// 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.Diagnostics;
using Microsoft.CodeAnalysis.Formatting;
 
namespace Microsoft.CodeAnalysis.CSharp.Formatting;
 
internal partial class CSharpTriviaFormatter
{
    private class DocumentationCommentExteriorCommentRewriter : CSharpSyntaxRewriter
    {
        private readonly bool _forceIndentation;
        private readonly int _indentation;
        private readonly int _indentationDelta;
        private readonly SyntaxFormattingOptions _options;
 
        public DocumentationCommentExteriorCommentRewriter(
            bool forceIndentation,
            int indentation,
            int indentationDelta,
            SyntaxFormattingOptions options,
            bool visitStructuredTrivia = true)
            : base(visitIntoStructuredTrivia: visitStructuredTrivia)
        {
            _forceIndentation = forceIndentation;
            _indentation = indentation;
            _indentationDelta = indentationDelta;
            _options = options;
        }
 
        public override SyntaxTrivia VisitTrivia(SyntaxTrivia trivia)
        {
            if (trivia.Kind() == SyntaxKind.DocumentationCommentExteriorTrivia)
            {
                if (IsBeginningOrEndOfDocumentComment(trivia))
                {
                    return base.VisitTrivia(trivia);
                }
                else
                {
                    var triviaText = trivia.ToFullString();
 
                    var newTriviaText = triviaText.AdjustIndentForXmlDocExteriorTrivia(
                                            _forceIndentation,
                                            _indentation,
                                            _indentationDelta,
                                            _options.UseTabs,
                                            _options.TabSize);
 
                    if (triviaText == newTriviaText)
                    {
                        return base.VisitTrivia(trivia);
                    }
 
                    var parsedNewTrivia = SyntaxFactory.DocumentationCommentExterior(newTriviaText);
 
                    return parsedNewTrivia;
                }
            }
 
            return base.VisitTrivia(trivia);
        }
 
        private static bool IsBeginningOrEndOfDocumentComment(SyntaxTrivia trivia)
        {
            var currentParent = trivia.Token.Parent;
 
            while (currentParent != null)
            {
                if (currentParent.Kind() is SyntaxKind.SingleLineDocumentationCommentTrivia or
                    SyntaxKind.MultiLineDocumentationCommentTrivia)
                {
                    if (trivia.Span.End == currentParent.SpanStart ||
                        trivia.Span.End == currentParent.Span.End)
                    {
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                }
 
                currentParent = currentParent.Parent;
            }
 
            return false;
        }
    }
}