// 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.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Formatting;
using Microsoft.CodeAnalysis.Options;
using Microsoft.CodeAnalysis.OrganizeImports;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Shared.Utilities;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Utilities;
using LSP = Roslyn.LanguageServer.Protocol;
 
namespace Microsoft.CodeAnalysis.LanguageServer.Handler
{
    internal abstract class AbstractFormatDocumentHandlerBase<RequestType, ResponseType> : ILspServiceDocumentRequestHandler<RequestType, ResponseType>
    {
        public bool MutatesSolutionState => false;
        public bool RequiresLSPSolution => true;
 
        protected static async Task<LSP.TextEdit[]?> GetTextEditsAsync(
            RequestContext context,
            LSP.FormattingOptions options,
            IGlobalOptionService globalOptions,
            CancellationToken cancellationToken,
            LSP.Range? range = null)
        {
            if (context.Document is not { } document)
                return null;
 
            var text = await document.GetValueTextAsync(cancellationToken).ConfigureAwait(false);
            var root = await document.GetRequiredSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
 
            var rangeSpan = (range != null) ? ProtocolConversions.RangeToTextSpan(range, text) : new TextSpan(0, root.FullSpan.Length);
            var formattingSpan = CommonFormattingHelpers.GetFormattingSpan(root, rangeSpan);
 
            // We should use the options passed in by LSP instead of the document's options.
            var formattingOptions = await ProtocolConversions.GetFormattingOptionsAsync(options, document, cancellationToken).ConfigureAwait(false);
            var services = document.Project.Solution.Services;
            var formattingChanges = Formatter.GetFormattedTextChanges(root, SpecializedCollections.SingletonEnumerable(formattingSpan), services, formattingOptions, cancellationToken);
 
            // We only organize the imports when formatting the entire document. This means we can stop
            // if we are provided a range or sorting imports is disabled/
            if (range is not null || !globalOptions.GetOption(LspOptionsStorage.LspOrganizeImportsOnFormat, document.Project.Language))
            {
                return [.. formattingChanges.Select(change => ProtocolConversions.TextChangeToTextEdit(change, text))];
            }
 
            var formattedDocument = document.WithText(text.WithChanges(formattingChanges));
 
            var organizeImports = formattedDocument.GetRequiredLanguageService<IOrganizeImportsService>();
            var organizeImportsOptions = await formattedDocument.GetOrganizeImportsOptionsAsync(cancellationToken).ConfigureAwait(false);
            var organizedDocument = await organizeImports.OrganizeImportsAsync(formattedDocument, organizeImportsOptions, cancellationToken).ConfigureAwait(false);
 
            var textChanges = await organizedDocument.GetTextChangesAsync(context.Document).ConfigureAwait(false);
            return [.. textChanges.Select(change => ProtocolConversions.TextChangeToTextEdit(change, text))];
        }
 
        public abstract LSP.TextDocumentIdentifier GetTextDocumentIdentifier(RequestType request);
        public abstract Task<ResponseType> HandleRequestAsync(RequestType request, RequestContext context, CancellationToken cancellationToken);
    }
}