Add namespace option to emitter (Azure#49466)

* Add namespace option to emitter

* more detail

* Add model-namespace

Author: JoshLove-msft

eng/packages/http-client-csharp/emitter/src/emitter.ts

@@ -5,12 +5,12 @@ import { EmitContext } from "@typespec/compiler";
 
 import {
   $onEmit as $onMTGEmit,
-  CSharpEmitterOptions
 } from "@typespec/http-client-csharp";
+import { AzureEmitterOptions } from "./options.js";
 
-export async function $onEmit(context: EmitContext<CSharpEmitterOptions>) {
+export async function $onEmit(context: EmitContext<AzureEmitterOptions>) {
   context.options["generator-name"] ??= "AzureClientGenerator";
   context.options["emitter-extension-path"] ??= import.meta.url;
   context.options["license"] ??= { name: "MIT License", company: "Microsoft Corporation" };
   await $onMTGEmit(context);
-}
+}

eng/packages/http-client-csharp/emitter/src/index.ts

@@ -1,4 +1,6 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
-export * from "./emitter.js";
+export { $onEmit } from "./emitter.js";
+export { AzureEmitterOptions, AzureEmitterOptionsSchema } from "./options.js";
+export { $lib } from "./lib/lib.js";

eng/packages/http-client-csharp/emitter/src/lib/lib.ts

@@ -0,0 +1,13 @@
+import { createTypeSpecLibrary } from "@typespec/compiler";
+import {
+    $lib as httpClientCSharpLib,
+  } from "@typespec/http-client-csharp";
+import { AzureEmitterOptionsSchema } from "../options.js";
+
+export const $lib = createTypeSpecLibrary({
+  name: "@azure-typespec/http-client-csharp",
+  diagnostics: httpClientCSharpLib.diagnostics,
+  emitter: {
+    options: AzureEmitterOptionsSchema,
+  },
+});

eng/packages/http-client-csharp/emitter/src/options.ts

@@ -0,0 +1,26 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+import { JSONSchemaType } from "@typespec/compiler";
+import { CSharpEmitterOptions, CSharpEmitterOptionsSchema } from "@typespec/http-client-csharp";
+
+export interface AzureEmitterOptions extends CSharpEmitterOptions {
+    namespace?: string;
+    "model-namespace"?: boolean;
+}
+  
+export const AzureEmitterOptionsSchema: JSONSchemaType<AzureEmitterOptions> = {
+  type: "object",
+  properties: {
+    ...CSharpEmitterOptionsSchema.properties,
+    namespace: {
+      type: "string",
+      description: "The C# namespace to use for the generated code. This will override the TypeSpec namespaces.",
+    },
+    "model-namespace": {
+      type: "boolean",
+      description: "Whether to put models under a separate 'Models' sub-namespace. This only applies if the 'namespace' option is set. " + 
+      " The default value is 'true' when the 'namespace' option is set. Otherwise, each model will be in the corresponding namespace defined in the TypeSpec.",
+    },
+  },
+};