// 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.

#nullable disable

using System.Collections.Generic;
using System.Linq;
using System.Threading;
using Microsoft.CodeAnalysis.CSharp.Formatting;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.CSharp.Utilities;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.CSharp.Extensions.ContextQuery
{
    internal static partial class SyntaxTreeExtensions
    {
        public static bool IsPreProcessorDirectiveContext(this SyntaxTree syntaxTree, int position, SyntaxToken preProcessorTokenOnLeftOfPosition, CancellationToken cancellationToken)
        {
            var token = preProcessorTokenOnLeftOfPosition;
            var directive = token.GetAncestor<DirectiveTriviaSyntax>();

            // Directives contain the EOL, so if the position is within the full span of the
            // directive, then it is on that line, the only exception is if the directive is on the
            // last line, the position at the end if technically not contained by the directive but
            // its also not on a new line, so it should be considered part of the preprocessor
            // context.
            if (directive == null)
            {
                return false;
            }

            return
                directive.FullSpan.Contains(position) ||
                directive.FullSpan.End == syntaxTree.GetRoot(cancellationToken).FullSpan.End;
        }
    }
}
