// 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.Immutable;
using System.Threading;
using Microsoft.CodeAnalysis.Completion.Providers;
using Microsoft.CodeAnalysis.CSharp.Extensions.ContextQuery;

namespace Microsoft.CodeAnalysis.CSharp.Completion.KeywordRecommenders;

internal abstract class AbstractNativeIntegerKeywordRecommender : IKeywordRecommender<CSharpSyntaxContext>
{
    protected abstract RecommendedKeyword Keyword { get; }

    private static bool IsValidContext(CSharpSyntaxContext context)
    {
        if (context.IsTaskLikeTypeContext ||
            context.IsGenericConstraintContext ||
            context.IsAttributeNameContext)
        {
            return false;
        }

        if (context.IsStatementContext ||
            context.IsGlobalStatementContext ||
            context.IsPossibleTupleContext ||
            context.IsAtStartOfPattern ||
            context.IsUsingAliasTypeContext ||
            (context.IsTypeContext && !context.IsEnumBaseListContext))
        {
            return true;
        }

        return context.IsLocalVariableDeclarationContext;
    }

    public ImmutableArray<RecommendedKeyword> RecommendKeywords(int position, CSharpSyntaxContext context, CancellationToken cancellationToken)
        => IsValidContext(context) ? [Keyword] : [];
}