SingleFile/WebContent/core/scripts/bg/nio.js

/*
 * Copyright 2011 Gildas Lormeau
 * contact : gildas.lormeau <at> gmail.com
 * 
 * This file is part of SingleFile Core.
 *
 *   SingleFile Core is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   SingleFile Core 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 Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with SingleFile Core.  If not, see <http://www.gnu.org/licenses/>.
 */

(function() {

	singlefile.nio = {};

	singlefile.nio.RequestManager = function() {
		var cache = {}, keys = [], pendingResponseHandlers = {}, XHR_TIMEOUT = 45000;

		function sendResponses(key) {
			if (pendingResponseHandlers[key]) {
				pendingResponseHandlers[key].forEach(function(callback) {
					callback(cache[key]);
				});
				delete pendingResponseHandlers[key];
			}
		}

		function arrayBufferToBase64(buffer) {
			var binary, bytes, len, i;
			binary = "";
			bytes = new Uint8Array(buffer);
			len = bytes.byteLength;
			for (i = 0; i < len; i++) {
				binary += String.fromCharCode(bytes[i]);
			}
			return btoa(binary);
		}

		this.reset = function() {
			cache = {};
			keys = [];
		};

		this.send = function(url, responseHandler, characterSet, mediaTypeParam) {
			var xhr, timeout, key = JSON.stringify({
				url : url,
				characterSet : characterSet,
				mediaTypeParam : mediaTypeParam
			});

			if (cache[key])
				setTimeout(function() {
					responseHandler(cache[key]);
				}, 1);
			else if (pendingResponseHandlers[key])
				pendingResponseHandlers[key].push(responseHandler);
			else {
				pendingResponseHandlers[key] = [ responseHandler ];
				xhr = new XMLHttpRequest();
				xhr.onload = function() {
					clearTimeout(timeout);
					cache[key] = {
						url : url,
						status : xhr.status,
						mediaType : xhr.getResponseHeader("Content-Type"),
						content : mediaTypeParam == "base64" ? arrayBufferToBase64(xhr.response) : xhr.responseText,
						mediaTypeParam : mediaTypeParam
					};
					keys.push(key);
					sendResponses(key);
				};
				xhr.onerror = function() {
					sendResponses(key);
				};
				xhr.open("GET", url, true);
				if (mediaTypeParam == "base64") {
					xhr.responseType = "arraybuffer";
				}
				timeout = setTimeout(function() {
					xhr.abort();
					sendResponses(key);
				}, XHR_TIMEOUT);
				try {
					xhr.send(null);
				} catch (e) {
					sendResponses(key);
				}
			}
		};
	};

})();