var App_Alias = new function()
{
    var _options = {};
    var _alias = null;
    var _source = null;

    var _buildAlias = function (value) {
        if (!value || value == '') {
            return ''
        }
        return value.replace(/^\s+/, '').replace(/\s+$/, '').replace(/&+/, '-and-')
              .replace(/[^\sA-Za-z0-9_\.-]/g, '').replace(/\s+/g, '-').replace(/-{2,}/g, '');
    }

    var _onSourceBlur = function () {
        if (_source.value != '' && (_alias.value == '' || _alias.isFromSource)) {
            _alias.isFromSource = true;
            _alias.value = _buildAlias(_source.value);
        }
    }

    var _onAliasBlur = function () {
        var alias = _buildAlias(_source.value);
        if (alias == _alias.value) {
            _alias.isFromSource = true;
        } else {
            _alias.isFromSource = false;
        }
    }

    var _addEvent = function (obj, type, func) {
        if ('object' != typeof obj && !(obj = document.getElementById(obj))) {
            return;
        }
        if (obj.addEventListener) {
            obj.addEventListener(type, func, false);
        } else if (obj.attachEvent) {
            var f = function(e) {func.call(obj, e);}
            obj.attachEvent('on' + type, f);
        }
    }

    var _init = function (o) {
        if (!o || !o.alias || !o.source) {
            throw 'App_Alias: "alias" and "source" must be defined in App_Alias.init()';
        }
        _options = o;
        _source = document.getElementById(_options.source);
        _alias = document.getElementById(_options.alias);
        if (!_alias || !_source) {
            return false;
            // throw 'App_Alias: Can not find element with id "'+_options.alias+'" or "'+_options.source+'"';
        }
        _addEvent(_source, 'blur', _onSourceBlur);
        _addEvent(_alias, 'blur', _onAliasBlur);
    }

    function _construct() {
        this.init = _init;
    }
    return new _construct();
}