#!/usr/bin/env node

'use strict';

/* eslint no-console: 0 */

const Net = require('net');

const kPort = 9999;
const kEscape = new Buffer([0xFF, 0xF4, 0XFF, 0xFD, 0x06]); // IAC IP IAC DO TIMING_MARK
const kNAWSRequest = new Buffer([0xFF, 0xFD, 0X1F]); // IAC DO NAWS
const kNAWSResponse = new Buffer([0xFF, 0xFB, 0X1F, 0xFF, 0xFA, 0X1F]); // IAC WILL NAWS IAC SB NAWS
const kFrequency = 333;
const kModulationSpeed = 5;

const run = function run () {
  const server = startServer();
  bindEvents(server);
};

const startServer = function startServer () {
  const server = Net.createServer();
  server.listen(kPort, function () {
    const address = server.address();
    console.log(`The server is now listening on ${address.address}:${address.port}`);
  });

  return server;
};

const bindEvents = function bindEvents (server) {
  server.on('error', function (err) {
    console.error(err.stack || err.message || err);
    process.exit(1);
  });

  server.on('connection', function (socket) {
    let connectionData = {
      width: null,
      height: null,
      modulation: 0,
      screen: screens[Math.floor(Math.random() * screens.length)],
      mode: modes[Math.floor(Math.random() * modes.length)]
    };
    let interval = null;

    socket.write(kNAWSRequest);

    // Currently this is naive, we should parse the buffer properly.
    socket.on('data', function (data) {

      // Only send message if NAWS is supported.
      if (data.slice(0, 6).compare(kNAWSResponse) === 0) {
        connectionData.width = parse16BitBuffer(data.slice(6, 8));
        connectionData.height = parse16BitBuffer(data.slice(8, 10));

        socket.write('\x1B[2J'); // Clear the Screen (CSI 2 J)
        interval = setInterval(writeMessage.bind(null, socket, connectionData), kFrequency);
      }

      if (data.compare(kEscape) === 0) {
        socket.write('\n');
        clearInterval(interval);
        socket.end();
      }
    });
  });
};

const writeMessage = function writeMessage (socket, connectionData) {
  let message = '';
  message += '\x1B[1;1H'; // Move cursor to top left (CSI 1;1 H)
  message += connectionData.screen(connectionData.modulation, connectionData.width, connectionData.height, getANSIColor.bind(null, connectionData.mode));

  connectionData.modulation = connectionData.modulation + kModulationSpeed;
  if (connectionData.modulation === 255) {
    connectionData.modulation = 0;
  }

  socket.write(message);
  // return '\x1B[2J*** SUCCESSS ***';
};

const parse16BitBuffer = function parse16BitBuffer (buffer) {
  return buffer[0] * 256 + buffer[1];
};

// SCREENS

const fillScreen = function fillScreen (modulation, width, height, getANSIColor) {
  let response = '';

  for (let i = 0; i < height; i++) {
    for (let j = 0; j < width; j++) {
      let red = ((modulation + i) * 255 / height) % 255;
      let blue = ((modulation + j) * 255 / width) % 255;
      let green = ((modulation + i * j) * 255 / (width * height)) % 255;

      response = response + getANSIColor(red, blue, green);
      response = response + ' ';
    }

    if (i < height - 1) {
      response = response + '\n';
    }
  }

  return response;
};

const randomScreen = function randomScreen (modulation, width, height, getANSIColor) {
  let response = '';

  for (let i = 0; i < height; i++) {
    for (let j = 0; j < width; j++) {
      let red = Math.floor(Math.random() * 255);
      let blue = Math.floor(Math.random() * 255);
      let green = Math.floor(Math.random() * 255);

      response = response + getANSIColor(red, blue, green);
      response = response + ' ';
    }

    if (i < height - 1) {
      response = response + '\n';
    }
  }

  return response;
};

const mirrorScreen = function mirrorScreen (modulation, width, height, getANSIColor) {
  let response = [];

  let scale = 2 + Math.round(Math.random() * 4);
  let scaledHeight = Math.floor(height / scale);
  let scaledWidth = Math.floor(width / scale);

  for (let i = 0; i < scaledHeight; i++) {
    let row = [];
    for (let j = 0; j < scaledWidth; j++) {
      let red = ((modulation + i) * 255 / height) % 255;
      let blue = ((modulation + j) * 255 / width) % 255;
      let green = ((modulation + i * j) * 255 / (width * height)) % 255;

      let cell = [getANSIColor(red, blue, green), ' '];
      row.push(cell.join(''));
    }

    let rowText = '';
    for (let j = 0; j < scale; j++) {
      rowText += row.reverse().join('');
    }

    for (let j = 1; j < scale; j++) {
      response[j * i] = rowText;
      response[(height - 1 - (j * i))] = rowText;
    }
  }

  return response.join('\n');
};

const randomSprinkles = function mirrorRandomScreen (modulation, width, height, getANSIColor) {
  let response = '';

  let maxSprinkleCount = (width * height) / 2;
  let minSprinkleCount = (width * height) / 8;
  let sprinkleCount = Math.round(Math.random() * (maxSprinkleCount - minSprinkleCount)) + minSprinkleCount;

  let red = Math.floor(Math.random() * 255);
  let blue = Math.floor(Math.random() * 255);
  let green = Math.floor(Math.random() * 255);

  for (let i = 0; i < sprinkleCount; i++) {
    let x = Math.round(Math.random() * (width - 1)) + 1;
    let y = Math.round(Math.random() * (height - 1)) + 1;

    let position = `\x1B[${y};${x}H`; // Move cursor to y,x (CSI y;x H)

    response += `${position}${getANSIColor(red, blue, green)} `;
  }

  return response;
};

const circlesScreen = function circlesScreen (modulation, width, height, getANSIColor) {
  let response = [];

  let circles = width > height ? height : width;

  for (let i = 0; i < circles; i++) {
    let centerX = Math.round(width / 2) + 1;
    let centerY = Math.round(height / 2) + 1;

    let red = Math.floor(Math.random() * 255);
    let blue = Math.floor(Math.random() * 255);
    let green = Math.floor(Math.random() * 255);

    for (let j = 0; j < 180; j++) {
      let angle =  2 * j * (Math.PI / 180);
      let x = Math.round(centerX + Math.sin(angle) * i);
      let y = Math.round(centerY + Math.cos(angle) * i);

      if (x <= width && x > 0 && y <= height && y > 0) {
        let position = `\x1B[${y};${x}H`; // Move cursor to y,x (CSI y;x H)
        response += `${position}${getANSIColor(red, blue, green)} `;
      }
    }
  }

  return response;
};

// instead of binding themode, return the one funciton...
const getANSIColor = function getANSIColor (mode, red, blue, green) {
  let colorCode;

  if (mode === '256') {
    let redValue = Math.round(red * 5 / 255);
    let blueValue = Math.round(blue * 5 / 255);
    let greenValue = Math.round(green * 5 / 255);

    let colorNumber = 16 + 36 * redValue + 6 * greenValue + blueValue;

    colorCode = `\x1B[48;5;${colorNumber}m`;
  } else if (mode === 'ansi') {
    let colorOffset = Math.round((red + blue + green) * 7 / (255 * 3));

    let colorNumber = 40 + colorOffset;

    colorCode = `\x1B[${colorNumber}m`;
  } else{
    colorCode = `\x1B[48;2;${Math.round(red)};${Math.round(green)};${Math.round(blue)}m`;
  }

  return colorCode;
};

const screens = [fillScreen, randomScreen, mirrorScreen, randomSprinkles, circlesScreen];
const modes = ['full', '256', 'ansi'];

run();