Personal blog written from scratch using Node.js, Bootstrap, and MySQL. https://jrtechs.net
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/**
* File: Includes.js
*
* Module used for fetching static content for the website
* like js, css, images, and other static html pages
*
* @author Jeffery Russell
*/
const HEADER_KEY = "header";
const FOOTER_KEY = "footer";
//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');
const fs = require('fs');
const readFile = function(filename)
{
return new Promise(function(resolve, reject)
{
try
{
resolve(fs.readFileSync(filename));
}
catch (e)
{
console.log(e);
console.log("Could not find " + filename);
return("");
}
})
};
/**
* 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)
{
readFile(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);
result.end();
}).catch(function(error)
{
cache.del(path);
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(templateContext)
{
return module.exports.includeInObject(HEADER_KEY, templateContext, HEADER_FILE);
},
includeInObject: function(key, context, fileName)
{
return new Promise(function(resolve, reject)
{
readFile(fileName).then(function(result)
{
context[key] = result;
resolve();
}).catch(function(error)
{
context[key] = "File Not Found";
reject(error);
console.log(error);
})
});
},
/**
* A function similar to the include statement in PHP
* This function writes a file to the output
*
* @param fileName the file to append to the result
*/
include: function(fileName)
{
return readFile(fileName);
},
/**
* Appends the footer to the result object
*
* @return {*|Promise}
*/
printFooter: function(templateContext)
{
return module.exports.includeInObject(FOOTER_KEY, templateContext, FOOTER_FILE);
},
/**
* Displays the admin header
*
* @returns {*|Promise}
*/
printAdminHeader(templateContext)
{
return module.exports.includeInObject(HEADER_KEY, templateContext, ADMIN_HEADER);
},
/**Sends a css file to the user
*
* @param result
* @param path
* @return {*}
*/
sendCSS: function(result, path)
{
sendCachedContent(path, 'text/css', result);
},
/**Sends the user an image from the specified fileName.
*
* @param result
* @param fileName
*/
sendImage: function(result, 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);
},
fetchTemplate: function(templateName)
{
return readFile("templates/" + templateName);
},
/**Sends the user an image from the specified fileName.
*
* @param result
* @param fileName
*/
sendHTML: function(result, fileName)
{
readFile(fileName).then(function(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);
},
/**
* Clears the cache
*/
clearCache: function()
{
console.log("Includes cache cleared");
cache.clear();
}
};