nextcloud/core/src/OC/eventsource.js

/**
 * ownCloud
 *
 * @author Robin Appelman
 * @copyright 2012 Robin Appelman icewind1991@gmail.com
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or any later version.
 *
 * This library 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 AFFERO GENERAL PUBLIC LICENSE for more details.
 *
 * You should have received a copy of the GNU Affero General Public
 * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

/**
 * Wrapper for server side events
 * (http://en.wikipedia.org/wiki/Server-sent_events)
 * includes a fallback for older browsers and IE
 *
 * use server side events with caution, too many open requests can hang the
 * server
 */

/* global EventSource */

import $ from 'jquery'

import {getToken} from './requesttoken'

/**
 * Create a new event source
 * @param {string} src
 * @param {object} [data] to be send as GET
 *
 * @constructs OCEventSource
 */
const OCEventSource = function (src, data) {
	var dataStr = '';
	var name;
	var joinChar;
	this.typelessListeners = [];
	this.closed = false;
	this.listeners = {};
	if (data) {
		for (name in data) {
			dataStr += name + '=' + encodeURIComponent(data[name]) + '&';
		}
	}
	dataStr += 'requesttoken=' + encodeURIComponent(getToken());
	if (!this.useFallBack && typeof EventSource !== 'undefined') {
		joinChar = '&';
		if (src.indexOf('?') === -1) {
			joinChar = '?';
		}
		this.source = new EventSource(src + joinChar + dataStr);
		this.source.onmessage = function (e) {
			for (var i = 0; i < this.typelessListeners.length; i++) {
				this.typelessListeners[i](JSON.parse(e.data));
			}
		}.bind(this);
	} else {
		var iframeId = 'oc_eventsource_iframe_' + OCEventSource.iframeCount;
		OCEventSource.fallBackSources[OCEventSource.iframeCount] = this;
		this.iframe = $('<iframe/>');
		this.iframe.attr('id', iframeId);
		this.iframe.hide();

		joinChar = '&';
		if (src.indexOf('?') === -1) {
			joinChar = '?';
		}
		this.iframe.attr('src', src + joinChar + 'fallback=true&fallback_id=' + OCEventSource.iframeCount + '&' + dataStr);
		$('body').append(this.iframe);
		this.useFallBack = true;
		OCEventSource.iframeCount++;
	}
	//add close listener
	this.listen('__internal__', function (data) {
		if (data === 'close') {
			this.close();
		}
	}.bind(this));
};
OCEventSource.fallBackSources = [];
OCEventSource.iframeCount = 0;//number of fallback iframes
OCEventSource.fallBackCallBack = function (id, type, data) {
	OCEventSource.fallBackSources[id].fallBackCallBack(type, data);
};
OCEventSource.prototype = {
	typelessListeners: [],
	iframe: null,
	listeners: {},//only for fallback
	useFallBack: false,
	/**
	 * Fallback callback for browsers that don't have the
	 * native EventSource object.
	 *
	 * Calls the registered listeners.
	 *
	 * @private
	 * @param {String} type event type
	 * @param {Object} data received data
	 */
	fallBackCallBack: function (type, data) {
		var i;
		// ignore messages that might appear after closing
		if (this.closed) {
			return;
		}
		if (type) {
			if (typeof this.listeners.done !== 'undefined') {
				for (i = 0; i < this.listeners[type].length; i++) {
					this.listeners[type][i](data);
				}
			}
		} else {
			for (i = 0; i < this.typelessListeners.length; i++) {
				this.typelessListeners[i](data);
			}
		}
	},
	lastLength: 0,//for fallback
	/**
	 * Listen to a given type of events.
	 *
	 * @param {String} type event type
	 * @param {Function} callback event callback
	 */
	listen: function (type, callback) {
		if (callback && callback.call) {

			if (type) {
				if (this.useFallBack) {
					if (!this.listeners[type]) {
						this.listeners[type] = [];
					}
					this.listeners[type].push(callback);
				} else {
					this.source.addEventListener(type, function (e) {
						if (typeof e.data !== 'undefined') {
							callback(JSON.parse(e.data));
						} else {
							callback('');
						}
					}, false);
				}
			} else {
				this.typelessListeners.push(callback);
			}
		}
	},
	/**
	 * Closes this event source.
	 */
	close: function () {
		this.closed = true;
		if (typeof this.source !== 'undefined') {
			this.source.close();
		}
	}
};

export default OCEventSource;