// 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.Composition;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.LanguageServer;
using Microsoft.CodeAnalysis.LanguageServer.Handler;
using Microsoft.CodeAnalysis.PooledObjects;
using Roslyn.LanguageServer.Protocol;
using Microsoft.VisualStudio.LanguageServices.Xaml.Features.Formatting;
 
namespace Microsoft.VisualStudio.LanguageServices.Xaml.LanguageServer.Handler;
 
[ExportStatelessXamlLspService(typeof(FormatDocumentOnTypeHandler)), Shared]
[Method(Methods.TextDocumentOnTypeFormattingName)]
internal sealed class FormatDocumentOnTypeHandler : ILspServiceRequestHandler<DocumentOnTypeFormattingParams, TextEdit[]>
{
    [ImportingConstructor]
    [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
    public FormatDocumentOnTypeHandler()
    {
    }
 
    public bool MutatesSolutionState => false;
    public bool RequiresLSPSolution => true;
 
    public TextDocumentIdentifier GetTextDocumentIdentifier(DocumentOnTypeFormattingParams request) => request.TextDocument;
 
    public async Task<TextEdit[]> HandleRequestAsync(DocumentOnTypeFormattingParams request, RequestContext context, CancellationToken cancellationToken)
    {
        if (string.IsNullOrEmpty(request.Character))
        {
            return [];
        }
 
        using var _ = ArrayBuilder<TextEdit>.GetInstance(out var edits);
        var document = context.Document;
        var formattingService = document?.Project.Services.GetService<IXamlFormattingService>();
        if (document != null && formattingService != null)
        {
            var position = await document.GetPositionFromLinePositionAsync(ProtocolConversions.PositionToLinePosition(request.Position), cancellationToken).ConfigureAwait(false);
            var options = new XamlFormattingOptions { InsertSpaces = request.Options.InsertSpaces, TabSize = request.Options.TabSize, OtherOptions = request.Options.OtherOptions?.AsUntyped() };
            var textChanges = await formattingService.GetFormattingChangesAsync(document, options, request.Character[0], position, cancellationToken).ConfigureAwait(false);
            if (textChanges != null)
            {
                var text = await document.GetValueTextAsync(cancellationToken).ConfigureAwait(false);
                edits.AddRange(textChanges.Select(change => ProtocolConversions.TextChangeToTextEdit(change, text)));
            }
        }
 
        return edits.ToArray();
    }
}