// 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 class VirtualKeywordRecommender : AbstractSyntacticSingleKeywordRecommender
{
    private static readonly ISet<SyntaxKind> s_validNonInterfaceMemberModifiers = new HashSet<SyntaxKind>(SyntaxFacts.EqualityComparer)
    {
        SyntaxKind.ExternKeyword,
        SyntaxKind.InternalKeyword,
        SyntaxKind.NewKeyword,
        SyntaxKind.PublicKeyword,
        SyntaxKind.ProtectedKeyword,
        SyntaxKind.PrivateKeyword,
        SyntaxKind.UnsafeKeyword,
    };
 
    private static readonly ISet<SyntaxKind> s_validInterfaceMemberModifiers = new HashSet<SyntaxKind>(SyntaxFacts.EqualityComparer)
    {
        SyntaxKind.ExternKeyword,
        SyntaxKind.InternalKeyword,
        SyntaxKind.NewKeyword,
        SyntaxKind.PublicKeyword,
        SyntaxKind.ProtectedKeyword,
        SyntaxKind.PrivateKeyword,
        SyntaxKind.StaticKeyword,
        SyntaxKind.UnsafeKeyword,
    };
 
    public VirtualKeywordRecommender()
        : base(SyntaxKind.VirtualKeyword)
    {
    }
 
    protected override bool IsValidContext(int position, CSharpSyntaxContext context, CancellationToken cancellationToken)
    {
        if (!context.IsMemberDeclarationContext(
                validModifiers: s_validNonInterfaceMemberModifiers,
                validTypeDeclarations: SyntaxKindSet.ClassRecordTypeDeclarations,
                canBePartial: false,
                cancellationToken: cancellationToken) &&
            !context.IsMemberDeclarationContext(
                validModifiers: s_validInterfaceMemberModifiers,
                validTypeDeclarations: SyntaxKindSet.InterfaceOnlyTypeDeclarations,
                canBePartial: false,
                cancellationToken: cancellationToken))
        {
            return false;
        }
 
        var modifiers = context.PrecedingModifiers;
        return !modifiers.Contains(SyntaxKind.PrivateKeyword) || modifiers.Contains(SyntaxKind.ProtectedKeyword);
    }
}