first commit

clientonly/index.js

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+"use strict";
+
+// Use separate scope to prevent global scope pollution
+(function () {
+	const config = {};
+
+	/**
+	 * Helper function to get server address/hostname from either the commandline or env
+	 */
+	function getServerAddress() {
+		/**
+		 * Get command line parameters
+		 * Assumes that a cmdline parameter is defined with `--key [value]`
+		 * @param {string} key key to look for at the command line
+		 * @param {string} defaultValue value if no key is given at the command line
+		 * @returns {string} the value of the parameter
+		 */
+		function getCommandLineParameter(key, defaultValue = undefined) {
+			const index = process.argv.indexOf(`--${key}`);
+			const value = index > -1 ? process.argv[index + 1] : undefined;
+			return value !== undefined ? String(value) : defaultValue;
+		}
+
+		// Prefer command line arguments over environment variables
+		["address", "port"].forEach((key) => {
+			config[key] = getCommandLineParameter(key, process.env[key.toUpperCase()]);
+		});
+
+		// determine if "--use-tls"-flag was provided
+		config["tls"] = process.argv.indexOf("--use-tls") > 0;
+	}
+
+	/**
+	 * Gets the config from the specified server url
+	 * @param {string} url location where the server is running.
+	 * @returns {Promise} the config
+	 */
+	function getServerConfig(url) {
+		// Return new pending promise
+		return new Promise((resolve, reject) => {
+			// Select http or https module, depending on requested url
+			const lib = url.startsWith("https") ? require("https") : require("http");
+			const request = lib.get(url, (response) => {
+				let configData = "";
+
+				// Gather incoming data
+				response.on("data", function (chunk) {
+					configData += chunk;
+				});
+				// Resolve promise at the end of the HTTP/HTTPS stream
+				response.on("end", function () {
+					resolve(JSON.parse(configData));
+				});
+			});
+
+			request.on("error", function (error) {
+				reject(new Error(`Unable to read config from server (${url} (${error.message}`));
+			});
+		});
+	}
+
+	/**
+	 * Print a message to the console in case of errors
+	 * @param {string} message error message to print
+	 * @param {number} code error code for the exit call
+	 */
+	function fail(message, code = 1) {
+		if (message !== undefined && typeof message === "string") {
+			console.log(message);
+		} else {
+			console.log("Usage: 'node clientonly --address 192.168.1.10 --port 8080 [--use-tls]'");
+		}
+		process.exit(code);
+	}
+
+	getServerAddress();
+
+	(config.address && config.port) || fail();
+	const prefix = config.tls ? "https://" : "http://";
+
+	// Only start the client if a non-local server was provided
+	if (["localhost", "127.0.0.1", "::1", "::ffff:127.0.0.1", undefined].indexOf(config.address) === -1) {
+		getServerConfig(`${prefix}${config.address}:${config.port}/config/`)
+			.then(function (configReturn) {
+				// Pass along the server config via an environment variable
+				const env = Object.create(process.env);
+				const options = { env: env };
+				configReturn.address = config.address;
+				configReturn.port = config.port;
+				configReturn.tls = config.tls;
+				env.config = JSON.stringify(configReturn);
+
+				// Spawn electron application
+				const electron = require("electron");
+				const child = require("child_process").spawn(electron, ["js/electron.js"], options);
+
+				// Pipe all child process output to current stdout
+				child.stdout.on("data", function (buf) {
+					process.stdout.write(`Client: ${buf}`);
+				});
+
+				// Pipe all child process errors to current stderr
+				child.stderr.on("data", function (buf) {
+					process.stderr.write(`Client: ${buf}`);
+				});
+
+				child.on("error", function (err) {
+					process.stdout.write(`Client: ${err}`);
+				});
+
+				child.on("close", (code) => {
+					if (code !== 0) {
+						console.log(`There something wrong. The clientonly is not running code ${code}`);
+					}
+				});
+			})
+			.catch(function (reason) {
+				fail(`Unable to connect to server: (${reason})`);
+			});
+	} else {
+		fail();
+	}
+})();