feat(rc): Add Remote Config Version Management API (#920)

* Get remote config template by version number (#874)

* Get remote config template by version number

* Refactor unit tests for Remote Config (#884)

* Refactor unit tests

* Add Remote Config Rollback operation (#885)

* Add Remote Config Rollback operation

* Update docs and move etag validation to a helper function

* Update docs

* Introduce a util to create a template from API response

* PR fixes

* Remote Config Add list versions operation (#896)

* Remote Config: Add list versions operation

* Add version Impl and other PR fixes

* PR fixes

* Imrpoved unit tests and some code clean up

* Fix code formatting

* Add a separate function to get a Template with version (#902)

* Add version meta data to RC templates (#906)

* Add version meta data to RC templates

* PR fixes

* Use assertion to unwrap template.version

* Update Remote Config Docstrings in index.d.ts

src/index.d.ts

@@ -880,6 +880,11 @@ declare namespace admin.remoteConfig {
      * ETag of the current Remote Config template (readonly).
      */
     readonly etag: string;
+
+    /**
+     * Version information for the current Remote Config template.
+     */
+    version?: Version;
   }
 
   /**
@@ -984,6 +989,123 @@ declare namespace admin.remoteConfig {
    */
   type RemoteConfigParameterValue = ExplicitParameterValue | InAppDefaultValue;
 
+  /**
+   * Interface representing a Remote Config template version.
+   * Output only, except for the version description. Contains metadata about a particular
+   * version of the Remote Config template. All fields are set at the time the specified Remote
+   * Config template is published. A version's description field may be specified in
+   * `publishTemplate` calls.
+   */
+  export interface Version {
+    /**
+     * The version number of a Remote Config template.
+     */
+    versionNumber?: string;
+
+    /**
+     * The timestamp of when this version of the Remote Config template was written to the
+     * Remote Config backend.
+     */
+    updateTime?: string;
+
+    /**
+     * The origin of the template update action.
+     */
+    updateOrigin?: ('REMOTE_CONFIG_UPDATE_ORIGIN_UNSPECIFIED' | 'CONSOLE' |
+      'REST_API' | 'ADMIN_SDK_NODE');
+
+    /**
+     * The type of the template update action.
+     */
+    updateType?: ('REMOTE_CONFIG_UPDATE_TYPE_UNSPECIFIED' |
+      'INCREMENTAL_UPDATE' | 'FORCED_UPDATE' | 'ROLLBACK');
+
+    /**
+     * Aggregation of all metadata fields about the account that performed the update.
+     */
+    updateUser?: RemoteConfigUser;
+
+    /**
+     * The user-provided description of the corresponding Remote Config template.
+     */
+    description?: string;
+
+    /**
+     * The version number of the Remote Config template that has become the current version
+     * due to a rollback. Only present if this version is the result of a rollback.
+     */
+    rollbackSource?: string;
+
+    /**
+     * Indicates whether this Remote Config template was published before version history was
+     * supported.
+     */
+    isLegacy?: boolean;
+  }
+
+  /** Interface representing a list of Remote Config template versions. */
+  export interface ListVersionsResult {
+    /**
+     * A list of version metadata objects, sorted in reverse chronological order.
+     */
+    versions: Version[];
+
+    /**
+     * Token to retrieve the next page of results, or empty if there are no more results
+     * in the list.
+     */
+    nextPageToken?: string;
+  }
+
+  /** Interface representing options for Remote Config list versions operation. */
+  export interface ListVersionsOptions {
+    /**
+     * The maximum number of items to return per page.
+     */
+    pageSize?: number;
+
+    /**
+     * The `nextPageToken` value returned from a previous list versions request, if any.
+     */
+    pageToken?: string;
+
+    /** 
+     * Specifies the newest version number to include in the results.
+     * If specified, must be greater than zero. Defaults to the newest version.
+     */
+    endVersionNumber?: string | number;
+
+    /**
+     * Specifies the earliest update time to include in the results. Any entries updated before this
+     * time are omitted.
+     */
+    startTime?: Date | string;
+
+    /**
+     * Specifies the latest update time to include in the results. Any entries updated on or after
+     * this time are omitted.
+     */
+    endTime?: Date | string;
+  }
+
+  /** Interface representing a Remote Config user.*/
+  export interface RemoteConfigUser {
+    /**
+     * Email address. Output only.
+     */
+    email: string;
+
+    /**
+     * Display name. Output only.
+     */
+    name?: string;
+
+    /**
+     * Image URL. Output only.
+     */
+    imageUrl?: string;
+  }
+
   /**
    * The Firebase `RemoteConfig` service interface.
    *
@@ -1001,6 +1123,16 @@ declare namespace admin.remoteConfig {
      */
     getTemplate(): Promise<RemoteConfigTemplate>;
 
+    /**
+     * Gets the requested version of the {@link admin.remoteConfig.RemoteConfigTemplate
+     * `RemoteConfigTemplate`} of the project.
+     * 
+     * @param versionNumber Version number of the Remote Config template to look up.
+     * 
+     * @return A promise that fulfills with a `RemoteConfigTemplate`.
+     */
+    getTemplateAtVersion(versionNumber: number | string): Promise<RemoteConfigTemplate>;
+
     /**
      * Validates a {@link admin.remoteConfig.RemoteConfigTemplate `RemoteConfigTemplate`}.
      *
@@ -1025,6 +1157,32 @@ declare namespace admin.remoteConfig {
      */
     publishTemplate(template: RemoteConfigTemplate, options?: { force: boolean }): Promise<RemoteConfigTemplate>;
 
+    /**
+    * Rolls back a project's published Remote Config template to the specified version.
+    * A rollback is equivalent to getting a previously published Remote Config
+    * template and re-publishing it using a force update.
+    * 
+    * @param versionNumber The version number of the Remote Config template to roll back to.
+    *    The specified version number must be lower than the current version number, and not have
+    *    been deleted due to staleness. Only the last 300 versions are stored.
+    *    All versions that correspond to non-active Remote Config templates (that is, all except the
+    *    template that is being fetched by clients) are also deleted if they are more than 90 days old.
+    * @return A promise that fulfills with the published `RemoteConfigTemplate`.
+    */
+    rollback(versionNumber: string | number): Promise<RemoteConfigTemplate>;
+
+    /**
+    * Gets a list of Remote Config template versions that have been published, sorted in reverse 
+    * chronological order. Only the last 300 versions are stored.
+    * All versions that correspond to non-active Remote Config templates (that is, all except the 
+    * template that is being fetched by clients) are also deleted if they are more than 90 days old.
+    * 
+    * @param options Optional {@link admin.remoteConfig.ListVersionsOptions `ListVersionsOptions`}
+    *    object for getting a list of template versions.
+    * @return A promise that fulfills with a `ListVersionsResult`.
+    */
+    listVersions(options?: ListVersionsOptions): Promise<ListVersionsResult>;
+
     /**
      * Creates and returns a new Remote Config template from a JSON string.
      *
@@ -1110,7 +1268,7 @@ declare namespace admin.machineLearning {
      *
      * Example: `tfliteModel: { gcsTfliteUri: 'gs://your-bucket/your-model.tflite' }`
      */
-    tfliteModel?: {gcsTfliteUri: string};
+    tfliteModel?: { gcsTfliteUri: string };
   }
 
   /**