Merge pull request #239 from microsoftgraph/build_middleware_chain

Simplify building middleware chain

Author: krototype

spec/core/HTTPClient.ts

@@ -7,9 +7,13 @@
 
 import { assert } from "chai";
 
+import { Client } from "../../src/Client";
 import { HTTPClient } from "../../src/HTTPClient";
 import { Context } from "../../src/IContext";
 import { FetchOptions } from "../../src/IFetchOptions";
+import { RedirectHandlerOptions } from "../../src/middleware/options/RedirectHandlerOptions";
+import { RedirectHandler } from "../../src/middleware/RedirectHandler";
+import { TelemetryHandler } from "../../src/middleware/TelemetryHandler";
 import { DummyHTTPMessageHandler } from "../DummyHTTPMessageHandler";
 
 describe("HTTPClient.ts", () => {
@@ -68,4 +72,39 @@ describe("HTTPClient.ts", () => {
 			}
 		});
 	});
+
+	describe("getMiddlewareArray", () => {
+		it("Should work fine for a single middleware in the chain, which does have a getNext method", () => {
+			const telemetryHandler = new TelemetryHandler();
+			const tempHttpClient: HTTPClient = new HTTPClient(telemetryHandler);
+			assert.equal(tempHttpClient.getMiddlewareArray().length, 1);
+		});
+
+		it("Should work fine for a single middleware in the chain, which doesn't have a getNext method", () => {
+			const tempHttpClient: HTTPClient = new HTTPClient(httpMessageHandler);
+			assert.equal(tempHttpClient.getMiddlewareArray().length, 1);
+		});
+
+		it("Should work fine for a chain containing many middlewares", () => {
+			const telemetryHandler = new TelemetryHandler();
+			const redirectHandler = new RedirectHandler(new RedirectHandlerOptions());
+			redirectHandler.setNext(telemetryHandler);
+			telemetryHandler.setNext(httpMessageHandler);
+			const tempHttpClient: HTTPClient = new HTTPClient(redirectHandler);
+			assert.equal(tempHttpClient.getMiddlewareArray().length, 3);
+		});
+	});
+
+	describe("setMiddlewareArray", () => {
+		it("Should make a chain out of the provided array of middlewares", () => {
+			const telemetryHandler = new TelemetryHandler();
+			const redirectHandler = new RedirectHandler(new RedirectHandlerOptions());
+			redirectHandler.setNext(httpMessageHandler);
+			const tempHttpClient: HTTPClient = new HTTPClient(redirectHandler);
+			const middlewareArray = tempHttpClient.getMiddlewareArray();
+			middlewareArray.splice(1, 0, telemetryHandler);
+			tempHttpClient.setMiddlewareArray(middlewareArray);
+			assert.equal(tempHttpClient.getMiddlewareArray().length, 3);
+		});
+	});
 });

src/Client.ts

@@ -16,6 +16,7 @@ import { HTTPClient } from "./HTTPClient";
 import { HTTPClientFactory } from "./HTTPClientFactory";
 import { ClientOptions } from "./IClientOptions";
 import { Options } from "./IOptions";
+import { Middleware } from "./middleware/IMiddleware";
 import { validatePolyFilling } from "./ValidatePolyFilling";
 
 export class Client {
@@ -103,6 +104,24 @@ export class Client {
 		this.httpClient = httpClient;
 	}
 
+	/**
+	 * @public
+	 * function to get the array of middlewares in use right now
+	 * @returns An array of middlewares
+	 */
+	public getMiddlewareChain() {
+		return this.httpClient.getMiddlewareArray();
+	}
+
+	/**
+	 * @public
+	 * function to set the middleware chain
+	 * @param {Middleware[]} middlewareArray - An array of middlewares
+	 */
+	public setMiddlewareChain(middlewareArray: Middleware[]) {
+		return this.httpClient.setMiddlewareArray(middlewareArray);
+	}
+
 	/**
 	 * @public
 	 * Entry point to make requests

src/HTTPClient.ts

@@ -33,6 +33,37 @@ export class HTTPClient {
 		this.middleware = middleware;
 	}
 
+	/**
+	 * @public
+	 * To get an array of Middleware, used in middleware chain
+	 * @returns An array of middlewares
+	 */
+	public getMiddlewareArray(): Middleware[] {
+		const middlewareArray: Middleware[] = [];
+		let currentMiddleware = this.middleware;
+		while (currentMiddleware) {
+			middlewareArray.push(currentMiddleware);
+			if (typeof currentMiddleware.getNext !== "undefined") {
+				currentMiddleware = currentMiddleware.getNext();
+			} else {
+				break;
+			}
+		}
+		return middlewareArray;
+	}
+
+	/**
+	 * @public
+	 * To set the middleware chain
+	 * @param {Middleware[]} middlewareArray - The array containing the middlewares
+	 */
+	public setMiddlewareArray(middlewareArray: Middleware[]) {
+		for (let num = 0; num < middlewareArray.length - 1; num += 1) {
+			middlewareArray[num].setNext(middlewareArray[num + 1]);
+		}
+		this.middleware = middlewareArray[0];
+	}
+
 	/**
 	 * @public
 	 * @async

src/middleware/AuthenticationHandler.ts

@@ -94,4 +94,13 @@ export class AuthenticationHandler implements Middleware {
 	public setNext(next: Middleware): void {
 		this.nextMiddleware = next;
 	}
+
+	/**
+	 * @public
+	 * To get the next middleware in the chain
+	 * @returns next Middleware instance
+	 */
+	public getNext(): Middleware {
+		return this.nextMiddleware;
+	}
 }

src/middleware/IMiddleware.ts

@@ -15,4 +15,5 @@ import { Context } from "../IContext";
 export interface Middleware {
 	execute: (context: Context) => Promise<void>;
 	setNext?: (middleware: Middleware) => void;
+	getNext?: () => Middleware;
 }

src/middleware/RedirectHandler.ts

@@ -243,4 +243,13 @@ export class RedirectHandler implements Middleware {
 	public setNext(next: Middleware): void {
 		this.nextMiddleware = next;
 	}
+
+	/**
+	 * @public
+	 * To get the next middleware in the chain
+	 * @returns next Middleware instance
+	 */
+	public getNext(): Middleware {
+		return this.nextMiddleware;
+	}
 }

src/middleware/RetryHandler.ts

@@ -216,4 +216,13 @@ export class RetryHandler implements Middleware {
 	public setNext(next: Middleware): void {
 		this.nextMiddleware = next;
 	}
+
+	/**
+	 * @public
+	 * To get the next middleware in the chain
+	 * @returns next Middleware instance
+	 */
+	public getNext(): Middleware {
+		return this.nextMiddleware;
+	}
 }

src/middleware/TelemetryHandler.ts

@@ -96,4 +96,13 @@ export class TelemetryHandler implements Middleware {
 	public setNext(next: Middleware): void {
 		this.nextMiddleware = next;
 	}
+
+	/**
+	 * @public
+	 * To get the next middleware in the chain
+	 * @returns next Middleware instance
+	 */
+	public getNext(): Middleware {
+		return this.nextMiddleware;
+	}
 }