// 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;
using Microsoft.CodeAnalysis.Shared.Extensions;

namespace Microsoft.CodeAnalysis.CSharp.Completion.KeywordRecommenders;

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

    private static readonly ISet<SyntaxKind> s_validStructModifiers = new HashSet<SyntaxKind>(s_validClassModifiers, SyntaxFacts.EqualityComparer)
        {
            SyntaxKind.ReadOnlyKeyword,
        };

    protected override bool IsValidContext(int position, CSharpSyntaxContext context, CancellationToken cancellationToken)
    {
        var syntaxTree = context.SyntaxTree;
        return
            (context.IsGlobalStatementContext && syntaxTree.IsScript()) ||
            syntaxTree.IsGlobalMemberDeclarationContext(position, SyntaxKindSet.AllGlobalMemberModifiers, cancellationToken) ||
            context.IsMemberDeclarationContext(validModifiers: s_validClassModifiers, validTypeDeclarations: SyntaxKindSet.NonEnumTypeDeclarations, canBePartial: true, cancellationToken: cancellationToken) ||
            context.IsMemberDeclarationContext(validModifiers: s_validStructModifiers, validTypeDeclarations: SyntaxKindSet.StructOnlyTypeDeclarations, canBePartial: true, cancellationToken: cancellationToken) ||
            context.IsMemberAttributeContext(SyntaxKindSet.NonEnumTypeDeclarations, includingRecordParameters: false, cancellationToken);
    }
}