HTTPClient.ts

/**
 * -------------------------------------------------------------------------------------------
 * Copyright (c) Microsoft Corporation. All Rights Reserved. Licensed under the MIT License.
 * See License in the project root for license information.
 * -------------------------------------------------------------------------------------------
 */

/**
 * @module HTTPClient
 */

import{Context}from"./IContext";
import{Middleware}from"./middleware/IMiddleware";

/**
 * @class
 * Class representing HTTPClient
 */
exportclassHTTPClient{
/**
 * @private
 * A member holding first middleware of the middleware chain
 */
privatemiddleware: Middleware;

/**
 * @public
 * @constructor
 * Creates an instance of a HTTPClient
 * @param {...Middleware} middleware - The first middleware of the middleware chain or a sequence of all the Middleware handlers
 */
publicconstructor(...middleware: Middleware[]){
if(!middleware||!middleware.length){
consterror=newError();
error.name="InvalidMiddlewareChain";
error.message="Please provide a default middleware chain or custom middleware chain";
throwerror;
}
this.setMiddleware(...middleware);
}

/**
 * @private
 * Processes the middleware parameter passed to set this.middleware property
 * The calling function should validate if middleware is not undefined or not empty.
 * @param {...Middleware} middleware - The middleware passed
 * @returns Nothing
 */
privatesetMiddleware(...middleware: Middleware[]): void{
if(middleware.length>1){
this.parseMiddleWareArray(middleware);
}else{
this.middleware=middleware[0];
}
}

/**
 * @private
 * Processes the middleware array to construct the chain
 * and sets this.middleware property to the first middleware handler of the array
 * The calling function should validate if middleware is not undefined or not empty
 * @param {Middleware[]} middlewareArray - The array of middleware handlers
 * @returns Nothing
 */
privateparseMiddleWareArray(middlewareArray: Middleware[]){
middlewareArray.forEach((element,index)=>{
if(index<middlewareArray.length-1){
element.setNext(middlewareArray[index+1]);
}
});
this.middleware=middlewareArray[0];
}

/**
 * @public
 * @async
 * To send the request through the middleware chain
 * @param {Context} context - The context of a request
 * @returns A promise that resolves to the Context
 */
publicasyncsendRequest(context: Context): Promise<Context>{
if(typeofcontext.request==="string"&&context.options===undefined){
consterror=newError();
error.name="InvalidRequestOptions";
error.message="Unable to execute the middleware, Please provide valid options for a request";
throwerror;
}
awaitthis.middleware.execute(context);
returncontext;
}
}