// 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 System.Threading;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Simplification;
using Microsoft.CodeAnalysis.Text;
using Microsoft.VisualStudio.LanguageServices.Implementation.Snippets.SnippetFunctions;
using Microsoft.VisualStudio.Text;
using Roslyn.Utilities;
 
namespace Microsoft.VisualStudio.LanguageServices.CSharp.Snippets.SnippetFunctions
{
    internal sealed class SnippetFunctionSimpleTypeName : AbstractSnippetFunctionSimpleTypeName
    {
        public SnippetFunctionSimpleTypeName(SnippetExpansionClient snippetExpansionClient, ITextBuffer subjectBuffer, string fieldName, string fullyQualifiedName)
            : base(snippetExpansionClient, subjectBuffer, fieldName, fullyQualifiedName)
        {
        }
 
        protected override bool TryGetSimplifiedTypeName(Document documentWithFullyQualifiedTypeName, TextSpan updatedTextSpan, CancellationToken cancellationToken, out string simplifiedTypeName)
        {
            simplifiedTypeName = string.Empty;
 
            var typeAnnotation = new SyntaxAnnotation();
            var syntaxRoot = documentWithFullyQualifiedTypeName.GetRequiredSyntaxRootSynchronously(cancellationToken);
            var nodeToReplace = syntaxRoot.DescendantNodes().FirstOrDefault(n => n.Span == updatedTextSpan);
 
            if (nodeToReplace == null)
            {
                return false;
            }
 
            var updatedRoot = syntaxRoot.ReplaceNode(nodeToReplace, nodeToReplace.WithAdditionalAnnotations(typeAnnotation, Simplifier.Annotation));
            var documentWithAnnotations = documentWithFullyQualifiedTypeName.WithSyntaxRoot(updatedRoot);
 
            var simplifierOptions = documentWithAnnotations.GetSimplifierOptionsAsync(_snippetExpansionClient.EditorOptionsService.GlobalOptions, cancellationToken).AsTask().WaitAndGetResult(cancellationToken);
            var simplifiedDocument = Simplifier.ReduceAsync(documentWithAnnotations, simplifierOptions, cancellationToken).WaitAndGetResult(cancellationToken);
            simplifiedTypeName = simplifiedDocument.GetRequiredSyntaxRootSynchronously(cancellationToken).GetAnnotatedNodesAndTokens(typeAnnotation).Single().ToString();
            return true;
        }
    }
}