AbstractConvertTupleToStructCodeRefactoringProvider.cs

// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.

using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeActions;
using Microsoft.CodeAnalysis.CodeGeneration;
using Microsoft.CodeAnalysis.CodeRefactorings;
using Microsoft.CodeAnalysis.Editing;
using Microsoft.CodeAnalysis.FindSymbols;
using Microsoft.CodeAnalysis.Formatting;
using Microsoft.CodeAnalysis.GenerateEqualsAndGetHashCodeFromMembers;
using Microsoft.CodeAnalysis.LanguageServices;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Shared.Utilities;
using Microsoft.CodeAnalysis.Simplification;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.ConvertTupleToStruct
{
    internal abstract partial class AbstractConvertTupleToStructCodeRefactoringProvider<
        TExpressionSyntax,
        TNameSyntax,
        TIdentifierNameSyntax,
        TLiteralExpressionSyntax,
        TObjectCreationExpressionSyntax,
        TTupleExpressionSyntax,
        TArgumentSyntax,
        TTupleTypeSyntax,
        TTypeBlockSyntax,
        TNamespaceDeclarationSyntax>
        : CodeRefactoringProvider
        where TExpressionSyntax : SyntaxNode
        where TNameSyntax : TExpressionSyntax
        where TIdentifierNameSyntax : TNameSyntax
        where TLiteralExpressionSyntax : TExpressionSyntax
        where TObjectCreationExpressionSyntax : TExpressionSyntax
        where TTupleExpressionSyntax : TExpressionSyntax
        where TArgumentSyntax: SyntaxNode
        where TTupleTypeSyntax : SyntaxNode
        where TTypeBlockSyntax : SyntaxNode
        where TNamespaceDeclarationSyntax : SyntaxNode
    {
        private enum Scope
        {
            ContainingMember,
            ContainingType,
            ContainingProject,
            DependentProjects
        }

        protected abstract TObjectCreationExpressionSyntax CreateObjectCreationExpression(
            TNameSyntax nameNode, SyntaxToken openParen, SeparatedSyntaxList<TArgumentSyntax> arguments, SyntaxToken closeParen);

        public override async Task ComputeRefactoringsAsync(CodeRefactoringContext context)
        {
            var document = context.Document;
            var cancellationToken = context.CancellationToken;

            var (tupleExprOrTypeNode, tupleType) = await TryGetTupleInfoAsync(
                document, context.Span, cancellationToken).ConfigureAwait(false);

            if (tupleExprOrTypeNode == null || tupleType == null)
            {
                return;
            }

            // Check if the tuple type actually references another anonymous type inside of it.
            // If it does, we can't convert this.  There is no way to describe this anonymous type
            // in the concrete type we create.
            var fields = tupleType.TupleElements;
            var containsAnonymousType = fields.Any(p => p.Type.ContainsAnonymousType());
            if (containsAnonymousType)
            {
                return;
            }

            var capturedTypeParameters =
                fields.Select(p => p.Type)
                      .SelectMany(t => t.GetReferencedTypeParameters())
                      .Distinct()
                      .ToImmutableArray();

            var scopes = ArrayBuilder<CodeAction>.GetInstance();
            scopes.Add(CreateAction(context, Scope.ContainingMember));

            // If we captured any Method type-parameters, we can only replace the tuple types we
            // find in the containing method.  No other tuple types in other members would be able
            // to reference this type parameter.
            if (!capturedTypeParameters.Any(tp => tp.TypeParameterKind == TypeParameterKind.Method))
            {
                var containingType = tupleExprOrTypeNode.GetAncestor<TTypeBlockSyntax>();
                if (containingType != null)
                {
                    scopes.Add(CreateAction(context, Scope.ContainingType));
                }

                // If we captured any Type type-parameters, we can only replace the tuple
                // types we find in the containing type.  No other tuple types in other
                // types would be able to reference this type parameter.
                if (!capturedTypeParameters.Any(tp => tp.TypeParameterKind == TypeParameterKind.Type))
                {
                    // To do a global find/replace of matching tuples, we need to search for documents
                    // containing tuples *and* which have the names of the tuple fields in them.  That means
                    // the tuple field name must exist in the document.
                    //
                    // this means we can only find tuples like ```(x: 1, ...)``` but not ```(1, 2)```.  The
                    // latter has members called Item1 and Item2, but those names don't show up in source.
                    if (fields.All(f => f.CorrespondingTupleField != f))
                    {
                        scopes.Add(CreateAction(context, Scope.ContainingProject));
                        scopes.Add(CreateAction(context, Scope.DependentProjects));
                    }
                }
            }

            context.RegisterRefactoring(new CodeAction.CodeActionWithNestedActions(
                FeaturesResources.Convert_to_struct,
                scopes.ToImmutableAndFree(),
                isInlinable: false));
        }

        private CodeAction CreateAction(CodeRefactoringContext context, Scope scope)
            => new MyCodeAction(GetTitle(scope), c => ConvertToStructAsync(context.Document, context.Span, scope, c));

        private static string GetTitle(Scope scope)
        {
            switch (scope)
            {
                case Scope.ContainingMember: return FeaturesResources.and_update_usages_in_containing_member;
                case Scope.ContainingType: return FeaturesResources.and_update_usages_in_containing_type;
                case Scope.ContainingProject: return FeaturesResources.and_update_usages_in_containing_project;
                case Scope.DependentProjects: return FeaturesResources.and_update_usages_in_dependent_projects;
                default:
                    throw ExceptionUtilities.UnexpectedValue(scope);
            }
        }

        private async Task<(SyntaxNode, INamedTypeSymbol)> TryGetTupleInfoAsync(
            Document document, TextSpan span, CancellationToken cancellationToken)
        {
            var position = span.Start;
            var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
            var token = root.FindToken(position);

            // Span actually has to be within the token (i.e. not in trivia around it).
            if (!token.Span.IntersectsWith(position))
            {
                return default;
            }

            if (!span.IsEmpty && span != token.Span)
            {
                // if there is a selection, it has to be of the whole token.
                return default;
            }

            var tupleExprNode = token.Parent as TTupleExpressionSyntax;
            var tupleTypeNode = token.Parent as TTupleTypeSyntax;
            if (tupleExprNode == null && tupleTypeNode == null)
            {
                return default;
            }

            var expressionOrType = tupleExprNode ?? (SyntaxNode)tupleTypeNode;

            // The position/selection must be of the open paren for the tuple, or the entire tuple.
            if (expressionOrType.GetFirstToken() != token)
            {
                return default;
            }

            var semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
            var tupleType = semanticModel.GetTypeInfo(expressionOrType, cancellationToken).Type as INamedTypeSymbol;
            if (tupleType?.IsTupleType != true)
            {
                return default;
            }

            return (expressionOrType, tupleType);
        }

        private async Task<Solution> ConvertToStructAsync(
            Document document, TextSpan span, Scope scope, CancellationToken cancellationToken)
        {
            var (tupleExprOrTypeNode, tupleType) = await TryGetTupleInfoAsync(
                document, span, cancellationToken).ConfigureAwait(false);

            Debug.Assert(tupleExprOrTypeNode != null);
            Debug.Assert(tupleType != null);

            var position = span.Start;
            var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
            var semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);

            var container = tupleExprOrTypeNode.GetAncestor<TNamespaceDeclarationSyntax>() ?? root;
            var containingNamespace = container is TNamespaceDeclarationSyntax namespaceDecl
                ? (INamespaceSymbol)semanticModel.GetDeclaredSymbol(namespaceDecl, cancellationToken)
                : semanticModel.Compilation.GlobalNamespace;

            // Generate a unique name for the struct we're creating.  We'll also add a rename
            // annotation so the user can pick the right name for the type afterwards.
            var structName = NameGenerator.GenerateUniqueName(
                "NewStruct", n => semanticModel.LookupSymbols(position, name: n).IsEmpty);

            var capturedTypeParameters =
                tupleType.TupleElements.Select(p => p.Type)
                                       .SelectMany(t => t.GetReferencedTypeParameters())
                                       .Distinct()
                                       .ToImmutableArray();

            // Next, generate the full struct that will be used to replace all instances of this
            // tuple type.
            var namedTypeSymbol = await GenerateFinalNamedTypeAsync(
                document, scope, structName, capturedTypeParameters, tupleType, cancellationToken).ConfigureAwait(false);

            var documentToEditorMap = new Dictionary<Document, SyntaxEditor>();
            var documentsToUpdate = await GetDocumentsToUpdateAsync(
                document, tupleExprOrTypeNode, tupleType, scope, cancellationToken).ConfigureAwait(false);

            // Next, go through and replace all matching tuple expressions and types in the appropriate
            // scope with the new named type we've generated.  
            await ReplaceExpressionAndTypesInScopeAsync(
                documentToEditorMap, documentsToUpdate, 
                tupleExprOrTypeNode, tupleType,
                structName, capturedTypeParameters,
                containingNamespace, cancellationToken).ConfigureAwait(false);

            await GenerateStructIntoContainingNamespaceAsync(
                document, tupleExprOrTypeNode, namedTypeSymbol,
                documentToEditorMap, cancellationToken).ConfigureAwait(false);

            var updatedSolution = await ApplyChangesAsync(
                document, documentToEditorMap, cancellationToken).ConfigureAwait(false);

            return updatedSolution;
        }

        private async Task ReplaceExpressionAndTypesInScopeAsync(
            Dictionary<Document, SyntaxEditor> documentToEditorMap, 
            ImmutableArray<DocumentToUpdate> documentsToUpdate,
            SyntaxNode tupleExprOrTypeNode, INamedTypeSymbol tupleType, 
            string structName, ImmutableArray<ITypeParameterSymbol> typeParameters,
            INamespaceSymbol containingNamespace, CancellationToken cancellationToken)
        {
            // Process the documents one project at a time.
            foreach (var group in documentsToUpdate.GroupBy(d => d.Document.Project))
            {
                // grab the compilation and keep it around as long as we're processing
                // the project so we don't clean things up in the middle.  To do this
                // we use a GC.KeepAlive below so that we can mark that this compilation
                // should stay around (even though we don't reference is directly in 
                // any other way here).
                var project = group.Key;
                var compilation = await project.GetCompilationAsync(cancellationToken).ConfigureAwait(false);

                var generator = project.LanguageServices.GetService<SyntaxGenerator>();

                // Get the fully qualified name for the new type we're creating.  We'll use this
                // at replacement points so that we can find the right type even if we're in a 
                // different namespace.

                // If the struct is being injected into the global namespace, then reference it with
                // "global::NewStruct",  Otherwise, get the full name to the namespace, and append
                // the NewStruct name to it.
                var structNameNode = CreateStructNameNode(
                    generator, structName, typeParameters, addRenameAnnotation: false);

                var fullTypeName = containingNamespace.IsGlobalNamespace
                    ? (TNameSyntax)generator.GlobalAliasedName(structNameNode)
                    : (TNameSyntax)generator.QualifiedName(generator.NameExpression(containingNamespace), structNameNode);

                fullTypeName = fullTypeName.WithAdditionalAnnotations(Simplifier.Annotation)
                                           .WithAdditionalAnnotations(DoNotAllowVarAnnotation.Annotation);

                foreach (var documentToUpdate in group)
                {
                    var document = documentToUpdate.Document;
                    var syntaxRoot = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
                    var semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);

                    // We should only ever get a default array (meaning, update the root), or a
                    // non-empty array.  We should never be asked to update exactly '0' nodes.
                    Debug.Assert(documentToUpdate.NodesToUpdate.IsDefault ||
                                 documentToUpdate.NodesToUpdate.Length >= 1);

                    // If we were given specific nodes to update, only update those.  Otherwise
                    // updated everything from the root down.
                    var nodesToUpdate = documentToUpdate.NodesToUpdate.IsDefault
                        ? ImmutableArray.Create(syntaxRoot)
                        : documentToUpdate.NodesToUpdate;

                    var editor = new SyntaxEditor(syntaxRoot, generator);

                    var replaced = false;

                    foreach (var container in nodesToUpdate)
                    {
                        replaced |= await ReplaceTupleExpressionsAndTypesInDocumentAsync(
                            document, editor, tupleExprOrTypeNode, tupleType,
                            fullTypeName, structName, typeParameters,
                            container, cancellationToken).ConfigureAwait(false);
                    }

                    if (replaced)
                    {
                        // We made a replacement.  Keep track of this so we can update our solution
                        // later.
                        documentToEditorMap.Add(document, editor);
                    }
                }

                GC.KeepAlive(compilation);
            }
        }

        private static TNameSyntax CreateStructNameNode(
            SyntaxGenerator generator, string structName,
            ImmutableArray<ITypeParameterSymbol> typeParameters, bool addRenameAnnotation)
        {
            var structNameToken = generator.Identifier(structName);
            if (addRenameAnnotation)
            {
                structNameToken = structNameToken.WithAdditionalAnnotations(RenameAnnotation.Create());
            }

            return typeParameters.Length == 0
                ? (TNameSyntax)generator.IdentifierName(structNameToken)
                : (TNameSyntax)generator.GenericName(structNameToken, typeParameters.Select(tp => generator.IdentifierName(tp.Name)));
        }

        private static async Task<ImmutableArray<DocumentToUpdate>> GetDocumentsToUpdateAsync(
            Document document, SyntaxNode tupleExprOrTypeNode,
            INamedTypeSymbol tupleType, Scope scope, CancellationToken cancellationToken)
        {
            switch (scope)
            {
                case Scope.ContainingMember:
                    return GetDocumentsToUpdateForContainingMember(document, tupleExprOrTypeNode);
                case Scope.ContainingType:
                    return await GetDocumentsToUpdateForContainingTypeAsync(
                        document, tupleExprOrTypeNode, cancellationToken).ConfigureAwait(false);
                case Scope.ContainingProject:
                    return await GetDocumentsToUpdateForContainingProjectAsync(
                        document.Project, tupleType, cancellationToken).ConfigureAwait(false);
                case Scope.DependentProjects:
                    return await GetDocumentsToUpdateForDependentProjectAsync(
                        document.Project, tupleType, cancellationToken).ConfigureAwait(false);
                default:
                    throw ExceptionUtilities.UnexpectedValue(scope);
            }
        }

        private static async Task<ImmutableArray<DocumentToUpdate>> GetDocumentsToUpdateForDependentProjectAsync(
            Project startingProject, INamedTypeSymbol tupleType, CancellationToken cancellationToken)
        {
            var solution = startingProject.Solution;
            var graph = solution.GetProjectDependencyGraph();

            // Note: there are a couple of approaches we can take here.  Processing 'direct'
            // dependencies, or processing 'transitive' dependencies.  Both have pros/cons:
            //
            // Direct Dependencies:
            //  Pros:
            //      All updated projects are able to see the newly added type.
            //      Transitive deps won't be updated to use a type they can't actually use.
            //  Cons:
            //      If that project then exports that new type, then transitive deps will
            //      break if they use those exported APIs since they won't know about the
            //      type.
            //
            // Transitive Dependencies:
            //  Pros:
            //      All affected code is updated.
            //  Cons: 
            //      Non-direct deps will not compile unless the take a reference on the
            //      starting project.

            var dependentProjects = graph.GetProjectsThatDirectlyDependOnThisProject(startingProject.Id);
            var allProjects = dependentProjects.Select(solution.GetProject).Concat(startingProject).ToSet();

            var result = ArrayBuilder<DocumentToUpdate>.GetInstance();
            var tupleFieldNames = tupleType.TupleElements.SelectAsArray(f => f.Name);

            foreach (var project in allProjects)
            {
                await AddDocumentsToUpdateForProjectAsync(
                    project, result, tupleFieldNames, cancellationToken).ConfigureAwait(false);
            }

            return result.ToImmutableAndFree();
        }

        private static async Task<ImmutableArray<DocumentToUpdate>> GetDocumentsToUpdateForContainingProjectAsync(
            Project project, INamedTypeSymbol tupleType, CancellationToken cancellationToken)
        {
            var result = ArrayBuilder<DocumentToUpdate>.GetInstance();
            var tupleFieldNames = tupleType.TupleElements.SelectAsArray(f => f.Name);

            await AddDocumentsToUpdateForProjectAsync(
                project, result, tupleFieldNames, cancellationToken).ConfigureAwait(false);

            return result.ToImmutableAndFree();
        }

        private static async Task AddDocumentsToUpdateForProjectAsync(Project project, ArrayBuilder<DocumentToUpdate> result, ImmutableArray<string> tupleFieldNames, CancellationToken cancellationToken)
        {
            foreach (var document in project.Documents)
            {
                var info = await document.GetSyntaxTreeIndexAsync(cancellationToken).ConfigureAwait(false);
                if (info.ContainsTupleExpressionOrTupleType &&
                    InfoProbablyContainsTupleFieldNames(info, tupleFieldNames))
                {
                    // Use 'default' for nodesToUpdate so we walk the entire document
                    result.Add(new DocumentToUpdate(document, nodesToUpdate: default));
                }
            }
        }

        private static bool InfoProbablyContainsTupleFieldNames(SyntaxTreeIndex info, ImmutableArray<string> tupleFieldNames)
        {
            foreach (var name in tupleFieldNames)
            {
                if (!info.ProbablyContainsIdentifier(name))
                {
                    return false;
                }
            }

            return true;
        }

        private static async Task<ImmutableArray<DocumentToUpdate>> GetDocumentsToUpdateForContainingTypeAsync(
            Document startingDocument, SyntaxNode tupleExprOrTypeNode, CancellationToken cancellationToken)
        {
            var containingType = tupleExprOrTypeNode.GetAncestor<TTypeBlockSyntax>();
            Debug.Assert(containingType != null,
                "We should always get a containing scope since we already checked for that to support Scope.ContainingType.");

            var solution = startingDocument.Project.Solution;
            var semanticModel = await startingDocument.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
            var typeSymbol = (INamedTypeSymbol)semanticModel.GetDeclaredSymbol(containingType, cancellationToken);

            var result = ArrayBuilder<DocumentToUpdate>.GetInstance();

            var declarationService = startingDocument.GetLanguageService<ISymbolDeclarationService>();
            foreach (var group in declarationService.GetDeclarations(typeSymbol).GroupBy(r => r.SyntaxTree))
            {
                var document = solution.GetDocument(group.Key);
                var nodes = group.SelectAsArray(r => r.GetSyntax(cancellationToken));

                result.Add(new DocumentToUpdate(document, nodes));
            }

            return result.ToImmutableAndFree();
        }

        private static ImmutableArray<DocumentToUpdate> GetDocumentsToUpdateForContainingMember(
            Document document, SyntaxNode tupleExprOrTypeNode)
        {
            var syntaxFacts = document.GetLanguageService<ISyntaxFactsService>();
            var containingMember = tupleExprOrTypeNode.FirstAncestorOrSelf<SyntaxNode>(syntaxFacts.IsMethodLevelMember) ?? tupleExprOrTypeNode;

            return ImmutableArray.Create(new DocumentToUpdate(
                document, ImmutableArray.Create(containingMember)));
        }

        private static async Task GenerateStructIntoContainingNamespaceAsync(
            Document document, SyntaxNode tupleExprOrTypeNode, INamedTypeSymbol namedTypeSymbol, 
            Dictionary<Document, SyntaxEditor> documentToEditorMap, CancellationToken cancellationToken)
        {
            var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);

            // If we don't already have an editor for the containing document, then make one.
            if (!documentToEditorMap.TryGetValue(document, out var editor))
            {
                var generator = SyntaxGenerator.GetGenerator(document);
                editor = new SyntaxEditor(root, generator);

                documentToEditorMap.Add(document, editor);
            }

            var syntaxFacts = document.GetLanguageService<ISyntaxFactsService>();
            var container = tupleExprOrTypeNode.GetAncestor<TNamespaceDeclarationSyntax>() ?? root;

            // Then, actually insert the new class in the appropriate container.
            editor.ReplaceNode(container, (currentContainer, _) =>
            {
                var codeGenService = document.GetLanguageService<ICodeGenerationService>();
                var options = new CodeGenerationOptions(
                    generateMembers: true,
                    sortMembers: false,
                    autoInsertionLocation: false);

                return codeGenService.AddNamedType(
                    currentContainer, namedTypeSymbol, options, cancellationToken);
            });
        }

        private static async Task<Solution> ApplyChangesAsync(
            Document startingDocument, Dictionary<Document, SyntaxEditor> documentToEditorMap, CancellationToken cancellationToken)
        {
            var currentSolution = startingDocument.Project.Solution;

            foreach (var (currentDoc, editor) in documentToEditorMap)
            {
                var docId = currentDoc.Id;
                var newRoot = editor.GetChangedRoot();
                var updatedDocument = currentSolution.WithDocumentSyntaxRoot(docId, newRoot, PreservationMode.PreserveIdentity)
                                                     .GetDocument(docId);

                if (currentDoc == startingDocument)
                {
                    // If this is the starting document, format using the equals+getHashCode service
                    // so that our generated methods follow any special formatting rules specific to
                    // them.
                    var equalsAndGetHashCodeService = startingDocument.GetLanguageService<IGenerateEqualsAndGetHashCodeService>();
                    updatedDocument = await equalsAndGetHashCodeService.FormatDocumentAsync(
                        updatedDocument, cancellationToken).ConfigureAwait(false);
                }

                currentSolution = updatedDocument.Project.Solution;
            }

            return currentSolution;
        }

        private async Task<bool> ReplaceTupleExpressionsAndTypesInDocumentAsync(
            Document document, SyntaxEditor editor, SyntaxNode startingNode, 
            INamedTypeSymbol tupleType, TNameSyntax fullyQualifiedStructName, 
            string structName, ImmutableArray<ITypeParameterSymbol> typeParameters,
            SyntaxNode containerToUpdate, CancellationToken cancellationToken)
        {
            var changed = false;
            changed |= await ReplaceMatchingTupleExpressionsAsync(
                document, editor, startingNode, tupleType,
                fullyQualifiedStructName, structName, typeParameters,
                containerToUpdate, cancellationToken).ConfigureAwait(false);

            changed |= await ReplaceMatchingTupleTypesAsync(
                document, editor, startingNode, tupleType,
                fullyQualifiedStructName, structName, typeParameters,
                containerToUpdate, cancellationToken).ConfigureAwait(false);

            return changed;
        }

        private async Task<bool> ReplaceMatchingTupleExpressionsAsync(
            Document document, SyntaxEditor editor, SyntaxNode startingNode, 
            INamedTypeSymbol tupleType, TNameSyntax qualifiedTypeName, 
            string typeName, ImmutableArray<ITypeParameterSymbol> typeParameters,
            SyntaxNode containingMember, CancellationToken cancellationToken)
        {
            var syntaxFacts = document.GetLanguageService<ISyntaxFactsService>();
            var comparer = syntaxFacts.StringComparer;
            var semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);

            var childCreationNodes = containingMember.DescendantNodesAndSelf()
                                                     .OfType<TTupleExpressionSyntax>();

            var changed = false;
            foreach (var childCreation in childCreationNodes)
            {
                var childType = semanticModel.GetTypeInfo(childCreation, cancellationToken).Type as INamedTypeSymbol;
                if (childType == null)
                {
                    Debug.Fail("We should always be able to get an tuple type for any tuple expression node.");
                    continue;
                }

                if (AreEquivalent(comparer, tupleType, childType))
                {
                    changed = true;
                    ReplaceWithObjectCreation(
                        syntaxFacts, editor, typeName, typeParameters, 
                        qualifiedTypeName, startingNode, childCreation);
                }
            }

            return changed;
        }

        private static bool AreEquivalent(StringComparer comparer, INamedTypeSymbol tupleType, INamedTypeSymbol childType)
            => SymbolEquivalenceComparer.Instance.Equals(tupleType, childType) &&
               NamesMatch(comparer, tupleType.TupleElements, childType.TupleElements);

        private static bool NamesMatch(
            StringComparer comparer, ImmutableArray<IFieldSymbol> fields1, ImmutableArray<IFieldSymbol> fields2)
        {
            if (fields1.Length != fields2.Length)
            {
                return false;
            }

            for (var i = 0; i < fields1.Length; i++)
            {
                if (!comparer.Equals(fields1[i].Name, fields2[i].Name))
                {
                    return false;
                }
            }

            return true;
        }

        private void ReplaceWithObjectCreation(
            ISyntaxFactsService syntaxFacts, SyntaxEditor editor, string typeName, ImmutableArray<ITypeParameterSymbol> typeParameters,
            TNameSyntax qualifiedTypeName, SyntaxNode startingCreationNode, TTupleExpressionSyntax childCreation)
        {
            // Use the callback form as tuples types may be nested, and we want to
            // properly replace them even in that case.
            editor.ReplaceNode(
                childCreation,
                (currentNode, g) =>
                {
                    var currentTupleExpr = (TTupleExpressionSyntax)currentNode;

                    // If we hit the node the user started on, then add the rename annotation here.
                    var typeNameNode = startingCreationNode == childCreation
                        ? CreateStructNameNode(g, typeName, typeParameters, addRenameAnnotation: true)
                        : qualifiedTypeName;

                    syntaxFacts.GetPartsOfTupleExpression<TArgumentSyntax>(
                        currentTupleExpr, out var openParen, out var arguments, out var closeParen);
                    arguments = ConvertArguments(syntaxFacts, g, arguments);

                    return CreateObjectCreationExpression(typeNameNode, openParen, arguments, closeParen)
                        .WithAdditionalAnnotations(Formatter.Annotation);
                });
        }

        private SeparatedSyntaxList<TArgumentSyntax> ConvertArguments(ISyntaxFactsService syntaxFacts, SyntaxGenerator generator, SeparatedSyntaxList<TArgumentSyntax> arguments)
            => generator.SeparatedList<TArgumentSyntax>(ConvertArguments(syntaxFacts, generator, arguments.GetWithSeparators()));

        private SyntaxNodeOrTokenList ConvertArguments(ISyntaxFactsService syntaxFacts, SyntaxGenerator generator, SyntaxNodeOrTokenList list)
            => new SyntaxNodeOrTokenList(list.Select(v => ConvertArgumentOrToken(syntaxFacts, generator, v)));

        private SyntaxNodeOrToken ConvertArgumentOrToken(ISyntaxFactsService syntaxFacts, SyntaxGenerator generator, SyntaxNodeOrToken arg)
            => arg.IsToken
                ? arg
                : ConvertArgument(syntaxFacts, generator, (TArgumentSyntax)arg.AsNode());

        private TArgumentSyntax ConvertArgument(
            ISyntaxFactsService syntaxFacts, SyntaxGenerator generator, TArgumentSyntax argument)
        {
            // Keep named arguments for literal args.  It helps keep the code self-documenting.
            // Remove for complex args as it's most likely just clutter a person doesn't need
            // when instantiating their new type.
            var expr = syntaxFacts.GetExpressionOfArgument(argument);
            if (expr is TLiteralExpressionSyntax)
            {
                return argument;
            }

            return (TArgumentSyntax)generator.Argument(expr).WithTriviaFrom(argument);
        }

        private async Task<bool> ReplaceMatchingTupleTypesAsync(
            Document document, SyntaxEditor editor, SyntaxNode startingNode, 
            INamedTypeSymbol tupleType, TNameSyntax qualifiedTypeName, 
            string typeName, ImmutableArray<ITypeParameterSymbol> typeParameters,
            SyntaxNode containingMember, CancellationToken cancellationToken)
        {
            var comparer = document.GetLanguageService<ISyntaxFactsService>().StringComparer;
            var semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);

            var childTupleNodes = containingMember.DescendantNodesAndSelf()
                                                  .OfType<TTupleTypeSyntax>();

            var changed = false;
            foreach (var childTupleType in childTupleNodes)
            {
                var childType = semanticModel.GetTypeInfo(childTupleType, cancellationToken).Type as INamedTypeSymbol;
                if (childType == null)
                {
                    Debug.Fail("We should always be able to get an tuple type for any tuple type syntax node.");
                    continue;
                }

                if (AreEquivalent(comparer, tupleType, childType))
                {
                    changed = true;
                    ReplaceWithTypeNode(
                        editor, typeName, typeParameters, qualifiedTypeName, startingNode, childTupleType);
                }
            }

            return changed;
        }

        private void ReplaceWithTypeNode(
            SyntaxEditor editor, string typeName, ImmutableArray<ITypeParameterSymbol> typeParameters,
            TNameSyntax qualifiedTypeName, SyntaxNode startingNode, TTupleTypeSyntax childTupleType)
        {
            // Use the callback form as tuple types may be nested, and we want to
            // properly replace them even in that case.
            editor.ReplaceNode(
                childTupleType,
                (currentNode, g) =>
                {
                    // If we hit the node the user started on, then add the rename annotation here.
                    var typeNameNode = startingNode == childTupleType
                        ? CreateStructNameNode(g, typeName, typeParameters, addRenameAnnotation: true)
                        : qualifiedTypeName;

                    return typeNameNode.WithTriviaFrom(currentNode);
                });
        }

        private static async Task<INamedTypeSymbol> GenerateFinalNamedTypeAsync(
            Document document, Scope scope, string structName, 
            ImmutableArray<ITypeParameterSymbol> typeParameters,
            INamedTypeSymbol tupleType, CancellationToken cancellationToken)
        {
            var semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
            var compilation = semanticModel.Compilation;

            var fields = tupleType.TupleElements;

            // Now try to generate all the members that will go in the new class. This is a bit
            // circular.  In order to generate some of the members, we need to know about the type.
            // But in order to create the type, we need the members.  To address this we do two
            // passes. First, we create an empty version of the class.  This can then be used to
            // help create members like Equals/GetHashCode.  Then, once we have all the members we
            // create the final type.
            var namedTypeWithoutMembers = CreateNamedType(
                scope, structName, typeParameters, members: default);

            var generator = SyntaxGenerator.GetGenerator(document);
            var constructor = CreateConstructor(compilation, structName, fields, generator);

            // Generate Equals/GetHashCode.  We can defer to our existing language service for this
            // so that we generate the same Equals/GetHashCode that our other IDE features generate.
            var equalsAndGetHashCodeService = document.GetLanguageService<IGenerateEqualsAndGetHashCodeService>();
                        
            var equalsMethod = await equalsAndGetHashCodeService.GenerateEqualsMethodAsync(
                document, namedTypeWithoutMembers, ImmutableArray<ISymbol>.CastUp(fields), 
                localNameOpt: ICodeDefinitionFactoryExtensions.OtherName, cancellationToken).ConfigureAwait(false);
            var getHashCodeMethod = await equalsAndGetHashCodeService.GenerateGetHashCodeMethodAsync(
                document, namedTypeWithoutMembers,
                ImmutableArray<ISymbol>.CastUp(fields), cancellationToken).ConfigureAwait(false);

            var members = ArrayBuilder<ISymbol>.GetInstance();
            members.AddRange(fields);
            members.Add(constructor);
            members.Add(equalsMethod);
            members.Add(getHashCodeMethod);
            members.Add(GenerateDeconstructMethod(semanticModel, generator, tupleType, constructor));
            AddConversions(generator, members, tupleType, namedTypeWithoutMembers);

            var namedTypeSymbol = CreateNamedType(scope, structName, typeParameters, members.ToImmutableAndFree());
            return namedTypeSymbol;
        }

        private static IMethodSymbol GenerateDeconstructMethod(
            SemanticModel model, SyntaxGenerator generator, 
            INamedTypeSymbol tupleType, IMethodSymbol constructor)
        {
            var assignments = tupleType.TupleElements.Select(
                (field, index) => generator.ExpressionStatement(
                    generator.AssignmentStatement(
                        generator.IdentifierName(constructor.Parameters[index].Name),
                        generator.MemberAccessExpression(
                            generator.ThisExpression(),
                            field.Name)))).ToImmutableArray();

            return CodeGenerationSymbolFactory.CreateMethodSymbol(
                attributes: default,
                Accessibility.Public,
                modifiers: default,
                model.Compilation.GetSpecialType(SpecialType.System_Void),
                RefKind.None,
                explicitInterfaceImplementations: default,
                WellKnownMemberNames.DeconstructMethodName,
                typeParameters: default,
                constructor.Parameters.SelectAsArray(p => 
                    CodeGenerationSymbolFactory.CreateParameterSymbol(RefKind.Out, p.Type, p.Name)),
                assignments);
        }

        private static void AddConversions(
            SyntaxGenerator generator, ArrayBuilder<ISymbol> members,
            INamedTypeSymbol tupleType, INamedTypeSymbol structType)
        {
            const string valueName = "value";

            var valueNode = generator.IdentifierName(valueName);
            var arguments = tupleType.TupleElements.SelectAsArray(
                field => generator.Argument(
                    generator.MemberAccessExpression(valueNode, field.Name)));

            var convertToTupleStatement = generator.ReturnStatement(
                generator.TupleExpression(arguments));

            var convertToStructStatement = generator.ReturnStatement(
                generator.ObjectCreationExpression(structType, arguments));

            members.Add(CodeGenerationSymbolFactory.CreateConversionSymbol(
                attributes: default,
                Accessibility.Public,
                DeclarationModifiers.Static,
                tupleType,
                CodeGenerationSymbolFactory.CreateParameterSymbol(structType, valueName),
                isImplicit: true,
                ImmutableArray.Create(convertToTupleStatement)));
            members.Add(CodeGenerationSymbolFactory.CreateConversionSymbol(
                attributes: default,
                Accessibility.Public,
                DeclarationModifiers.Static,
                structType,
                CodeGenerationSymbolFactory.CreateParameterSymbol(tupleType, valueName),
                isImplicit: true,
                ImmutableArray.Create(convertToStructStatement)));
        }

        private static INamedTypeSymbol CreateNamedType(
            Scope scope, string structName, 
            ImmutableArray<ITypeParameterSymbol> typeParameters, ImmutableArray<ISymbol> members)
        {
            var accessibility = scope == Scope.DependentProjects
                ? Accessibility.Public
                : Accessibility.Internal;
            return CodeGenerationSymbolFactory.CreateNamedTypeSymbol(
                attributes: default, accessibility, modifiers: default, 
                TypeKind.Struct, structName, typeParameters, members: members);
        }

        private static IMethodSymbol CreateConstructor(
            Compilation compilation, string className,
            ImmutableArray<IFieldSymbol> fields, SyntaxGenerator generator)
        {
            // For every property, create a corresponding parameter, as well as an assignment
            // statement from that parameter to the property.
            var parameterToPropMap = new Dictionary<string, ISymbol>();
            var parameters = fields.SelectAsArray(field =>
            {
                var parameter = CodeGenerationSymbolFactory.CreateParameterSymbol(
                    field.Type, field.Name.ToCamelCase(trimLeadingTypePrefix: false));

                parameterToPropMap[parameter.Name] = field;

                return parameter;
            });

            var assignmentStatements = generator.CreateAssignmentStatements(
                compilation, parameters, parameterToPropMap, ImmutableDictionary<string, string>.Empty,
                addNullChecks: false, preferThrowExpression: false);

            var constructor = CodeGenerationSymbolFactory.CreateConstructorSymbol(
                attributes: default, Accessibility.Public, modifiers: default,
                className, parameters, assignmentStatements);

            return constructor;
        }

        private class MyCodeAction : CodeAction.SolutionChangeAction
        {
            public MyCodeAction(string title, Func<CancellationToken, Task<Solution>> createChangedSolution)
                : base(title, createChangedSolution)
            {
            }
        }
    }
}