feat: refactor core to use Promises instead of callbacks (#55)

BREAKING CHANGE: None of the authenticators or request methods take callbacks as arguments anymore - they return Promises instead.

auth/authenticators/authenticator-interface.ts

@@ -23,9 +23,6 @@ export interface AuthenticateOptions {
   [propName: string]: any;
 }
 
-// callback can send one arg, error or null
-export type AuthenticateCallback = (result: null | Error) => void;
-
 export interface AuthenticatorInterface {
-  authenticate(options: AuthenticateOptions, callback: AuthenticateCallback): void
+  authenticate(options: AuthenticateOptions): Promise<void | Error>
 }

auth/authenticators/authenticator.ts

@@ -15,7 +15,7 @@
  */
 
 import { OutgoingHttpHeaders } from 'http';
-import { AuthenticateCallback, AuthenticateOptions, AuthenticatorInterface } from './authenticator-interface';
+import { AuthenticateOptions, AuthenticatorInterface } from './authenticator-interface';
 
 export class Authenticator implements AuthenticatorInterface {
   /**
@@ -31,7 +31,8 @@ export class Authenticator implements AuthenticatorInterface {
     }
   }
 
-  public authenticate(options: AuthenticateOptions, callback: AuthenticateCallback): void {
-    throw new Error('Should be implemented by subclass!');
+  public authenticate(options: AuthenticateOptions): Promise<void | Error> {
+    const error = new Error('Should be implemented by subclass!');
+    return Promise.reject(error);
   }
 }

auth/authenticators/basic-authenticator.ts

@@ -17,7 +17,7 @@
 import extend = require('extend');
 import { computeBasicAuthHeader, validateInput } from '../utils';
 import { Authenticator } from './authenticator';
-import { AuthenticateCallback, AuthenticateOptions, AuthenticatorInterface } from './authenticator-interface';
+import { AuthenticateOptions, AuthenticatorInterface } from './authenticator-interface';
 
 export type Options = {
   username?: string;
@@ -48,11 +48,13 @@ export class BasicAuthenticator extends Authenticator implements AuthenticatorIn
     this.password = options.password;
   }
 
-  public authenticate(options: AuthenticateOptions, callback: AuthenticateCallback): void {
-    const authHeaderString = computeBasicAuthHeader(this.username, this.password);
-    const authHeader = { Authorization: authHeaderString }
+  public authenticate(options: AuthenticateOptions): Promise<void> {
+    return new Promise((resolve, reject) => {
+      const authHeaderString = computeBasicAuthHeader(this.username, this.password);
+      const authHeader = { Authorization: authHeaderString }
 
-    options.headers = extend(true, {}, options.headers, authHeader);
-    callback(null);
+      options.headers = extend(true, {}, options.headers, authHeader);
+      resolve();
+    });
   }
 }

auth/authenticators/bearer-token-authenticator.ts

@@ -17,7 +17,7 @@
 import extend = require('extend');
 import { validateInput } from '../utils';
 import { Authenticator } from './authenticator';
-import { AuthenticateCallback, AuthenticateOptions, AuthenticatorInterface } from './authenticator-interface';
+import { AuthenticateOptions, AuthenticatorInterface } from './authenticator-interface';
 
 export type Options = {
   bearerToken: string;
@@ -48,9 +48,11 @@ export class BearerTokenAuthenticator extends Authenticator implements Authentic
     this.bearerToken = bearerToken;
   }
 
-  public authenticate(options: AuthenticateOptions, callback: AuthenticateCallback): void {
-    const authHeader = { Authorization: `Bearer ${this.bearerToken}` };
-    options.headers = extend(true, {}, options.headers, authHeader);
-    callback(null);
+  public authenticate(options: AuthenticateOptions): Promise<void> {
+    return new Promise((resolve, reject) => {
+      const authHeader = { Authorization: `Bearer ${this.bearerToken}` };
+      options.headers = extend(true, {}, options.headers, authHeader);
+      resolve();
+    });
   }
 }

auth/authenticators/no-auth-authenticator.ts

@@ -15,7 +15,7 @@
  */
 
 import { Authenticator } from './authenticator';
-import { AuthenticateCallback, AuthenticateOptions, AuthenticatorInterface } from './authenticator-interface';
+import { AuthenticateOptions, AuthenticatorInterface } from './authenticator-interface';
 
 export class NoAuthAuthenticator extends Authenticator implements AuthenticatorInterface {
   /**
@@ -29,8 +29,8 @@ export class NoAuthAuthenticator extends Authenticator implements AuthenticatorI
     super();
   }
 
-  public authenticate(options: AuthenticateOptions, callback: AuthenticateCallback): void {
+  public authenticate(options: AuthenticateOptions): Promise<void> {
     // immediately proceed to request. it will probably fail
-    callback(null);
+    return Promise.resolve();
   }
 }

auth/authenticators/token-request-based-authenticator.ts

@@ -18,7 +18,7 @@ import extend = require('extend');
 import { OutgoingHttpHeaders } from 'http';
 import { JwtTokenManager } from '../token-managers';
 import { Authenticator } from './authenticator';
-import { AuthenticateCallback, AuthenticateOptions, AuthenticatorInterface } from './authenticator-interface';
+import { AuthenticateOptions, AuthenticatorInterface } from './authenticator-interface';
 
 export type BaseOptions = {
   headers?: OutgoingHttpHeaders;
@@ -84,15 +84,11 @@ export class TokenRequestBasedAuthenticator extends Authenticator implements Aut
     this.tokenManager.setHeaders(this.headers);
   }
 
-  public authenticate(options: AuthenticateOptions, callback: AuthenticateCallback): void {
-    this.tokenManager.getToken((err, token) => {
-      if (err) {
-        callback(err);
-      } else {
-        const authHeader = { Authorization: `Bearer ${token}` };
-        options.headers = extend(true, {}, options.headers, authHeader);
-        callback(null);
-      }
+  public authenticate(options: AuthenticateOptions): Promise<void | Error> {
+    return this.tokenManager.getToken().then(token => {
+      const authHeader = { Authorization: `Bearer ${token}` };
+      options.headers = extend(true, {}, options.headers, authHeader);
+      return;
     });
   }
 }

auth/token-managers/cp4d-token-manager.ts

@@ -76,20 +76,12 @@ export class Cp4dTokenManager extends JwtTokenManager {
     this.password = options.password;
   }
 
-  /**
-   * Callback for handling response.
-   *
-   * @callback requestTokenCallback
-   * @param {Error} An error if there is one, null otherwise
-   * @param {Object} The response if request is successful, null otherwise
-   */
   /**
    * Request an CP4D token using a basic auth header.
    *
-   * @param {requestTokenCallback} callback - The callback that handles the response.
-   * @returns {void}
+   * @returns {Promise}
    */
-  protected requestToken(callback: Function): void {
+  protected requestToken(): Promise<any> {
     // these cannot be overwritten
     const requiredHeaders = {
       Authorization: computeBasicAuthHeader(this.username, this.password),
@@ -103,6 +95,6 @@ export class Cp4dTokenManager extends JwtTokenManager {
         rejectUnauthorized: !this.disableSslVerification,
       }
     };
-    this.requestWrapperInstance.sendRequest(parameters, callback);
+    return this.requestWrapperInstance.sendRequest(parameters);
   }
 }

auth/token-managers/iam-token-manager.ts

@@ -111,20 +111,12 @@ export class IamTokenManager extends JwtTokenManager {
     }
   }
 
-  /**
-   * Callback for handling response.
-   *
-   * @callback requestTokenCallback
-   * @param {Error} An error if there is one, null otherwise
-   * @param {Object} The response if request is successful, null otherwise
-   */
   /**
    * Request an IAM token using an API key.
    *
-   * @param {requestTokenCallback} callback - The callback that handles the response.
-   * @returns {void}
+   * @returns {Promise}
    */
-  protected requestToken(callback: Function): void {
+  protected requestToken(): Promise<any> {
     // these cannot be overwritten
     const requiredHeaders = {
       'Content-type': 'application/x-www-form-urlencoded',
@@ -148,6 +140,7 @@ export class IamTokenManager extends JwtTokenManager {
         rejectUnauthorized: !this.disableSslVerification,
       }
     };
-    this.requestWrapperInstance.sendRequest(parameters, callback);
+
+    return this.requestWrapperInstance.sendRequest(parameters);
   }
 }

auth/token-managers/jwt-token-manager.ts

@@ -36,7 +36,7 @@ export class JwtTokenManager {
   protected tokenName: string;
   protected disableSslVerification: boolean;
   protected headers: OutgoingHttpHeaders;
-  protected requestWrapperInstance;
+  protected requestWrapperInstance: RequestWrapper;
   private tokenInfo: any;
   private expireTime: number;
 
@@ -70,33 +70,24 @@ export class JwtTokenManager {
   }
 
   /**
-   * This function sends an access token back through a callback. The source of the token
-   * is determined by the following logic:
+   * This function returns a Promise that resolves with an access token, if successful.
+   * The source of the token is determined by the following logic:
    * 1. If user provides their own managed access token, assume it is valid and send it
    * 2. a) If this class is managing tokens and does not yet have one, make a request for one
    *    b) If this class is managing tokens and the token has expired, request a new one
    * 3. If this class is managing tokens and has a valid token stored, send it
    *
-   * @param {Function} cb - callback function that the token will be passed to
    */
-  public getToken(cb: Function) {
+  public getToken(): Promise<any> {
     if (!this.tokenInfo[this.tokenName] || this.isTokenExpired()) {
       // 1. request a new token
-      this.requestToken((err, tokenResponse) => {
-        if (!err) {
-          try {
-            this.saveTokenInfo(tokenResponse.result);
-          } catch(e) {
-            // send lower level error through callback for user to handle
-            err = e;
-          }
-        }
-        // return null for access_token if there is an error
-        return cb(err, this.tokenInfo[this.tokenName] || null);
+      return this.requestToken().then(tokenResponse => {
+        this.saveTokenInfo(tokenResponse.result);
+        return this.tokenInfo[this.tokenName];
       });
     } else {
       // 2. use valid, managed token
-      return cb(null, this.tokenInfo[this.tokenName]);
+      return Promise.resolve(this.tokenInfo[this.tokenName]);
     }
   }
 
@@ -129,12 +120,11 @@ export class JwtTokenManager {
   /**
    * Request a JWT using an API key.
    *
-   * @param {Function} cb - The callback that handles the response.
-   * @returns {void}
+   * @returns {Promise}
    */
-  protected requestToken(cb: Function): void {
+  protected requestToken(): Promise<any> {
     const err = new Error('`requestToken` MUST be overridden by a subclass of JwtTokenManagerV1.');
-    cb(err, null);
+    return Promise.reject(err);
   }
 
   /**

lib/base_service.ts

@@ -149,18 +149,18 @@ export class BaseService {
    * @param {Object} parameters.defaultOptions
    * @param {string} parameters.defaultOptions.serviceUrl - the base URL of the service
    * @param {OutgoingHttpHeaders} parameters.defaultOptions.headers - additional headers to be passed on the request.
-   * @param {Function} callback - callback function to pass the response back to
-   * @returns {ReadableStream|undefined}
+   * @returns {Promise<any>}
    */
-  protected createRequest(parameters, callback) {
+  protected createRequest(parameters): Promise<any> {
     // validate serviceUrl parameter has been set
     const serviceUrl = parameters.defaultOptions && parameters.defaultOptions.serviceUrl;
     if (!serviceUrl || typeof serviceUrl !== 'string') {
-      return callback(new Error('The service URL is required'), null);
+      return Promise.reject(new Error('The service URL is required'));
     }
 
-    this.authenticator.authenticate(parameters.defaultOptions, err => {
-      err ? callback(err) : this.requestWrapperInstance.sendRequest(parameters, callback);
+    return this.authenticator.authenticate(parameters.defaultOptions).then(() => {
+      // resolve() handles rejection as well, so resolving the result of sendRequest should allow for proper handling later
+      return this.requestWrapperInstance.sendRequest(parameters);
     });
   }
 

lib/requestwrapper.ts

@@ -120,7 +120,7 @@ export class RequestWrapper {
    * @returns {ReadableStream|undefined}
    * @throws {Error}
    */
-  public sendRequest(parameters, _callback) {
+  public sendRequest(parameters): Promise<any> {
     const options = extend(true, {}, parameters.defaultOptions, parameters.options);
     const { path, body, form, formData, qs, method, serviceUrl } = options;
     let { headers, url } = options;
@@ -201,14 +201,8 @@ export class RequestWrapper {
       },
     };
 
-    this.axiosInstance(requestParams)
-      // placing `catch` block first because it is for catching request errors
-      // if it is after the `then` block, it will also catch errors if they occur
-      // inside of the `then` block
-      .catch(error => {
-        _callback(this.formatError(error));
-      })
-      .then(res => {
+    return this.axiosInstance(requestParams).then(
+      res => {
         // sometimes error responses will still trigger the `then` block - escape that behavior here
         if (!res) { return };
 
@@ -221,17 +215,23 @@ export class RequestWrapper {
         res.result = res.data;
         delete res.data;
 
-        _callback(null, res);
-      });
+        // return another promise that resolves with 'res' to be handled in generated code
+        return res;
+      },
+      err => {
+        // return another promise that rejects with 'err' to be handled in generated code
+        throw this.formatError(err);
+      }
+    );
   }
 
   /**
    * Format error returned by axios
-   * @param  {Function} cb the request callback
+   * @param  {object} the object returned by axios via rejection
    * @private
-   * @returns {request.RequestCallback}
+   * @returns {Error}
    */
-  public formatError(axiosError: any) {
+  public formatError(axiosError: any): Error {
     // return an actual error object,
     // but make it flexible so we can add properties like 'body'
     const error: any = new Error();