/**
 * @module Shared
 */


/**
 * I am the RouteNavigation.
 *
 * I parse the query and the hash fragment of the current URL, and expose those parameters to the app.
 * Also, I listen to changes in the hash fragment, and can call callbacks for them.
 *
 * @class RouteNavigation
 * @static
 */



FrameTrail.defineModule('RouteNavigation', function(){


    var projectID    = getQueryVariable('project'),
        hypervideoID = getQueryVariable('hypervideo'),
        annotationID = '',
        hashTime     = '',

        oldAnnotationID = '',
        onAnnotationChange,

        oldHashTime     = '',
        onHashTimeChange;


    /**
     * I return a complete path (or URL) for a resource file based on the src attribute of a resource object.
     * @method getResourceURL
     * @param {String} src
     * @return String
     */
    function getResourceURL(src) {

        if (/^https?:/.exec(src)) {
            
            return src;

        } else {
        
            return '../_data/projects/' + projectID + '/resources/' + src;

        }

    };


    /**
     * I return the value of a query parameter.
     * @method getQueryVariable
     * @param {String} variable
     * @return String
     * @private
     */
    function getQueryVariable(variable) {

        var query = window.location.search.substring(1),
            vars = query.split("&"),
            pair;

        for (var i = 0; i < vars.length; i++) {
            pair = vars[i].split("=");
            if (pair[0] == variable) {
                return pair[1];
            }
        }

    }

    /**
     * I return the value of a hash parameter.
     * @method getHashVariable
     * @param {String} variable
     * @return String
     * @private 
     */
    function getHashVariable(variable) {

        var hash = window.location.hash.substring(1),
            vars = hash.split("&"),
            pair;

        for (var i = 0; i < vars.length; i++) {
            pair = vars[i].split("=");
            if (pair[0] == variable) {
                return pair[1];
            }
        }

    }

    /**
     * I return an object with various info about the execution environment.
     * @method checkEnvironment
     * @return Object
     * @private 
     */
    function checkEnvironment() {

        var environmentObj = {
            'server': (document.location.protocol == 'file:') ? false : true,
            'hostname': document.location.hostname
        }
        
        return environmentObj;

    }

    /**
     * I set the hypervideo id 
     * (in case it changes while the application is running).
     * @method setHashVariable
     * @param {String} id
     * @private
     */
    function setHypervideoID(id) {

        hypervideoID = id;

    }

    /**
     * I change the value of a hash parameter.
     * @method setHashVariable
     * @param {String} key
     * @param {String} value
     * @private
     */
    function setHashVariable(key, value) {

        var hash = window.location.hash.substring(1),
            vars = hash.split("&"),
            pair;

        for (var i = 0; i < vars.length; i++) {
            pair = vars[i].split("=");
            if (pair[0] == key) {
                pair[1] =  value.toString();
            }
            vars[i] = pair.join('=')
        }

         window.location.hash = vars.join('&')

    }


    /**
     * I update the application state, when the hash fragment has changed.
     *
     * Currently, I am only listing to changes of the parameter "annotations" and "t" (hashTime).
     *
     * @method routeHasChanged
     * @private
     */
    function routeHasChanged(){
        
        annotationID = getHashVariable('annotations');

        if (annotationID !== oldAnnotationID) {
            oldAnnotationID = annotationID;
            onAnnotationChange && onAnnotationChange.call();
        }

        hashTime = getHashVariable('t');

        if (hashTime !== oldHashTime) {
            oldHashTime = hashTime;
            onHashTimeChange && onHashTimeChange.call();
        }

    }

    
    $(window).on('hashchange', routeHasChanged);

    
    $(window).on('popstate', function(event) {
         
        /* 
        * when accessed from the overview panel, 
        * event.originalEvent.state.editMode
        * contains the previous editMode state
        */

        var hypervideoID = getQueryVariable('hypervideo');

        if ( hypervideoID ) {
                        
            if ( FrameTrail.getState('editMode') ) {
                FrameTrail.changeState('editMode', false);
                FrameTrail.module('HypervideoModel').updateHypervideo(hypervideoID, true);
            } else {
                FrameTrail.module('HypervideoModel').updateHypervideo(hypervideoID);
            }

            
        }
        

     });


    routeHasChanged();



    
       return {


           /**
         * The projectID, as parsed from the query part of the URL.
         * @attribute projectID
         * @type String
         * @readOnly
         */
        get projectID()    {  return projectID    },


        /**
         * The hypervideoID, as parsed from the query part of the URL.
         * @attribute hypervideoID
         * @type String
         * @readOnly
         */
        get hypervideoID() {  return hypervideoID },

        /**
         * Manually set the hypervideo id.
         *
         * @attribute id
         * @type String
         */
        set hypervideoID(id) { return setHypervideoID(id) },

        /**
         * NOT USED YET
          *
         * @attribute annotationID
         * @type String
         */
        get annotationID()   { return annotationID                       },
        set annotationID(id) { return setHashVariable('annotations', id) },

        /**
         * NOT USED YET
         *
         * Will be called, when the hash fragment's annotationID changes.
         *
         * @attribute onAnnotationChange
         * @type Function
         */
        set onAnnotationChange(handler) { return onAnnotationChange = handler },

        /**
          * I get or set the hashTime (#t=) fragment
         * @attribute hashTime
         * @type String
         */
        get hashTime()        { return hashTime                       },
        set hashTime(seconds) { return setHashVariable('t', seconds)  },

        /**
          * I get the object containing various info about the execution environment
         * @type Object
         */
        get environment()        { return checkEnvironment() },

        /**
         * Will be called, when the hashTime (#t=) fragment changes.
         *
         * @attribute onHashTimeChange
         * @type Function
         */
        set onHashTimeChange(handler) { return onHashTimeChange = handler },


           getResourceURL: getResourceURL


       };

});