/**
 * @prototype QueryParams
 * This prototype contains methods to manipulate the query parameters of the
 * web pages url
 */
function QueryParams ()  {}

/**
 * get an object value with all parameters in the query params
 * @return {Object} query    object containing key/values
 */
QueryParams.prototype.getQuery = function () {
    var search = window.location.search.substring(1); // skip the ? character
    var params = search.split('&');
    var query = {};
    for (var i = 0, iMax = params.length; i < iMax; i++) {
        var keyvalue = params[i].split('=');
        if (keyvalue.length == 2) {
            var key = decodeURIComponent(keyvalue[0]);
            var value = decodeURIComponent(keyvalue[1]);
            query[key] = value;
        }
    }
    return query;
};

/**
 * Set query parameters parameters
 * @param {Object} query    object with strings
 */
QueryParams.prototype.setQuery = function (query) {
    var search = '';

    for (var key in query) {
        if (query.hasOwnProperty(key)) {
            var value = query[key];
            if (value != undefined) {
                if (search.length) {
                    search += '&';
                }
                search += encodeURIComponent(key);
                search += '=';
                search += encodeURIComponent(query[key]);
            }
        }
    }

    window.location.search = (search.length ? ('#' + search) : '');
};


/**
 * Retrieve a parameter value from the query params
 * @param {String} key
 * @return {String} value   undefined when the value is not found
 */
QueryParams.prototype.getValue = function (key) {
    var query = this.getQuery();
    return query[key];
};

/**
 * Set an query parameter
 * @param {String} key
 * @param {String} value
 */
QueryParams.prototype.setValue = function (key, value) {
    var query = this.getQuery();
    query[key] = value;
    this.setQuery(query);
};