const http = require('http');
const url = require('url');
const fs = require('fs');
const ws = require('ws');
const redis = require('redis')

//redis client
const redis_client = redis.createClient()
redis_client.on("error", function (error) {
  console.error(error)
})

//HTTP server
http.createServer(function (req, res) {
  const q = url.parse(req.url, true);
  let filename = "./public" + q.pathname;
  if (filename === "./public/") filename = "./public/index.html";
  fs.readFile(filename, function(err, data) {
    if (err) {
      res.writeHead(404, {'Content-Type': 'text/html'});
      return res.end("404 Not Found");
    }
    res.writeHead(200, {'Content-Type': 'text/html'});
    res.write(data);
    return res.end();
  });
}).listen(8080);

//WS server
const wss = new ws.Server({
  port: 8081,
  perMessageDeflate: {
    zlibDeflateOptions: {
      // See zlib defaults.
      chunkSize: 1024,
      memLevel: 7,
      level: 3
    },
    zlibInflateOptions: {
      chunkSize: 10 * 1024
    },
    // Other options settable:
    clientNoContextTakeover: true, // Defaults to negotiated value.
    serverNoContextTakeover: true, // Defaults to negotiated value.
    serverMaxWindowBits: 10, // Defaults to negotiated value.
    // Below options specified as default values.
    concurrencyLimit: 10, // Limits zlib concurrency for perf.
    threshold: 1024 // Size (in bytes) below which messages
    // should not be compressed.
  }
});

//WS handler
wss.on('connection', ws => {
  ws.on('message', message => {
    console.log(`Received message => ${message}`)
    let msg = `${message}`.split(";", 2)
    if (msg[0] === 'long_url') {
      if (msg[1] === '') ws.send('error;url is empty')
      if (msg[1].length > 2000) ws.send('error;your url is too big')
      else{
        let ran_key = get_key(8)
        //redis_client.set("key", "value", redis.print)
        ws.send('short_url;http://127.0.0.1'+ran_key)
      }
    }
    //ws.send('got your request: '+msg)
    console.log(msg[0])
  })
  ws.send('websocket connected')
})

//random key
const forbidden_array = ['sym', 'admin', 'stats']
function get_key(length) {
  let forbidden = false; let output = ''
  let characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'
  do{
    for (let i = 0; i < length; i++ )
      output += characters.charAt(Math.floor(Math.random() * characters.length))
    for (let i = 0; i < forbidden_array.length; i++) if (output === forbidden_array[i]) forbidden = true
  } while (forbidden)
  return output
}