using System;

using System.Collections;

using System.Collections.Generic;

using System.Runtime.Serialization;

using System.Timers;

namespace SharpMap.Layers

{

/// <summary>

/// Types of layer collections

/// </summary>

public enum LayerCollectionType

{

/// <summary>

/// Layer collection for layers with datasources that are more or less static (e.g ShapeFiles)

/// </summary>

Static,

/// <summary>

/// Layer collection for layers with datasources that update frequently (e.g. moving vehicle)

/// </summary>

Variable,

/// <summary>

/// Layer collection for layers are completely opaque and serve as Background (e.g. WMS, OSM)

/// </summary>

Background,

}

/// <summary>

/// Signature of function to handle VariableLayerCollectionRequery event

/// </summary>

/// <param name="sender">The sender of the event</param>

/// <param name="e">The arguments, <c>EventArgs.Empty</c> in all cases</param>

public delegate void VariableLayerCollectionRequeryHandler(object sender, EventArgs e);

/// <summary>

/// Layer collection

/// </summary>

/// TODO:REEVALUEATE

[Serializable]

public class VariableLayerCollection : LayerCollection

{

//private readonly LayerCollection _variableLayers;

//[NonSerialized]

//private Timer _timer;

private volatile bool _isQuerying;

//[NonSerialized]

//private EventHandler<ElapsedEventArgs> _handler;

private bool _pause;

/// <summary>

/// Method to restart the internal Timer

/// </summary>

public void TouchTimer()

{

// check for pending re-draw (eg after map pan/zoom completed)

//if (_timer.Enabled) return;

if (_isQuerying) return;

//_timer.Start();

foreach (var lyr in this)

{

if (lyr is ILayerEx lyrEx)

lyrEx.RaiseRenderRequired();

}

System.Threading.ThreadPool.QueueUserWorkItem(new System.Threading.WaitCallback(OnRequery));

}

/// <summary>

/// Method called when deserializing this object.

/// </summary>

/// <param name="context"></param>

[OnDeserializing]

public void OnDeserializing(StreamingContext context)

{

//_timer = new Timer();

}

/// <summary>

/// Event fired every <see cref="Interval"/> to force requery;

/// </summary>

public event VariableLayerCollectionRequeryHandler VariableLayerCollectionRequery;

/// <summary>

/// Creates an instance of this class

/// </summary>

/// <param name="variableLayers">Layer collection that holds layers with data sources updating frequently</param>

public VariableLayerCollection(LayerCollection variableLayers)

{

AddCollection(variableLayers);

//_variableLayers = variableLayers;

//if (_handler == null)

//{

// //_timer = new Timer();

// //_timer.Interval = 500;

// //_timer.Elapsed += new ElapsedEventHandler(TimerElapsed);

//}

}

private void TimerElapsed(object sender, ElapsedEventArgs e)

{

OnRequery(null);

}

/// <inheritdoc/>

protected override void InsertItem(int index, ILayer layer)

{

if (layer == null)

throw new ArgumentNullException("layer", "The passed argument is null or not an ILayer");

lock (((ICollection)this).SyncRoot)

{

TestLayerPresent(this, layer);

base.InsertItem(index, layer);

}

}

/*

protected override void OnAddingNew(System.ComponentModel.AddingNewEventArgs e)

{

ILayer newLayer = (e.NewObject as ILayer);

if (newLayer == null) throw new ArgumentNullException("value", "The passed argument is null or not an ILayer");

TestLayerPresent(_variableLayers, newLayer);

base.OnAddingNew(e);

}

*/

private static void TestLayerPresent(IEnumerable<ILayer> layers, ILayer newLayer)

{

foreach (var layer in layers)

{

var comparison = String.Compare(layer.LayerName,

newLayer.LayerName, StringComparison.CurrentCultureIgnoreCase);

if (comparison == 0) throw new DuplicateLayerException(newLayer.LayerName);

}

}

private void OnRequery(object obj)

{

// if pan/zoom operation in progress then retry on next _timer.Elapsed

if (Pause) return;

// check for race condition when timer has been stopped while event has just been submitted on threadpool.QueueUserWorkItem

//if (!_timer.Enabled) return;

if (_isQuerying) return;

//_timer.Stop();

_isQuerying = true;

VariableLayerCollectionRequery?.Invoke(this, EventArgs.Empty);

_isQuerying = false;

}

/// <summary>

/// Gets/sets the interval in which to update layers

/// </summary>

public double Interval

{

get

{

return 0;//_timer.Interval;

}

set

{

// map sets Interval == 0 when disposing, to prevent race condition

/*

if (value <= 0)

_timer.Stop();

else

_timer.Interval = value;

*/

}

}

/// <summary>

/// Gets/Sets whether this collection should currently be updated or not

/// </summary>

public bool Pause

{

get { return _pause; }

set { _pause = value; }

}

}

}