Personal blog written from scratch using Node.js, Bootstrap, and MySQL.
https://jrtechs.net
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235 lines
5.3 KiB
235 lines
5.3 KiB
/**
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* File: Includes.js
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*
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* Module used for fetching static content for the website
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* like js, css, images, and other static html pages
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*
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* @author Jeffery Russell
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*/
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const HEADER_KEY = "header";
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const FOOTER_KEY = "footer";
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//name of header file
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const HEADER_FILE = "includes/html/header.html";
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//path of footer file
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const FOOTER_FILE = "includes/html/footer.html";
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//admin header path
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const ADMIN_HEADER = "includes/html/adminHeader.html";
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//used for hashing stuff for the header's e-tag for clients cache
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const crypto = require('crypto');
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//caching program to make the application run faster
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const cache = require('memory-cache');
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const fs = require('fs');
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const readFile = function(filename)
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{
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return new Promise(function(resolve, reject)
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{
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try
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{
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resolve(fs.readFileSync(filename));
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}
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catch (e)
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{
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console.log(e);
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console.log("Could not find " + filename);
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return("");
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}
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})
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};
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/**
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* Sends a static file to the client in a way which the web browser
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* caches the contents sent.
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*
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* @param cache -- server's hashmap which reduces file io
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* @param path -- file requested by user
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* @param type -- type of file for the header
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* @param result -- sent to client
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*/
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const sendCachedContent = function(path, type, result)
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{
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const goods = cache.get(path);
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if(goods == null)
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{
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readFile(path).then(function(content)
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{
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const eTag = crypto.createHash('md5').update(content).digest('hex');
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result.writeHead(200, {'Content-Type': type, 'Cache-Control':
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'public, max-age=2678400', 'ETag': '"' + eTag + '"',
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'Vary': 'Accept-Encoding'});
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result.write(content);
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result.end();
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}).catch(function(error)
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{
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cache.del(path);
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console.log(error);
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});
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}
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else
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{
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const eTag = crypto.createHash('md5').update(goods).digest('hex');
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result.writeHead(200, {'Content-Type': type,
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'Cache-Control': 'public, max-age=2678400',
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'ETag': '"' + eTag + '"',
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'Vary': 'Accept-Encoding'});
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result.write(goods);
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result.end();
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}
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};
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module.exports =
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{
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/** Appends the header html section to the result which is
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* sent to the user.
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*
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* @param result
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* @return {*} a promise retrieved from the utils.include function
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*/
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printHeader: function(templateContext)
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{
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return module.exports.includeInObject(HEADER_KEY, templateContext, HEADER_FILE);
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},
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includeInObject: function(key, context, fileName)
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{
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return new Promise(function(resolve, reject)
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{
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readFile(fileName).then(function(result)
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{
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context[key] = result;
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resolve();
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}).catch(function(error)
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{
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context[key] = "File Not Found";
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reject(error);
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console.log(error);
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})
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});
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},
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/**
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* A function similar to the include statement in PHP
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* This function writes a file to the output
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*
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* @param fileName the file to append to the result
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*/
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include: function(fileName)
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{
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return readFile(fileName);
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},
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/**
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* Appends the footer to the result object
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*
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* @return {*|Promise}
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*/
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printFooter: function(templateContext)
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{
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return module.exports.includeInObject(FOOTER_KEY, templateContext, FOOTER_FILE);
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},
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/**
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* Displays the admin header
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*
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* @returns {*|Promise}
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*/
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printAdminHeader(templateContext)
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{
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return module.exports.includeInObject(HEADER_KEY, templateContext, ADMIN_HEADER);
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},
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/**Sends a css file to the user
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*
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* @param result
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* @param path
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* @return {*}
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*/
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sendCSS: function(result, path)
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{
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sendCachedContent(path, 'text/css', result);
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},
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/**Sends the user an image from the specified fileName.
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*
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* @param result
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* @param fileName
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*/
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sendImage: function(result, fileName)
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{
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sendCachedContent(fileName, 'image/png', result);
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},
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/**Sends the user an image from the specified fileName.
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*
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* @param result
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* @param fileName
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*/
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sendJS: function(result, fileName)
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{
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sendCachedContent(fileName, 'application/javascript', result);
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},
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fetchTemplate: function(templateName)
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{
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return readFile("templates/" + templateName);
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},
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/**Sends the user an image from the specified fileName.
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*
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* @param result
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* @param fileName
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*/
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sendHTML: function(result, fileName)
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{
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readFile(fileName).then(function(content)
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{
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result.writeHead(200, {'Content-Type': 'text/html'});
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result.write(content);
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result.end();
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}).catch(function(error)
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{
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console.log(error);
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});
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},
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/**
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* Sends a svg file to the client.
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*
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* @param result
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* @param fileName
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*/
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sendSVG: function(result, fileName)
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{
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sendCachedContent(fileName, 'image/svg+xml', result);
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},
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/**
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* Clears the cache
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*/
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clearCache: function()
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{
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console.log("Includes cache cleared");
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cache.clear();
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}
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};
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