$http interceptor

httpInterceptor.js

/**
 * App Factory: httpInterceptor
 * -------------------------
 * The $http interceptor.
 * This is where you can modify the $http message before/after the request is sent to the server.
 * 
 * Here's a very useful article regarding $http interceptors:
 *     https://thinkster.io/interceptors
 *     
 * USEFUL TIP:
 *    You can directly refer to the Engage API by just passing the api route in the URL parameter.
 *    eg: $http.post('/o/token', apiParam)
 *    This will automatically determine that you will be calling the Engage API,
 *    unless you provide another specific url. eg: $http.post('https://another-api/just/another/method', apiParam).
 *    See httpInterceptor.js for reference.
 */
(function() {

    'use strict';

    angular.module('Engage.Factories').factory('httpInterceptor', httpInterceptor);

    function httpInterceptor($q, ENGAGE_API) {

        return {
            request: OnRequest
        };

        ////////////////////////////
        /// FUNCTION DEFINITIONS ///
        ////////////////////////////

        /**
         * On request interceptor.
         * 
         * @param {Object} req - The $http request
         *
         * @return {Promise}
         */
        function OnRequest(req) {
            
            var d = $q.defer();

            // If the url starts with forward slash (/),
            // we will assume that we are referring to the Engage API.
            // So we'll change the target URL before sending a $http request to avoid request error.
            if (req.url.indexOf('/') === 0)
                req.url = ENGAGE_API.BASE_URL + req.url;

            d.resolve(req);

            return d.promise;

        }

    }

}());