// 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.
 
#nullable disable
 
using System.ComponentModel.Composition;
using System.Diagnostics.CodeAnalysis;
using System.Threading;
using Microsoft.CodeAnalysis.Editor.Shared.Utilities;
using Microsoft.CodeAnalysis.Options;
using Microsoft.CodeAnalysis.Shared.TestHooks;
using Microsoft.VisualStudio.Commanding;
using Microsoft.VisualStudio.Utilities;
 
namespace Microsoft.CodeAnalysis.Editor.CSharp.EventHookup;
 
/// <summary>
/// Ignores commands until '=' is pressed, at which point we determine if the '=' is part of a
/// "+=" that is used to attach an event handler to an event. Once we determine that it is a
/// "+=" attaching an event handler to an event, we show a UI that tells the user they can hit
/// tab to generate a handler method.
///
/// Once we receive the '=' we watch all actions within the buffer. Anything (including use of
/// directional arrows) other than a typed space removes the UI or cancels any background
/// computation.
///
/// The determination of whether the "+=" is being used to attach an event handler to an event
/// can be costly, so it operates on a background thread. After the '=' of a "+=" is typed,
/// only a tab will cause the UI thread to block while it determines whether we should
/// intercept the tab and generate an event handler or just let the tab through to other
/// handlers.
///
/// Because we are explicitly asking the user to tab, so we should handle the tab command before
/// Automatic Completion.
/// </summary>
[Export(typeof(ICommandHandler))]
[ContentType(ContentTypeNames.CSharpContentType)]
[Name(PredefinedCommandHandlerNames.EventHookup)]
[Order(Before = PredefinedCommandHandlerNames.AutomaticCompletion)]
[method: ImportingConstructor]
[method: SuppressMessage("RoslynDiagnosticsReliability", "RS0033:Importing constructor should be [Obsolete]", Justification = "Used in test code: https://github.com/dotnet/roslyn/issues/42814")]
internal partial class EventHookupCommandHandler(
    IThreadingContext threadingContext,
    IInlineRenameService inlineRenameService,
    EventHookupSessionManager eventHookupSessionManager,
    IGlobalOptionService globalOptions,
    IAsynchronousOperationListenerProvider listenerProvider)
{
    private readonly IThreadingContext _threadingContext = threadingContext;
    private readonly IInlineRenameService _inlineRenameService = inlineRenameService;
    private readonly IAsynchronousOperationListener _asyncListener = listenerProvider.GetListener(FeatureAttribute.EventHookup);
    private readonly IGlobalOptionService _globalOptions = globalOptions;
 
    internal readonly EventHookupSessionManager EventHookupSessionManager = eventHookupSessionManager;
 
    // For testing purposes only! Will always be null except in certain tests.
    internal Mutex TESTSessionHookupMutex;
}