Analytics decorator

decorators.js

/**
 * This function is used to push client side events to redshift. It should only be used for client side only events,
 * any event that involves a request to the backend, will create similar events there
 *
 * ::USAGE::
 * ========
 *
 * analyticsDecorator({
 *   constant: 'CONSTANT', mapping(arg1, arg2) {
 *      return {
 *         userClicked: arg1,
 *         colorOfButton: arg2
 *    }
 *})
 *
 * decoratedMethod (arg1, arg2) {}
 *
 * @param constant {string}     This is a constant that will be used for running Map/Reduce jobs or similar, and for
 *                              generating dashboards
 * @param mapping {function}    This function takes the same arguments as the function we're decorating, and is used to
 *                              provide readable information about the event occurring
 * @returns {function}
 */
export default function analyticsDecorator ({constant, mapping}) {

    /**
     *
     * @param classDefintion {object}
     * @param methodName {string}
     * @param descriptor {object}
     * @returns {object}
     */
    return function analyticsInterceptor (classDefinition, methodName, descriptor) {
        // the method calls that require analytics binding, must also be bound the the class instance, this happens at
        // runtime, SHOULD_BIND is so that class is bound marked as needing, and the corresponding methods marked with
        // BIND_TO_INSTANCE are bound to the class
        classDefinition.SHOULD_BIND = true;

        const originalFunc = descriptor.value;

        function sendAnalytics (instance, ...args) {
            originalFunc.apply(instance, args);

            // requestAnimationFrame for minor performance improvements, ensure analytics only runs on client side
            window && window.requestAnimationFrame(() => {
                let additionalData = {};
                if (mapping) {
                    additionalData = mapping(...args);
                }
                analytics.track(constant, additionalData);
            });
        }

        sendAnalytics.BIND_TO_INSTANCE = true;

        // enumerable is set so that the methods can be enumerated and bound to the class
        descriptor.enumerable = true;
        descriptor.value = sendAnalytics;

        return descriptor;
    };
}