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'use strict';
const Net = require('net');
const EventEmitter = require('events');
const Util = require('./util');
const internals = {
// Interpret as Command Sequences.
kEscape: Buffer.from([0xFF, 0xF4, 0XFF, 0xFD, 0x06]), // IAC IP IAC DO TIMING_MARK
kNAWSRequest: Buffer.from([0xFF, 0xFD, 0X1F]), // IAC DO NAWS
kNAWSResponse: Buffer.from([0xFF, 0xFB, 0X1F, 0xFF, 0xFA, 0X1F]) // IAC WILL NAWS IAC SB NAWS
};
/**
* A function that represents a screen, it is called frequently and should
* return a string consisting of commands to run.
*
* @interface IScreen
* @type function
* @param {Number} modulation A number between 0 and 255 representing the current
* step of the modulation
* @param {Number} width The width of the screen
* @param {Number} height The height of the screen
* @param {IRenderer} renderer The renderer used to colorize the scfeen
* @return {String} The commands used to render the screen elements
*/
/**
* A function that represents a renderer, it should take in a color in RGB and
* return a string with the appropriate code to colorize the terminal.
*
* @interface IRenderer
* @type function
* @param {Number} red The red component of the color between 0 and 255
* @param {Number} green The green component of the color between 0 and 255
* @param {Number} blue The green component of the color between 0 and 255
* @return {String} The commands used to colorize the terminal
*/
/**
* The main application for tomato sauce. Listens for connections and serves
* random combinations of screens and renderers
*
* The main entry point is the `#run()` function.
*
* It emits a listening event that contains the server information on
* the `server` key inside the `data` property of the event.
*
* It also emits an error event that contains the error information on
* the `error` key inside the `data` property of the event.
*
* @class TomatoSauce
* @extends EventEmitter
*
* @param {object} config the configuration object used to extend the properties.
*
* @property {Array<IScreen>} screens an array of screens available to serve
* @property {Array<IRenderer>} renderers an array of renderers available to colorize
* @property {Number} [port=9999] the port to listen on
* @property {Number} [frequency=333] how often to update the screen
* @property {Number} [modulation=5] number between 0-255 depicting current modulation step
*/
const TomatoSauce = class TomatoSauce extends EventEmitter {
constructor(config = {}) {
super();
this.screens = [];
this.renderers = [];
// Defaults.
this.port = 9999;
this.frequency = 333;
this.modulation = 5;
Object.assign(this, config);
}
/**
* Main entry point, initializes the server and binds events for connections
*
* @function run
* @instance
* @memberof TomatoSauce
*/
run() {
this._startServer();
this._bindEvents();
}
// Creates a socket, server based on the configuration. Emits the
// listening event when ready.
_startServer() {
const server = Net.createServer();
this.server = server;
server.listen(this.port, () => {
this.emit('listening', {
data: {
server
}
});
});
}
// Binds the connection and error events
_bindEvents() {
// Send the error event all the way up.
this.server.on('error', (error) => {
this.emit('error', {
data: {
error
}
});
});
// Send the error event all the way up.
this.server.on('connection', (socket) => {
this._renderScreen(socket);
});
}
// Obtains viewport size, and initializes a random screen with a random
// renderer, setting the required interval to draw.
_renderScreen(socket) {
const connectionData = {
width: null,
height: null,
modulation: 0,
screen: this._getScreen(),
renderer: this._getRenderer(),
socket
};
let interval = null;
socket.write(internals.kNAWSRequest);
socket.on('data', (data) => {
if (data.slice(0, 6).compare(internals.kNAWSResponse) === 0) {
connectionData.width = Util.parse16BitBuffer(data.slice(6, 8));
connectionData.height = Util.parse16BitBuffer(data.slice(8, 10));
socket.write('\x1B[2J'); // Clear the Screen (CSI 2 J)
interval = setInterval(this._writeMessage.bind(this, connectionData), this.frequency);
}
if (data.compare(internals.kEscape) === 0) {
socket.write('\n');
clearInterval(interval);
socket.end();
}
});
}
// Resets the cursor, gets a frame and sends it to the socket.
_writeMessage(connectionData) {
const payload = connectionData.screen(connectionData.modulation, connectionData.width, connectionData.height, connectionData.renderer);
const message = `\x1B[1;1H${payload}`; // reset cursor position before payload
connectionData.modulation = (connectionData.modulation + this.modulation) % 256;
connectionData.socket.write(message);
}
_getScreen() {
return Util.pickRandom(this.screens);
}
_getRenderer() {
return Util.pickRandom(this.renderers);
}
};
module.exports = TomatoSauce;
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