domotz-remote-pawn/src/http/app.js

Domotz Agent

/** This file is part of Domotz Agent.
  * Copyright (C) 2016  Domotz Ltd
  *
  * Domotz Agent is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation, either version 3 of the License, or
  * (at your option) any later version.
  *
  * Domotz Agent is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Domotz Agent.  If not, see <http://www.gnu.org/licenses/>.
  **/
/**
 *
 * Created by Iacopo Papalini <ipapalini@domotz.com> on 08/09/15.
 */

// Starts up an HTTP server that enables the hub setup
var createApp = function (fs, http, express, event, bodyParser, favicon, path, routes) {

    var app = express();
    /**
     * Listening port: if not available, it will be increased until a free one is found
     * @type {number}
     */
    var port = 3000;
    var port_file = process.env.DOMOTZ_LISTENER_PORT_FILE;
    /**
     * The HTTP server
     * @type {null}
     */
    var server = null;

    /**
     * Resource path
     */
    var viewsPath = path.join(__dirname, '..', '..', 'webapp', 'views');
    var faviconPath = path.join(__dirname, '..', '..', 'webapp', 'images', 'favicon.ico');
    var webappRootPath = path.join(__dirname, '..', '..', 'webapp');

    app.use(function(req, res, next) {
        res.header("Access-Control-Allow-Origin", "*");
        res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, X-API-Minor-Version, Authorization");
        next();
    });

    // view engine setup
    app.set('views', viewsPath);
    app.set('view engine', 'ejs');

    app.use(favicon(faviconPath));
    app.use(bodyParser.json()); // for parsing application/json
    app.use(express.static(webappRootPath));

    app.use('/', routes);

    // catch 404 and forward to error handler
    app.use(function (req, res, next) {
        var err = new Error('Not Found');
        err.status = 404;
        next(err);
    });

    app.use(function (err, req, res, next) {
        res.status(err.status || 500);
        res.render('error', {
            message: err.message,
            error: err
        });
    });


    app.startServing = function () {
        app.set('port', port);

        server = http.createServer(app);

        console.debug("WEBAPP - Try start domotz webapp on port " + port);

        server.on('error', onError);
        server.on('listening', onListening);

        server.listen(port);
    };

    /**
     * Event listener for HTTP server "listening" event.
     */
    var onListening = function () {
        var port = app.get('port');
        console.info('WEBAPP - Domotz is listening on port ' + port + '... ' +
                     'Writing port number on ' + port_file);
        setTimeout(event.onListeningWebapp, 2000);
        fs.writeFileSync(port_file, port);
    };

    /**
     * Error handler: starts from
     * @param error
     */
    var onError = function onError(error) {
        if (error.syscall !== 'listen') {
            console.error('Error on System call ' + error.syscall);
            throw error;
        }

        var bind = typeof port === 'string' ? 'Pipe ' + port : 'Port ' + port;

        // handle specific listen errors with friendly messages
        switch (error.code) {
            case 'EACCES':
                signalCriticalFailureAndExit(bind + ' requires elevated privileges');
                break;
            case 'EADDRINUSE':
                port += 1;
                if (port < 65535) {
                    app.startServing();
                } else {
                    signalCriticalFailureAndExit('Cannot find a free port to listen to');
                }

                break;
            default:
                throw error;
        }
    };

    /**
     * Logs a critical error and waits 30s then exit abnormally.
     * The wait is a cool down period before a possible restart.
     * @param message
     */
    function signalCriticalFailureAndExit(message) {
        console.error(message);
        setTimeout(function () {
            process.exit(1);
        }, 30000);
    }

    return app;
};
module.exports.createApp = createApp;