// 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 Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Formatting.Rules;
 
namespace Microsoft.CodeAnalysis.CSharp.Formatting
{
    internal class StructuredTriviaFormattingRule : BaseFormattingRule
    {
        internal const string Name = "CSharp Structured Trivia Formatting Rule";
 
        public override AdjustNewLinesOperation? GetAdjustNewLinesOperation(in SyntaxToken previousToken, in SyntaxToken currentToken, in NextGetAdjustNewLinesOperation nextOperation)
        {
            if (previousToken.Parent is StructuredTriviaSyntax || currentToken.Parent is StructuredTriviaSyntax)
            {
                return null;
            }
 
            return nextOperation.Invoke(in previousToken, in currentToken);
        }
 
        public override AdjustSpacesOperation? GetAdjustSpacesOperation(in SyntaxToken previousToken, in SyntaxToken currentToken, in NextGetAdjustSpacesOperation nextOperation)
        {
            if (previousToken.Parent is StructuredTriviaSyntax || currentToken.Parent is StructuredTriviaSyntax)
            {
                // this doesn't take care of all cases where tokens belong to structured trivia. this is only for cases we care
                if (previousToken.Kind() == SyntaxKind.HashToken && SyntaxFacts.IsPreprocessorKeyword(currentToken.Kind()))
                {
                    return CreateAdjustSpacesOperation(space: 0, option: AdjustSpacesOption.ForceSpacesIfOnSingleLine);
                }
 
                if (previousToken.Kind() == SyntaxKind.RegionKeyword && currentToken.Kind() == SyntaxKind.EndOfDirectiveToken)
                {
                    return CreateAdjustSpacesOperation(space: 0, option: AdjustSpacesOption.PreserveSpaces);
                }
 
                if (currentToken.Kind() == SyntaxKind.EndOfDirectiveToken)
                {
                    return CreateAdjustSpacesOperation(space: 0, option: AdjustSpacesOption.ForceSpacesIfOnSingleLine);
                }
            }
 
            return nextOperation.Invoke(in previousToken, in currentToken);
        }
    }
}