Remove the code, downloading packages, add restore

Author: nick863

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

@@ -275,9 +275,38 @@ internal static async Task AddPackageReferencesFromProject()
             {
                 return;
             }
-
+            // Use the dotnet restore mechanism to get all the dependent packages.
+            Process restore = new();
+            ProcessStartInfo info = new()
+            {
+                UseShellExecute = false,
+                WindowStyle = ProcessWindowStyle.Hidden,
+                FileName = "dotnet",
+                Arguments = $"restore {projectFilePath}",
+                RedirectStandardOutput = true,
+                RedirectStandardError = true,
+            };
+            restore.StartInfo = info;
+            if (restore.Start())
+            {
+                await restore.WaitForExitAsync();
+                if (restore.ExitCode != 0)
+                {
+                    string output = await restore.StandardOutput.ReadToEndAsync();
+                    string error = await restore.StandardError.ReadToEndAsync();
+                    CodeModelGenerator.Instance.Emitter.Debug(
+                        $"The dotnet restore {projectFilePath} command exited with {restore.ExitCode}.]\n" +
+                        $"Standard output: {output}\n" +
+                        $"Error output: {error}"
+                        );
+                }
+            }
+            else
+            {
+                CodeModelGenerator.Instance.Emitter.Debug(
+                            $"Unable to run dotnet restore on the project {projectFilePath}");
+            }
             var projectRoot = ProjectRootElement.Open(projectFilePath, new MSBuildProjectCollection());
-
             var nugetSettings = Settings.LoadDefaultSettings(projectFilePath);
             var globalPackagesFolder = SettingsUtility.GetGlobalPackagesFolder(nugetSettings);
 

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator/src/Utilities/ExternalTypeReferenceResolver.cs

@@ -236,52 +236,6 @@ private static async Task<ResolutionResult> ResolveResultAsync(InputExternalType
             string? assemblyPath = NugetPackageResolver.FindPackageAssembly(
                 globalPackagesFolder, external.Package!, external.MinVersion);
 
-            if (assemblyPath == null)
-            {
-                try
-                {
-                    string? resolvedVersion;
-                    // Search for the compatible version.
-                    if (!string.IsNullOrEmpty(external.MinVersion))
-                    {
-                        // If min version was provided, we
-                        // 1. Search if it is in our repositories;
-                        // 2. Get the latest one if it is not.
-                        // 3. If our version is a pre release, include pre released versions in our search.
-                        NuGetVersion minVersion = new(external.MinVersion);
-                        IList<NuGetVersion> versions = await NugetPackageResolver.GetAllVersions(external.Package!, nugetSettings, allowPrerelease: minVersion.IsPrerelease);
-                        if (versions.Any(x => x == minVersion))
-                        {
-                            resolvedVersion = external.MinVersion;
-                        }
-                        else
-                        {
-                            resolvedVersion = versions.Max()?.ToString();
-                        }
-                    }
-                    else
-                    {
-                        // If min version was not provided, get the latest stable version.
-                        resolvedVersion = await NugetPackageResolver.ResolveLatestPackageVersion(external.Package!, nugetSettings);
-                    }
-                    if (!string.IsNullOrEmpty(resolvedVersion))
-                    {
-                        var downloader = new NugetPackageDownloader(external.Package!, resolvedVersion!, null, nugetSettings);
-                        var downloadedPath = await downloader.DownloadAndInstallPackage();
-                        var downloadedAssembly = Path.Combine(downloadedPath, $"{external.Package}.dll");
-                        if (File.Exists(downloadedAssembly))
-                        {
-                            assemblyPath = downloadedAssembly;
-                        }
-                    }
-                }
-                catch (Exception ex)
-                {
-                    generator.Emitter?.Debug(
-                        $"Could not download package '{external.Package}' for external type '{external.Identity}': {ex.Message}");
-                }
-            }
-
             if (assemblyPath == null || !File.Exists(assemblyPath))
             {
                 var versionQualifier = string.IsNullOrEmpty(external.MinVersion)