node.js + express example

const express = require('express')
const cors = require('cors')
const path = require('path')
const fs = require('fs')

const clf_date = require('clf-date')
const date_format = require('dateformat')
const moment = require('moment-timezone')
const morgan = require('morgan')

const qwk = require('./functions.js')
const app = express()

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var settings = { port: 1010, next_id: 0 }
var shortcuts = []

__dirname = path.join(__dirname, '..')
var currentLogPath = path.join(__dirname, 'logs', `${date_format(new Date(), "yyyy-mm-dd HH.MM.ss")}.log`)
var accessLogStream = fs.createWriteStream(currentLogPath, { flags: 'a' })

morgan.token('date', (req, res) => {
  return clf_date(new Date())
})

app.use(morgan(`[:date] :method :url :status :res[content-length] - :response-time ms`, { stream: accessLogStream }))
app.use(morgan(`[:date] :method :url :status :res[content-length] - :response-time ms`))
app.use(cors())

app.use('/', express.static(path.join(__dirname, 'public')))

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function normalizeUrl(url) {
  if (url.includes('https://')) {
    return url
  } else if (url.includes('http://')) {
    return url
  } else {
    return `https://${url}`
  }
}

function saveState() {
  fs.writeFileSync(path.join(__dirname, 'settings', 'settings.json'), JSON.stringify(settings, null, 2))
  fs.writeFileSync(path.join(__dirname, 'data', 'shortcuts.json'), JSON.stringify(shortcuts, null, 2))
}

function startup() {
  try {
    qwk.log(`Loading settings...`, 'Startup')
    settings = JSON.parse(fs.readFileSync(path.join(__dirname, 'settings', 'settings.json'), 'utf8'))
  } catch (e) {
    qwk.log(`Loading error, creating new settings file.`, 'Startup')
    fs.writeFileSync(path.join(__dirname, 'settings', 'settings.json'), JSON.stringify(settings, null, 2))
  }

  try {
    qwk.log(`Loading shortucts...`, 'Startup')
    shortcuts = JSON.parse(fs.readFileSync(path.join(__dirname, 'data', 'shortcuts.json'), 'utf8'))
    qwk.log(`Loaded ${shortcuts.length} shortucts`, 'Startup')
  } catch (e) {
    qwk.log(`Loading error, creating new shortucts file.`, 'Startup')
    fs.writeFileSync(path.join(__dirname, 'data', 'shortcuts.json'), JSON.stringify(shortcuts, null, 2))
  }
}

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// /api/create-shortcut/:
// params: url - string
// request example: /api/create-shortcut/?url=google.com
app.get('/api/create-shortcut/', function(request, response) {
  let url = request.query.url

  if (url == undefined) {
    response.status(400).send(`Error: param 'url' not found in request`)
    return
  }

  obj = { id: settings.next_id++, url: normalizeUrl(url) }

  for (var i = 0; i < shortcuts.length; i++) {
    if (shortcuts[i].url == obj.url) {
      response.send(JSON.stringify(shortcuts[i], null, 2))
      return
    }
  }

  shortcuts.push(obj)

  response.send(JSON.stringify(obj, null, 2))
  saveState()
})

// /:id:        (redirect by id)
// params: id - integer
// request example: /$integer
app.get('/:id/', function(request, response) {
  let id = request.params.id

  if (id == undefined) {
    response.status(400).send(`Error: param 'id' not found in request<br>Use sh.url/id`)
    return
  }

  for (var i = 0; i < shortcuts.length; i++) {
    if (shortcuts[i].id == id) {
      response.redirect(shortcuts[i].url)
      return
    }
  }

  response.status(404).sendFile(`${__dirname}/public/missing.html`)
})

// /api/redirect/:  (redirect by request)
// params: url - string
// request example: /api/redirect/?url=google.com
app.get('/api/redirect/', function(request, response) {
  let url = request.query.url

  if (url == undefined) {
    response.status(400).send(`Error: param 'url' not found in request`)
    return
  }

  response.redirect(normalizeUrl(url))
})

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startup()
app.listen(settings.port)
qwk.log(`Server started on ${settings.port}`, 'Startup')