/**
 * This module is not in use since Yii provides an build in mechanism for blocking
 * ajax requests for scripts already loaded.
 * 
 * This module provides functions to keep track of loaded scripts and load scripts
 * once synchronously or asynchronously.
 * 
 * @param {type} param1
 * @param {type} param2
 */
humhub.initModule('scripts', function(module, require, $) {
    var _scripts = [];
    
    $(document).ready(function() {
        $('script[src]').each(function() {
            addScript(cutTimestamp($(this).attr('src')));
        });
    });
    
    var cutTimestamp = function(url) {
        return url.split('?')[0];
    };
    
    var loadOnce = function(urls) {
        urls = $.isArray(urls) ? urls : [urls];
            
        var promises = [];
        $.each(urls, function(index, scriptUrl) {            
            if(!containsScript(scriptUrl)) {
                addScript(scriptUrl);
                promises.push($.getScript(scriptUrl));
            }
        });
            
        promises.push($.Deferred(function( deferred ){
            $( deferred.resolve );
        }));
            
        return $.when.apply(null, promises);
    };
    
    var loadOnceSync = function(urls, callback) {
        var deferred = new $.Deferred();
        var promise = deferred.promise();
        $.each(urls, function(index, scriptUrl) {
             if(!containsScript(scriptUrl)) {
                // we need an immediately invoked function expression to capture
                // the current value of the iteration 
                (function(url) {
                    // chaining the promises, 
                    // by assigning the new promise to the variable
                    // and returning a promise from the callback
                    promise = promise.then(function() {
                        addScript(url);
                        return $.getScript(url).done(function(){});
                    });
                }(scriptUrl));
             }
         });
         
        promise.done(function() {
            callback.apply();
        });
        
        promise.fail(function(arg) {
           console.error('Failed loading scripts for: '+arg); 
           //Call callback anyway
           callback.apply();
        });
        
        deferred.resolve();
    };
    
    var containsScript = function(url) {
        var result = false;
        url = cutTimestamp(url);
        $.each(_scripts, function(index, scriptUrl) {
            if(scriptUrl === url) {
                result = true;
                return false; //leave each
            }
        });
        return result;
    };
    
    var addScript = function(url) {
        url = cutTimestamp(url);
        _scripts.push(url);
    };
    
    module.export({
        loadOnce: loadOnce,
        loadOnceSync: loadOnceSync,
        containsScript: containsScript,
        addScript:addScript
    });
});