feat(client): add and export a module that allows the client proxy to…

… be injected

Provide a GooglePubSubModule that exports a client proxy instance, allowing it to be injected

re #2

lib/client/client-google-pubsub.ts

@@ -30,6 +30,15 @@ export class ClientGooglePubSub extends ClientProxy {
         this.googlePubSubClient = options?.pubSubClient ?? new PubSub(options?.pubSubClientConfig);
     }
 
+    /**
+     * Create and return a new ClientGooglePubSub instance
+     * @param options
+     * @returns
+     */
+    public static create(options?: GooglePubSubOptions): ClientGooglePubSub {
+        return new this(options);
+    }
+
     /**
      * Since the client on starts listening for messages when event subscribers are added, this
      * method does nothing

lib/client/google-pubsub.module.ts

@@ -0,0 +1,88 @@
+import { DynamicModule, Module, Provider } from '@nestjs/common';
+import { GOOGLE_PUBSUB_CLIENT_TOKEN, GOOGLE_PUBSUB_MODULE_OPTIONS } from '../constants';
+import {
+    GooglePubSubModuleAsyncOptions,
+    GooglePubSubModuleOptionsFactory,
+    GooglePubSubOptions,
+} from '../interfaces';
+import { ClientGooglePubSub } from './client-google-pubsub';
+
+// This bit is adapted from the built from http-service:
+// https://github.com/nestjs/nest/tree/6a61a593b9d388144ea5497909c03612c298214c/packages/common/http
+@Module({
+    providers: [
+        {
+            provide: GOOGLE_PUBSUB_CLIENT_TOKEN,
+            useValue: ClientGooglePubSub,
+        },
+    ],
+    exports: [GOOGLE_PUBSUB_CLIENT_TOKEN],
+})
+export class GooglePubSubModule {
+    static register(options: GooglePubSubOptions): DynamicModule {
+        return {
+            module: GooglePubSubModule,
+            providers: [
+                {
+                    provide: GOOGLE_PUBSUB_CLIENT_TOKEN,
+                    useValue: ClientGooglePubSub.create(options),
+                },
+            ],
+        };
+    }
+
+    static registerAsync(options: GooglePubSubModuleAsyncOptions): DynamicModule {
+        return {
+            module: GooglePubSubModule,
+            imports: options.imports,
+            providers: [
+                ...this.createAsyncProviders(options),
+                {
+                    provide: GOOGLE_PUBSUB_CLIENT_TOKEN,
+                    useFactory: (config: GooglePubSubOptions) => ClientGooglePubSub.create(config),
+                    inject: [GOOGLE_PUBSUB_MODULE_OPTIONS],
+                },
+                ...(options.extraProviders || []),
+            ],
+        };
+    }
+
+    private static createAsyncProviders(options: GooglePubSubModuleAsyncOptions): Provider[] {
+        if (options.useExisting || options.useFactory) {
+            return [this.createAsyncOptionsProvider(options)];
+        }
+        return [
+            this.createAsyncOptionsProvider(options),
+            {
+                // TODO: Change the options to a conditional type so we can be assured _at least_
+                // one of these is present
+                // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+                // @ts-ignore
+                provide: options.useClass,
+                // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+                // @ts-ignore
+                useClass: options.useClass,
+            },
+        ];
+    }
+
+    private static createAsyncOptionsProvider(options: GooglePubSubModuleAsyncOptions): Provider {
+        if (options.useFactory) {
+            return {
+                provide: GOOGLE_PUBSUB_MODULE_OPTIONS,
+                useFactory: options.useFactory,
+                inject: options.inject || [],
+            };
+        }
+        return {
+            provide: GOOGLE_PUBSUB_MODULE_OPTIONS,
+            useFactory: async (optionsFactory: GooglePubSubModuleOptionsFactory) =>
+                optionsFactory.createGooglePubSubOptions(),
+            // TODO: Change the options to a conditional type so we can be assured _at least_
+            // one of these is present
+            // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+            // @ts-ignore
+            inject: [options.useExisting || options.useClass],
+        };
+    }
+}

lib/constants.ts

@@ -1 +1,3 @@
 export const GOOGLE_PUBSUB_SUBSCRIPTION_MESSAGE_EVENT = 'message';
+export const GOOGLE_PUBSUB_CLIENT_TOKEN = 'GOOGLE_PUBSUB_INSTANCE_TOKEN';
+export const GOOGLE_PUBSUB_MODULE_OPTIONS = 'GOOGLE_PUBSUB_MODULE_OPTIONS';

lib/interfaces.ts

@@ -1,4 +1,5 @@
 import { ClientConfig, Message, PubSub, Subscription, Topic } from '@google-cloud/pubsub';
+import { ModuleMetadata, Provider, Type } from '@nestjs/common';
 import { ClientGooglePubSub } from './client';
 import { GooglePubSubContext } from './ctx-host';
 
@@ -66,3 +67,15 @@ export interface GooglePubSubOptions {
     pubSubClient?: PubSub;
     pubSubClientConfig?: ClientConfig;
 }
+
+export interface GooglePubSubModuleOptionsFactory {
+    createGooglePubSubOptions(): Promise<GooglePubSubOptions> | GooglePubSubOptions;
+}
+
+export interface GooglePubSubModuleAsyncOptions extends Pick<ModuleMetadata, 'imports'> {
+    useExisting?: Type<GooglePubSubModuleOptionsFactory>;
+    useClass?: Type<GooglePubSubModuleOptionsFactory>;
+    useFactory?: (...args: any[]) => Promise<GooglePubSubOptions> | GooglePubSubOptions;
+    inject?: any[];
+    extraProviders?: Provider[];
+}