// Copyright © 2021 The CefSharp Authors. All rights reserved.

//

// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.

//Originally based on https://github.com/CefNet/CefNet.DevTools.Protocol/blob/0a124720474a469b5cef03839418f5e1debaf2f0/CefNet.DevTools.Protocol/Internal/EventProxy.T.cs

using System;

using System.IO;

using System.Threading;

namespace CefSharp.DevTools

{

/// <summary>

/// Generic Typed Event Proxy

/// </summary>

/// <typeparam name="T">Event Args Type</typeparam>

internal class EventProxy<T> : IEventProxy

{

private event EventHandler<T> handlers;

private Func<string, Stream, T> convert;

/// <summary>

/// Constructor

/// </summary>

/// <param name="convert">Delegate used to convert from the Stream to event args</param>

public EventProxy(Func<string, Stream, T> convert)

{

this.convert = convert;

}

/// <summary>

/// Add the event handler

/// </summary>

/// <param name="handler">event handler to add</param>

public void AddHandler(EventHandler<T> handler)

{

handlers += handler;

}

/// <summary>

/// Remove the event handler

/// </summary>

/// <param name="handler">event handler to remove</param>

/// <returns>returns true if the last event handler for this proxy was removed.</returns>

public bool RemoveHandler(EventHandler<T> handler)

{

handlers -= handler;

return handlers == null;

}

/// <inheritdoc/>

public void Raise(object sender, string eventName, Stream stream, SynchronizationContext syncContext)

{

stream.Position = 0;

var args = convert(eventName, stream);

if (syncContext == null)

{

handlers?.Invoke(sender, args);

}

else

{

syncContext.Post(new SendOrPostCallback(state =>

{

handlers?.Invoke(sender, args);

}), null);

}

}

/// <inheritdoc/>

public void Dispose()

{

handlers = null;

}

}

}