// 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;
using System.Threading;
using Microsoft.CodeAnalysis.Diagnostics;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.Formatting;
 
internal abstract partial class AbstractTriviaDataFactory
{
    protected sealed class ModifiedWhitespace : Whitespace
    {
        private readonly Whitespace? _original;
 
        public ModifiedWhitespace(LineFormattingOptions options, int lineBreaks, int indentation, bool elastic)
            : base(options, lineBreaks, indentation, elastic)
        {
            _original = null;
        }
 
        public ModifiedWhitespace(LineFormattingOptions options, Whitespace original, int lineBreaks, int indentation, bool elastic)
            : base(options, lineBreaks, indentation, elastic)
        {
            Contract.ThrowIfNull(original);
            _original = original;
        }
 
        public override bool ContainsChanges => false;
 
        public override TriviaData WithSpace(int space, FormattingContext context, ChainedFormattingRules formattingRules)
        {
            if (_original == null)
            {
                return base.WithSpace(space, context, formattingRules);
            }
 
            if (this.LineBreaks == _original.LineBreaks && _original.Spaces == space)
            {
                return _original;
            }
 
            return base.WithSpace(space, context, formattingRules);
        }
 
        public override TriviaData WithLine(int line, int indentation, FormattingContext context, ChainedFormattingRules formattingRules, CancellationToken cancellationToken)
        {
            if (_original == null)
            {
                return base.WithLine(line, indentation, context, formattingRules, cancellationToken);
            }
 
            if (_original.LineBreaks == line && _original.Spaces == indentation)
            {
                return _original;
            }
 
            return base.WithLine(line, indentation, context, formattingRules, cancellationToken);
        }
 
        public override TriviaData WithIndentation(
            int indentation, FormattingContext context, ChainedFormattingRules formattingRules, CancellationToken cancellationToken)
        {
            if (_original == null)
            {
                return base.WithIndentation(indentation, context, formattingRules, cancellationToken);
            }
 
            if (this.LineBreaks == _original.LineBreaks && _original.Spaces == indentation)
            {
                return _original;
            }
 
            return base.WithIndentation(indentation, context, formattingRules, cancellationToken);
        }
 
        public override void Format(
            FormattingContext context,
            ChainedFormattingRules formattingRules,
            Action<int, TokenStream, TriviaData> formattingResultApplier,
            CancellationToken cancellationToken,
            int tokenPairIndex = TokenPairIndexNotNeeded)
        {
            formattingResultApplier(tokenPairIndex, context.TokenStream, new FormattedWhitespace(this.Options, this.LineBreaks, this.Spaces));
        }
    }
}