implement the feature of changing the name of a model (microsoft#4285)

Fixes microsoft#4256 
Fixes microsoft#4261

In order to get our mocking system working properly and make everything
aligned, I changed the `SourceInputModel` to public and added it to the
`CodeModelPlugin` so that our plugin writers could override something on
it to do some advanced stuffs

packages/http-client-csharp/generator/Microsoft.Generator.CSharp.ClientModel/test/TestHelpers/MockHelpers.cs

@@ -5,10 +5,12 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Reflection;
+using Microsoft.CodeAnalysis;
 using Microsoft.Generator.CSharp.ClientModel.Providers;
 using Microsoft.Generator.CSharp.Input;
 using Microsoft.Generator.CSharp.Primitives;
 using Microsoft.Generator.CSharp.Providers;
+using Microsoft.Generator.CSharp.SourceInput;
 using Moq;
 using Moq.Protected;
 
@@ -96,6 +98,9 @@ public static Mock<ClientModelPlugin> LoadMockPlugin(
                 mockPluginInstance.Setup(p => p.InputLibrary).Returns(createInputLibrary);
             }
 
+            var sourceInputModel = new Mock<SourceInputModel>(() => new SourceInputModel(null)) { CallBase = true };
+            mockPluginInstance.Setup(p => p.SourceInputModel).Returns(sourceInputModel.Object);
+
             codeModelInstance!.SetValue(null, mockPluginInstance.Object);
             clientModelInstance!.SetValue(null, mockPluginInstance.Object);
             mockPluginInstance.Object.Configure();

packages/http-client-csharp/generator/Microsoft.Generator.CSharp/src/CSharpGen.cs

@@ -7,14 +7,14 @@
 using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.Generator.CSharp.Primitives;
+using Microsoft.Generator.CSharp.SourceInput;
 
 namespace Microsoft.Generator.CSharp
 {
     internal sealed class CSharpGen
     {
         private const string ConfigurationFileName = "Configuration.json";
         private const string CodeModelFileName = "tspCodeModel.json";
-        private const string GeneratedFolderName = "Generated";
 
         private static readonly string[] _filesToKeep = [ConfigurationFileName, CodeModelFileName];
 
@@ -25,10 +25,11 @@ public async Task ExecuteAsync()
         {
             GeneratedCodeWorkspace.Initialize();
             var outputPath = CodeModelPlugin.Instance.Configuration.OutputDirectory;
-            var generatedSourceOutputPath = ParseGeneratedSourceOutputPath(outputPath);
-            var generatedTestOutputPath = Path.Combine(outputPath, "..", "..", "tests", GeneratedFolderName);
+            var generatedSourceOutputPath = CodeModelPlugin.Instance.Configuration.ProjectGeneratedDirectory;
+            var generatedTestOutputPath = CodeModelPlugin.Instance.Configuration.TestGeneratedDirectory;
 
             GeneratedCodeWorkspace workspace = await GeneratedCodeWorkspace.Create();
+            await CodeModelPlugin.Instance.InitializeSourceInputModelAsync();
 
             var output = CodeModelPlugin.Instance.OutputLibrary;
             Directory.CreateDirectory(Path.Combine(generatedSourceOutputPath, "Models"));
@@ -82,23 +83,6 @@ public async Task ExecuteAsync()
             }
         }
 
-        /// <summary>
-        /// Parses and updates the output path for the generated code.
-        /// </summary>
-        /// <param name="outputPath">The output path.</param>
-        /// <returns>The parsed output path string.</returns>
-        internal static string ParseGeneratedSourceOutputPath(string outputPath)
-        {
-            if (!outputPath.EndsWith("src", StringComparison.Ordinal) && !outputPath.EndsWith("src/", StringComparison.Ordinal))
-            {
-                outputPath = Path.Combine(outputPath, "src");
-            }
-
-            outputPath = Path.Combine(outputPath, GeneratedFolderName);
-
-            return outputPath;
-        }
-
         /// <summary>
         /// Clears the output directory specified by <paramref name="path"/>. If <paramref name="filesToKeep"/> is not null,
         /// the specified files in the output directory will not be deleted.

packages/http-client-csharp/generator/Microsoft.Generator.CSharp/src/CodeModelPlugin.cs

@@ -4,10 +4,12 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel.Composition;
+using System.Threading.Tasks;
 using Microsoft.CodeAnalysis;
 using Microsoft.Generator.CSharp.Input;
 using Microsoft.Generator.CSharp.Primitives;
 using Microsoft.Generator.CSharp.Providers;
+using Microsoft.Generator.CSharp.SourceInput;
 
 namespace Microsoft.Generator.CSharp
 {
@@ -53,11 +55,11 @@ protected CodeModelPlugin()
         }
 
         internal bool IsNewProject { get; set; }
-
         private Lazy<InputLibrary> _inputLibrary;
 
         // Extensibility points to be implemented by a plugin
         public virtual TypeFactory TypeFactory { get; }
+        public virtual SourceInputModel SourceInputModel => _sourceInputModel ?? throw new InvalidOperationException($"SourceInputModel has not been initialized yet");
         public virtual string LicenseString => string.Empty;
         public virtual OutputLibrary OutputLibrary { get; } = new();
         public virtual InputLibrary InputLibrary => _inputLibrary.Value;
@@ -72,5 +74,12 @@ public virtual void AddVisitor(LibraryVisitor visitor)
         {
             _visitors.Add(visitor);
         }
+
+        private SourceInputModel? _sourceInputModel;
+        internal async Task InitializeSourceInputModelAsync()
+        {
+            GeneratedCodeWorkspace existingCode = GeneratedCodeWorkspace.CreateExistingCodeProject(Instance.Configuration.ProjectDirectory, Instance.Configuration.ProjectGeneratedDirectory);
+            _sourceInputModel =  new SourceInputModel(await existingCode.GetCompilationAsync());
+        }
     }
 }

packages/http-client-csharp/generator/Microsoft.Generator.CSharp/src/Configuration.cs

@@ -20,6 +20,7 @@ public class Configuration
             "Enum",
         ];
 
+        private const string GeneratedFolderName = "Generated";
         private const string ConfigurationFileName = "Configuration.json";
 
         // for mocking
@@ -144,6 +145,15 @@ private static class Options
         private string? _projectDirectory;
         internal string ProjectDirectory => _projectDirectory ??= Path.Combine(OutputDirectory, "src");
 
+        private string? _testProjectDirectory;
+        internal string TestProjectDirectory => _testProjectDirectory ??= Path.Combine(OutputDirectory, "tests");
+
+        private string? _projectGeneratedDirectory;
+        internal string ProjectGeneratedDirectory => _projectGeneratedDirectory ??= Path.Combine(ProjectDirectory, GeneratedFolderName);
+
+        private string? _testGeneratedDirectory;
+        internal string TestGeneratedDirectory => _testGeneratedDirectory ??= Path.Combine(TestProjectDirectory, GeneratedFolderName);
+
         internal string LibraryName { get; }
 
         /// <summary>

packages/http-client-csharp/generator/Microsoft.Generator.CSharp/src/PostProcessing/GeneratedCodeWorkspace.cs

@@ -47,6 +47,14 @@ public static void Initialize()
             _cachedProject = Task.Run(CreateGeneratedCodeProject);
         }
 
+        internal async Task<CSharpCompilation> GetCompilationAsync()
+        {
+            var compilation = await _project.GetCompilationAsync();
+            Debug.Assert(compilation is CSharpCompilation);
+
+            return (CSharpCompilation)compilation;
+        }
+
         public void AddPlainFiles(string name, string content)
         {
             PlainFiles.Add(name, content);
@@ -140,17 +148,18 @@ internal static async Task<GeneratedCodeWorkspace> Create()
             return new GeneratedCodeWorkspace(generatedCodeProject);
         }
 
-        public static GeneratedCodeWorkspace CreateExistingCodeProject(string outputDirectory)
+        internal static GeneratedCodeWorkspace CreateExistingCodeProject(string projectDirectory, string generatedDirectory)
         {
             var workspace = new AdhocWorkspace();
             var newOptionSet = workspace.Options.WithChangedOption(FormattingOptions.NewLine, LanguageNames.CSharp, _newLine);
             workspace.TryApplyChanges(workspace.CurrentSolution.WithOptions(newOptionSet));
             Project project = workspace.AddProject("ExistingCode", LanguageNames.CSharp);
 
-            if (Path.IsPathRooted(outputDirectory))
+            if (Path.IsPathRooted(projectDirectory))
             {
-                outputDirectory = Path.GetFullPath(outputDirectory);
-                project = AddDirectory(project, outputDirectory, null);
+                projectDirectory = Path.GetFullPath(projectDirectory);
+
+                project = AddDirectory(project, projectDirectory, skipPredicate: sourceFile => sourceFile.StartsWith(generatedDirectory));
             }
 
             project = project
@@ -161,7 +170,7 @@ public static GeneratedCodeWorkspace CreateExistingCodeProject(string outputDire
             return new GeneratedCodeWorkspace(project);
         }
 
-        public static async Task<Compilation?> CreatePreviousContractFromDll(string xmlDocumentationpath, string dllPath)
+        internal static async Task<Compilation?> CreatePreviousContractFromDll(string xmlDocumentationpath, string dllPath)
         {
             var workspace = new AdhocWorkspace();
             Project project = workspace.AddProject("PreviousContract", LanguageNames.CSharp);

packages/http-client-csharp/generator/Microsoft.Generator.CSharp/src/Providers/NamedTypeSymbolProvider.cs

@@ -6,13 +6,12 @@
 using System.Linq;
 using System.Xml.Linq;
 using Microsoft.CodeAnalysis;
-using Microsoft.Generator.CSharp.Expressions;
 using Microsoft.Generator.CSharp.Primitives;
 using Microsoft.Generator.CSharp.Statements;
 
 namespace Microsoft.Generator.CSharp.Providers
 {
-    public class NamedTypeSymbolProvider : TypeProvider
+    internal sealed class NamedTypeSymbolProvider : TypeProvider
     {
         private INamedTypeSymbol _namedTypeSymbol;
 
@@ -21,6 +20,8 @@ public NamedTypeSymbolProvider(INamedTypeSymbol namedTypeSymbol)
             _namedTypeSymbol = namedTypeSymbol;
         }
 
+        private protected sealed override TypeProvider? GetCustomCodeView() => null;
+
         protected override string BuildRelativeFilePath() => throw new InvalidOperationException("This type should not be writting in generation");
 
         protected override string BuildName() => _namedTypeSymbol.Name;

packages/http-client-csharp/generator/Microsoft.Generator.CSharp/src/Providers/TypeProvider.cs

@@ -12,6 +12,17 @@ namespace Microsoft.Generator.CSharp.Providers
 {
     public abstract class TypeProvider
     {
+        private Lazy<TypeProvider?> _customCodeView;
+        protected TypeProvider()
+        {
+            _customCodeView = new(GetCustomCodeView);
+        }
+
+        private protected virtual TypeProvider? GetCustomCodeView()
+            => CodeModelPlugin.Instance.SourceInputModel.FindForType(GetNamespace(), BuildName());
+
+        public TypeProvider? CustomCodeView => _customCodeView.Value;
+
         protected string? _deprecated;
 
         /// <summary>
@@ -22,7 +33,7 @@ public abstract class TypeProvider
 
         private string? _relativeFilePath;
 
-        public string Name => _name ??= BuildName();
+        public string Name => _name ??= CustomCodeView?.Name ?? BuildName();
 
         private string? _name;
 
@@ -45,7 +56,7 @@ public string? Deprecated
         private CSharpType? _type;
         public CSharpType Type => _type ??= new(
             this,
-            GetNamespace(),
+            CustomCodeView?.GetNamespace() ?? GetNamespace(),
             GetTypeArguments(),
             GetBaseType());