/* 

 * 	

 *	Copyright 2010 Institut de recherche et d'innovation 

 *	contributor(s) : Samuel Huron 

 *	 

 *	contact@iri.centrepompidou.fr

 *	http://www.iri.centrepompidou.fr 

 *	 

 *	This software is a computer program whose purpose is to show and add annotations on a video .

 *	This software is governed by the CeCILL-C license under French law and

 *	abiding by the rules of distribution of free software. You can  use, 

 *	modify and/ or redistribute the software under the terms of the CeCILL-C

 *	license as circulated by CEA, CNRS and INRIA at the following URL

 *	"http://www.cecill.info". 

 *	

 *	The fact that you are presently reading this means that you have had

 *	knowledge of the CeCILL-C license and that you accept its terms.

*/

/*! LAB.js (LABjs :: Loading And Blocking JavaScript)

    v2.0.3 (c) Kyle Simpson

    MIT License

*/

(function(global){

	var _$LAB = global.$LAB,

		// constants for the valid keys of the options object

		_UseLocalXHR = "UseLocalXHR",

		_AlwaysPreserveOrder = "AlwaysPreserveOrder",

		_AllowDuplicates = "AllowDuplicates",

		_CacheBust = "CacheBust",

		/*!START_DEBUG*/_Debug = "Debug",/*!END_DEBUG*/

		_BasePath = "BasePath",

		// stateless variables used across all $LAB instances

		root_page = /^[^?#]*\//.exec(location.href)[0],

		root_domain = /^\w+\:\/\/\/?[^\/]+/.exec(root_page)[0],

		append_to = document.head || document.getElementsByTagName("head"),

		// inferences... ick, but still necessary

		opera_or_gecko = (global.opera && Object.prototype.toString.call(global.opera) == "[object Opera]") || ("MozAppearance" in document.documentElement.style),

/*!START_DEBUG*/

		// console.log() and console.error() wrappers

		log_msg = function(){}, 

		log_error = log_msg,

/*!END_DEBUG*/

		// feature sniffs (yay!)

		test_script_elem = document.createElement("script"),

		explicit_preloading = typeof test_script_elem.preload == "boolean", // http://wiki.whatwg.org/wiki/Script_Execution_Control#Proposal_1_.28Nicholas_Zakas.29

		real_preloading = explicit_preloading || (test_script_elem.readyState && test_script_elem.readyState == "uninitialized"), // will a script preload with `src` set before DOM append?

		script_ordered_async = !real_preloading && test_script_elem.async === true, // http://wiki.whatwg.org/wiki/Dynamic_Script_Execution_Order

		// XHR preloading (same-domain) and cache-preloading (remote-domain) are the fallbacks (for some browsers)

		xhr_or_cache_preloading = !real_preloading && !script_ordered_async && !opera_or_gecko

	;

/*!START_DEBUG*/

	// define console wrapper functions if applicable

	if (global.console && global.console.log) {

		if (!global.console.error) global.console.error = global.console.log;

		log_msg = function(msg) { global.console.log(msg); };

		log_error = function(msg,err) { global.console.error(msg,err); };

	}

/*!END_DEBUG*/

	// test for function

	function is_func(func) { return Object.prototype.toString.call(func) == "[object Function]"; }

	// test for array

	function is_array(arr) { return Object.prototype.toString.call(arr) == "[object Array]"; }

	// make script URL absolute/canonical

	function canonical_uri(src,base_path) {

		var absolute_regex = /^\w+\:\/\//;

		// is `src` is protocol-relative (begins with // or ///), prepend protocol

		if (/^\/\/\/?/.test(src)) {

			src = location.protocol + src;

		}

		// is `src` page-relative? (not an absolute URL, and not a domain-relative path, beginning with /)

		else if (!absolute_regex.test(src) && src.charAt(0) != "/") {

			// prepend `base_path`, if any

			src = (base_path || "") + src;

		}

		// make sure to return `src` as absolute

		return absolute_regex.test(src) ? src : ((src.charAt(0) == "/" ? root_domain : root_page) + src);

	}

	// merge `source` into `target`

	function merge_objs(source,target) {

		for (var k in source) { if (source.hasOwnProperty(k)) {

			target[k] = source[k]; // TODO: does this need to be recursive for our purposes?

		}}

		return target;

	}

	// does the chain group have any ready-to-execute scripts?

	function check_chain_group_scripts_ready(chain_group) {

		var any_scripts_ready = false;

		for (var i=0; i<chain_group.scripts.length; i++) {

			if (chain_group.scripts[i].ready && chain_group.scripts[i].exec_trigger) {

				any_scripts_ready = true;

				chain_group.scripts[i].exec_trigger();

				chain_group.scripts[i].exec_trigger = null;

			}

		}

		return any_scripts_ready;

	}

	// creates a script load listener

	function create_script_load_listener(elem,registry_item,flag,onload) {

		elem.onload = elem.onreadystatechange = function() {

			if ((elem.readyState && elem.readyState != "complete" && elem.readyState != "loaded") || registry_item[flag]) return;

			elem.onload = elem.onreadystatechange = null;

			onload();

		};

	}

	// script executed handler

	function script_executed(registry_item) {

		registry_item.ready = registry_item.finished = true;

		for (var i=0; i<registry_item.finished_listeners.length; i++) {

			registry_item.finished_listeners[i]();

		}

		registry_item.ready_listeners = [];

		registry_item.finished_listeners = [];

	}

	// make the request for a scriptha

	function request_script(chain_opts,script_obj,registry_item,onload,preload_this_script) {

		// setTimeout() "yielding" prevents some weird race/crash conditions in older browsers

		setTimeout(function(){

			var script, src = script_obj.real_src, xhr;

			// don't proceed until `append_to` is ready to append to

			if ("item" in append_to) { // check if `append_to` ref is still a live node list

				if (!append_to[0]) { // `append_to` node not yet ready

					// try again in a little bit -- note: will re-call the anonymous function in the outer setTimeout, not the parent `request_script()`

					setTimeout(arguments.callee,25);

					return;

				}

				// reassign from live node list ref to pure node ref -- avoids nasty IE bug where changes to DOM invalidate live node lists

				append_to = append_to[0];

			}

			script = document.createElement("script");

			if (script_obj.type) script.type = script_obj.type;

			if (script_obj.charset) script.charset = script_obj.charset;

			// should preloading be used for this script?

			if (preload_this_script) {

				// real script preloading?

				if (real_preloading) {

					/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("start script preload: "+src);/*!END_DEBUG*/

					registry_item.elem = script;

					if (explicit_preloading) { // explicit preloading (aka, Zakas' proposal)

						script.preload = true;

						script.onpreload = onload;

					}

					else {

						script.onreadystatechange = function(){

							if (script.readyState == "loaded") onload();

						};

					}

					script.src = src;

					// NOTE: no append to DOM yet, appending will happen when ready to execute

				}

				// same-domain and XHR allowed? use XHR preloading

				else if (preload_this_script && src.indexOf(root_domain) == 0 && chain_opts[_UseLocalXHR]) {

					xhr = new XMLHttpRequest(); // note: IE never uses XHR (it supports true preloading), so no more need for ActiveXObject fallback for IE <= 7

					/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("start script preload (xhr): "+src);/*!END_DEBUG*/

					xhr.onreadystatechange = function() {

						if (xhr.readyState == 4) {

							xhr.onreadystatechange = function(){}; // fix a memory leak in IE

							registry_item.text = xhr.responseText + "\n//@ sourceURL=" + src; // http://blog.getfirebug.com/2009/08/11/give-your-eval-a-name-with-sourceurl/

							onload();

						}

					};

					xhr.open("GET",src);

					xhr.send();

				}

				// as a last resort, use cache-preloading

				else {

					/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("start script preload (cache): "+src);/*!END_DEBUG*/

					script.type = "text/cache-script";

					create_script_load_listener(script,registry_item,"ready",function() {

						append_to.removeChild(script);

						onload();

					});

					script.src = src;

					append_to.insertBefore(script,append_to.firstChild);

				}

			}

			// use async=false for ordered async? parallel-load-serial-execute http://wiki.whatwg.org/wiki/Dynamic_Script_Execution_Order

			else if (script_ordered_async) {

				/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("start script load (ordered async): "+src);/*!END_DEBUG*/

				script.async = false;

				create_script_load_listener(script,registry_item,"finished",onload);

				script.src = src;

				append_to.insertBefore(script,append_to.firstChild);

			}

			// otherwise, just a normal script element

			else {

				/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("start script load: "+src);/*!END_DEBUG*/

				create_script_load_listener(script,registry_item,"finished",onload);

				script.src = src;

				append_to.insertBefore(script,append_to.firstChild);

			}

		},0);

	}

	// create a clean instance of $LAB

	function create_sandbox() {

		var global_defaults = {},

			can_use_preloading = real_preloading || xhr_or_cache_preloading,

			queue = [],

			registry = {},

			instanceAPI

		;

		// global defaults

		global_defaults[_UseLocalXHR] = true;

		global_defaults[_AlwaysPreserveOrder] = false;

		global_defaults[_AllowDuplicates] = false;

		global_defaults[_CacheBust] = false;

		/*!START_DEBUG*/global_defaults[_Debug] = false;/*!END_DEBUG*/

		global_defaults[_BasePath] = "";

		// execute a script that has been preloaded already

		function execute_preloaded_script(chain_opts,script_obj,registry_item) {

			var script;

			function preload_execute_finished() {

				if (script != null) { // make sure this only ever fires once

					script = null;

					script_executed(registry_item);

				}

			}

			if (registry[script_obj.src].finished) return;

			if (!chain_opts[_AllowDuplicates]) registry[script_obj.src].finished = true;

			script = registry_item.elem || document.createElement("script");

			if (script_obj.type) script.type = script_obj.type;

			if (script_obj.charset) script.charset = script_obj.charset;

			create_script_load_listener(script,registry_item,"finished",preload_execute_finished);

			// script elem was real-preloaded

			if (registry_item.elem) {

				registry_item.elem = null;

			}

			// script was XHR preloaded

			else if (registry_item.text) {

				script.onload = script.onreadystatechange = null;	// script injection doesn't fire these events

				script.text = registry_item.text;

			}

			// script was cache-preloaded

			else {

				script.src = script_obj.real_src;

			}

			append_to.insertBefore(script,append_to.firstChild);

			// manually fire execution callback for injected scripts, since events don't fire

			if (registry_item.text) {

				preload_execute_finished();

			}

		}

		// process the script request setup

		function do_script(chain_opts,script_obj,chain_group,preload_this_script) {

			var registry_item,

				registry_items,

				ready_cb = function(){ script_obj.ready_cb(script_obj,function(){ execute_preloaded_script(chain_opts,script_obj,registry_item); }); },

				finished_cb = function(){ script_obj.finished_cb(script_obj,chain_group); }

			;

			script_obj.src = canonical_uri(script_obj.src,chain_opts[_BasePath]);

			script_obj.real_src = script_obj.src + 

				// append cache-bust param to URL?

				(chain_opts[_CacheBust] ? ((/\?.*$/.test(script_obj.src) ? "&_" : "?_") + ~~(Math.random()*1E9) + "=") : "")

			;

			if (!registry[script_obj.src]) registry[script_obj.src] = {items:[],finished:false};

			registry_items = registry[script_obj.src].items;

			// allowing duplicates, or is this the first recorded load of this script?

			if (chain_opts[_AllowDuplicates] || registry_items.length == 0) {

				registry_item = registry_items[registry_items.length] = {

					ready:false,

					finished:false,

					ready_listeners:[ready_cb],

					finished_listeners:[finished_cb]

				};

				request_script(chain_opts,script_obj,registry_item,

					// which callback type to pass?

					(

					 	(preload_this_script) ? // depends on script-preloading

						function(){

							registry_item.ready = true;

							for (var i=0; i<registry_item.ready_listeners.length; i++) {

								registry_item.ready_listeners[i]();

							}

							registry_item.ready_listeners = [];

						} :

						function(){ script_executed(registry_item); }

					),

					// signal if script-preloading should be used or not

					preload_this_script

				);

			}

			else {

				registry_item = registry_items[0];

				if (registry_item.finished) {

					finished_cb();

				}

				else {

					registry_item.finished_listeners.push(finished_cb);

				}

			}

		}

		// creates a closure for each separate chain spawned from this $LAB instance, to keep state cleanly separated between chains

		function create_chain() {

			var chainedAPI,

				chain_opts = merge_objs(global_defaults,{}),

				chain = [],

				exec_cursor = 0,

				scripts_currently_loading = false,

				group

			;

			// called when a script has finished preloading

			function chain_script_ready(script_obj,exec_trigger) {

				/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("script preload finished: "+script_obj.real_src);/*!END_DEBUG*/

				script_obj.ready = true;

				script_obj.exec_trigger = exec_trigger;

				advance_exec_cursor(); // will only check for 'ready' scripts to be executed

			}

			// called when a script has finished executing

			function chain_script_executed(script_obj,chain_group) {

				/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("script execution finished: "+script_obj.real_src);/*!END_DEBUG*/

				script_obj.ready = script_obj.finished = true;

				script_obj.exec_trigger = null;

				// check if chain group is all finished

				for (var i=0; i<chain_group.scripts.length; i++) {

					if (!chain_group.scripts[i].finished) return;

				}

				// chain_group is all finished if we get this far

				chain_group.finished = true;

				advance_exec_cursor();

			}

			// main driver for executing each part of the chain

			function advance_exec_cursor() {

				while (exec_cursor < chain.length) {

					if (is_func(chain[exec_cursor])) {

						/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("$LAB.wait() executing: "+chain[exec_cursor]);/*!END_DEBUG*/

						try { chain[exec_cursor++](); } catch (err) {

							/*!START_DEBUG*/if (chain_opts[_Debug]) log_error("$LAB.wait() error caught: ",err);/*!END_DEBUG*/

						}

						continue;

					}

					else if (!chain[exec_cursor].finished) {

						if (check_chain_group_scripts_ready(chain[exec_cursor])) continue;

						break;

					}

					exec_cursor++;

				}

				// we've reached the end of the chain (so far)

				if (exec_cursor == chain.length) {

					scripts_currently_loading = false;

					group = false;

				}

			}

			// setup next chain script group

			function init_script_chain_group() {

				if (!group || !group.scripts) {

					chain.push(group = {scripts:[],finished:true});

				}

			}

			// API for $LAB chains

			chainedAPI = {

				// start loading one or more scripts

				script:function(){

					for (var i=0; i<arguments.length; i++) {

						(function(script_obj,script_list){

							var splice_args;

							if (!is_array(script_obj)) {

								script_list = [script_obj];

							}

							for (var j=0; j<script_list.length; j++) {

								init_script_chain_group();

								script_obj = script_list[j];

								if (is_func(script_obj)) script_obj = script_obj();

								if (!script_obj) continue;

								if (is_array(script_obj)) {

									// set up an array of arguments to pass to splice()

									splice_args = [].slice.call(script_obj); // first include the actual array elements we want to splice in

									splice_args.unshift(j,1); // next, put the `index` and `howMany` parameters onto the beginning of the splice-arguments array

									[].splice.apply(script_list,splice_args); // use the splice-arguments array as arguments for splice()

									j--; // adjust `j` to account for the loop's subsequent `j++`, so that the next loop iteration uses the same `j` index value

									continue;

								}

								if (typeof script_obj == "string") script_obj = {src:script_obj};

								script_obj = merge_objs(script_obj,{

									ready:false,

									ready_cb:chain_script_ready,

									finished:false,

									finished_cb:chain_script_executed

								});

								group.finished = false;

								group.scripts.push(script_obj);

								do_script(chain_opts,script_obj,group,(can_use_preloading && scripts_currently_loading));

								scripts_currently_loading = true;

								if (chain_opts[_AlwaysPreserveOrder]) chainedAPI.wait();

							}

						})(arguments[i],arguments[i]);

					}

					return chainedAPI;

				},

				// force LABjs to pause in execution at this point in the chain, until the execution thus far finishes, before proceeding

				wait:function(){

					if (arguments.length > 0) {

						for (var i=0; i<arguments.length; i++) {

							chain.push(arguments[i]);

						}

						group = chain[chain.length-1];

					}

					else group = false;

					advance_exec_cursor();

					return chainedAPI;

				}

			};

			// the first chain link API (includes `setOptions` only this first time)

			return {

				script:chainedAPI.script, 

				wait:chainedAPI.wait, 

				setOptions:function(opts){

					merge_objs(opts,chain_opts);

					return chainedAPI;

				}

			};

		}

		// API for each initial $LAB instance (before chaining starts)

		instanceAPI = {

			// main API functions

			setGlobalDefaults:function(opts){

				merge_objs(opts,global_defaults);

				return instanceAPI;

			},

			setOptions:function(){

				return create_chain().setOptions.apply(null,arguments);

			},

			script:function(){

				return create_chain().script.apply(null,arguments);

			},

			wait:function(){

				return create_chain().wait.apply(null,arguments);

			},

			// built-in queuing for $LAB `script()` and `wait()` calls

			// useful for building up a chain programmatically across various script locations, and simulating

			// execution of the chain

			queueScript:function(){

				queue[queue.length] = {type:"script", args:[].slice.call(arguments)};

				return instanceAPI;

			},

			queueWait:function(){

				queue[queue.length] = {type:"wait", args:[].slice.call(arguments)};

				return instanceAPI;

			},

			runQueue:function(){

				var $L = instanceAPI, len=queue.length, i=len, val;

				for (;--i>=0;) {

					val = queue.shift();

					$L = $L[val.type].apply(null,val.args);

				}

				return $L;

			},

			// rollback `[global].$LAB` to what it was before this file was loaded, the return this current instance of $LAB

			noConflict:function(){

				global.$LAB = _$LAB;

				return instanceAPI;

			},

			// create another clean instance of $LAB

			sandbox:function(){

				return create_sandbox();

			}

		};

		return instanceAPI;

	}

	// create the main instance of $LAB

	global.$LAB = create_sandbox();

	/* The following "hack" was suggested by Andrea Giammarchi and adapted from: http://webreflection.blogspot.com/2009/11/195-chars-to-help-lazy-loading.html

	   NOTE: this hack only operates in FF and then only in versions where document.readyState is not present (FF < 3.6?).

	   The hack essentially "patches" the **page** that LABjs is loaded onto so that it has a proper conforming document.readyState, so that if a script which does 

	   proper and safe dom-ready detection is loaded onto a page, after dom-ready has passed, it will still be able to detect this state, by inspecting the now hacked 

	   document.readyState property. The loaded script in question can then immediately trigger any queued code executions that were waiting for the DOM to be ready. 

	   For instance, jQuery 1.4+ has been patched to take advantage of document.readyState, which is enabled by this hack. But 1.3.2 and before are **not** safe or 

	   fixed by this hack, and should therefore **not** be lazy-loaded by script loader tools such as LABjs.

	*/ 

	(function(addEvent,domLoaded,handler){

		if (document.readyState == null && document[addEvent]){

			document.readyState = "loading";

			document[addEvent](domLoaded,handler = function(){

				document.removeEventListener(domLoaded,handler,false);

				document.readyState = "complete";

			},false);

		}