@barchart/common-node-js/aws/lambda/LambdaValidator.js

Common classes, utilities, and functions for building Node.js servers

const is = require('@barchart/common-js/lang/is');

const LambdaTriggerType = require('./LambdaTriggerType');

module.exports = (() => {
	'use strict';

	// 2020/11/29, BRI. This class will be removed in the next major version.
	// It will be replaced with the "LambdaEventValidator" ...

	/**
	 * Evaluates a Lambda event, checking the messages it contains to determine
	 * which are valid for processing.
	 *
	 * @public
	 */
	class LambdaValidator {
		constructor() {
		}

		/**
		 * Checks messages contained within a Lambda event for validity.
		 *
		 * @public
		 * @async
		 * @param {Object} event
		 * @return {Promise<Boolean>}
		 */
		async validate(event) {
			return Promise.resolve()
				.then(() => {
					let messages;

					if (is.array(event.Records)) {
						messages = event.Records;
					} else {
						messages = [ event ];
					}
					
					return Promise.all(messages.map((message) => {
						const trigger = LambdaTriggerType.fromMessage(message);

						let messageId;

						if (trigger !== null) {
							messageId = trigger.getId(message);
						} else {
							messageId = null;
						}
						
						let validatePromise;
						
						if (trigger !== null && messageId !== null) {
							validatePromise = Promise.resolve(this._validate(process.env.AWS_LAMBDA_FUNCTION_NAME, trigger, messageId));
						} else {
							validatePromise = Promise.resolve(true);
						}
						
						return validatePromise;
					}));
				}).then((results) => {
					return results.every(r => r === true);
				});
		}

		/**
		 * @protected
		 * @param {String} name
		 * @param {LambdaTriggerType} trigger
		 * @param {String} messageId
		 * @returns {Boolean|Promise<Boolean>}
		 */
		_validate(name, trigger, messageId) {
			return true;
		}
		
		toString() {
			return '[LambdaValidator]';
		}
	}

	return LambdaValidator;
})();