Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
const LinkSchema = require('../models/link');
const isUrl = require('../node_modules/validator/lib/isURL');
const alphabets = '23456789bcdfghjkmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ-_',
base = alphabets.length;
/**
* Saves the link to the database and returns a shortened one
*
* @param req URL to save and shorten
* @param res Shortened URL and other resource information
*/
const saveUrl = (req, res) => {
if(req.body.url && isUrl(req.body.url)){
const link = new LinkSchema(req.body);
link.save((err, doc) => {
if(err) {
return res.status(500).json({ message: 'Internal Server Error', error: err });
}
if(doc) {
const code = encode(doc._id);
res.status(201).json({
code: code,
link: req.protocol + '://' + req.get('host') + '/' + code
});
}
});
} else {
res.status(400).json({ message: 'Bad request: url is undefined or not formatted properly'});
}
};
/**
* Takes the code, decodes it, and searches
* the database for the record to redirect user
*
* @param req link code as request parameter
* @param res URL
*/
const getUrl = (req, res) => {
if(req.params.code){
const id = decode(req.params.code);
// todo extend with query params to include other metadata
const projection =
{ _id: false, url: true }; // only return URL in payload
LinkSchema.findById(id, projection, (err, link) => {
if(err) {
return res.status(500).json({ message: 'Internal Server Error', error: err });
}
if(link === null) return res.status(404).json({ message: 'Resource Not Found' });
res.status(200).json(link);
});
}
};
/**
* Taken from
* https://github.com/delight-im/ShortURL/blob/master/JavaScript/ShortURL.js
*
* @param num
* @returns returns shortened code that maps to the database
*/
const encode = (num) => {
let code = '';
while (num > 0) {
code = alphabets.charAt(num % base) + code;
num = Math.floor(num / base);
}
return code;
};
/**
* Taken from
* https://github.com/delight-im/ShortURL/blob/master/JavaScript/ShortURL.js
*
* @param code
* @returns ID in database
*/
const decode = (code) => {
let num = 0;
for (let i = 0; i < code.length; i++) {
num = num * base + alphabets.indexOf(code.charAt(i));
}
return num;
};
module.exports = {
saveUrl,
getUrl
};
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.