal volatile bool IsStarted = false;
      int zoom;

      internal double scaleX = 1;
      internal double scaleY = 1;

      internal int maxZoom = 2;
      internal int minZoom = 2;
      internal int Width;
      internal int Height;

      internal int pxRes100m;  // 100 meters
      internal int pxRes1000m;  // 1km  
      internal int pxRes10km; // 10km
      internal int pxRes100km; // 100km
      internal int pxRes1000km; // 1000km
      internal int pxRes5000km; // 5000km

      /// <summary>
      /// is user dragging map
      /// </summary>
      public bool IsDragging = false;

      public Core()
      {
         Provider = EmptyProvider.Instance;
      }

      /// <summary>
      /// map zoom
      /// </summary>
      public int Zoom
      {
         get
         {
            return zoom;
         }
         set
         {
            if(zoom != value && !IsDragging)
            {
               zoom = value;

               minOfTiles = Provider.Projection.GetTileMatrixMinXY(value);
               maxOfTiles = Provider.Projection.GetTileMatrixMaxXY(value);

               positionPixel = Provider.Projection.FromLatLngToPixel(Position, value);

               if(IsStarted)
               {
                  Monitor.Enter(tileLoadQueue);
                  try
                  {
                     tileLoadQueue.Clear();
                  }
                  finally
                  {
                     Monitor.Exit(tileLoadQueue);
                  }

                  Matrix.ClearLevelsBelove(zoom - LevelsKeepInMemmory);
                  Matrix.ClearLevelsAbove(zoom + LevelsKeepInMemmory);

                  lock(FailedLoads)
                  {
                     FailedLoads.Clear();
                     RaiseEmptyTileError = true;
                  }

                  GoToCurrentPositionOnZoom();
                  UpdateBounds();

                  if(OnMapZoomChanged != null)
                  {
                     OnMapZoomChanged();
                  }
               }
            }
         }
      }

      /// <summary>
      /// current marker position in pixel coordinates
      /// </summary>
      public GPoint PositionPixel
      {
         get
         {
            return positionPixel;
         }
      }

      /// <summary>
      /// current marker position
      /// </summary>
      public PointLatLng Position
      {
         get
         {

            return position;
         }
         set
         {
            position = value;
            positionPixel = Provider.Projection.FromLatLngToPixel(value, Zoom);

            if(IsStarted)
            {
               if(!IsDragging)
               {
                  GoToCurrentPosition();
               }

               if(OnCurrentPositionChanged != null)
                  OnCurrentPositionChanged(position);
            }
         }
      }

      public GMapProvider provider;
      public GMapProvider Provider
      {
         get
         {
            return provider;
         }
         set
         {
            if(provider == null || !provider.Equals(value))
            {
               provider = value;

               if(!provider.IsInitialized)
               {
                  provider.IsInitialized = true;
                  provider.OnInitialized();
               }

               if(Provider.Projection != null)
               {
                  tileRect = new GRect(GPoint.Empty, Provider.Projection.TileSize);
                  tileRectBearing = tileRect;
                  if(IsRotated)
                  {
                     tileRectBearing.Inflate(1, 1);
                  }

                  minOfTiles = Provider.Projection.GetTileMatrixMinXY(Zoom);
                  maxOfTiles = Provider.Projection.GetTileMatrixMaxXY(Zoom);
                  positionPixel = Provider.Projection.FromLatLngToPixel(Position, Zoom);
               }

               if(IsStarted)
               {
                  CancelAsyncTasks();
                  OnMapSizeChanged(Width, Height);
                  ReloadMap();

                  if(minZoom < provider.MinZoom)
                  {
                     minZoom = provider.MinZoom;
                  }

                  //if(provider.MaxZoom.HasValue && maxZoom > provider.MaxZoom)
                  //{
                  //   maxZoom = provider.MaxZoom.Value;
                  //}

                  zoomToArea = true;

                  if(provider.Area.HasValue && !provider.Area.Value.Contains(Position))
                  {
                     SetZoomToFitRect(provider.Area.Value);
                     zoomToArea = false;
                  }

                  if(OnMapTypeChanged != null)
                  {
                     OnMapTypeChanged(value);
                  }
               }
            }
         }
      }

      internal bool zoomToArea = true;

      /// <summary>
      /// sets zoom to max to fit rect
      /// </summary>
      /// <param name="rect"></param>
      /// <returns></returns>
      public bool SetZoomToFitRect(RectLatLng rect)
      {
         int mmaxZoom = GetMaxZoomToFitRect(rect);
         if(mmaxZoom > 0)
         {
            PointLatLng center = new PointLatLng(rect.Lat - (rect.HeightLat / 2), rect.Lng + (rect.WidthLng / 2));
            Position = center;

            if(mmaxZoom > maxZoom)
            {
               mmaxZoom = maxZoom;
            }

            if(Zoom != mmaxZoom)
            {
               Zoom = (int)mmaxZoom;
            }

            return true;
         }
         return false;
      }

      /// <summary>
      /// is polygons enabled
      /// </summary>
      public bool PolygonsEnabled = true;

      /// <summary>
      /// is routes enabled
      /// </summary>
      public bool RoutesEnabled = true;

      /// <summary>
      /// is markers enabled
      /// </summary>
      public bool MarkersEnabled = true;

      /// <summary>
      /// can user drag map
      /// </summary>
      public bool CanDragMap = true;

      /// <summary>
      /// retry count to get tile 
      /// </summary>
#if !PocketPC
      public int RetryLoadTile = 0;
#else
      public int RetryLoadTile = 1;
#endif

      /// <summary>
      /// how many levels of tiles are staying decompresed in memory
      /// </summary>
#if !PocketPC
      public int LevelsKeepInMemmory = 5;
#else
      public int LevelsKeepInMemmory = 1;
#endif

      /// <summary>
      /// map render mode
      /// </summary>
      public RenderMode RenderMode = RenderMode.GDI_PLUS;

      /// <summary>
      /// occurs when current position is changed
      /// </summary>
      public event PositionChanged OnCurrentPositionChanged;

      /// <summary>
      /// occurs when tile set load is complete
      /// </summary>
      public event TileLoadComplete OnTileLoadComplete;

      /// <summary>
      /// occurs when tile set is starting to load
      /// </summary>
      public event TileLoadStart OnTileLoadStart;

      /// <summary>
      /// occurs on empty tile displayed
      /// </summary>
      public event EmptyTileError OnEmptyTileError;

      /// <summary>
      /// occurs on map drag
      /// </summary>
      public event MapDrag OnMapDrag;

      /// <summary>
      /// occurs on map zoom changed
      /// </summary>
      public event MapZoomChanged OnMapZoomChanged;

      /// <summary>
      /// occurs on map type changed
      /// </summary>
      public event MapTypeChanged OnMapTypeChanged;

      readonly List<Thread> GThreadPool = new List<Thread>();
      // ^
      // should be only one pool for multiply controls, any ideas how to fix?
      //static readonly List<Thread> GThreadPool = new List<Thread>();

      // windows forms or wpf
      internal string SystemType;

      internal static int instances = 0;

      BackgroundWorker invalidator;

      public BackgroundWorker OnMapOpen()
      {
         if(!IsStarted)
         {
            int x = Interlocked.Increment(ref instances);
            Debug.WriteLine("OnMapOpen: " + x);

            IsStarted = true;

            if(x == 1)
            {
               GMaps.Instance.noMapInstances = false;
            }

            GoToCurrentPosition();

            invalidator = new BackgroundWorker();
            invalidator.WorkerSupportsCancellation = true;
            invalidator.WorkerReportsProgress = true;
            invalidator.DoWork += new DoWorkEventHandler(invalidatorWatch);
            invalidator.RunWorkerAsync();

            //if(x == 1)
            //{
            // first control shown
            //}
         }
         return invalidator;
      }

      public void OnMapClose()
      {
         Dispose();
      }

      internal readonly object invalidationLock = new object();
      internal DateTime lastInvalidation = DateTime.Now;

      void invalidatorWatch(object sender, DoWorkEventArgs e)
      {
         var w = sender as BackgroundWorker;

         TimeSpan span = TimeSpan.FromMilliseconds(111);
         int spanMs = (int)span.TotalMilliseconds;
         bool skiped = false;
         TimeSpan delta;
         DateTime now = DateTime.Now;

         while(Refresh != null && (!skiped && Refresh.WaitOne() || (Refresh.WaitOne(spanMs, false) || true)))
         {
            if(w.CancellationPending)
               break;

            now = DateTime.Now;
            lock(invalidationLock)
            {
               delta = now - lastInvalidation;
            }

            if(delta > span)
            {
               lock(invalidationLock)
               {
                  lastInvalidation = now;
               }
               skiped = false;

               w.ReportProgress(1);
               Debug.WriteLine("Invalidate delta: " + (int)delta.TotalMilliseconds + "ms");
            }
            else
            {
               skiped = true;
            }
         }
      }

      public void UpdateCenterTileXYLocation()
      {
         PointLatLng center = FromLocalToLatLng(Width / 2, Height / 2);
         GPoint centerPixel = Provider.Projection.FromLatLngToPixel(center, Zoom);
         centerTileXYLocation = Provider.Projection.FromPixelToTileXY(centerPixel);
      }

      public int vWidth = 800;
      public int vHeight = 400;

      public void OnMapSizeChanged(int width, int height)
      {
         this.Width = width;
         this.Height = height;

         if(IsRotated)
         {
#if !PocketPC
            int diag = (int)Math.Round(Math.Sqrt(Width * Width + Height * Height) / Provider.Projection.TileSize.Width, MidpointRounding.AwayFromZero);
#else
            int diag = (int) Math.Round(Math.Sqrt(Width * Width + Height * Height) / Provider.Projection.TileSize.Width);
#endif
            sizeOfMapArea.Width = 1 + (diag / 2);
            sizeOfMapArea.Height = 1 + (diag / 2);
         }
         else
         {
            sizeOfMapArea.Width = 1 + (Width / Provider.Projection.TileSize.Width) / 2;
            sizeOfMapArea.Height = 1 + (Height / Provider.Projection.TileSize.Height) / 2;
         }

         Debug.WriteLine("OnMapSizeChanged, w: " + width + ", h: " + height + ", size: " + sizeOfMapArea);

         if(IsStarted)
         {
            UpdateBounds();
            GoToCurrentPosition();
         }
      }

      /// <summary>
      /// gets current map view top/left coordinate, width in Lng, height in Lat
      /// </summary>
      /// <returns></returns>
      public RectLatLng ViewArea
      {
         get
         {
            if(Provider.Projection != null)
            {
               var p = FromLocalToLatLng(0, 0);
               var p2 = FromLocalToLatLng(Width, Height);

               return RectLatLng.FromLTRB(p.Lng, p.Lat, p2.Lng, p2.Lat);
            }
            return RectLatLng.Empty;
         }
      }

      /// <summary>
      /// gets lat/lng from local control coordinates
      /// </summary>
      /// <param name="x"></param>
      /// <param name="y"></param>
      /// <returns></returns>
      public PointLatLng FromLocalToLatLng(long x, long y)
      {
         GPoint p = new GPoint(x, y);
         p.OffsetNegative(renderOffset);
         p.Offset(compensationOffset);

         return Provider.Projection.FromPixelToLatLng(p, Zoom);
      }

      /// <summary>
      /// return local coordinates from lat/lng
      /// </summary>
      /// <param name="latlng"></param>
      /// <returns></returns>
      public GPoint FromLatLngToLocal(PointLatLng latlng)
      {
         GPoint pLocal = Provider.Projection.FromLatLngToPixel(latlng, Zoom);
         pLocal.Offset(renderOffset);
         pLocal.OffsetNegative(compensationOffset);
         return pLocal;
      }

      /// <summary>
      /// gets max zoom level to fit rectangle
      /// </summary>
      /// <param name="rect"></param>
      /// <returns></returns>
      public int GetMaxZoomToFitRect(RectLatLng rect)
      {
         int zoom = minZoom;

         if(rect.HeightLat == 0 || rect.WidthLng == 0)
         {
            zoom = maxZoom / 2;
         }
         else
         {
            for(int i = (int)zoom; i <= maxZoom; i++)
            {
               GPoint p1 = Provider.Projection.FromLatLngToPixel(rect.LocationTopLeft, i);
               GPoint p2 = Provider.Projection.FromLatLngToPixel(rect.LocationRightBottom, i);

               if(((p2.X - p1.X) <= Width + 10) && (p2.Y - p1.Y) <= Height + 10)
               {
                  zoom = i;
               }
               else
               {
                  break;
               }
            }
         }

         return zoom;
      }

      /// <summary>
      /// initiates map dragging
      /// </summary>
      /// <param name="pt"></param>
      public void BeginDrag(GPoint pt)
      {
         dragPoint.X = pt.X - renderOffset.X;
         dragPoint.Y = pt.Y - renderOffset.Y;
         IsDragging = true;
      }

      /// <summary>
      /// ends map dragging
      /// </summary>
      public void EndDrag()
      {
         IsDragging = false;
         mouseDown = GPoint.Empty;

         Refresh.Set();
      }

      /// <summary>
      /// reloads map
      /// </summary>
      public void ReloadMap()
      {
         if(IsStarted)
         {
            Debug.WriteLine("------------------");

            okZoom = 0;
            skipOverZoom = 0;

            Monitor.Enter(tileLoadQueue);
            try
            {
               tileLoadQueue.Clear();
            }
            finally
            {
               Monitor.Exit(tileLoadQueue);
            }

            Matrix.ClearAllLevels();

            lock(FailedLoads)
            {
               FailedLoads.Clear();
               RaiseEmptyTileError = true;
            }

            Refresh.Set();

            UpdateBounds();
         }
         else
         {
            throw new Exception("Please, do not call ReloadMap before form is loaded, it's useless");
         }
      }

      /// <summary>
      /// moves current position into map center
      /// </summary>
      public void GoToCurrentPosition()
      {
         compensationOffset = positionPixel; // TODO: fix

         // reset stuff
         renderOffset = GPoint.Empty;
         dragPoint = GPoint.Empty;

         //var dd = new GPoint(-(CurrentPositionGPixel.X - Width / 2), -(CurrentPositionGPixel.Y - Height / 2));
         //dd.Offset(compensationOffset);

         var d = new GPoint(Width / 2, Height / 2);

         this.Drag(d);
      }

      public bool MouseWheelZooming = false;

      /// <summary>
      /// moves current position into map center
      /// </summary>
      internal void GoToCurrentPositionOnZoom()
      {
         compensationOffset = positionPixel; // TODO: fix

         // reset stuff
         renderOffset = GPoint.Empty;
         dragPoint = GPoint.Empty;

         // goto location and centering
         if(MouseWheelZooming)
         {
            if(MouseWheelZoomType != MouseWheelZoomType.MousePositionWithoutCenter)
            {
               GPoint pt = new GPoint(-(positionPixel.X - Width / 2), -(positionPixel.Y - Height / 2));
               pt.Offset(compensationOffset);
               renderOffset.X = pt.X - dragPoint.X;
               renderOffset.Y = pt.Y - dragPoint.Y;
            }
            else // without centering
            {
               renderOffset.X = -positionPixel.X - dragPoint.X;
               renderOffset.Y = -positionPixel.Y - dragPoint.Y;
               renderOffset.Offset(mouseLastZoom);
               renderOffset.Offset(compensationOffset);
            }
         }
         else // use current map center
         {
            mouseLastZoom = GPoint.Empty;

            GPoint pt = new GPoint(-(positionPixel.X - Width / 2), -(positionPixel.Y - Height / 2));
            pt.Offset(compensationOffset);
            renderOffset.X = pt.X - dragPoint.X;
            renderOffset.Y = pt.Y - dragPoint.Y;
         }

         UpdateCenterTileXYLocation();
      }

      /// <summary>
      /// darg map by offset in pixels
      /// </summary>
      /// <param name="offset"></param>
      public void DragOffset(GPoint offset)
      {
         renderOffset.Offset(offset);

         UpdateCenterTileXYLocation();

         if(centerTileXYLocation != centerTileXYLocationLast)
         {
            centerTileXYLocationLast = centerTileXYLocation;
            UpdateBounds();
         }

         {
            LastLocationInBounds = Position;

            IsDragging = true;
            Position = FromLocalToLatLng((int)Width / 2, (int)Height / 2);
            IsDragging = false;
         }

         if(OnMapDrag != null)
         {
            OnMapDrag();
         }
      }

      /// <summary>
      /// drag map
      /// </summary>
      /// <param name="pt"></param>
      public void Drag(GPoint pt)
      {
         renderOffset.X = pt.X - dragPoint.X;
         renderOffset.Y = pt.Y - dragPoint.Y;

         UpdateCenterTileXYLocation();

         if(centerTileXYLocation != centerTileXYLocationLast)
         {
            centerTileXYLocationLast = centerTileXYLocation;
            UpdateBounds();
         }

         if(IsDragging)
         {
            LastLocationInBounds = Position;
            Position = FromLocalToLatLng((int)Width / 2, (int)Height / 2);

            if(OnMapDrag != null)
            {
               OnMapDrag();
            }
         }
      }

      /// <summary>
      /// cancels tile loaders and bounds checker
      /// </summary>
      public void CancelAsyncTasks()
      {
         if(IsStarted)
         {
            Monitor.Enter(tileLoadQueue);
            try
            {
               tileLoadQueue.Clear();
            }
            finally
            {
               Monitor.Exit(tileLoadQueue);
            }
         }
      }

      bool RaiseEmptyTileError = false;
      internal Dictionary<LoadTask, Exception> FailedLoads = new Dictionary<LoadTask, Exception>();

      internal static readonly int WaitForTileLoadThreadTimeout = 5 * 1000 * 60; // 5 min.

      byte loadWaitCount = 0;
      volatile int okZoom = 0;
      volatile int skipOverZoom = 0;

      // tile consumer thread
      void ProcessLoadTask()
      {
         LoadTask? task = null;
         long lastTileLoadTimeMs;
         bool stop = false;

#if !PocketPC
         Thread ct = Thread.CurrentThread;
         string ctid = "Thread[" + ct.ManagedThreadId + "]";
#else
         int ctid = 0;
#endif
         while(!stop && IsStarted)
         {
            task = null;

            Monitor.Enter(tileLoadQueue);
            try
            {
               while(tileLoadQueue.Count == 0)
               {
                  Debug.WriteLine(ctid + " - Wait " + loadWaitCount + " - " + DateTime.Now.TimeOfDay);

                  if(++loadWaitCount >= GThreadPoolSize)
                  {
                     loadWaitCount = 0;

                     #region -- last thread takes action --

                     {
                        LastTileLoadEnd = DateTime.Now;
                        lastTileLoadTimeMs = (long)(LastTileLoadEnd - LastTileLoadStart).TotalMilliseconds;
                     }

                     #region -- clear stuff--
                     if(IsStarted)
                     {
                        GMaps.Instance.MemoryCache.RemoveOverload();

                        tileDrawingListLock.AcquireReaderLock();
                        try
                        {
                           Matrix.ClearLevelAndPointsNotIn(Zoom, tileDrawingList);
                        }
                        finally
                        {
                           tileDrawingListLock.ReleaseReaderLock();
                        }
                     }
                     #endregion

                     UpdateGroundResolution();
#if UseGC
                     GC.Collect();
                     GC.WaitForPendingFinalizers();
                     GC.Collect();
#endif

                     Debug.WriteLine(ctid + " - OnTileLoadComplete: " + lastTileLoadTimeMs + "ms, MemoryCacheSize: " + GMaps.Instance.MemoryCache.Size + "MB");

                     if(OnTileLoadComplete != null)
                     {
                        OnTileLoadComplete(lastTileLoadTimeMs);
                     }
                     #endregion
                  }

                  if(!IsStarted || false == Monitor.Wait(tileLoadQueue, WaitForTileLoadThreadTimeout, false) || !IsStarted)
                  {
                     stop = true;
                     break;
                  }
               }

               if(IsStarted && !stop || tileLoadQueue.Count > 0)
               {
                  task = tileLoadQueue.Pop();
               }
            }
            finally
            {
               Monitor.Exit(tileLoadQueue);
            }

            if(task.HasValue && IsStarted)
            {
               try
               {
                  #region -- execute --

                  var m = Matrix.GetTileWithReadLock(task.Value.Zoom, task.Value.Pos);
                  if(!m.NotEmpty)
                  {
                     Debug.WriteLine(ctid + " - try load: " + task);

                     Tile t = new Tile(task.Value.Zoom, task.Value.Pos);

                     foreach(var tl in provider.Overlays)
                     {
                        int retry = 0;
                        do
                        {
                           PureImage img = null;
                           Exception ex = null;

                           if(!provider.MaxZoom.HasValue || task.Value.Zoom <= provider.MaxZoom)
                           {
                              if(skipOverZoom == 0 || task.Value.Zoom <= skipOverZoom)
                              {
                                 // tile number inversion(BottomLeft -> TopLeft)
                                 if(tl.InvertedAxisY)
                                 {
                                    img = GMaps.Instance.GetImageFrom(tl, new GPoint(task.Value.Pos.X, maxOfTiles.Height - task.Value.Pos.Y), task.Value.Zoom, out ex);
                                 }
                                 else // ok
                                 {
                                    img = GMaps.Instance.GetImageFrom(tl, task.Value.Pos, task.Value.Zoom, out ex);
                                 }
                              }
                           }

                           if(img != null && ex == null)
                           {
                              if(okZoom < task.Value.Zoom)
                              {
                                 okZoom = task.Value.Zoom;
                                 skipOverZoom = 0;
                                 Debug.WriteLine("skipOverZoom disabled, okZoom: " + okZoom);
                              }
                           }
                           else if(ex != null)
                           {
                              if(skipOverZoom != okZoom)
                              {
                                 if(ex.Message.Contains("(404) Not Found"))
                                 {
                                    skipOverZoom = okZoom;
                                    Debug.WriteLine("skipOverZoom enabled: " + skipOverZoom);
                                 }
                              }
                           }

                           // check for parent tiles if not found
                           if(img == null && okZoom > 0 && fillEmptyTiles && Provider.Projection is MercatorProjection)
                           {
                              int zoomOffset = task.Value.Zoom > okZoom ? task.Value.Zoom - okZoom : 1;
                              long Ix = 0;
                              GPoint parentTile = GPoint.Empty;

                              while(img == null && zoomOffset < task.Value.Zoom)
                              {
                                 Ix = (long)Math.Pow(2, zoomOffset);
                                 parentTile = new GMap.NET.GPoint((task.Value.Pos.X / Ix), (task.Value.Pos.Y / Ix));
                                 img = GMaps.Instance.GetImageFrom(tl, parentTile, task.Value.Zoom - zoomOffset++, out ex);
                              }

                              if(img != null)
                              {
                                 // offsets in quadrant
                                 long Xoff = Math.Abs(task.Value.Pos.X - (parentTile.X * Ix));
                                 long Yoff = Math.Abs(task.Value.Pos.Y - (parentTile.Y * Ix));

                                 img.IsParent = true;
                                 img.Ix = Ix;
                                 img.Xoff = Xoff;
                                 img.Yoff = Yoff;

                                 // wpf
                                 //var geometry = new RectangleGeometry(new Rect(Core.tileRect.X + 0.6, Core.tileRect.Y + 0.6, Core.tileRect.Width + 0.6, Core.tileRect.Height + 0.6));
                                 //var parentImgRect = new Rect(Core.tileRect.X - Core.tileRect.Width * Xoff + 0.6, Core.tileRect.Y - Core.tileRect.Height * Yoff + 0.6, Core.tileRect.Width * Ix + 0.6, Core.tileRect.Height * Ix + 0.6);

                                 // gdi+
                                 //System.Drawing.Rectangle dst = new System.Drawing.Rectangle((int)Core.tileRect.X, (int)Core.tileRect.Y, (int)Core.tileRect.Width, (int)Core.tileRect.Height);
                                 //System.Drawing.RectangleF srcRect = new System.Drawing.RectangleF((float)(Xoff * (img.Img.Width / Ix)), (float)(Yoff * (img.Img.Height / Ix)), (img.Img.Width / Ix), (img.Img.Height / Ix));
                              }
                           }

                           if(img != null)
                           {
                              Debug.WriteLine(ctid + " - tile loaded: " + img.Data.Length / 1024 + "KB, " + task);
                              {
                                 t.AddOverlay(img);
                              }
                              break;
                           }
                           else
                           {
                              if(ex != null)
                              {
                                 lock(FailedLoads)
                                 {
                                    if(!FailedLoads.ContainsKey(task.Value))
                                    {
                                       FailedLoads.Add(task.Value, ex);

                                       if(OnEmptyTileError != null)
                                       {
                                          if(!RaiseEmptyTileError)
                                          {
                                             RaiseEmptyTileError = true;
                                             OnEmptyTileError(task.Value.Zoom, task.Value.Pos);
                                          }
                                       }
                                    }
                                 }
                              }

                              if(RetryLoadTile > 0)
                              {
                                 Debug.WriteLine(ctid + " - ProcessLoadTask: " + task + " -> empty tile, retry " + retry);
                                 {
                                    Thread.Sleep(1111);
                                 }
                              }
                           }
                        }
                        while(++retry < RetryLoadTile);
                     }

                     if(t.HasAnyOverlays && IsStarted)
                     {
                        Matrix.SetTile(t);
                     }
                     else
                     {
                        t.Dispose();
                     }
                  }

                  #endregion
               }
               catch(Exception ex)
               {
                  Debug.WriteLine(ctid + " - ProcessLoadTask: " + ex.ToString());
               }
               finally
               {
                  if(Refresh != null)
                  {
                     Refresh.Set();
                  }
               }
            }
         }

#if !PocketPC
         Monitor.Enter(tileLoadQueue);
         try
         {
            Debug.WriteLine("Quit - " + ct.Name);
            lock(GThreadPool)
            {
               GThreadPool.Remove(ct);
            }
         }
         finally
         {
            Monitor.Exit(tileLoadQueue);
         }
#endif
      }

      public AutoResetEvent Refresh = new AutoResetEvent(false);

      public bool updatingBounds = false;

      /// <summary>
      /// updates map bounds
      /// </summary>
      void UpdateBounds()
      {
         if(!IsStarted || Provider.Equals(EmptyProvider.Instance))
         {
            return;
         }

         updatingBounds = true;

         tileDrawingListLock.AcquireWriterLock();
         try
         {
            #region -- find tiles around --
            tileDrawingList.Clear();

            for(long i = (int)Math.Floor(-sizeOfMapArea.Width * scaleX), countI = (int)Math.Ceiling(sizeOfMapArea.Width * scaleX); i <= countI; i++)
            {
               for (long j = (int)Math.Floor(-sizeOfMapArea.Height * scaleY), countJ = (int)Math.Ceiling(sizeOfMapArea.Height * scaleY); j <= countJ; j++)
               {
                  GPoint p = centerTileXYLocation;
                  p.X += i;
                  p.Y += j;

#if ContinuesMap
               // ----------------------------
               if(p.X < minOfTiles.Width)
               {
                  p.X += (maxOfTiles.Width + 1);
               }

               if(p.X > maxOfTiles.Width)
               {
                  p.X -= (maxOfTiles.Width + 1);
               }
               // ----------------------------
#endif

                  if(p.X >= minOfTiles.Width && p.Y >= minOfTiles.Height && p.X <= maxOfTiles.Width && p.Y <= maxOfTiles.Height)
                  {
                     DrawTile dt = new DrawTile()
                     {
                        PosXY = p,
                        PosPixel = new GPoint(p.X * tileRect.Width, p.Y * tileRect.Height),
                        DistanceSqr = (centerTileXYLocation.X - p.X) * (centerTileXYLocation.X - p.X) + (centerTileXYLocation.Y - p.Y) * (centerTileXYLocation.Y - p.Y)
                     };

                     if(!tileDrawingList.Contains(dt))
                     {
                        tileDrawingList.Add(dt);
                     }
                  }
               }
            }

            if(GMaps.Instance.ShuffleTilesOnLoad)
            {
               Stuff.Shuffle<DrawTile>(tileDrawingList);
            }
            else
            {
               tileDrawingList.Sort();
            }
            #endregion
         }
         finally
         {
            tileDrawingListLock.ReleaseWriterLock();
         }

         Monitor.Enter(tileLoadQueue);
         try
         {
            tileDrawingListLock.AcquireReaderLock();
            try
            {
               foreach(DrawTile p in tileDrawingList)
               {
                  LoadTask task = new LoadTask(p.PosXY, Zoom);
                  {
                     if(!tileLoadQueue.Contains(task))
                     {
                        tileLoadQueue.Push(task);
                     }
                  }
               }
            }
            finally
            {
               tileDrawingListLock.ReleaseReaderLock();
            }

            #region -- starts loader threads if needed --

            lock(GThreadPool)
            {
               while(GThreadPool.Count < GThreadPoolSize)
               {
                  Thread t = new Thread(new ThreadStart(ProcessLoadTask));
                  {
                     t.Name = "TileLoader: " + GThreadPool.Count;
                     t.IsBackground = true;
                     t.Priority = ThreadPriority.BelowNormal;
                  }
                  GThreadPool.Add(t);

                  Debug.WriteLine("add " + t.Name + " to GThreadPool");

                  t.Start();
               }
            }
            #endregion

            {
               LastTileLoadStart = DateTime.Now;
               Debug.WriteLine("OnTileLoadStart - at zoom " + Zoom + ", time: " + LastTileLoadStart.TimeOfDay);
            }

            loadWaitCount = 0;
            Monitor.PulseAll(tileLoadQueue);
         }
         finally
         {
            Monitor.Exit(tileLoadQueue);
         }

         updatingBounds = false;

         if(OnTileLoadStart != null)
         {
            OnTileLoadStart();
         }
      }

      /// <summary>
      /// updates ground resolution info
      /// </summary>
      void UpdateGroundResolution()
      {
         double rez = Provider.Projection.GetGroundResolution(Zoom, Position.Lat);
         pxRes100m = (int)(100.0 / rez); // 100 meters
         pxRes1000m = (int)(1000.0 / rez); // 1km  
         pxRes10km = (int)(10000.0 / rez); // 10km
         pxRes100km = (int)(100000.0 / rez); // 100km
         pxRes1000km = (int)(1000000.0 / rez); // 1000km
         pxRes5000km = (int)(5000000.0 / rez); // 5000km
      }

      #region IDisposable Members

      ~Core()
      {
         Dispose(false);
      }

      void Dispose(bool disposing)
      {
         if(IsStarted)
         {
            if(invalidator != null)
            {
               invalidator.CancelAsync();
               invalidator.DoWork -= new DoWorkEventHandler(invalidatorWatch);
               invalidator.Dispose();
               invalidator = null;
            }

            if(Refresh != null)
            {
               Refresh.Set();
               Refresh.Close();
               Refresh = null;
            }

            int x = Interlocked.Decrement(ref instances);
            Debug.WriteLine("OnMapClose: " + x);

            CancelAsyncTasks();
            IsStarted = false;

            if(Matrix != null)
            {
               Matrix.Dispose();
               Matrix = null;
            }

            if(FailedLoads != null)
            {
               lock(FailedLoads)
               {
                  FailedLoads.Clear();
                  RaiseEmptyTileError = false;
               }
               FailedLoads = null;
            }

            // cancel waiting loaders
            Monitor.Enter(tileLoadQueue);
            try
            {
               Monitor.PulseAll(tileLoadQueue);
               tileDrawingList.Clear();
            }
            finally
            {
               Monitor.Exit(tileLoadQueue);
            }

            lock(GThreadPool)
            {
#if PocketPC
                Debug.WriteLine("waiting until loaders are stopped...");
                while(GThreadPool.Count > 0)
                {
                    var t = GThreadPool[0];

                    if (t.State != ThreadState.Stopped)
                    {
                        var tr = t.Join(1111);

                        Debug.WriteLine(t.Name + ", " + t.State);

                        if (!tr)
                        {
                            continue;
                        }
                        else
                        {
                            GThreadPool.Remove(t);
                        }
                    }
                    else
                    {
                        GThreadPool.Remove(t);
                    }
                }
                Thread.Sleep(1111);
#endif
            }

            if(tileDrawingListLock != null)
            {
               tileDrawingListLock.Dispose();
               tileDrawingListLock = null;
               tileDrawingList = null;
            }

            if(x == 0)
            {
#if DEBUG
               GMaps.Instance.CancelTileCaching();
#endif
               GMaps.Instance.noMapInstances = true;
               GMaps.Instance.WaitForCache.Set();
               if(disposing)
               {
                  GMaps.Instance.MemoryCache.Clear();
               }
            }
         }
      }

      public void Dispose()
      {
         Dispose(true);
         GC.SuppressFinalize(this);
      }

      #endregion
   }
}