#!/usr/bin/node

// Get some libraries
const random_bytes = require("random-bytes");
const bsplit = require("buffer-split");
const node_rsa = require("node-rsa");
const btoa = require("btoa");
const atob = require("atob");
const net = require("net");
const fs = require("fs");

// Load the settings
var settings = require("./settings.json");

console.log("Ready.");


function toBuffer(bytes)
{
  // String
  if(typeof(bytes) == 'string')
  {
    // Create a buffer
    var buffer = new Buffer.alloc(bytes.length);

    // Loop over the bytes
    for(var i=0;i<bytes.length;i++)
    {
      // Save to the buffer
      buffer[i] = bytes[i].charCodeAt(0);
    }

    // Return the buffer
    return buffer;
  }

  // Return if this is anything else
  return bytes;
}

function toBytes(buffer)
{
  // Make sure the buffer is a buffer
  buffer = toBuffer(buffer);

  // Create some bytes
  var bytes = "";

  // Loop over the buffer
  for(var i=0;i<buffer.length;i++)
  {
    // Add to the bytes string
    bytes += String.fromCharCode(buffer[i]);
  }

  // Return the bytes
  return bytes;
}

// Recieve helper global varibles
var recieve_buffer = new Buffer.alloc(0);
var recieve_get = false;
var recieve_size = 0;

function recieve_ordered(data, callback)
{
  // Convert the data into a buffer
  data = toBuffer(data);

  // Loop over the data
  for(var i=0;i<data.length;i++)
  {
    // Add the data to the buffer
    recieve_buffer = new Buffer.concat([recieve_buffer, Buffer([data[i]])]);

    // Is the buffer getting data
    if(!recieve_get)
    {
      // Does the buffer contain a number
      if(recieve_buffer.length >= 4)
      {
        // Get the number
        recieve_size = recieve_buffer.readUInt32BE(0);

        // Reset the buffer
        recieve_buffer = new Buffer.alloc(0);

        // Set the get data mode to true
        recieve_get = true;
      }
    }

    else
    {
      // Is the recieve buffer as big as the size
      if(recieve_buffer.length == recieve_size)
      {
        // Call the callback
        callback(recieve_buffer);

        // Reset the buffer and the size
        recieve_buffer = new Buffer.alloc(0);
        recieve_size = 0;

        // Set the get data mode to false
        recieve_get = false;
      }
    }
  }
}

function send_ordered(data)
{
  // Convert the data into a buffer
  data = toBuffer(data);

  // Get the size of the data
  var size = data.length;

  // Turn it into a 32 bit buffer
  var bytes = new Buffer.alloc(4);
  bytes.writeUInt32BE(size, 0);

  // Return the buffer and the data
  return new Buffer.concat([bytes, data]);
}

function string_decrypt(key, string)
{
  // Convert the string to a buffer
  var buff = toBuffer(string);

  // Create some new data
  var decrypted = new Buffer.alloc(buff.length);

  // Iterate over the string
  for(var i=0;i<string.length;i++)
  {
    // Convert the string item to a number
    var d = buff[i]-key.str[key.at.rx];
    while(d < 0) d += 256;
    decrypted[i] = d;

    // Add 1 to the key counter
    key.at.rx += 1;

    // Is the key counter out of range
    if(key.at.rx >= key.str.length)
    {
      // Set to zero
      key.at.rx = 0;
    }
  }

  // Return the encrypted data
  return decrypted;
}

function string_encrypt(key, string)
{
  // Convert the string to a buffer
  var buff = toBuffer(string);

  // Create some new data
  var encrypted = new Buffer.alloc(buff.length);

  // Iterate over the string
  for(var i=0;i<string.length;i++)
  {
    // Convert the string item to a number
    var e = buff[i]+key.str[key.at.tx];
    while(e > 255) e -= 256;
    encrypted[i] = e;

    // Add 1 to the key counter
    key.at.tx += 1;

    // Is the key counter out of range
    if(key.at.tx >= key.str.length)
    {
      // Set to zero
      key.at.tx = 0;
    }
  }

  // Return the encrypted data
  return encrypted;
}

function make_encryption_key(string)
{
  // Make a new key
  var key = new Object();

  // Set the varibles
  key.str = toBuffer(string);
  key.at = new Object();
  key.at.rx = 0;
  key.at.tx = 0;

  console.log("make_encryption_key:", key.str);

  // Return the key
  return key;
}

function socket_write(socket, data)
{
  // Send the data encrypted with JSON
  socket.sock.write(send_ordered(string_encrypt(socket.key, JSON.stringify(data)+"\n")));
}

function socket_init(socket, callback, ondata)
{
  // Set the socket
  var sock = new Object();
  sock.sock = socket;
  sock.new = true;

  console.log("Connection from "+socket.localAdress);

  // Wait for data
  sock.sock.on('data', function(data)
  {
    // Recieve data in order
    recieve_ordered(data, function(data)
    {
      console.log(data);

      // Is the socket new
      if(sock.new)
      {
        // Set sock new
        sock.new = false;

        // Convert from JSON
        data = JSON.parse(data);

        // Is this the public key
        if(data.mode == 'pubkey')
        {
          // Load the key
          var key = new node_rsa();
          key.importKey(data.key, 'public');
          console.log("Loaded the RSA key", data);

          // Get some random bytes
          random_bytes(settings.encryption_key_size, function(error,string)
          {
            console.log("btoa(string):",btoa(string));

            // Throw an error if there is one
            if(error) throw error;

            // Make the key
            sock.key = make_encryption_key(string);
            console.log("Created an encryption key")

            // Encrypt the key with RSA
            var key_encrypted = key.encrypt(string, 'base64');
            console.log("Encrypted the key: ", toBytes(key_encrypted));

            // Send the key to the client
            sock.sock.write(send_ordered(JSON.stringify({
              key: toBytes(key_encrypted),
              mode: "encryption_key"
            })));

            console.log("Sent the key to the client");
          });
        }
      }

      else
      {
        // Decrypt the data
        data = string_decrypt(sock.key, data);

        console.log(data);

        // Parse the json data
        var data = JSON.parse(data);

        // Is the data status 1
        if(data == 1)
        {
          console.log("Recieved 1");
          // Send the callback
          callback(sock);
        }

        else
        {
          console.log(data);
          // Send the parsed data to the callback
          ondata(data);
        }
      }
    });
  });

  // Return the socket
  return sock;
}

// Create a server
var server = net.createServer(function(socket)
{
  var sock;

  // Initialise the socket and wait for data
  socket_init(socket, function(socket)
  {
    socket_write(socket, {message: "From the server! :D", array: [1,2,3,4,6,5,"xD",12]});
    sock = socket;
  },
  function(data)
  {
    console.log(data);
    socket_write(sock, {echo: data});
  });
});

// Listen for data
server.listen(22068, '');