// 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.Collections.Immutable;
using System.ComponentModel.Composition;
using System.Threading;
using Microsoft.CodeAnalysis.Completion;
using Microsoft.CodeAnalysis.CSharp.Extensions;
using Microsoft.CodeAnalysis.Editor;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.Interactive;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;
using Microsoft.VisualStudio.InteractiveWindow;
using Microsoft.VisualStudio.Text.Editor;
using Microsoft.VisualStudio.Utilities;
 
namespace Microsoft.CodeAnalysis.CSharp.Completion.Providers;
 
/// <summary>
/// Provides completion items for Interactive Window commands (such as #help, #cls, etc.) at the start of a C# language buffer.
/// </summary>
[ExportCompletionProviderMef1("ReplCommandCompletionProvider", LanguageNames.CSharp)]
[TextViewRole(PredefinedInteractiveTextViewRoles.InteractiveTextViewRole)]
[Order(Before = PredefinedCompletionProviderNames.Keyword)]
internal sealed class CSharpInteractiveWindowCommandCompletionProvider : AbstractInteractiveWindowCommandCompletionProvider
{
    [ImportingConstructor]
    [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
    public CSharpInteractiveWindowCommandCompletionProvider()
    {
    }
 
    internal override string Language
        => LanguageNames.CSharp;
 
    protected override string GetCompletionString(string commandName)
        => commandName;
 
    public override bool IsInsertionTrigger(SourceText text, int characterPosition, CompletionOptions options)
        => CompletionUtilities.IsTriggerAfterSpaceOrStartOfWordCharacter(text, characterPosition, options);
 
    public override ImmutableHashSet<char> TriggerCharacters { get; } = CompletionUtilities.SpaceTriggerCharacter;
 
    protected override bool ShouldDisplayCommandCompletions(SyntaxTree tree, int position, CancellationToken cancellationToken)
        => tree.IsBeforeFirstToken(position, cancellationToken) &&
           tree.IsPreProcessorKeywordContext(position, cancellationToken);
}