// 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.Rename;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;
using Roslyn.LanguageServer.Protocol;
using Roslyn.Utilities;
using LSP = Roslyn.LanguageServer.Protocol;
 
namespace Microsoft.CodeAnalysis.LanguageServer.Handler
{
    [ExportCSharpVisualBasicStatelessLspService(typeof(RenameHandler)), Shared]
    [Method(LSP.Methods.TextDocumentRenameName)]
    [method: ImportingConstructor]
    [method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
    internal sealed class RenameHandler() : ILspServiceDocumentRequestHandler<LSP.RenameParams, WorkspaceEdit?>
    {
        public bool MutatesSolutionState => false;
        public bool RequiresLSPSolution => true;
 
        public TextDocumentIdentifier GetTextDocumentIdentifier(RenameParams request) => request.TextDocument;
 
        public Task<WorkspaceEdit?> HandleRequestAsync(RenameParams request, RequestContext context, CancellationToken cancellationToken)
            => GetRenameEditAsync(context.GetRequiredDocument(), ProtocolConversions.PositionToLinePosition(request.Position), request.NewName, cancellationToken);
 
        internal static async Task<WorkspaceEdit?> GetRenameEditAsync(Document document, LinePosition linePosition, string newName, CancellationToken cancellationToken)
        {
            var oldSolution = document.Project.Solution;
            var position = await document.GetPositionFromLinePositionAsync(linePosition, cancellationToken).ConfigureAwait(false);
 
            var symbolicRenameInfo = await SymbolicRenameInfo.GetRenameInfoAsync(
                document, position, cancellationToken).ConfigureAwait(false);
            if (symbolicRenameInfo.IsError)
                return null;
 
            var options = new SymbolRenameOptions(
                RenameOverloads: false,
                RenameInStrings: false,
                RenameInComments: false,
                RenameFile: false);
 
            var renameLocationSet = await Renamer.FindRenameLocationsAsync(
                oldSolution,
                symbolicRenameInfo.Symbol,
                options,
                cancellationToken).ConfigureAwait(false);
 
            var renameReplacementInfo = await renameLocationSet.ResolveConflictsAsync(
                symbolicRenameInfo.Symbol, symbolicRenameInfo.GetFinalSymbolName(newName),
                nonConflictSymbolKeys: default,
                cancellationToken).ConfigureAwait(false);
 
            if (!renameReplacementInfo.IsSuccessful ||
                !renameReplacementInfo.ReplacementTextValid)
            {
                return null;
            }
 
            var renamedSolution = renameReplacementInfo.NewSolution;
            var solutionChanges = renamedSolution.GetChanges(oldSolution);
 
            // Linked files can correspond to multiple roslyn documents each with changes.  Merge the changes in the linked files so that all linked documents have the same text.
            // Then we can just take the text changes from the first document to avoid returning duplicate edits.
            renamedSolution = await renamedSolution.WithMergedLinkedFileChangesAsync(oldSolution, solutionChanges, cancellationToken: cancellationToken).ConfigureAwait(false);
            solutionChanges = renamedSolution.GetChanges(oldSolution);
            var changedDocuments = solutionChanges
                .GetProjectChanges()
                .SelectMany(p => p.GetChangedDocuments(onlyGetDocumentsWithTextChanges: true))
                .GroupBy(docId => renamedSolution.GetRequiredDocument(docId).FilePath, StringComparer.OrdinalIgnoreCase).Select(group => group.First());
 
            var textDiffService = renamedSolution.Services.GetRequiredService<IDocumentTextDifferencingService>();
 
            var documentEdits = await ProtocolConversions.ChangedDocumentsToTextDocumentEditsAsync(changedDocuments, renamedSolution.GetRequiredDocument, oldSolution.GetRequiredDocument,
                textDiffService, cancellationToken).ConfigureAwait(false);
 
            return new WorkspaceEdit { DocumentChanges = documentEdits };
        }
    }
}