// 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.Linq;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Shared.Extensions;
 
namespace Microsoft.CodeAnalysis.CSharp.Extensions
{
    internal static class StatementSyntaxExtensions
    {
        public static StatementSyntax WithoutLeadingBlankLinesInTrivia(this StatementSyntax statement)
            => statement.WithLeadingTrivia(statement.GetLeadingTrivia().WithoutLeadingBlankLines());
 
        public static StatementSyntax? GetPreviousStatement(this StatementSyntax? statement)
        {
            if (statement != null)
            {
                var previousToken = statement.GetFirstToken().GetPreviousToken();
                return previousToken.GetAncestors<StatementSyntax>().FirstOrDefault(s => AreSiblingStatements(s, statement));
            }
 
            return null;
        }
 
        public static StatementSyntax? GetNextStatement(this StatementSyntax? statement)
        {
            if (statement != null)
            {
                var nextToken = statement.GetLastToken().GetNextToken();
                return nextToken.GetAncestors<StatementSyntax>().FirstOrDefault(s => AreSiblingStatements(s, statement));
            }
 
            return null;
        }
 
        private static bool AreSiblingStatements(StatementSyntax first, StatementSyntax second)
        {
            if (first.Parent.IsKind(SyntaxKind.GlobalStatement))
                return second.Parent.IsKind(SyntaxKind.GlobalStatement);
            else
                return first.Parent == second.Parent;
        }
    }
}