// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System;
using System.Threading;
using System.Threading.Tasks;
 
namespace Microsoft.CodeAnalysis.ExternalAccess.UnitTesting.Api
{
    internal static class UnitTestingWorkspaceExtensions
    {
        public static IDisposable RegisterTextDocumentOpenedEventHandler(this Workspace workspace, Action<UnitTestingTextDocumentEventArgsWrapper> action)
            => new EventHandlerWrapper(workspace, action, opened: true);
 
        public static IDisposable RegisterTextDocumentClosedEventHandler(this Workspace workspace, Action<UnitTestingTextDocumentEventArgsWrapper> action)
            => new EventHandlerWrapper(workspace, action, opened: false);
 
        private sealed class EventHandlerWrapper : IDisposable
        {
            private readonly Workspace _workspace;
            private readonly EventHandler<TextDocumentEventArgs> _handler;
            private readonly bool _opened;
 
            internal EventHandlerWrapper(Workspace workspace, Action<UnitTestingTextDocumentEventArgsWrapper> action, bool opened)
            {
                _workspace = workspace;
                _handler = (sender, args) => action(new UnitTestingTextDocumentEventArgsWrapper(args));
                _opened = opened;
 
                if (_opened)
                    _workspace.TextDocumentOpened += _handler;
                else
                    _workspace.TextDocumentClosed += _handler;
            }
 
            public void Dispose()
            {
                if (_opened)
                    _workspace.TextDocumentOpened -= _handler;
                else
                    _workspace.TextDocumentClosed -= _handler;
            }
        }
    }
}