// 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 AbstractKeywordRecommender() : AbstractSyntacticSingleKeywordRecommender(SyntaxKind.AbstractKeyword)
{
    private static readonly ISet<SyntaxKind> s_validNonInterfaceMemberModifiers = new HashSet<SyntaxKind>(SyntaxFacts.EqualityComparer)
    {
        SyntaxKind.ExternKeyword,
        SyntaxKind.InternalKeyword,
        SyntaxKind.NewKeyword,
        SyntaxKind.PublicKeyword,
        SyntaxKind.ProtectedKeyword,
        SyntaxKind.UnsafeKeyword,
        SyntaxKind.OverrideKeyword,
    };

    private static readonly ISet<SyntaxKind> s_validInterfaceMemberModifiers = new HashSet<SyntaxKind>(SyntaxFacts.EqualityComparer)
    {
        SyntaxKind.ExternKeyword,
        SyntaxKind.InternalKeyword,
        SyntaxKind.NewKeyword,
        SyntaxKind.PublicKeyword,
        SyntaxKind.ProtectedKeyword,
        SyntaxKind.StaticKeyword,
        SyntaxKind.UnsafeKeyword,
        SyntaxKind.OverrideKeyword,
    };

    private static readonly ISet<SyntaxKind> s_validTypeModifiers = new HashSet<SyntaxKind>(SyntaxFacts.EqualityComparer)
        {
            SyntaxKind.InternalKeyword,
            SyntaxKind.NewKeyword,
            SyntaxKind.PublicKeyword,
            SyntaxKind.PrivateKeyword,
            SyntaxKind.ProtectedKeyword,
            SyntaxKind.UnsafeKeyword,
            SyntaxKind.FileKeyword,
        };

    protected override bool IsValidContext(int position, CSharpSyntaxContext context, CancellationToken cancellationToken)
    {
        return
            context.IsGlobalStatementContext ||
            context.IsMemberDeclarationContext(
                validModifiers: s_validNonInterfaceMemberModifiers,
                validTypeDeclarations: SyntaxKindSet.ClassRecordTypeDeclarations,
                canBePartial: false,
                cancellationToken: cancellationToken) ||
            context.IsMemberDeclarationContext(
                validModifiers: s_validInterfaceMemberModifiers,
                validTypeDeclarations: SyntaxKindSet.InterfaceOnlyTypeDeclarations,
                canBePartial: false,
                cancellationToken: cancellationToken) ||
            context.IsTypeDeclarationContext(
                validModifiers: s_validTypeModifiers,
                validTypeDeclarations: SyntaxKindSet.ClassInterfaceStructRecordTypeDeclarations,
                canBePartial: false,
                cancellationToken: cancellationToken);
    }
}