app.js

/*******************************
	WS2812 LED Control
		A tiny, primitive app for controlling WS2812 LEDs.

	Austin Brown - 2020
	http://luxdvie.github.io
	austinbrown2500@gmail.com
*******************************/

/* Common Libraries & Setup */
var express = require("express");
var app = express();
var bodyParser = require("body-parser");
var path = require("path");
var os = require('os');

app.use(express.static(__dirname + "/public"));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));

/* The port the server will listen on */
var HTTP_PORT = 8080;

/* Global reference to the LED strip */
var strip = require("./strip.js");

/*  Animation Libraries */
var xmas = require("./animations/xmas.js");
var fade = require("./animations/fade.js");
var rainbow = require("./animations/rainbow.js");
var control = require("./animations/control.js");
var dance = require("./animations/dance.js");
var twinkle = require("./animations/twinkle.js");

// Find the first local, ipv4 address
// This is a 'best guess' that the web server can be accessed
// via this address. Your mileage may vary!
// https://stackoverflow.com/questions/10750303/how-can-i-get-the-local-ip-address-in-node-js
// https://nodejs.org/api/os.html#os_os_networkinterfaces
var interfaces = os.networkInterfaces();
var localAddress = "";
for (var k in interfaces) {
    for (var k2 in interfaces[k]) {
        var address = interfaces[k][k2];
        if (address.family === 'IPv4' && !address.internal) {
			localAddress = address.address;
			break;
        }
    }
}

/*****************
	Web Methods
*****************/

/**
 * Generic handler for an animation request.
 * 	All requests should be in the format
 * 		lib => name of animation package you're referencing
 * 		method => name of method in package you're calling
 * 		args => object containing any arguments you want to pass to the animation method
 */
app.post("/AnimationRequest", function (request, response) {
	response.header("Access-Control-Allow-Origin", "*");

	var lib = request.body.hasOwnProperty("lib") ? request.body.lib : "";
	var instance = GetLibraryInstance(lib);
	if (instance === null || typeof instance === "undefined") {
		response.send("Library not found.");
		return;
	}

	var method = request.body.hasOwnProperty("method")
		? request.body.method
		: null;
	if (method === null) {
		response.send("Method not found.");
		return;
	}

	var args = request.body.hasOwnProperty("args") ? request.body.args : "";

	if (typeof instance[method] === "function") {
		var rsp = instance[method](args, strip);
		response.send(rsp);
	} else {
		response.send("Function not found");
	}
});

/**
 * Home
 */
app.get("/", function (req, res) {
	res.header("Access-Control-Allow-Origin", "*");
	res.sendFile(path.join(__dirname + "/app.html"));
});

/*****************
	Admin
*****************/

app.get("/admin/reboot", function (req, res) {
	res.header("Access-Control-Allow-Origin", "*");
	res.send("Issuing shutdown command.");
	require('child_process').exec('sudo reboot', function (msg) { console.log("Issuing reboot command.") });
});

app.get("/admin/poweroff", function (req, res) {
	res.header("Access-Control-Allow-Origin", "*");
	res.send("Issuing shutdown command.");
	require('child_process').exec('sudo poweroff', function (msg) { console.log("Issuing shutdown command.") });
});


/*****************
	Common
*****************/

/**
 * Find the correct reference to a specific library name;
 * @param {string} key The name of the library to find
 */
function GetLibraryInstance(key) {
	var lib = null;
	switch (key) {
		case "xmas":
			lib = xmas;
			break;
		case "fade":
			lib = fade;
			break;
		case "rainbow":
			lib = rainbow;
			break;
		case "control":
			lib = control;
			break;
		case "dance":
			lib = dance;
			break;
		case "twinkle":
			lib = twinkle;
			break;
	}

	return lib;
}

/*****************
	Startup
*****************/

var server = app.listen(HTTP_PORT, function () {
	console.log("***************************");
	console.log(" WS2812 CONTROLLER STARTUP ");
	console.log(" Web Server listening at the location below, or by host name and port. ");
	console.log(" http://" + localAddress + ":" + HTTP_PORT);
	console.log("***************************");

	// Run the 'Rainbow' routing on startup
	var rainbowInstance = GetLibraryInstance("rainbow");
	if (rainbowInstance) {
        	rainbowInstance.GoRainbow("", strip);
	}
});