// 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.Threading;
using Microsoft.CodeAnalysis.CSharp.Extensions.ContextQuery;
 
namespace Microsoft.CodeAnalysis.CSharp.Completion.KeywordRecommenders;
 
internal class ThrowKeywordRecommender : AbstractSyntacticSingleKeywordRecommender
{
    public ThrowKeywordRecommender()
        : base(SyntaxKind.ThrowKeyword)
    {
    }
 
    protected override bool IsValidContext(int position, CSharpSyntaxContext context, CancellationToken cancellationToken)
    {
        if (context.IsStatementContext || context.IsGlobalStatementContext)
        {
            return true;
        }
 
        // void M() => throw
        if (context.TargetToken.IsKind(SyntaxKind.EqualsGreaterThanToken))
        {
            return true;
        }
 
        // val ?? throw
        if (context.TargetToken.IsKind(SyntaxKind.QuestionQuestionToken))
        {
            return true;
        }
 
        //  expr ? throw : ...
        //  expr ? ... : throw
        if (context.TargetToken.Kind() is SyntaxKind.QuestionToken or
            SyntaxKind.ColonToken)
        {
            return context.TargetToken.Parent.IsKind(SyntaxKind.ConditionalExpression);
        }
 
        return false;
    }
}