// 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.Collections.Generic;
using System.Threading;
using Microsoft.CodeAnalysis.CSharp.Extensions.ContextQuery;
using Microsoft.CodeAnalysis.CSharp.Utilities;

namespace Microsoft.CodeAnalysis.CSharp.Completion.KeywordRecommenders;

internal sealed class OverrideKeywordRecommender() : AbstractSyntacticSingleKeywordRecommender(SyntaxKind.OverrideKeyword)
{
    private static readonly ISet<SyntaxKind> s_validMemberModifiers = new HashSet<SyntaxKind>(SyntaxFacts.EqualityComparer)
    {
        SyntaxKind.ExternKeyword,
        SyntaxKind.InternalKeyword,
        SyntaxKind.PublicKeyword,
        SyntaxKind.ProtectedKeyword,
        SyntaxKind.PrivateKeyword,
        SyntaxKind.UnsafeKeyword,
        SyntaxKind.SealedKeyword,
        SyntaxKind.AbstractKeyword,
    };

    protected override bool IsValidContext(int position, CSharpSyntaxContext context, CancellationToken cancellationToken)
    {
        if (!context.IsMemberDeclarationContext(
            validModifiers: s_validMemberModifiers,
            validTypeDeclarations: SyntaxKindSet.ClassStructRecordTypeDeclarations,
            canBePartial: false,
            cancellationToken: cancellationToken))
        {
            return false;
        }

        var modifiers = context.PrecedingModifiers;
        return !modifiers.Contains(SyntaxKind.PrivateKeyword) || modifiers.Contains(SyntaxKind.ProtectedKeyword);
    }
}