/** * File: Includes.js * * Module used for fetching static content for the website * like js, css, images, and other static html pages * * @author Jeffery Russell */ //used for file IO const utils = require('../utils/utils.js'); //name of header file const HEADER_FILE = "includes/html/header.html"; //path of footer file const FOOTER_FILE = "includes/html/footer.html"; //admin header path const ADMIN_HEADER = "includes/html/adminHeader.html"; //used for hashing stuff for the header's e-tag for clients cache const crypto = require('crypto'); //caching program to make the application run faster const cache = require('memory-cache'); /** * Sends a static file to the client in a way which the web browser * caches the contents sent. * * @param cache -- server's hashmap which reduces file io * @param path -- file requested by user * @param type -- type of file for the header * @param result -- sent to client */ const sendCachedContent = function(path, type, result) { const goods = cache.get(path); if(goods == null) { utils.include("." + path).then(function(content) { const eTag = crypto.createHash('md5').update(content).digest('hex'); result.writeHead(200, {'Content-Type': type, 'Cache-Control': 'public, max-age=2678400', 'ETag': '"' + eTag + '"', 'Vary': 'Accept-Encoding'}); result.write(content); console.log(content); result.end(); cache.put(path, content); }).catch(function(error) { console.log(error); }); } else { const eTag = crypto.createHash('md5').update(goods).digest('hex'); result.writeHead(200, {'Content-Type': type, 'Cache-Control': 'public, max-age=2678400', 'ETag': '"' + eTag + '"', 'Vary': 'Accept-Encoding'}); result.write(goods); result.end(); } }; module.exports = { /** Appends the header html section to the result which is * sent to the user. * * @param result * @return {*} a promise retrieved from the utils.include function */ printHeader: function() { return utils.include(HEADER_FILE); }, /** * Appends the footer to the result object * * @return {*|Promise} */ printFooter: function() { return utils.include(FOOTER_FILE); }, /** * Displays the admin header * * @returns {*|Promise} */ printAdminHeader() { return utils.include(ADMIN_HEADER); }, /**Sends a css file to the user * * @param result * @param path * @return {*} */ sendCSS: function(result, path, cache) { sendCachedContent(path, 'text/css', result); }, /**Sends the user an image from the specified fileName. * * @param result * @param fileName */ sendImage: function(result, fileName) { console.log(fileName); sendCachedContent(fileName, 'image/png', result); }, /**Sends the user an image from the specified fileName. * * @param result * @param fileName */ sendJS: function(result, fileName) { sendCachedContent(fileName, 'application/javascript', result); }, /**Sends the user an image from the specified fileName. * * @param result * @param fileName */ sendHTML: function(result, fileName) { utils.include("." + fileName).then(function(content) { console.log(fileName); console.log(content); result.writeHead(200, {'Content-Type': 'text/html'}); result.write(content); result.end(); }).catch(function(error) { console.log(error); }); }, /** * Sends a svg file to the client. * * @param result * @param fileName */ sendSVG: function(result, fileName) { sendCachedContent(fileName, 'image/svg+xml', result); } };