/**
 * Durandal 2.1.0 Copyright (c) 2012 Blue Spire Consulting, Inc. All Rights Reserved.
 * Available via the MIT license.
 * see: http://durandaljs.com or https://github.com/BlueSpire/Durandal for details.
 */
/**
 * The app module controls app startup, plugin loading/configuration and root visual display.
 * @module app
 * @requires system
 * @requires viewEngine
 * @requires composition
 * @requires events
 * @requires jquery
 */
define(['durandal/system', 'durandal/viewEngine', 'durandal/composition', 'durandal/events', 'jquery'], function(system, viewEngine, composition, Events, $) {
    var app,
        allPluginIds = [],
        allPluginConfigs = [];

    function loadPlugins(){
        return system.defer(function(dfd){
            if(allPluginIds.length == 0){
                dfd.resolve();
                return;
            }

            system.acquire(allPluginIds).then(function(loaded){
                for(var i = 0; i < loaded.length; i++){
                    var currentModule = loaded[i];

                    if(currentModule.install){
                        var config = allPluginConfigs[i];
                        if(!system.isObject(config)){
                            config = {};
                        }

                        currentModule.install(config);
                        system.log('Plugin:Installed ' + allPluginIds[i]);
                    }else{
                        system.log('Plugin:Loaded ' + allPluginIds[i]);
                    }
                }

                dfd.resolve();
            }).fail(function(err){
                system.error('Failed to load plugin(s). Details: ' + err.message);
            });
        }).promise();
    }

    /**
     * @class AppModule
     * @static
     * @uses Events
     */
    app = {
        /**
         * The title of your application.
         * @property {string} title
         */
        title: 'Application',
        /**
         * Configures one or more plugins to be loaded and installed into the application.
         * @method configurePlugins
         * @param {object} config Keys are plugin names. Values can be truthy, to simply install the plugin, or a configuration object to pass to the plugin.
         * @param {string} [baseUrl] The base url to load the plugins from.
         */
        configurePlugins:function(config, baseUrl){
            var pluginIds = system.keys(config);
            baseUrl = baseUrl || 'plugins/';

            if(baseUrl.indexOf('/', baseUrl.length - 1) === -1){
                baseUrl += '/';
            }

            for(var i = 0; i < pluginIds.length; i++){
                var key = pluginIds[i];
                allPluginIds.push(baseUrl + key);
                allPluginConfigs.push(config[key]);
            }
        },
        /**
         * Starts the application.
         * @method start
         * @return {promise}
         */
        start: function() {
            system.log('Application:Starting');

            if (this.title) {
                document.title = this.title;
            }

            return system.defer(function (dfd) {
                $(function() {
                    loadPlugins().then(function(){
                        dfd.resolve();
                        system.log('Application:Started');
                    });
                });
            }).promise();
        },
        /**
         * Sets the root module/view for the application.
         * @method setRoot
         * @param {string} root The root view or module.
         * @param {string} [transition] The transition to use from the previous root (or splash screen) into the new root.
         * @param {string} [applicationHost] The application host element or id. By default the id 'applicationHost' will be used.
         */
        setRoot: function(root, transition, applicationHost) {
            var hostElement, settings = { activate:true, transition: transition };

            if (!applicationHost || system.isString(applicationHost)) {
                hostElement = document.getElementById(applicationHost || 'applicationHost');
            } else {
                hostElement = applicationHost;
            }

            if (system.isString(root)) {
                if (viewEngine.isViewUrl(root)) {
                    settings.view = root;
                } else {
                    settings.model = root;
                }
            } else {
                settings.model = root;
            }

            function finishComposition() {
                if(settings.model) {
                    if (settings.model.canActivate) {
                        try {
                            var result = settings.model.canActivate();
                            if (result && result.then) {
                                result.then(function (actualResult) {
                                    if (actualResult) {
                                        composition.compose(hostElement, settings);
                                    }
                                }).fail(function (err) {
                                    system.error(err);
                                });
                            } else if (result) {
                                composition.compose(hostElement, settings);
                            }
                        } catch (er) {
                            system.error(er);
                        }
                    } else {
                        composition.compose(hostElement, settings);
                    }
                } else {
                    composition.compose(hostElement, settings);
                }
            }

            if(system.isString(settings.model)) {
                system.acquire(settings.model).then(function(module) {
                    settings.model = system.resolveObject(module);
                    finishComposition();
                }).fail(function(err) {
                    system.error('Failed to load root module (' + settings.model + '). Details: ' + err.message);
                });
            } else {
                finishComposition();
            }
        }
    };

    Events.includeIn(app);

    return app;
});
